Oral-History:David W. Allan

About David Allan

David W. Allan.jpg

David Wayne Allan was born in Mapleton, UT in 1936 and was raised on a farm. At age 14 he became a white-water guide and was the first to run the Hell’s Half Mile rapid in Ladore Canyon on the Green River in a kayak. He married his Sweetheart, Edna Love Ramsay, in the Salt Lake Temple. They have had 60 wonderful years together – celebrating their 60th anniversary on February 20, 2019. They feel greatly blessed to have a wonderful family and friends. David obtained a BS in Physics from Brigham Young University and an MS in physics from the University of Colorado. He worked for 32 years at NBS/NIST in Boulder, CO, and after retiring he set up his consulting company, Time Interval Metrology Enterprise (TIME).

David’s 1965 master’s thesis gave birth to the Allan variance. In collaboration with colleagues at NBS, he later developed the Modified Allan variance and the Time variance, all three of which became international standards. In 1968 he wrote the time-scale algorithm AT-1 for optimally combining atomic-clock readings to generate official time for the USA. In addition to his work on software and measurement statistics, David has made many contributions to measurement hardware and instrumentation, including the development of the dual-mixer time difference technique, receiver technology for GPS common-view timing, and a special “SmartClock” GPS receiver to remove the civil signal degradation applied to GPS signals and greatly improve timing precision for the telecom industry. He also assisted with the APOLLO, GPS, and NASA/JPL Deep Space Network programs, as well as precision timing measurements for millisecond pulsars.

Dave has received many awards, including the I. I. Rabi Award from the IEEE International Frequency Control Symposium (a year after Rabi, the original recipient), the Time Lord Award from the International Timing & Sync Forum in 2011, an Achievement Award in 2016 from the IEEE UFFC, and the IEEE Keithley Award in 2018. He is a Fellow in the Institute of Navigation and an IEEE Life Senior Member. He was a member of URSI and served on the International Radio Consultative Committee, where Richard L. Sydnor and he were editors of an International Telecommunication Union HANDBOOK: Selection and Use of Precise Frequency and Time Systems, which he did in 1997 after his retirement. He remains a member of the International Astronomical Union. He also served as a US representative for the Consultative Committee for the Definition of the Second for many years. In 2018, the IEEE UFFC celebrated the 50th anniversary of the Allan variance with a Special Issue of the Transactions of the UFFC with several authors contributing. Dave has also contributed a lifetime of service to the Church of Jesus Christ of Latter-day Saints. In addition to serving two full-time missions, he served as Bishop of the newly formed Boulder Second Ward for six years, as Stake President of the Boulder Stake for ten years, and in the Denver Mission Presidency for three years. After moving back to Utah, he taught institute for the Moroni Stake for 11 years, and he continues to give firesides and talks about his research as well as write blog articles.

About the Interview

David Allan: An Interview conducted by Elizabeth Donley in Fountain Green, Utah on November 6, 2018.

Interview #825 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

Copyright Statement

Copyright Statement

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Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, IEEE History Center at Stevens Institute of Technology, Castle Point on Hudson, Hoboken, NJ 07030 USA or ieee-history@ieee.org. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.

It is recommended that this oral history be cited as follows:

David Allan, an oral history conducted in 2018 by Elizabeth Donley, IEEE History Center, Hoboken, NJ, USA.

Interview

INTERVIEWEE: David W. Allan

INTERVIEWER: Elizabeth A. Donley

DATE: 6 November 2018

PLACE: Fountain Green, UT

Donley:

My name is Elizabeth Donley and I'm here with David Allan in his home in Fountain Green, Utah. David is one of the fathers of modern frequency control and I’m here to do an Oral History of his career and life for the IEEE. And I’m sponsored for this trip by the Ultrasonics, Ferroelectrics, and Frequency Control Society. I’m very happy to be here. Thank you.

Allan:

Great to have you.

Donley:

So, I’m going to ask a series of questions about your life and discuss different topics. I'd like to start with your early life. Can you tell me where and when you were born?

Allan:

25th of September, 1936 Mapleton. A little town below the mountains, in Utah County. Not far from Provo. Little farming community. I was born at home. Humble circumstances. My folks had bought what used to be the old schoolhouse in south Mapleton and fixed it up for their family and I was the third child. Older brother and sister. I have a younger sister. And the community is a wonderful place to be raised -- a farming community. Everyone worked hard to make a living. Most of the folks there were members of the Church of Jesus Christ of Latter-day Day Saints. We had a couple of Catholic families, the Bleggies and Carneseccas. For me, everybody was the same. Loved everybody and it was just a great community.

Donley:

So, your parents were farmers as well?

Allan:

Yes, Dad did a variety of things. He had his own truck and hauled logs and lumber and did construction, but we had a 120-acre farm, and I milked cows for many years; so, I was raised working hard.

Donley:

Mm-hmm, and what did you do for fun as a child growing up?

Allan:

I didn't have young folks my age living close by, but I had cousins ... I spent a lot of my time alone. I really learned to enjoy myself. (laughs)

Donley:

Yeah.

Allan:

Taking things apart and putting them back together, and I loved to make things. I'd ride my bike across town and visit friends and I loved to ski, loved to be outdoors. Loved to go out and hunt and fish with family. But we worked hard. We spent a lot of time farming, but my childhood was really great. I feel very blessed to have been raised in such a loving, caring community.

Donley:

And so, what were your favorite topics in school as a child? Were you already interested in technical subjects?

Allan:

High school yearbook photo

Not really, until I went to Springville Junior High and High School. That’s where I graduated and then went on to BYU from there. But I was very interested in the sciences. I had, a physics and chemistry teacher, Omar Hanson, in High School who was awesome. He really got me excited about understanding nature and physics and that was really a blessing in my life to have outstanding teachers, both for math and other subjects, geometry, et cetera. They all seemed to really click for me.

Donley:

Uh-huh.

Allan:

So, I really enjoyed the sciences as I was going to school in Springville.

Donley:

So, it was obvious to you that you were going to go to college and study physics?

Allan:

Yeah. I was taking classes directly, so I could get a scholarship at BYU and they had an aptitude test, physics test, that I took I think it was in my senior year; I got 99 plus percentile. (laughs)

Donley:

Mm-hmm.

Allan:

It just seemed to fit for me. So, I really enjoyed learning about how the world works.

Donley:

Did you have to work to earn money to go to school?

Allan:

Dad, and my brother a little bit, but mainly my Dad and I ... we'd run the farm, but then we also helped Bus Hatch River Expeditions in Vernal, Utah. My brother, Dean, was in the Air Force for four years in the Korean War during that time on a B-29 crew. I was a white-water guide for several years and earned money to pay for my tuition by guiding people down the Green, the Yampa and we ran the Colorado, the Middle-Fork of the Salmon, the Salmon, and the Snake rivers. Dad and I took a group down the headwaters of the Columbia River one time; it was an incredible and unique experience. Can you imagine a turbulent river 100 feet wide and 300 feet deep?

So yeah. Got to meet lots of neat folks. Hatch River Expeditions would take Sierra Club Groups down the Yampa and Green Rivers … five different groups over five weeks of Sierra club folks mostly from California each summer. My dad tied in with the Appalachian Club. We met lots of really fun people and had some great experiences river running.

Donley:

And did you go off by yourself and challenge yourself a little bit more than when you were taking out clients?

Allan:

(Laughs) Always. The boatmen always had to play around with the little one-man rafts and climb the canyon walls. The Sierra Club had one of their cooks, Roger Paris, had won the Arkansas River Race, kayak race, three years running. He was part of the Sierra Club staff, and he taught me how to Eskimo roll. I didn't have my own kayak, but I'd borrow others and when the Sierra club would come down the Lodore Canyon on the Green River, some of them would bring their kayaks, and then they'd come to Disaster Falls, Triplet Falls, and Hell's Half Mile. And when they'd come to Disaster Falls, they would say, "We're not going to run this!" (laughs)

Donley:

Mm-hmm (affirmative).

Allan:

And, uh, Roger would say, "Dave, jump in." (laughs). So, he would get in one kayak and I would get in another and we'd run their kayaks through for them.

Donley:

Oh. So, you wouldn't have to carry them around?

Allan:

Otherwise, someone would have to carry them and that was a nuisance. So, I'd just follow him down these rapids.

Donley:

Oh, wow. Did it ever scare you?

Allan:

The river -- I had great respect for it. But I knew how to read the current and to look out for rocks and to navigate and how to maneuver down, so you'd usually go on and study a rapid, if it was a dangerous one, so you knew where to go and what to do to get through safely.

I knew these rapids well. I'd run them several times, so I knew where the bad rocks and the big holes were.

Donley:

Mm-hmm (affirmative).

Allan:

So, I could make it safely through. We had a lot of fun. I'd watch Roger disappear in a wave and then dive in right behind him. (laughs)

Donley:

Was it a lifetime sport for you, then? Did you keep doing it after you worked for Hatch Expeditions?

Allan:

Yeah, I worked for Hatch's even after we were married. The year after we were married, Hatch’s hired me and my brother to be the guides for the University of Utah Survey Team before the Flaming Gorge Dam went in on the Green River.

Donley:

Oh, wow.

Allan:

So, we spent 35 days going from Green River, Wyoming, down to the dam site. My brother and I would find campgrounds and bring supplies, and while they were going out studying all of the flora and fauna and the fish and everything that would be covered by the water, so they could do a mapping of the whole thing over those 35 days, and my brother and I had a great time.

Donley:

Oh, that's quite an experience.

Allan:

It was- it was great.

Donley:

So, you worked as a river guide to save money for college and I know you also went on a mission at some point. Where did that fit in, before or after you went to the University?

Allan:

I did two years at BYU and then went on a two-year mission in the eastern states and then came back and finished in 1960 at BYU with my physics degree.

Donley:

Okay.

Allan:

Yeah, the mission was an extremely important part of my life. That was from '56-'58, and I was just turning 20 when I went on the mission. And basically, two things happened. I fell in love with the scriptures and the author of them. I just really enjoyed studying and sharing with others and met some great people. I served about a year in Wilmington, Delaware. There were lots of PhD folks from DuPont and a variety of folks there and then I spent a part of a year in Philadelphia with a big variety of folks there as well. And toward the end of the mission I traveled for the mission president in upstate New York.

But, as the Lord would orchestrate it, I met my wife to be – this beautiful lady from Snowflake, Arizona, came out to New York to participate in the Hill Cumorah Pageant. (laughs).

Donley:

Mm-hmm (affirmative).

Allan:

We were both participants in the Pageant which is up near Rochester, near the little town of Palmyra and she had come out to New York with three busloads of participants from Utah. And I was one of the missionaries there and the combined 300 people would put on this pageant on the Hill Cumorah, which is where Joseph Smith was given the plates, the gold plates that the Angel Moroni had given him to translate into the Book of Mormon, which is where we get our nickname. The pageant is a portrayal of how that happened and the visit of the Savior here in ancient America. People come from all over to see this pageant. It was really fun to be part of it and we were in the same study group together, so we got to meet at that point and I was impressed with her. When I came home, two months later, we started dating and then we got married, five months later in the Salt Lake Temple.

Donley:

Wow, it all went pretty quickly.

Allan:

It did, yeah. It was a very important time of my life.

Donley:

Mm-hmm (affirmative), and so then you came back to BYU and finished your degree?

Allan:

We got married in February of '59 and then I finished in May in '60. That's when I had an opportunity to continue with graduate work at BYU with Dean Barnett and Tracy Hall, who had invented the tetrahedral press for synthetic diamond research and it would've been a fun project, but I felt to visit with the folks who came over from NBS.

At that time, physicists could get jobs anywhere and really good pay. Both east and west coast. I wanted to stay in the mountains.

Donley:

Mm-hmm (affirmative).

Allan:

Loved- loved the mountains, and so I interviewed with the NBS rep, and I learned that they would pay my tuition at the University of Colorado for graduate work if I worked full time. So, that sounded like a good direction to go.

Donley:

So, they came out here on a recruiting trip?

Allan:

Uh-huh.

Donley:

Okay.

Allan:

Yeah. I had two offers. One at CRPL with the atmospheric folks and one with the Frequency Standards Section, and you can see the wise choice I made!

Donley:

Mm-hmm (affirmative).

Allan:

The Frequency Standard Section was what it was called then. Richard Mockler was the Section Chief, and Jim Barnes was my project leader. It was an incredible blessing in my life to have Jim be my mentor. Yardley Beers was the Division Chief.

Donley:

So, when did you start having children? Before you went to Colorado?

Allan:

Shelli was born December 18th, '59, so, half a year before I graduated. So, we had a half year old daughter when we went to Boulder, and we had never been to Boulder before. Allen Newell and I had studied physics together at BYU, and he accepted a job at NBS as well. We stayed with them until we found a basement apartment to rent at 990 Arapahoe, where we lived until we could buy a home on 830 36thth Street. I could ride my bike to work from there. That’s close to where you live!

Donley:

Wow Indeed! One block away from where we live.

Allan:

Yeah, but one experience that I had that might be fun to share before moving on in terms of my river guide experiences, if you like-

Donley:

Yes, of course...

Allan:

Dave and Ray Simpson after running the Hell’s Half Mile rapid in a 2-person kayak.

There was one rapid in Lodore Canyon on the Green River in the Dinosaur National Monument that had never been run in a kayak or a canoe. We would run it in the big riverboats, and we'd make the passengers walk around because it was too dangerous to take them through. And the boatmen would take turns running their big pontoons or their ten-man rafts through.

It was a very difficult rapid and I would look at it each time we would run through. Roger Paris had taught me how to run a kayak. And so I felt like this would be fun ... because nobody had done it. A first descent (laughs) so I'd look at it each week when we would go down and figured out a way to do it. Ray Simpson, who was a cook on the Sierra Club had a two-man kayak. He says, “You know, if you want to do it we can do it in mine with the two of us to run it.” It was really a momentum study problem as well as having strength and stroke to move quickly when needed. There's a huge hole that would just consume a kayak that you had to miss and going down the current, you just couldn't miss it because everything kind of converged as the water fell in this huge hole behind some big rocks.

And so instead of trying to go down and miss that, I went to the other side of the river and then did a momentum transfer across the current as rapidly as we could so that our momentum would carry us around this big hole, and we succeeded. It was fun. Unfortunately, the spray cover for the center section of the kayak caved in while we were running the upper part of the rapid just before we went around the big hole, and following the big hole we swamped the kayak. The poor thing got beat up by the rocks as we were running the rest of the rapid. Ray and I had run the rapid the week before putting in just below the big hole that made the rapid so difficult; the rest of the rapid was a piece of cake! The Sierra Club gave us hero badges that night at the campfire made from tin can lids!


Donley:

So, wow. So that's a famous rapid, then?

Allan:

Hell's Half Mile.

Donley:

Wow.

Allan:

Yeah.

Donley:

I think I've heard of that before. It's still a test piece for people today, I suppose. (laughs)

Allan:

Well, things have changed because of the dam.

Donley:

Oh.

Allan:

You don't have high water anymore.

Donley:

Uh-huh.

Allan:

Because of the Flaming Gorge Dam.

Donley:

Okay.

Allan:

So, it's different than it used to be. In the springtime, you get these high, high waters and it would be pretty awesome.

Donley:

(Laughs) So you did that before you left.

Allan:

On the mission.

Donley:

Mm-hmm (affirmative). Okay.

Allan:

So my wife didn't have to worry, 'cause we weren't married then. (laughs)

Donley:

(laughs) Did she worry about it after she knew what you were doing?

Allan:

She loved to go on river trips. When we got to Boulder, we spoiled everybody because we taught them how to get boats and run rivers and we would take big groups down different river trips. What we could do back then, easily, now you can't because of permits.

Donley:

Did you take people from NBS or mostly from your church?

Allan:

Some of the folks at NBS that worked there became river nuts as we are (laughs).

Donley:

(Laughs).

Allan:

Yeah. We converted a lot of folks.

Donley:

That's good.

Donley:

Okay, so let's talk about your time in graduate school. So, you went to the University of Colorado and you did your research at NBS, so you were working during the early days of Atomic Clocks. So, could you tell us about what you started working on when you went there?

Allan:

Yes, Jim had me working on an N-14 ammonia maser. Lyons and his crew at NBS in Washington, D.C., were the first ones to build an atomic clock based on a 23-gigahertz transition in ammonia and so, because the ammonia maser was an active device ... you actually got a signal out, and it had very good short-term stability. So, you had this special microwave cavity to interrogate the ammonia resonance, and so the short-term stability in the maser was always of interest to people. But there were a lot of systematic problems with it. So anyway, I started out studying ammonia masers.

Donley:

Mm-hmm (affirmative).

Allan:

And Hughes had a contract with the government to build two N-15, it's an isotope, ammonia masers for relativity research. They wanted to try and see if they could prove Einstein's theories.

And anyway, they built these two units and those experiments didn't pan out, so they became available, and so I went down to Malibu and got these two masers from Hughes, and we started doing N-15 work, and that was fun because you had an improvement of almost in the order of magnitude in short term stability with the N-15 masers.

And it was fun because Boulder had the study of the sun. So, we knew about sun activity, the solar winds, and this big magnetic storm was expected to come through, and so the magnetic field of the earth would be changing dramatically.

Donley:

Mm-hmm (affirmative).

Allan:

And so I stayed over the night with that N-15 maser because it had some magnetic field dependence and very good short-term stability. I watched the correlation of the magnetic storm affect the maser frequency.

Donley:

Oh, wow.

Allan:

Because of the excellent short-term stability, so it was a fun experiment.

Donley:

Uh-huh. So how long did you work on the ammonia masers, then?

Allan:

Uh, for probably basically until we started building up a time scale -- Jim and me. We started out with three quartz crystal oscillators and NBS- 2. NBS-1 had been brought from Washington, but it had a horrible vacuum chamber.

Donley:

And that was another ammonia maser, NBS-1?

Allan:

NBS-1 was the first cesium.

Donley:

Oh, it was the first cesium.

Allan:

Yeah, so Lyons gets credit for the first cesium frequency standard at NBS, in the early '50s. He did the ammonia maser in '48, '49, which was the first atomic clock that could keep time. NBS-1 was never used as a clock. The first cesium-beam atomic clock was started in June 1955 by Essen and Parry at NPL in England. Most people don’t realize a clock is a two-part device composed of an oscillator and then a counter to add up those oscillations. Lyons only did the first part by determining the frequency of oscillation of the cesium hyperfine-transition, which gives us our definition of the second, 9 192 631 770 periods of that oscillation frequency.

Donley:

Mm-hmm (affirmative).

Allan:

In the early '50s, he built the first cesium frequency standard, NBS-1 back in Washington, and then NBS moved out to Boulder, I think in '54 if I recall.

Donley:

Mm-hmm (affirmative).

Allan:

We did some experiments using thallium with the NBS-1 vacuum chamber, and Jacques Bonanomi at the Observatory in Neuchatel was researching that, and we decided to look a little bit at it, but the work function was horrible and high temperatures were needed, so that never panned out.

But then we had the time scale across the hall and NBS-2 was next door to calibrate the three clocks as we started keeping a timescale in 1963. I came to NBS in '60 and Lowell Fey and Jim had built a quartz crystal portable clock, because time was kept by the Bureau at WWV, basically. It was our time distribution system in Beltsville, Maryland.

Donley:

Mm-hmm (affirmative).

Allan:

And so Jim and Lowell Fey took this quartz clock back there and transferred time from WWV in Beltsville to the ensemble of quartz oscillators calibrated in rate by NBS-2 in 1963.

Donley:

Did you work directly on NBS-2 also? Or did you also focus on the timescale?

Allan:

Oh, no. Roger Beehler was in charge of that and Chuck Snider. I remember Roger sweeping the Ramsey resonance to ascertain the frequency of the quartz oscillators that were being calibrated and it was manual data. No servos.

Donley:

Wow. So how did you all characterize the clocks in those early days before you developed the Allan Variance?

Allan:

Beat frequency techniques.

Donley:

Okay, so what statistics did you use?

Allan:

You had a quartz oscillator that you would use to sweep the resonance and so you'd say okay the frequency from cesium of this quartz oscillator calibrated with the Ramsey transition was such and so, and so you'd use that to measure the frequency of the quartz oscillators across the hall. We had the three of them and Jim developed this program that's basically part of his thesis that gave you an algorithm for computing time from the ensemble that would mirror the frequency of NBS-2, which Roger would determine for us.

Donley:

Mm-hmm (affirmative).

Allan:

And the time having been determined by the transfer of time from WWV in Beltsville to Boulder.

Donley:

So, was that kind of the early days of the development of the time scale?

Allan:

Exactly. Those three quartz oscillators were our time scale. Before atomic clocks, all the timing centers were using quartz-crystal oscillators to keep time.

Donley:

Mm-hmm (affirmative).

Allan:

Then later on, as mainly Hewlett Packard started making commercial cesium clocks, we then acquired those. When I did the AT-1 algorithm in '68, I think we had eight commercial cesium atomic clocks. So we had taken advantage of the commercialization of the cesium concept mainly thanks to Hewlett Packard.

Donley:

So, when did you start to focus on characterizing their stability and the statistical measures?

Allan:

The big question back then was with quartz oscillators, which were our timekeepers because they were like the flywheels to remember the frequency of the primary standard. So they were the memory bank.

And the problem with quartz was the frequency would drift and if you removed the drift, you were left with flicker noise frequency modulation (FM). And a lot of people studied it ... Atkinson and Fey wrote a paper about it. The Germans had studied it. Everybody knew that the long-term stability of quartz, after you remove the drift, was limited by 1/f frequency modulation, flicker noise.

And so, that was, from a statistical point of view, a serious problem because if the mathematician took the integral of 1/f to calculate the classical variance, it blew up at both limits: at zero and at infinity; however, the upper limit was never a problem because that was limited by the measurement bandwidth. But the lower limit was a big problem, and Atkinson and Fey actually tried to see if they could find the lower limit. (laughs) 'Cause they knew the integral would go to infinity and so the classical variance for flicker noise blew up. It was not a good statistic, and everybody knew that.

See "Technical Background on the Fundamental Noise Problem" for more detailed technical explanation.

Donley:

Mm-hmm (affirmative).

Allan:

And so it was statistically a problem for people to know how we should characterize flicker-noise. They were doing spectral densities showing evidence of flicker-noise, but then arose this mathematical-statistical-convergence problem. We were using the beat frequency technique to make measurements, and then trying to analyze the performance and stability of these quartz crystal oscillators. It was a big problem knowing that the classical variance was not a good statistic.

And so, that's when the IEEE and NASA combined their efforts in 1964 and they had a short-term stability symposium back at NASA Goddard. And Jim and I went there and presented a paper. Jim had prepared this special autocorrelation function that would work for flicker noise and he had also shown that if you took the second difference of the phase and did a variance using the second difference using this autocorrelation function that he had developed that you'd get a convergent measure for flicker noise. So that was a big step.

Donley:

Mm-hmm (affirmative).

Allan:

And I, of course, was just helping Jim with his work. And we wrote the paper together and he presented that at this conference back in Beltsville, and it was very well received. So that was kind of the first building block -- Jim's breakthrough on that autocorrelation function and how to use the second difference of phase as a measure of stability.

So, both second and third difference metrics were part of his thesis and his timescale algorithm is based on second and third difference of phase variations of clocks. So that was his main thrust. At the same time, my thesis was asking the question -- how does the classical variance change with the measurement parameters we had to deal with. I can explain in more detail if you wish on this whiteboard.

Donley:

Sure.

Allan:

Okay, so let's suppose we have x(t) being the time deviations between two clocks. So, you have an x(t) variation and this plot is probably not far different from what flicker noise would actually look like in terms of the time deviations from a quartz clock or between two clocks.

Back at that time, the best way to measure frequency was using what's called the heterodyne technique or the beat frequency technique. So you'd have frequency one and frequency two going into a Schottky-barrier-diode mixer and then coming through a low pass filter to get the difference frequency, the beat frequency. And this gave you huge leverage. The clocks were so good that that beat frequency would give you a huge factor -- like a factor of a million or ten million -- ability to measure the instability of these clocks.

So, this beat frequency would come into a frequency counter and you would run the counter, and you would sample so many cycles of the beat frequency for some sample time tau and then the counter would lock that value and print it out, and then you would have to wait a cycle to start the next measurement. So you had dead time between this measurement and the next measurement and you can show that has serious consequences in metrology. So, then you take the next set of zero crossings to measure the beat frequency in the next tau interval, and so the measurement, period, was capital T from the beginning of this one to the beginning of the next one. And so you had dead time equaled to T minus tau between each one of these measurements.

Donley:

Mm- hmm (affirmative).

Allan:

So, you'd be losing data, and it turns out we were able to show later that has serious consequences to the statistics.

Donley:

Uh-huh.

Allan:

So anyway, this is how we took the data. So you have a set of measurements going out to say N data points for some data run that you had measured the quartz oscillators against NBS-2's quartz oscillator which was tied to the Ramsey resonance for the frequency determination.

And so basically my thesis asked the question -- what happens to the classical variance as a function of the number of samples, N, as a function of T, the data period, tau the sampling interval, and the measurement bandwidth. And you can write that equation in general terms as a function x(t), as may be written for the classical variance for N samples, as thus shown here.

Donley:

And x is the phase?

Allan:

Yeah, x is actually the time error of the clock. You can write it x(t), as the phase divided by two pi nu zero.

Donley:

Okay.

Allan:

So, if you look at the phase relationship, these are just tied together with a constant.

Donley:

Mm-hmm (affirmative).

Allan:

So, this is the time error and you can also write the integral; x(t) is equal to the integral from zero to t of y(t') dt', so x is the integral of the frequency variations.

Donley:

Mm-hmm (affirmative).

Allan:

These are fractions, where y is the ratio of the actual frequency coming out minus the nominal frequency, nu zero, all divided by nu zero, so it's a fractional frequency. So, when the frequency is right on, y is zero, and the deviations are measured in y as the frequency varies with time. So, anyway, what I was able to show thanks to Jim's help and Lighthill's book, that if we set N constant and the ratio of T over tau constant, which we call r. if we set those constant then we get a dependence of the classical variance going as tau to the mu, and if we have a spectral density Sy going as f to the alpha, from Lighthill's page 43, we were able to do the transform relationship for general noise processes showing that alpha is equal to minus mu minus one.

So, it's a very elegant, what we call, super-fast Fourier transform, as you analyze the time domain data. And the thing that dropped out of my thesis which shows the elegance of the two sample variances, that if N equals two and T equals tau then you get the two-sample variance with no dead time. It was some years later that we developed the techniques using the dual mixer time difference and Jim's chronograph, how to do this elegantly so we got rid of the dead time and the finesse of measuring frequency stability improved dramatically as a result.

Donley:

Mm-hmm (affirmative). The elegance (laughs).

Allan:

But we had the one nagging problem with the two-sample variance that there is an ambiguity in whether you have white-noise phase modulation (PM) or flicker-noise PM, which was a problem we were able to solve 16 years later with the Modified Allan variance. So, it's really interesting that today with optical clocks, where you have this huge finesse, at 10 to the minus 18 kinds of frequency stabilities, that these same concepts are still extremely useful.

Donley:

Mm-hmm (affirmative).

Allan:

In measuring the phase relationships at optical frequencies.

Donley:

Mm-hmm (affirmative). Yep.

Allan:

Thanks to the laser combs, etc.

See "The Development of MVAR and TVAR" for more detailed technical explanation.

Donley:

And so ... what year did you finish your master's thesis then?

Allan:

Uh, Jim and I both did our theses in 1965. And Jim's was his Ph.D. thesis and was used to construct the time scale with three quartz clocks and NBS-3, and then we started acquiring some of the cesium clocks and I got involved with the ensemble work as we started getting cesium clocks. And how to measure those and compare them... So, in 1965, the same year as we were doing our theses, that fall we had an extremely important clock comparison activity in Boulder.

Donley:

Wow. Please tell us the details about the 1965 clock comparison.

Allan:

Len Cutler and Lee Bodily had brought their best commercial cesium 5060-A from Hewlett Packard to Boulder. Roger Beehler had NBS-3 operating by that time. And Bob Vessot had brought his best hydrogen maser from the Smithsonian and Harry Peters had brought his best hydrogen maser from NASA Goddard. And so, we had this shootout comparison.

I was responsible for the measurement system and data analysis and we used a frequency stability program that I had developed. The program gave both the N dependence and the tau dependence, and it became apparent with all involved the value of the two-sample variance. This was the launch pad for comparing clocks showing sigma-tau diagrams with N = 2 and showing the difference in stability of all these different kinds of standards -- the best in the world. A twelve-authored paper came out of that.

It helped me significantly as I was looking at the clocks and designing algorithms for AT1 to look at the white noise, the flicker noise, and then optimally combine those so that the long-term and short-term stability could be optimized using a sigma-tau diagram for each clock, which you could get from what we called “a three-cornered hat” comparison of three independent clocks, since you can never compare a clock against a perfect standard.

Donley:

Did you guys already know at that time the limitations and advantages of the different types of clocks, or did you learn that through this study?

Allan:

We didn't know. We learned as we saw the characteristics of the clocks became more and more apparent. On a single sigma-tau diagram you could see the white-noise FM (frequency modulation) and the flicker noise FM. Then typically over the years we observed random-walk FM for the long-term stability often caused by environmental perturbations on a clock. That's why Len Cutler's clock is so valuable because he was able to remove a lot of those systematics and environmental perturbation effects. For us, the time scale environmental chamber Howard Machlan built for our atomic clocks gave us environmental immunity and much better long-term stability.

So, one cannot see that unless you have long-term data to see what's going on, and a sigma-tau diagram can tell you most of the story.

Donley:

Yeah, comparing different clocks to each other.

Allan:

The goal is to remove temperature effects and other environmental perturbations. So, you always want to look at what causes a perturbation and then remove it as best you can.

Donley:

Mm-hmm (affirmative)

Allan:

We studied which clocks were the best and how things performed. And I was pretty much responsible for the measurement system and comparing the clocks and analyzing the data. And we had a program that I developed showing sigma as a function of the number, N, of samples, and as a function of tau. The IBM computer would print out the dependence of the stability as a function of N and a function of tau, so it was a matrix.

Donley:

Mm-hmm (affirmative).

Allan:

A twelve-authored paper resulted: https://tf.nist.gov/general/pdf/172.pdf, where you see log-log plots of sigma versus tau with N=2. The T/tau = r ratio was fixed, so the plot could tell us directly the kind of noise: White FM or flicker-noise FM, etc. And you could see the long-term drift of the hydrogen masers. The flicker-floor of the masers at that time was about ten to the minus 14. One chart shows a dramatic comparison of the commercial cesium, the NBS primary cesium standard, and the hydrogen masers.

Donley:

Wow, that was an exciting time to be working in frequency control.

Allan:

Yeah.

Donley:

So, you were just learning about the properties of these clocks.

Allan:

Yeah, we were using the tools that came from my thesis.

See "Perspectives on the Development of Commercial Cesium Beam Clocks" for more detailed technical explanation.

Donley:

Mm-hmm (affirmative).

Allan:

It became very evident to everybody present that the N = 2 approach was extremely useful, and that's when Don Halford named it after me and anyway, I call it the two-sample variance everyone else calls it the Allan variance.

Donley:

(laughs).

Allan:

The physics is two samples.

Donley:

Was Don also one of the coauthors on that paper that you guys were working on?

Allan:

Don Halford was the section chief.

Donley:

Oh, okay, so he was the section chief.

Allan:

Yeah, he had just named it. He had developed script L(f) for frequency domain measurements, and he saw the value of the two-sample variance. Because when we had that shoot out with all those different clocks, this matrix of N equal two and tau dependence became the one that we plotted, and so we could see how things changed, the white noise, the flicker noise, the drift and everything was there... You're able to see on the sigma tau plot and the behavior of the clocks.

Allan:

That twelve-author paper has a whole bunch of two sample variance plots in it to show the characteristics of the different clocks... the hydrogen masers, cesium, and commercial cesium and primary standard.

Donley:

That must have been really satisfying for you to work on that.

Allan:

Yeah, yeah. It was very satisfying.

Allan:

So, that was really the launchpad for the value of understanding that the classical variance wouldn't work but the two-sample variance was extremely useful to give us the full spectrum of colors of the characteristics of the clocks we were measuring.

Donley:

Well yeah, it was a crucial thing to be able to characterize the behavior on all time scales, right?

Allan:

Yeah.

Donley:

Did you ever think that the work you did as a graduate student would have such a lasting impact on frequency control?

Allan:

Didn't have a clue. No one at that time saw where it was going - we just knew it was a useful tool. I guess I should share that Dr. Mochler was on my thesis committee and one of the members of the committee said, after reviewing my work, “What will he do for an encore?”

Jim had become my section chief and then he later became division chief and the IEEE asked him to chair a committee to write a standard for characterizing clocks, and that was in 1971 when I believe they published that standard, so that kind of became the first, both for frequency domain and time domain. The two sample “Allan variance” was recommended as the best metric for time-domain measurements in that publication.

Donley:

Was that the same standard that has been revised multiple times and still exists today? Or is it a different one?

Allan:

I was asked to chair a committee for the IEEE later and in 1988 that standard came out.

Donley:

That's the 1139 standard?

Allan:

Yeah.

Donley:

Mm-hmm (affirmative).

Allan:

It came quite a bit later, and it has been updated since.

Donley:

Okay. So, one of the things that you worked on that you get a lot of credit for is the development of this dual mixer time difference technique. Can you say just a little bit more about that? How that came to be?

Allan:

Yeah you know, I guess I have to backtrack to a special experience that I had after I finished my mission. My religious experience was so deep and profound that when I came back I seriously considered changing my major in physics to teaching church education, institute, seminary and so forth. I had an excellent physics professor at BYU, Richard Hales, and I went to his home one evening and said, "I need some counsel." (laughs).

And he gave me some of the best counsel that I have ever received. I mean, it has stayed with me through my whole life, and that summer he said, "Your career path is not nearly as important as going forth to serve, to really try and help the world, to use your time and talents to best help the world be a better place." And, you know, he said, "Don't worry about money. The Lord will take care if you'll focus on service and helping the world progress." And so, given that counsel I stayed in physics because I love physics and had the feeling that I'd be able to still do my religious pursuits in parallel while I was doing physics.

And, so that counsel has really had a major part in my career path and so when problems would arise ... I, you know, I'm a praying physicist (laughs). I believe in meditation and thinking things through and that we can get divine help. I feel like I had significant divine help with the thesis and I definitely believe that I had a really special experience in pulling that together, that I had help from the other side. http://allanstime.com/AllanVariance/inspiration.htm The Lord knew where it would go even though we didn't.

And, so I believe it was um ... '74, '75, um ... we had a seminar and one of the guys at the seminar came in my office and he said, "How do you measure the beat frequency between two cesiums?"

Donley:

Mm-hmm (affirmative).

Allan:

And I said, "Well, it's a very long beat frequency." (laughs). You don't. It's not very useful because a beat frequency of five megahertz can be a cycle per day (laughs).

Donley:

Mm-hmm (affirmative).

Allan:

I was just not useful. So, you use the heterodyne technique, you take your quartz oscillator and you beat it, or a synthesizer, some way to offset the frequency so you can have a useful beat frequency to measure.

Donley:

Mm-hmm (affirmative).

Allan:

And the idea came to me as I was sharing with him, I could take two cesiums and a very stable quartz oscillator and compare them simultaneously and so I'd have two beat frequencies and then I could take the difference, the time difference, between those phase points, those two zero crossings, and it ends up being a double heterodyne with no dead-time. So, it gives you an incredible leverage value, and anyway, I shared that idea with him, and thought that's fun, so I went down in the lab that afternoon and prototyped it.

I got some dual mixers, I got a couple of Schottky diode mixers and set it up and got some measurements and thought, wow, this is neat. And I learned later that Herman Daams up in NRC Canada had been doing some similar things with VLF, and so I asked him to join me in a paper and so we did this paper on dual mixer time difference concept. https://tf.nist.gov/general/pdf/78.pdf "Picosecond Time Difference Measurement System." I built a box made out of mu metal because of the interference of 60 Hertz and put batteries in it so I could get rid of all those instabilities of the environment and I was able to push the time error down to like 50 femtoseconds at 5 MHz. The fun thing is that the concept will work at any frequency, at optical frequencies for example as is needed with the newest atomic clocks today.

Donley:

Wow.

Allan:

So that was a major step and then it was commercialized, and Sam Stein picked it up and digitized it. It's just grown from there. So, Sam has built these sigma tau machines that have incredible precision...

Donley:

They are all over the place.

Allan:

Yeah. So anyway, the concept of being able to take a problem and think about it, pray, meditate, I feel like the Lord will help us.

Donley:

It's been fruitful for you (laughs).

Allan:

(Laughs).

Donley:

Okay. So, you were also very active in the early development of the GPS system. Do you want to tell us how that came about? And how long had others been working on it when you started picking it up?

Allan:

Yeah, the NavStar program, Roger Easton and NRL, they had been doing some preliminary research. Brad Parkinson and the Aerospace people and the Air Force people would come to our seminars to learn about clocks and I can remember early on, Helmut Hellwig, who was then Division Chief, as I recall. So, this would've been ... in the early '70s as well. He was aware of the GPS program and the need for atomic clocks on board. And as you look at GPS, for me, the heart of GPS is an atomic clock. It would not work without the synchronization needed at the nanosecond level across the satellite constellation.

Allan:

So, understanding atomic clocks, characterizing them, the noise properties, the systematics, doing time prediction was extremely important. And so, our seminar was the best place in the world for people to come and learn how to use these new atomic clocks that have been built by folks.

Donley:

So, you're talking about the NIST Time and Frequency Seminar that keeps going?

Allan:

It was NBS then, yes.

Donley:

Then it was NBS.

Allan:

Yes.

Donley:

So, it continues today but it goes back to those years.

Allan:

I actually organized some of the first ones. And I remember Brad Parkinson, who I consider to be the father of GPS, and his AF entourage were in one of my classes. I still remember one of Brad’s questions; a very well thought out one as you can imagine.

Donley:

And he was an officer in the Air Force? Is that right?

Allan:

He was a colonel.

Donley:

So, he was a colonel, but he was also-

Allan:

Had his PhD, very bright, wonderful man.

Donley:

So, an engineer? Or physicist?

Allan:

Brad was assigned to a Ph.D. program at Stanford University graduating in 1966, with a degree in Aeronautics and Astronautics the same year my thesis was published in the IEEE Proceedings.

Donley:

And also, a colonel in the Air Force. That's pretty impressive.

Allan:

Yeah. He is a very impressive individual; I feel honored to count him a friend.

Donley:

And now he's a professor at Stanford, if I remember.

Allan:

Yes. Emeritus, and just received a medal of honor from IEEE.

Donley:

Oh.

Allan:

For his GPS work.

Donley:

So that early work was in good hands then? (laughs).

Allan:

(Laughs).

Donley:

So how far along in the process did you become involved then?

Allan:

As soon as they started launching, they had three satellites up. And they had them in 12-hour orbit periods. Configured so that could be seen at Yuma, which was their test ground. As the satellites would pass over Yuma, and they had a very good clock on the ground, 'cause you need four ... clocks to get a solution, and anyway, that was their test bed and they organized what was called a DAWG committee. Data Analysis Working Group, and they asked me to be on that DAWG committee, so we would look at the data, we'd go down to Vandenberg every month and look at the data and the problems and solutions to fix things.

Donley:

That's a good acronym for it, 'cause it sounds like a lot of hard work (laughs).

Allan:

(Laughs).

Donley:

Did you have to use tape to do the measurements or print outs, or were you using computers by then?

Allan:

Well the data were coming down from the satellites and I was not involved with data logging.

Donley:

Okay.

Allan:

Only analysis of the results, mainly the concern with how the clocks were performing. The early first clocks were rubidium gas cell. Efratom made the physics package and as I recall, Rockwell packaged that into a space qualified system with electronics and put those three rubidium clocks on board each satellite, and early on that was a real problem because they were getting failures after like three months. They didn't know why, and it nearly killed the program.

Allan:

Had Congress not realized they could use GPS for nuclear detonation detection during the Cold War, GPS probably would've died.

Donley:

Wow.

Allan:

But anyway, they sent one of the rubidium clocks to us in Boulder and Aerospace started looking into the failures. Sam Stein, who was working for me at the time, built this beautiful environmental chamber to simulate the temperature and vacuum conditions of GPS orbits -- except for zero-g. :) And we found significant frequency deviations due to magnetic field and to temperature variations. So, we were able to fix a few things to improve the stability, but the Aerospace folks were the ones that found that the buffer gas in the cell was leaking out, and so they'd lose the buffer gas and it would stop oscillating.

Donley:

Mm-hmm (affirmative).

Allan:

So, they couldn't determine the resonance of the rubidium line. So that was fixed and then the rubidiums became more reliable and useful. Later on, they put cesiums on board. Helmut had become president of Frequency and Time Systems. Bob Kern's cesium had been manufactured by them and Helmut took over that company and they started manufacturing cesium clocks for GPS at that time.

Donley:

And so how did they determine the specs for the clocks? Or did they just write the specs based on what they thought they could do with the clocks?

Allan:

Then again, because we were the characterizers of clock performance, Helmut had suggested that they use the two sample Allan variance for it. And they set up a performance level metric based on a sigma tau diagram. So, you had a certain level of white noise, frequency modulation, and you had a certain level of flicker that the clocks had to meet to satisfy the time dispersion, because the satellite configuration had to remember and predict time forward to the next crossing.

Donley:

Mm-hmm (affirmative).

Allan:

So initially it was 12 hours and later as they put five tracking stations around the globe, it was three or four or five hours between, so that the clocks would have to remember time and predict time forward, and so the prediction algorithms had to account for the clock's systematic deviations as well as its noise properties. Helmut and I actually wrote a paper on time prediction techniques, dependent upon the systematics and noise properties of the clocks needed for GPS, which became quite useful for the GPS folks. https://tf.nist.gov/general/pdf/136.pdf 'Cause that was key to synchronizing the system as you'd upload the data, and then you'd have to remember until you had another upload.

Donley:

Uh-huh (affirmative).

Allan:

Another crossing of the tracking station.

Donley:

I'm sure they're still using those same techniques today, except for the clocks are probably linked a lot more thoroughly, so maybe they don't have to hold over for as long.

Allan:

Yeah, and there are more tracking stations.

Donley:

Uh-huh (affirmative).

Allan:

Yes. Still 12-hour period. The clocks have better stabilities and better performance.

Donley:

Mm-hmm (affirmative).

Allan:

And the goal is to basically have the system's GPS timing synchronized to about a nanosecond.

Donley:

And so, what ... I mean, perhaps it's obvious, but what are the special challenges for these clocks that have to go into space and work for years?

Allan:

(Laughs). Well you have GPS as a three-segment program. You have the user segment, and the control segment, then the space segment. And so, they have to work together. You have to take the data from the satellites, analyze them, and look and see what's going on. The control segment then basically uploads the data then you have these clocks in space, which are in a zero-g environment, basically. But they go into the shadow of the earth, and so the temperatures drop significantly as they go in that shadow.

Donley:

Mm-hmm (affirmative).

Allan:

And so, the temperature coefficient of the clocks was a big issue and the rubidiums had a significant coefficient.

Donley:

Yeah, they still do.

Allan:

So, they ended up having to put a temperature base plate control on them to reduce the effect of temperature as you would go into the shadow of the earth.

Donley:

And the magnetic field changes a lot too.

Allan:

Yeah.

Donley:

I mean, depending on the trajectory of the satellite.

Allan:

Yeah. Yeah. So, some of the findings we had to show magnetic field dependence and temperature dependence on different parameters in the clocks were helpful in giving them better flicker floor and better stability.

Donley:

Okay. And so ... with these statistical tools you can model the clock drift during these dead periods, but how are they controlled? I assume they're all steered with uh information that you get from the measurements.

Allan:

Actually, they're not steered because you can show that a clock performs best if you leave it alone; no knob twiddlers.

Donley:

Okay. So, you just characterize it and you know what it's going to do?

Allan:

Yeah, so you write your time dispersion equation; synchronization error, the syntonization error, and the frequency drift term and then you look at the noise; white noise, flicker noise, and so you characterize the systematics and then you write an equation that tells you where the time difference is between GPS time and where the clock is actually performing. So, you have an equation for that clock that will mirror what you think is best time for the GPS system. So, you want to synchronize that software calculation to the best level possible for all of the satellites.

Donley:

And then the satellite makes some kind of correction to the signal it transmits, I suppose.

Allan:

Yeah. The satellite transmits its time equation.

Donley:

Mm-hmm (affirmative).

Allan:

And its parameters, its ephemeris, its position and so all those parameters are part of the data word. So, when Marc Weiss and I, years later, were able to deconvolve a five-element matrix to sort out all of these errors, and we helped the Air Force set the Kalman parameters by doing that every month. We'd send them a report to try to deconvolve the error terms. But we had essentially a perfect reference clock in Boulder to measure against. So, satellites transmit the equation for the free running clock and its ephemeris that describes its best estimate of GPS time.

And, so all the clocks have their GPS estimate, and hopefully those are all synchronized to about a nanosecond in software.

Donley:

Uh-huh (affirmative). That's interesting. So, the receivers do a lot of processing then because they get this information.

Allan:

Right.

Donley:

Yep.

Allan:

Right. So, you have to decode the data words and get your position; x, y, z, and t. So you solve from four satellites. The way I like to describe how GPS works for people who don't know clocks is, you can think of a tripod ... an upside down tripod, and if you look at the velocity of light at 186,000 miles per second, you can translate that to precise terms that light travels, 30 centimeters in one billionth of a second, one nanosecond.

Allan:

So, you can think of it in English terms as one nanosecond per foot (laughs). I have an article on my book’s web site on “How to understand how GPS works in five minutes.” https://itsabouttimebook.com/how-gps-works/

Donley:

Mm-hmm (affirmative).

Allan:

And so if you have these three satellites in different parts of the sky, all synchronized, these software clocks are all synchronized to a nanosecond and they broadcast their time and their position, and let's suppose for the moment you have an atomic clock also synchronized to GPS time, so you can measure how long it took each one of those signals to come down each leg of that tripod and know your position to one foot. But of course, you can't have an atomic clock in your receiver. It's too expensive, too heavy, and so what's used in practice is you have a very stable quartz crystal oscillator, doesn't have to be accurate, but it's very, very stable so that you can take measurements over four satellites and write four equations with four unknowns which allows you then to calculate x, y, z, and t.

Allan:

Longitude, latitude, altitude, and GPS time, so you then basically turn your quartz oscillator in your GPS receiver into an atomic clock.

Donley:

Mm-hmm (affirmative). Wow, yeah. So, who first realized that special relativity would play a role for clocks in the GPS?

Allan:

I'm sure there were several people who worried and thought about that. At the lab, Jim Barnes could see that it was an issue and he and I contracted with Professor Neil Ashby to study the problem. And I was privileged to be part of the contract relationship, so I worked directly with Neil and he could see that the best coordinate system to be used was an earth centered non-rotating frame. So, you have the earth spinning inside of this coordinate system which is going around the sun, so it's an inertial frame.

Donley:

Mm-hmm (affirmative).

Allan:

But it's basically in free space and years later Neil Ashby showed that the terms of the elliptical orbit around the sun canceled in pairs so that you really could treat the earth as a free space object ... so, anyway, he was able to work through the math of the relativity for that and you end up with three terms that have to be used ... the velocity of the satellites in this coordinate system, and then also the gravitational potential where the clocks live and then lastly, you have to worry about the earth's rotation, the Sagnac Effect, in this coordinate system.

And that has to be done in the receiver, the other two terms are done at the satellite.

Donley:

And so how large are the effects?

Allan:

Neil Ashby (left), Dave Allan (center) and Marc Weiss (right) with NBS GPS antenna.

Large. If you don't do it, you get kilometers and growing. So, it was fun to see that first test because the Air Force didn't want to believe relativity and then we had to have a switch when they put up the first satellites ... they had the option (laughs) to do relativity or not and when the relativity was turned on you got this nice convergence and otherwise it blew up.

Donley:

That must have blown their minds (laughs).

Allan:

(Laughs). Yeah. Made believers out of the Air Force folks.

So, GPS is really the first engineering, operational, reality of relativity.

Donley:

Uh-huh (affirmative).

Allan:

And Neil actually gets the credit.

Donley:

Yeah, I should interview him for one of these oral histories.

Allan:

Neil Ashby (left), Dave Allan (center) and Marc Weiss (right) discussing GPS common-view time transfer.

Yeah, you should.

But I guess we should also say that that work that we had contracted Neil to do was picked up by General Dynamics, and they're the ones that actually incorporated it.

Donley:

Okay.

Allan:

So that was the next step, to actually make it happen within the system.


Donley:

Mm-hmm (affirmative). So, let's talk a little bit about the concept of selective availability. Can you explain it, what it is, and then your work related to it?

Allan:

So the military GPS receivers were configured so that they were keyed and secure so that you could only get military accuracy if you had that key.

The civilian folks could only use the L1 frequency, so they were not allowed to have the key and to do full accuracy. So the military had configured it so that only they could get full accuracy and the civil sector got less, so Chuck Wheatley, I think was working at Rockwell at the time, he designed both the synthesizer and the modulation technique to modulate the signal so that the spec would be 100 nanoseconds of timing error for the civilian folks.

Donley:

To deliberately degrade the performance.

Allan:

Yeah, so the synthesizer would degrade the clock so the civilian sector could not have the performance of the military, and that was called selective availability (SA), so it was a modulation on the atomic clock.

Allan:

So anyway, that was implemented and a nuisance. When I retired from NIST in 1992, I had the idea that we might be able to remove the selective availability (SA) from GPS for the civil sector. SA was a modulation purposely put on the civil L1 frequency to give degraded performance. I talked to both military folks I knew as well as commercial GPS receiver manufacturers and no-one could tell me the spectrum of SA. Wayne Dewey at True Time in Santa Rosa offered to take the data, and then I could analyze it. I used TDEV to look at the time-domain spectrum, and I was able to come up with a digital filter to filter out the SA. We were able to test the algorithm at USNO by tracking a military receiver and obtained 1 1/2 ns rms variation over a month.

Donley:

What does the military guys think about it when they see these results?

Allan:

Yeah, I made one fun presentation at the ION-GPS meeting in 1993 at the Abravanel Hall in Salt Lake City where there were a whole bunch of blue-suits-AF folks in the audience. You could see the look on their faces, "You can't do that." If it had been a solution for position, they would have probably taken me out front and shot me! But timing is not their thing.

Donley:

Or were they saying, "You shouldn't do that?"

Allan:

But the first presentation with this SA filtering and Smart-Clock technology implemented at HP was with Qualcomm. Chuck Wheatley, who was their VP of technology used to work for Rockwell on the GPS program, and he had designed both the algorithm for SA and the synthesizer to add it to the atomic clock on board to give the SA degradation. He was in the audience, when I presented our results at HP, Santa Clara. He sat in the back of the room with a big smile on his face. It was really fun to see his response to how well we had removed what he had done.

They sold these HP 58503 GPS receivers all over the globe to synchronize cell-towers. You can see that they could keep the timing error under 10 ns most of the time, and if the GPS signal was interrupted, the Smart-Clock technology would keep the errors within the specification of a microsecond over a day.

Donley:

And so this was an important problem for a lot of different industries. Were there other industries ... like for commercial airlines for example, that were also using this? Or did they solve the problem independently? Do you know about that?

Allan:

The SA problem?

Donley:

Yeah.

Allan:

I don't know much about that ... but because I was on the civil GPS service interface committee for the Air Force and the Department of Transportation, I got to hear conversations. But they typically would have transmitters, GPS pseudolites near the airport, so that they could do differential removal of some of these effects... so I think they took care of those problems in other ways.

And the Coast Guard did the same thing. They would broadcast the corrections.

Donley:

Like their own radio signals after they figured out the errors.

Allan:

Yeah.

Donley:

So, did all these methods to bypass selective availability influence the military's decision to turn it off? Or were there other factors?

Allan:

I recall the main key was the Russian MIG shooting down a Korean airliner that had gotten out of position due to a navigation error problem, and it was shot down, and because this got international attention, and realizing that if SA were turned off that maybe that would not have happened, so that was a big factor along with other issues.

Allan:

It has been very satisfying to be part of the GPS development from the ground floor. I have spent many man-years of effort in helping in a variety of ways, and have had a close working relationship with several great people in the AF, at NRL, at Aerospace, and at USNO. The Aerospace people set up a clock test facility patterned after ours in Boulder. They were very proud to show me how well it worked. https://itsabouttimebook.com/my-involvement-with-gps-development/

Donley:

Okay, so, let's move on to talk about some of your other technical contributions. You did a lot of work on timescales. We've talked about that a little bit already, but let's talk about it a little bit more.

You worked to develop AT1, one of the timescales at NBS. Is that still in operation or used today?

Allan:

Jim helped me ... he had written an algorithm based on his thesis for a timescale, and when I had the responsibility for the clock system, he was then section chief, and then I started working with some of these statistical concepts of how to take the time readings between an ensemble of clocks and how to combine them optimally, and I came up with an algorithm that weights the clocks both short-term and long-term due to their sigma tau performance, so you have a weighting scheme which can be dynamic, namely you learn the clock's performance and as the clock changes you kind of breathe and go with what the clock does over time.

One interesting challenge you have with each clock being compared to ensemble time is that it is part of the ensemble. So it is looking at itself to some percentage. Under the assumption of a normal distribution of errors, I was able to remove this bias. Otherwise, the best clock would take over the time scale. I actually witnessed this dynamically when we had hydrogen masers being compared with cesium clocks with their excellent short-term stability.

So you have an optimum weighting for each of the clocks in the ensemble, and you can show that when you do this, you end up with ensemble time which is better than the best clock, and even the worst clock enhances the output.

So it's a beautiful concept. It also is robust. It can deal with malfunctions, and I remember one time I ran the scale, and I had eight clocks, and three of them failed in one measurement cycle, and it picked up all three errors, walked on through...

So anyway you have this robustness and elegance and the fact that it can be real time. USNO would calculate their time each month from a much larger set of atomic clocks that they had at the Observatory. We only had eight, and we could show that our timescale stability with a good environment, was better than theirs after the fact, so the fact that you had both a real time scale and a breathing system that would deal with white noise and flicker noise made AT1 extremely useful, and as far as I know, with lots of upgrades by Judah Levine, Tom Parker, and others dealing with drift of hydrogen masers, that it is still being used today.

Donley:

And so the software was at the heart of it? Let me make sure I understand. It takes measurements that have been performed with hardware with this dual mixer time difference technique (DMTD), and then it uses software to compute the proper weighting and generate an output. So what is the format of the software? What language is it written in?

Allan:

In 1968, that was before the DMTD was developed; all I had was 0.1 nanosecond counter, and I measured at exactly the same time each day, so that we had no dead-time, and the measurement noise was less than the clock noise with a one day tau. We had just gotten our first timescale computer, it was a PDP8S -- the S stands for slow! (laugh) A big tall thing with eight kilobytes of memory (laughs) ... and 92 lines of code...

Donley:

How long was each line? That seems like pretty compact code.

Donley:

I guess you had to be pretty efficient with your coding.

Allan:

In 1974, Byron Blair published NBS Monograph 140 and I share this because it has two chapters that I wrote. One on characterizing clocks and one on the time-scale algorithm that was developed in 1968 to combine the readings of atomic clocks. That has a very important basis for timekeeping at the bureau, and so that Monograph is one place where you can find the code that I wrote. The code was Fortran IV and I had to use some variables three times. How we laugh at that today.

Donley:

Well, reading and understanding that code might be a good way to learn about time scales.

Allan:

It was really a fun program, and so you would make a set of time difference measurements between all of the clocks, and you would then compute the time error; you'd determine optimum time, and then you'd look at the time error of each, and the time error of each then would update through a recursive filter, an exponential filter, the weighting factor; so every time you'd take a measurement, you'd get an update. Every time you made a measurement you'd also compute time as well as update the weighting factors. So it was a breathing scale ... always dynamic and changing appropriate to the clock's behavior.

Sam Stein and I have had a good friendship over the years. He was a great asset to the Division and later became Division Chief. One morning, while he was working for me, he came up to me and jokingly said, “I hate you!” He had stayed up all night studying the code and with variables used more than once, it was confusing, but I had to do it to make it fit for eight clocks. But he got his head around it. He went on years later to write an excellent time-scale program using Kalman filtering. Judah tested it, and it seemed comparable to AT1. Since NIST owned AT1, they stayed with it. Also, Kalman filters don’t deal with flicker noise very well unless you get really mathematically elaborate.

Donley:

And is there a physical output, like you steer a quartz, a single quartz based on everything...

Allan:

Time-scale computer (PDP-11) with (back row left to right) Dave Allan and Jim Gray and (front row left to right) Marc Weiss and Trudi Peppler
Time Scale and Coordination Group. Back row from left to right: Howard Machlan, Jim Gray, Al Clements and Judah Levine. Front row left to right: Dave Allan, Trudi Peppler, Dick Davis and Marc Weiss.

Yes, thanks again to Judah, we had a rubidium ... I think it was the first thing we tied to the software clock. We had a real time output that would be tightly synchronized to the software clock, so that then became your output signal servoed to the software value that was computed by the ensemble, and then that ensemble of course is calibrated against your primary standard so that you know that the rate is correct with respect to the primary cesium frequency standard. In practice, we would keep the rate of UTC(NBS) the same as UTC, which was computed once a month at the BIPM, as best we could. That was a time prediction challenge that kept us on our toes. Our joke was that BIPM calculates UTC to tell you what time it was! Our job is to provide accurate time NOW, so that it can be made available to the world in real time. Marc Weiss and I tackled this problem in 1994, after I had retired – suggesting how UTC could be real time for the world community. https://tf.nist.gov/general/pdf/217.pdf “The Variance of Predictable of Hydrogen Masers and of Primary Standards in Support of a Real Time Prediction of UTC.”


Donley:

And UTC(NIST) is also used in international comparisons, right, via satellite? So, how does NIST tie the output of this timescale into international time?

Allan:

Uh, so back in...

Donley:

...or NBS?

Allan:

Yeah. Um, we had WWV, I mean that goes way back. As I recall, WWV was used in comparing standards for the definition of the second in terms of cesium in 1967, and then later on you had LF and VLF transmissions. Loran-C is a 100 kHz transmission, which was a navigation system that the Department of Transportation operated with cesium clocks and those were synchronized by the United States Naval Observatory so that ships at sea and airplanes could do Loran navigation.

So they had cesium clocks at these transmitters and those clocks were distributed so that we could listen to a Loran station in Boulder, and it could go in a chain across the Atlantic all the way so that people at the Paris Observatory, where the International Bureau of the Hour (BIH) was, where time was kept back then; Bernard Guinot was in charge.

So we would transfer the times of our clocks from different world community clocks using Loran-C to transfer time to the BIH at the Paris Observatory, where TAI and UTC were generated back then. We could see instabilities in the Loran-C propagation path of the order of one or two microseconds over the course of the year. It was really hard because the clocks were so much better than the propagation delay variations that it was a challenge.

Donley:

... frustrating I bet ...

Allan:

It was frustrating.

Donley:

Yeah.

Allan:

Yeah. So, um, in, in 1972 they ... well let me go back one step. After we developed AT1, people could see the value of it and we held an algorithm symposium in Boulder, and I was chair of that, and we had Bernard Guinot and people came from all over to share ideas about how to do ensembles, because these were new kids, atomic clocks were ... how to use them and so forth, so the algorithm concept caught on quite quickly, and Michael Granvaugh, who worked for Bernard Guinot, came to Boulder as a guest worker, and worked with me for several months and then he went back to Paris and wrote ALGOS for International timekeeping. He did that at the BIH. So ALGOS became the international timescale combining all the clocks from different laboratories that would contribute from around the world to compute International Atomic Time (TAI) and UTC.

Donley:

OK, and those initial measurements, those were all done through the Loran-C system.

Allan:

Yeah. Yeah.

Donley:

And when did people start using GPS satellites for time transfer?

Allan:

Um, it was a military system and people didn't really use it for time transfer. In about 1980 ... things were not going that well at the bureau for me.

Donley:

Oh really?

Allan:

... In looking ... in terms of my long-term career, I was seriously considering changing jobs, and at that time I was responsible for the timescale and had a very excellent group of folks working with me, Jim Gray, Howard Macklan, and Trudi Peppler, and that work was going well, but administrative issues and whatever. It looked like I was dead ended I guess is the way to say it ... and in the previous year the bureau had gone through a reduction in force, and four people went out the door from our division, as a result of that RIF, and they were all from the time dissemination research group.

Donley:

Oh.

Allan:

And so that was kind of the low peg on the totem pole for them to cut when they cut budget, and they came to me and said, would you like to reform that group? We'd like you to keep the timescale but we'd like you to also look at some research opportunities in time and frequency transfer, again we were using Loran-C, and my first reaction was, no thank you. I was not interested.

But then being the kind of person I am, I really wanted to see if it was something maybe I should do that would be of service, that would be helpful, and that I could use my time and talents to maybe do something new, and so I made it a matter of prayer again, and talked to my wife, and one evening as I was pondering and praying... Is there something here? Do you want me to take this job? It's not a new job, it's adding to what I already have with the timescale, and immediately several ideas came to mind, and one of them was GPS common view - it just popped in. I thought, “Wow, that's an interesting concept.”

And so I talked to Marc Weiss, and we looked at the theory; the GPS satellites are 4.2 earth radii, and looking at the constellation and so forth; so we looked at the equations for how much reduction in error you would get by doing Common View; so in other words, we could listen to a satellite in Boulder at the same time it was being listened to in Paris, and then you look at those errors, and when we did the calculations, it looked like we could do a nanosecond time transfer.

So this was like 100 times better than Loran-C. I remember sharing the idea with Dr. Winkler; he was director of Time Services for the USNO. We were good friends, and I told him we had common-view not only between Boulder and Paris but also between Boulder and New Delhi. His reaction was, “No way!” But with the height of the satellites and their large inclination to the ecliptic plane that amazingly works out.

Donley:

How do you get around the ionospheric problems or ... how do you know the ionospheric delays and those type of measurements to make corrections at that level?

Allan:

Jack Klobechar had a model that was broadcast by the satellites. It was an eight-element model. And so we'd use the Klobechar correction terms to estimate the ionospheric delay and that would take us down to a few nanoseconds.

Donley:

So when did it start to go into practice then to use common view?

Allan:

After Marc and I had worked up the theory, while still having the timescale group, I had Marc Weiss, Dick Davis, and Al Clements to help me with this research of GPS Common View. And it was a really fun team. The navigation receivers didn't worry about the time delays inside the receivers. They were made for navigation and so we learned immediately that they would not work for time transfer. We had to know the delay was constant, and basically what it was so that when we took A minus GPS and B minus GPS, and we subtracted those terms to get A minus B between Boulder and Paris, for example, that those terms would cancel at the nanosecond level.

So you'd get the Common View cancellation, collapse the errors down to a very small amount.

Donley:

Mm-hmm.

Allan:

NBS GPS receiver with (left to right) Dick Davis, Dave Allan and Al Clements.

So the receiver delays, the antenna delay, and so forth all had to be calibrated, and so we worried about those at the nanosecond level. And Dick built this beautiful little simple counter that nobody's taken advantage of, a 0.1 self-calibrating nanosecond counter, inside of our receiver. It was pretty elegant.

Donley:

Mm-hmm.

Allan:

Early NBS GPS antenna with Marc Weis and Al Clements (left to right standing), Dave Allan and Dick Davis (left to right squatting).

So that was part of, of this new GPS Common View receiver that was built in 1981, and later, once we built a set of those, then we sent them out to USNO, to PTB and to Paris and NRC, and we had several places that helped us test the theory with these receivers that we had built, and it worked. I mean we had this multi-authored paper showing how we could compare clocks around the globe using GPS Common View.

So it became the main means of communicating the times of clocks around the globe after that was developed. In 1985 a highly successful 13 authored paper was written by folks from key timing centers around the world documenting these results: https://tf.nist.gov/general/pdf/689.pdf “Accuracy of International Time and Frequency Comparisons Via Global Positioning System Satellites in Common-View.”

Donley:

So then you dropped the uncertainties or the timing errors by a factor of 100 from about a microsecond to 10 nanoseconds or something like that.

Allan:

Yeah. Yeah.

See "Dave’s Story on how GPS helped NASA/JPL synchronize their Deep Space  Network tracking stations" for more detailed technical explanation.

Donley:

So, one of the other things that I know that you worked on was Advanced Common View. Can you tell us a little bit about that and how is that different from the regular Common View that you were just describing?

Allan:

Uh yes, that's a fun topic and is relevant today. When I was consulting for Hewlett-Packard, I basically did three things for them: helped them develop the SA filter and smart clock concept for synchronizing cell towers, and they sold a bunch of those receivers around the globe, and then they had me write this Science of Timekeeping application note and I had Ashby and Cliff Hodge help me do that to help educate people on what GPS was and is and how to use it and the value of it (http://allanstime.com/Publications/DWA/Science_Timekeeping/index.html). And then I had this idea, because if you have an ideal time measurement system, the best noise you can achieve is white noise phase modulation, if you get rid of all the systematics, then that will be your limiting noise and you can't do better than whatever that is. So that's the limit.

Robin Giffard and I developed GPS Advanced Common-View on the assumption that the best you can do with GPS is to get rid of the systematics and one should be only limited by the white-noise PM measurement noise. We had a Motorola Encore GPS receiver and Robin went into the very heart of that receiver to look at all systematic issues and how to remove them.

We looked at multipath, ephemeris systematics per satellite, and receiver delays in the coding. Robin had figured a way to look across the spectrum of the L1 signal to estimate the ionospheric delay, since it is 1/f^2 dependent. We did the test across the US with a receiver at USNO in Washington D.C. and one in Palo Alto, CA. We came very close to the ideal noise-model of white PM at a level of white pm noise at six nanoseconds at one second going down as tau^-½ on a TDEV diagram. If extrapolated, we could reach 1e-18 in two months. One could imagine a set of these receivers across the globe with super-optical clocks running continuously connecting all the major timing centers at this level of stability and allowing accuracy comparisons at this level. With longer baselines there are more challenges, but the concepts and the extrapolations have general validity because of the technique and the fundamental theory behind it. For global frequency comparisons, in theory, on an MDEV plot, the improvement for GPS ACV would go as tau^-3/2, which is extremely advantageous because ideal atomic clocks only go down in performance as tau^-½.

Donley:

Is there anything that makes it difficult to implement or is there a reason why it never took off?

Allan:

Robin died, and my wife and I went on a mission, and it’s not trivial. But I think it should all be resurrected. I'm retired almost. But yes, it could be resurrected, and I would think it could be extremely useful given the enormous improvements in optical standards over the past years. HP called me up and asked if I wanted Robin's information on GPS ACV, and they sent it to me, and I think I have that box they sent, if I can find it! We did that work in '96 and 7.

Donley:

So that was after you were already retired, quote unquote retired? From NIST.

Allan:

I never, I never retired from life. (laugh)

Donley:

Okay, so were you also involved in the early days of using the internet for time transfer?

Allan:

That is a very pleasant memory. I can remember Don Sullivan and Dick Davis and Judah Levine, and myself sitting around the table in the division office saying, you know, what can we do with a 300 baud modem, and can we do this automatic computer time service? And the idea came that we could estimate a delay and send a signal in advance and then have the modem at the other end echo that signal back, and so we'd measure the round-trip time, and we'd measure that for like, say three times, get an average, and then send the next one on time so that it would arrive at the receiver site on time.

So it would be, in other words. Self-calibrating.

Donley:

Yeah, because you never know the path if I understand the internet, the signals can go through nodes and they'll go one way one time and another way the other time so that there's a high level of jitter in the timings ...

Allan:

Yeah. And Judah sorted that out. I mean, what he's done is the best you can do with what's available. I think Judah has done an incredible job of taking that concept to fruition. Dick Davis built the first ACTS system and I tested it. I have it on my diagrams and it was really fun because like we could see in Boulder. I think it was between JILA and the lab, and it was a mile apart we had a 300 baud modem, and we could see this beautiful white PM on a MDEV (mod sig tau) diagram and it went down as tau to the minus three halves to three parts in ten to the 11th ... 300 baud modem. That was really fun.

Donley:

Wow.

Allan:

So in other words, you'd realize this ideal measurement noise for a very simple concept.

Donley:

Mm-hmm. Okay, you also told me that you spent a long part of your career working on a committee that establishes the definition of the second. Can you tell us a little bit about that and what your role has been or was?

Allan:

Yeah. Jim Barnes invited me to go with him. NBS had a representative and USNO had a representative for the U.S. to go to the International Bureau of Weights and Measures for the Consultative Committee for the Definition of the Second. I served for several years on the CCDS.

Great memories, with neat people, looking at how to do things better, and GPS Common View and how to transfer time were issues, so I was kind of in the middle of that having developed that at Boulder. So we were always thinking about ways to make international atomic time (TAI) and UTC more stable and more accurate with the primary standards that were available.

The primary standards were getting 10 times better about every seven years and so you always had dynamics as to how to do things better, so it was a fun piece of committee work.

Donley:

How often would you meet?

Allan:

Like every three years.

Donley:

Okay.

Allan:

So we'd go to the BIPM at this beautiful facility on the Seine, that would overlook the river and it's a library that's got books that you can't believe all the way back to Galileo and the like.

Donley:

Wow.

Allan:

Famous physicists going back to the reformation had their works there, and it was really a neat place to work. This being the BIPM, they had all the standards there, so all of the SI standards were kept there, and they moved the computation of atomic time from the Observatoire de Paris, where was the BIH (Bureau of the Hour) where Dr. Guinot computed TAI and UTC. So in 1986 Bernard Guinot moved his office from the Paris Observatory out to the BIPM.

Donley:

Mm-hmm.

Allan:

And so they then became the repository for all the atomic clock data from around the world, and they had a GPS Common View receiver and an HP 5071-A cesium-beam atomic clock. They would collect the data from the primary standards as well, and one of my jobs was to take our value in Boulder for the primary standard and communicate that to the BIPM, and they would then take values from other primary standards. Because of our elevation, I had to apply a correction of 18 ns/day to our primary standard to move its value lower to normalize it to sea-level to best compare with the other primary standards in the world to accommodate that general relativity effect.

Allan:

So after our folks would run the clock, the primary standard calibrated our ensemble, then I would do the transfer of that data to the international folks that compute international time.

Donley:

So did the committee work run efficiently or was there a lot of arguing about techniques or was it mostly interesting technical discussions?

Allan:

It was very academic. There were always disagreements and discussions and how to do things better but a great group of folks. I really enjoyed that work, meeting those folks from other countries.

Donley:

Uh huh.

Allan:

I had some great experiences. I met Dr. Nickolay (Nick) Koshelyaevsky. We became very good friends through that in 1989 before the wall came down, so he was the representative, he was the official person from the USSR and the VENIFTRI laboratory. Nick and I worked up a recommendation, which was approved by the CCDS to help synchronize their time-scale to UTC.

Donley:

One of the things that you told me about was just how you came to go to Israel with your family. Can you tell us a little bit about that story?

Allan:

Yes. The president of our church went to Israel years ago and ... It was back during the oil crisis and people were not traveling, but he came back and wrote an article in our Church magazine and said that if you can go, you should go. It's such an incredible experience, and I never thought I'd have that opportunity, but in 1986, Marty Block called me one day and he said, "Dave, if you go to Israel and give some lectures, why I'll play for you and your wives." (laughs) I said, "Marty, I've only got one wife." And he says, "Well, that's your problem. If you hadn't done away with polygamy, I might have joined your church!" (laughs)

Donley:

(laughs)

Allan:

Anyway ... In 1987, they had an IAU meeting in Israel and I had some responsibility with a millisecond pulsar sub-session that I was chairing and, and thought, "Great, we'll go to that." And so I asked the lab if Marty could support me in going to give these lectures, and they said, "Yes, that would be fine." But, when I found out they wouldn't pay for my wife, I called Marty back up and said, "We've got a problem." And he says, "Oh, there's no problem. What can your wife do?" I says, "Hmm. (laughs) How about making zucchini squash fruit leather?" (laughs)

Donley:

(laughs)

Allan:

And, uh, he says, "Well, that sounds like a winner." So, I put together a PowerPoint presentation and she made a whole bunch of this. She takes zucchini squash, and adds fresh fruit to it, and so it takes on the flavor of the fruit that she picks and it tastes wonderful. Anyway, we gave this presentation during the lecture series that we did over there for him, and the wives came and the husbands. (laughs) It was very popular, and Marty said, "If you'll make it, I'll sell it." (laughs)

Donley:

(laughs) Sounds like him.

Allan:

Dave with a photo of the Israeli time scale from Dr. Shenhar.

(laughs) Yeah. Anyway, having that opportunity, when, Dr. Shenhar, who directed the lab at, NPL Israel in Jerusalem, learned that I was coming, he said, "Would you come a week earlier and help us with our timescale?" And so, I said, "Sure, we'll do that." And so, we spent a week in Jerusalem, helping them with their atomic clock system and, and then we went to the IAU meeting and did the lecture series, in Tel Aviv, and then I did a one week tour with Dan RONA, with my wife and I and two of our children, and that was an incredible tour, going all over the state of Israel and it was a life-changing experience for me. Had many, many very, very spiritual experiences. I had studied in detail the walkings and teachings of Jesus in the New Testament in preparation so I was prepared, and it became one of the spiritual highlights in my life. And subsequent to that, I took a GPS common view receiver over to Shenhar's laboratory and set it up along with the AT1 ensemble techniques, we integrated that, and I ended up going four different times, back to help them set up their system and they gave me a nice notation plaque. We did some papers together, and so they ended up actually long-term phase-locking to UTC. So, it was a very nice technique that we employed for their UTC. NPL-Israel, NPLI, is the acronym for their timescale that contributes to the international clock set. Anyway, it was a very choice experience. Those four trips to Israel were great experiences for us.

Donley:

You got to do a lot of other interesting world travel. So, you got to go to Russia.

Allan:

Four times.

Donley:

Wow.

Allan:

Yeah, we went St. Petersburg twice and Moscow twice, um, over a 30-year span, totally different feeling over those years. I'm amazed at the changes, but yes, I met lots of wonderful Russian colleagues as part of those experiences. Neil and I had done a relativity paper, which we presented in St. Petersburg, and then I went to the Moscow lab in '89. Uh, at Dr, Nickolay Koshelyaevsky's invitation. Got to see their whole setup with their hydrogen masers and cesium, and then I was invited by a Dr. Koshelyaevsky' in, in 2014, to an International Time and Space Symposium in Suzdal, and that was a great conference. Judah Levine was there. Great conference, and I was privileged to give a plenary talk at that conference.

Donley:

So, what year was the first time you went to Russia then?

Allan:

Um, the one with Nick was in '89, and the one in St. Petersburg would have been like '85, I suppose. About '85. That was the first trip.

Donley:

Mm-hmm (affirmative).

Allan:

And then, after the Suzdal meeting, the navigation folks invited me to chair a panel, write a paper, and give a paper at their international navigation conference in St. Petersburg in 2015. So I went back over for them. Um, that was another really nice experience.

Donley:

Mm-hmm (affirmative).

Allan:

Um, the first time I have been on an airplane from Salt Lake to, Amsterdam in seat 1A with a full bed.

Donley:

Wow.

Allan:

A sleeper. I've never seen that before.

Donley:

So, somebody paid for your trip? (laughs)

Allan:

Yeah. I told them that it's hard for people my age to travel. They said, "Well, we'll see what we can do."

Donley:

Yeah.

Allan:

So, it worked out really well.

Donley:

Did you get opportunities to go to China as well?

Allan:

In 1985, the State Department sponsored me to do a three-week lecture tour throughout several cities. I went to Beijing, I went to Xian, the Shangxian Observatory, where they had their atomic-clock ensemble. I went to, Shanghai and Guangzhou and gave lectures there as well. I had a, a real fun experience when I first went to Beijing. People had come from all over and they'd read all of my papers and they were extremely well versed in what we had done. So, I was giving this lecture in Beijing and just after I had started my talk, this robust gentleman walked in and I could tell he was somebody of stature because everybody looked at him and he came right up front and sat down and, and he started helping with the translation in very good English, so I wondered "who is this guy?" (laughs)

Donley:

Mm-hmm (affirmative).

Allan:

And during the break, they introduced me to Professor Wang, of Shimoda, Wang, and Townes, who were some of the first publishers and inventors of the maser.

Donley:

Mm-hmm (affirmative).

Allan:

So, that was the groundbreaking maser development, and so they said, "Professor Wang, go out with him in the garden and go and invent something." (laughs)

Donley:

(laughs)

Allan:

But because he knew a lot of folks that I knew in the states, he was at Columbia, we had a lot to talk about it and so we had a really nice visit. It was wonderful to meet Professor Wang.

Donley:

Uh, and you and Edna, you also went on a mission well after you retired, right? So, you went on a mission as a young person and you went on another one in the late '90s. Can you tell us about that?

Allan:

Dave and Edna at home in Fountain Green

Yeah, after I finished working for Hewlett-Packard as a consultant in 1997, on Edna's birthday, 27 August, we entered the missionary training center in Provo to learn French. (laughs) at age 61 (laughs) to go to Cote d'Ivoire. So we spent a year and a half in Ivory Coast in West Africa serving the people there. We developed a love for those great people, had a super experience there. It was very choice. We made lots of friends and ... Very, very choice.

Donley:

Mm-hmm (affirmative).

Allan:

Yeah. So, we have been blessed.


Donley:

Yeah. What did you do when you were in Cote d'Ivoire? Did you, counsel the younger missionaries?

Allan:

Yes, we were up in Bouake. The Capital of Ivory Coast is Abidjan, and traveling in those highways there is terrible, and so you don't travel unless you have to because the roads are often busted up and accidents often happen and people go off the road and you don't travel at night. (laughs)

Donley:

Mm-hmm (affirmative).

Allan:

Um, so anyway, it's hazardous driving, and so the mission president wanted us to serve in the center of the state in Bouake. We had two branches of the church up there, and we had eight missionaries. So I was kind of helping the Mission President look after them, and so we worked with the missionaries, we worked with the members, we taught the gospel to a lot of people. They were very receptive.

Donley:

Mm-hmm (affirmative).

Allan:

Did lots of really fun things and almost learned French!

See "“Sound of Music” Experience in Italy (1969)" for more detailed technical explanation.

Donley:

(laughs) But, you were telling me earlier how you practice your French daily, right?

Allan:

Yeah. (laughs) I've developed a love for it. I learned from Dr. Marian Diamond that there are seven learning centers in the brain, and one of them is language so if you keep your language skills going for multiple languages or your own language, this grows the brain. You can actually grow the brain by exercising those seven learning centers, and so one of the habits that I have, along with doing chin-ups and pull-ups and push-ups and exercises, I do those lifting light five-pound weights and so forth while I'm listening to the Book of Mormon in French. So, I get the spiritual, I get the physical and the mental and the language all intermixed and, uh, and it's really fun because I don't have anybody to practice with to speak French in Fountain Green (laughs). https://itsabouttimebook.com/the-miracle-of-the-human-brain/

Donley:

Yeah. (laughs)

Allan:

And so I can listen now and I can go to the exact verse that I'm listening to in English, so I can track it well enough. We've been home since 1999, so it's been, you know, 19 years of delay from when I learned it.

Donley:

Mm-hmm (affirmative).

Allan:

By keeping it up, why it keeps growing, and I'm grateful for that.

Donley:

So you retired from NBS in 1992 and that would have been a few years before the typical age of retirement I think. What made you decide to retire and make the change?

Allan:

We wanted to come back to Utah. My folks were getting up in years and to be closer to them, and one of my sons-in-law is a financial planner, and he said, you know if you were to go into consulting, you'd probably do better and have more freedom than if you stayed on with the government.

Donley:

You mean make more money even. (laughs)

Allan:

So, we looked at that and decided to retire in '92 and build this home here in Fountain Green without a furnace which was fun.

Donley:

Tell us a little bit more about your home.

Allan:

It basically is solar and mostly passive and has six different solar mechanisms, and I use a trombe wall so that the tilt angle of the earth of 23 and a half degrees to our ecliptic plane is our switch; so as the sun goes south, the windows in the home are such that you can see, as we speak, the sun shining on that trombe wall.

Donley:

Mm-hmm.

Allan:

... and so it warms the center of the home in the winter and turns off in the summertime; so we have full heating in the winter and no heating due to that trombe wall. And we have a solarium on the south side, which gets up to 100 degrees in January on a sunny day, and it pumps hot air from the south side through five tubes that I've designed to the north side of the home coming back through the floor joists and French doors, so that it circulates the hot air to the north side of the house.

Donley:

So you, you designed the home and you also built the home.

Allan:

Yeah, our family helped, almost all of our kids helped... one of them was in San Diego, she couldn't come, but the rest of our kids all helped. We just moved to Fountain Green and ...

Camped out? (laughs) Roughed it for a little while?

No hotels here. (laughs) Uh, yeah, so ... we have a solarium and a trombe wall, and hot water panels, and photovoltaic to generate electricity. And I use the berm principle because at this latitude, if you go down about six feet you have 54 F degrees temperature year-round.

Donley:

Mm-hmm (affirmative).

Allan:

So if you couple into that berm temperature, all you have to do is go from 54 to 68 to have radiant heat comfort and then I also have what's called a eutectic salt in a chamber, using sodium sulfate decahydrate, that melts at 90 degrees Fahrenheit, and so those salts have a heat of fusion of about 80 calories per gram. So you have an excellent heat-storage mechanism as you turn that solid into a liquid at 90 degrees, and then at night when it freezes it dumps that 90-degree temperature, which is what heated your bedroom.

Donley:

Mm-hmm (affirmative). And so how much of that salt is down there?

Allan:

It doesn't take much. There's a room with black tubes of these salts, and it was developed by Maria Telkas at Maryland, she did a patent and showed the concept and built a home based on this concept.

Donley:

Un huh (affirmative). That's interesting. So you retired from NBS and then you came and built your home and then you ...

Allan:

Started consulting. Yes, I consulted with Hewlett Packard from '93 'til we went on our mission in '97.

Donley:

Mm-hmm (affirmative). And so, how do think working conditions were different then than now? I know you're not working at NIST now, but you keep in touch.

Allan:

Yeah. When I go there to teach at the NIST seminars, I don't know how you survive (laughs). Um, it was so much better back then because security was not a problem. You had a key to your office and the lab, and you walked in any time of the day or night to work and the academic atmosphere was outstanding. The relationship with the university... I don't know how I could've had a better working environment.

Donley:

Yeah.

Allan:

There was government red tape and there were problems, and I think, the Time and Frequency Division was the best Division in Commerce, with outstanding opportunities for the folks there. So, the way it is now, seems to me, really challenging to see all the security and the difficulties.

Donley:

Yeah. Well, the security doesn't seem like too big of a challenge, but there's always more, more and more red tape, you know? Some of it's important, though with safety. We have to spend a lot of time on safety these days.

Allan:

Yeah.

Donley:

Um, so, so what did you find or what have you found to be the most rewarding part of your career?

Allan:

I think the people that I was able to work with, outstanding folks, and I have this phrase - I think I was privileged to stand on the shoulders of giants.

Donley:

Mm-hmm (affirmative).

Allan:

And, uh, it's getting to know them, work with them. It has been really a great experience. I've had those experiences, and they have been very complimentary to me and it's been very collegial.

Donley:

Mm-hmm (affirmative).

Allan:

Wonderful relationship with most of those folks.

Donley:

Mm-hmm (affirmative).

Allan:

So I, I'm extremely grateful for the interactions I've had with lots of good people.

Donley:

And do you have professional goals, new professional goals for the future?

Allan:

(Laughs) I work for the Lord. (laughs) Whatever's going to help the world be a better place and use my time and talents, and that counsel I got from my professor back at BYU years ago is still operative. So I, basically, ask questions of the Lord ... what I can do to best serve.

I wrote a book in 2013, harmonizing science and religion, and that's now out. My website now has over 70 nations that visit the site, and the book is going international, and it's basically designed to help a world that seems to be going away from God, to help them find faith and hope and purpose. The visits to the site are in the thousands from around the world and growing exponentially.

Donley:

Mm-hmm (affirmative).

Allan:

It is basically educational for body, mind, and spirit. And I have some really, really fun, if you will, scientific evidence showing harmony between science and religion. So it's a unique book in that regard. It has a lot of fascinating data, and details that are quite unique to the book.

Donley:

People can find it on your website. Can they buy it on Amazon?

Allan:

Yeah. It's available on Audible and i-tunes also on the web site. www.ItsAboutTimeBook.com

Donley:

Audible. Oh, okay.

Allan:

Yeah. So the book is called It's about Time. Good title (laughs).

Donley:

(laughs)

Allan:

The name of my company is Time Interval Metrology Enterprise, TIME.

Donley:

(laughs)

Allan:

(laughs) And the website is www.itsabouttimebook.com, and I write like two blog articles per month, helping people with religious questions, heath issues, what's going on, some fun ones on how to grow the brain at any age. In my book and on the web site, I love to share the many miracles I have witnessed God performing in our lives – showing His love. https://itsabouttimebook.com/the-miracle-of-the-human-brain/

Donley:

Mm-hmm (affirmative).

Allan:

So I'm doing research all the time, always learning.

Donley:

Mm-hmm (affirmative).

Allan:

Trying to find things that will be helpful to people.

Donley:

And do you have any special secrets for staying healthy?

Allan:

Ride a bike. I love Michael Pollan’s counsel, “Eat FOOD (real food not processed) and mostly plant based, and not too much!” One of my jokes is, “Chocolate is my favorite vegetable!” Exercise body, mind, and spirit. Have a positive attitude. Be filled with faith. The whole middle part of my book, Section II, is all about these kinds of issues. Trust in God. Um, I know He's there. One of the best pieces of knowledge I have in my heart is to know that God loves you.

Donley:

Mm-hmm (affirmative).

Allan:

Dave on his bike with his dog Gertie at home in Fountain Green.

He loves all of His children, and His plan is perfect. We're imperfect, and as we listen to our hearts and to Him, we can come to a unity and a oneness and learn that the first two great commandments: love Him and to love our neighbor really work.

Donley:

Mm-hmm (affirmative). Yup. And how do you manage stress?

Allan:

That's a very good question because I had a heart attack two years ago (laughs) that was caused by stress, and I learned from that experience and have shared it with the world on my blogs that the model that we have for heart disease in America is wrong. It's flawed. I have three useful articles on my web site that might be useful for folks: https://itsabouttimebook.com/heart-health-avoid-heart-attack/ https://itsabouttimebook.com/how-to-avoid-a-heart-attack/ https://itsabouttimebook.com/fast-food-is-killing-americans/

And, uh, there are ways to deal with stress. Um, one of the books, one of the best books that I know of is one by Dr. Dharma Singh Khalsa called Brain Longevity, and it's on audio as well as a book you can buy. It was so profound to me that I wrote a book report, and I have it on my Allan's Time website. http://allanstime.com/Health/Abundant_Life.htm But he is an incredible contributor to helping us realize how ... I mean, you can't get rid of stress, but you can deal with it, and how to deal with it is, for him, very simple and elegant. It really goes to how to learn how to meditate, how to really focus in on your connection with the divine so that you move the brain, the body, the spirit. Everything moves into a oneness with your Creator.

Donley:

Mm-hmm (affirmative).

Allan:

And he can do that in 15 minutes and be kind of a new person, and he's helped doctoral students who are getting ready to do their med exams, go from like 65 to 90% pass rate by meditating and doing so much better on exams because they get rid of that stress. I have that in my book, too.

Donley:

Can you describe the process?

Allan:

Yeah. I can do that. Um, basically, you don't take a set time, but you go into a full-body relaxation mode, so starting with your toes all the way to the top of your head, you move your body into a full, complete relaxed state. And then once you're there, then you move your mind into thinking about something that is very uplifting, like God is love, light, light is truth ... something that resonates with your heart and your mind that causes you and your mind to move into a state of oneness and peace with the Creator.

Donley:

It's something simple.

Allan:

Something simple.

Donley:

Mm-hmm (affirmative).

Allan:

Uh, for me, my love of God and His love for me are affirmations that I can think about and are very mind-fulfilling and pleasant, and so you get rid of brain chatter.

Donley:

Mm-hmm (affirmative).

Allan:

It will come in anyway, but you just keep focused on some divine thought, something that's very, very peaceful and beautiful and uplifting, and you repeat that. You just keep going, uh, for five, ten minutes you just keep going. You don't set a time ... you just keep doing that and let the mind move in to a very peaceful state, so it's a mind-body-spirit oneness with the Creator. And it works. I have a blog article sharing Dr. Khalsa’s technique: https://itsabouttimebook.com/power-of-fifth-dimension-meditation-prayer/

Donley:

Sounds wonderful. I need to get into that. (laughs)

Allan:

Yeah, my mother had blood pressure problems, and I inherited that, so high blood pressure, hypertension is a problem for me. And I can go through this, and I can lower my blood pressure several points. It helps tremendously. Because that caused my heart attack, dealing with stress is extremely important. I have an article in the book about how to do that in detail, and I have a blog article as well: https://itsabouttimebook.com/power-of-fifth-dimension-meditation-prayer/

Donley:

I'm going to look at that. A lot of, or most scientists that I know are not very religious. Some are. I've known many, including you, but how do you connect the technical and spiritual sides of your life? Is that, was that ever an issue for you, or is it natural?

Allan:

Uh, I grew up in this community, which was religious, but I was not necessarily ... I didn't go to church. I was not really religiously inclined as a young person. But in my late teens, um, I had these wonderful friends, both boy and girl friends, at high school in Springville, and they were a very good influence. My cousin served a mission for our church in Hawaii, Collin Allan, he was a great influence on me, and when I, in my late teens, I connected with religious thought in terms of there being religious concepts that could be in harmony with truth, with science. So in other words, bringing them into harmony was kind of my paradigm in my late teens, and I basically attained a oneness, if you will, with my Creator in my teens. And that's why I went on a mission because I was so excited about it, here was some religious concepts that were harmonious with my scientific thinking.

Donley:

Mm-hmm (affirmative).

Allan:

So I had that harmony beginning way back in my teenage years, and with my mission experience, for me, truth cannot contradict truth. If you have religious truth and scientific truth, there has to be a harmony if they're true. And so over the course of my life, I continue to look at that harmony, and I have some beautiful examples in my book showing, with scientific data, how things can harmonize, and ... um, when you look ... and some of it's unique. I don't know of anybody else who's really kind of found some of the things I've found. So it's been fun research for me to take. Because 93% of the leading scientists in America are atheists, believe the Bible's a myth, I share data in the book that gives solid validity to the Scriptures, and I have a “New Discovery” blog article that is relevant: https://itsabouttimebook.com/trust-in-the-lord-king-james-bible/

Donley:

Mm-hmm (affirmative).

Allan:

They actually give you direct evidence to have faith in God (laughs). So, for me, it's exciting to share this because people who are troubled by all the problems in the world, all the pain and suffering, it can help them see why it's there and how those problems can be solved if we will look to the Creator.

Donley:

Mm-hmm (affirmative).

Allan:

And trust in Him, so ... trusting in God ... I have one scripture that's really fun. If you look at the history, the King James Bible has had more influence for good on this planet than any other book, and still does to this day. Now, it's not the one that's always used by people because there have been lots of other English translations of it, but if you look at the data, it has influenced more people for good. Look at Handel's Messiah. It is the most inspiring music that's ever been written, and the language is from the King James Bible (KJB), even though it's archaic for us, it is considered by experts to be the most beautiful language ever written.

Donley:

Mm-hmm (affirmative).

Allan:

And how it came together is most inspiring. As you look at the history, King James was raised up to make it happen, and he had his 51 scholars take seven years to bring that about in 1611. Yet this 400-year-old book is still the most popular book today doing the most good. If you look at what person influenced the KJB the most, it was William Tyndale. Seventy-six percent of the King James Bible is his translation into English. He knew eight languages fluently. He totally devoted his life to helping bring it to the world.

Donley:

Mm-hmm (affirmative).

Allan:

He was the major player in God's arithmetic to help bring about good. And he died at the stake.

Donley:

Mm-hmm (affirmative).

Allan:

As a martyr because they didn't want it in English -- the leadership -- both church and state. So you look at the history, and it's so profound as you see what happened. The following is a new discovery on my part and an inspiring example of the divinity of the Bible. I discovered that we find the main message of the KJB, “Trust in the Lord,” twice, back to back, in both Psalms 118:8 and 118:9, and that there are exactly 1189 chapters in the KJB – which number aligns perfectly with Psalms 118:9. Then I discovered that the center chapter of the entire KJB is Psalms 117:1-2. There are 594 chapters before this chapter and 594 after, and 594 + 594 = 1188, which aligns perfectly with the numbering in Psalms 118:8. Then I found that the Lord gives us another highlight when we see that Psalms 117 is not only the shortest chapter in the KJB – being the center of all the chapters – but it shares as well the fundamental message, “O praise the Lord, all ye nations: praise him, all ye people. For his merciful kindness is great toward us: and the truth of the Lord endureth for ever. Praise ye the Lord,” which ties us to the infinite mercy and grace of the Lord’s infinite atonement (https://itsabouttimebook.com/the-infinite-atonement-of-jesus-christ/). Then behold this shortest chapter combines with the longest chapter, Psalms 119, to surround Psalms 118 with these two verses containing the main message of the KJB. Additionally, Psalms 119 is also unique in that it has eight verses for each of the 22 letters in the Hebrew alphabet -- 176 verses, so it's like six or seven pages long after this center message, and in addition in the Hebrew Bible each of the eight verses starts with that particular letter in the Hebrew alphabet: alef, bet, etc. As we think about it further, “Trust in the Lord” is not only in these two twin verses (Psalms 118:8-9), but is throughout all of our scriptures in a fundamental way (https://itsabouttimebook.com/trust-in-the-lord-king-james-bible/). While Psalms 117 ties to His mercy, which covers our sins when we come unto Him and repent, (https://itsabouttimebook.com/gps-or-come-follow-me/)“Trust in the Lord” covers His perfect divine justice and mercy, as He totally overcame the Fall of Adam and Eve in that all are resurrected. “For as in Adam all die, even so in Christ shall all be made alive.” (1 Corinthians 15:22). His GLORIOUS RESURRECTION is the seventh step of His infinite atonement –– that brings us back into the presence of the Lord to be perfectly judged (https://itsabouttimebook.com/the-infinite-atonement-of-jesus-christ/). If we have chosen to follow Him and receive of His mercy and grace, then we have eternal life (John 17:3) – the greatest of all the gifts of God. (D&C 14:7). Otherwise, we lose that most important of all opportunities, as we follow instead the appetites of the flesh. “Adam fell that men might be; and men are, that they might have joy,” if we will but follow Him. (2 Nephi 2: 25-29; Mosiah 3:19)

We see that the translators and the people who carried the KJB forward, had God's hand in their lives (https://itsabouttimebook.com/william-tyndale-king-james-bible/). It is hard to believe this all could have been so by happenstance. There it is. The Lord has highlighted the main message and the center message in the center of His book – all tying to the infinite atonement of Christ. And the two “trust in the Lord” verses being back-to-back give both the number of chapters in the KJB and at the same time point to the center chapter, Psalms 117 with a most apropos message as well. So these two messages all converge perfectly and symmetrically in that great book to bring us to Christ, and yet all of this is in the Old Testament. It is no wonder why this book has had more influence for good than any other in the world (https://itsabouttimebook.com/the-book-that-influenced-the-world-religion/). I believe God’s infinitely loving ways have highlighted these messages for those who have eyes to see and hearts to feel of His goodness. I thank Him for showing me this discovery that I may share it with you. Indeed, let us trust in Him ( https://itsabouttimebook.com/gps-or-come-follow-me/).

And then I go on in my book and show how all of the scriptures that we have, modern day scriptures, have phraseology tying back to the language of Adam, and they all tie together. And so, you see God's fingerprint all over the place when you look. In my research, I have found that the later English translations miss this phraseology, which ties back to the ancient Hebrew Kabbalah. There are 1600 occurrences of these phrases throughout the KJB and modern scriptures that have come forth through the Prophet Joseph Smith. As brilliant as William Tyndale and Joseph Smith were, there is no way they could have included this phraseology as it is without God’s hand in their lives. As I have studied it, the probability of it being coincidental is zero. So my book is designed to build faith in God’s love for all His children.

Donley:

And so you told me that you consider your unified field theory to be one of your greatest overall technical and spiritual accomplishments. Can you tell us a little bit about that?

Allan:

Um, for me, it's been the most fun and exciting physics that I've ever done ... when we went on our mission to West Africa, Ivory Coast, while there, John Wiley and Sons asked me to write a book on GPS and precise timing, and I told them I wanted to look if there was a need when I got back, because it's a lot of work.

Donley:

Mm-hmm (affirmative).

Allan:

And it looked like yes, that would be worthwhile. So I started on that book for them as a college text view of GPS and precise timing. And as I started, I got involved with looking at unified field theory (UFT) concepts again because of motivation by thoughts, friends, and others that this is where the Lord wanted me to go rather than do this book for a college text, and so we branched off to study the UFT. What we've found is a new concept called diallel-field lines, and they carry all four force fields in physics: gravitational, electromagnetic, and the two nuclear force fields. And so when these concepts came, I started asking the Lord, please give me experiments, so that I can show my colleagues.

Donley:

Mm-hmm (affirmative).

Allan:

And we've done seven experiments to date, and all of them have been able to show validity to this concept of diallel-field lines. Chapter 21 of my book shares these. And one of them I did here at this home; we showed the attraction between bodies is a function of energy density. It's not just mass. In other words, you can write the gravitational mass equation of attraction using big G and so forth, but we can show that's a special case that really one has to look at energy density. And so I did an experiment with two pendula and showed that by changing the energy density underneath one and then moving it over to the other, I used chemical, electrical and magnetic energy densities. I was able to change the period of the pendulum as a result of changing the energy density underneath for all three kinds. So it was a big step.

Donley:

And you also used this concept of diallel-field lines to explain metaphysical things. Am I correct?

Allan:

Yes. In fact, that experiment, when you looked at the data and extrapolated it out, the inference of what the data were telling us, you ended up with a fifth dimension, which we call the eternity domain, which, for me, the model that I have for us humans on this planet is that we're limited by space and time, x, y, z, and t. This is our mortal juncture. But when we couple to God, we actually couple to the fifth dimension. This experiment gave evidence of this fifth dimension, and the complementary database that I used was from the some 13 million near death experiences on this planet that have been documented, and several books that I've read; I’ve gotten to know several of the authors of these books. I've tried to look at that data to look at consistency across that data set. And when a person has a near-death experience, they move in to this fifth dimension. Time and space totally change as they move into an NDE, because they can see their whole life before them in what we would say in an instant of time.

And so my model is that when I pray and meditate, I can couple into thinking of God's way of doing things, and so that became a very important part of our experimentation. We would then ask in prayer, what can we do next? I did an experiment up at BYU, which had never been done before to show that these diallel-field lines have quantum transitions. And so I set up the energy density configuration and a laser to focus on a mirror where I had focused a high diallel-field line energy density. In prayer, we had learned that we needed a UV spectrometer. BYU didn’t have one. I called up my good friend, Len Cutler, and he had one and he shipped it to me to do the spectroscopy so that we could find this quantum transition. And we found it, and I went right through the roof with excitement -- a 421 nm line.

Donley:

And so these diallel-field lines, they're a means to tap into your sixth sense or to explain your sixth sense?

Allan:

Yes. It allows you to couple to the eternity domain. So when people meditate and think about their Creator, and it's interesting that a person can't really go there if they're in hate and fear and anguish and noise (laughs), so ... one needs to move into peace and love and joy and the feelings of the spirit help you to couple and to be able to meditate and to learn. I have a keystone above our entry to our home that says "Truth is Light" and so as we listen to God's light, then new truths flow into our minds and new ideas. So I, I think that's how Newton wrote his Principia is because he was coupled, and he was a very God- fearing man. He spent more time studying the Bible than he did on science.

Donley:

Yeah. Uh-huh.

Allan:

Most people don't know that.

Donley:

Mm-hmm (affirmative). So in addition to these meditative techniques, what other types of activities and exercises do you think people can use to, to reach their best potential, like exercise, for example, or ...?

Allan:

Uh, Dr. Marian Diamond has a classic book called The Magic Trees of the Mind. She was the first one to show that you could grow the brain at any age, and her success with and understanding this allowed her to do the autopsy on Einstein's brain. And she shows, actually, quoting from the work of Benson at MIT as I recall, that there are seven learning centers in the brain like there are seven electron shells for the elements, or seven is God's number for how things are organized. There are seven levels in the diallel-field structure, seven energy bands and so you get this number seven in God's arithmetic, which is really fun. So, having these seven learning centers in the brain and your meditation and your exercises, for me, is very informative because what she shows is that if you use those in a complementary way--and in fact in Boulder, Colorado, they developed the Mozart effect, which if you listen to Mozart's beautiful music--because one of those is music-

Donley:

Mm-hmm (affirmative).

Allan:

And you listen, you study your math or calculus while you're listening to Mozart, you'll remember it better. And so I do that a lot. I exercise and listen to spiritual things. I listen to the Book of Mormon in French, language is one of the seven, in my morning exercise, and so it couples these different centers in the brain so that you can retain, and some of my best thoughts come as I'm riding my mountain bike out in nature and communing with the Lord and thinking about, uh, service opportunities and so forth.

Donley:

All right.

Allan:

Uh, so it's a body, mind, and spirit exercise. It's not just aerobic.

Donley:

Mm-hmm (affirmative).

Allan:

It's multi-dimensional. Its full human being oneness with God, but it helps you to get out of stress... I think I mentioned to you earlier, I've overcome, you know, like 13, 14 major health challenges in my life by doing these kinds of things.

Donley:

Mm-hmm (affirmative).

Allan:

And learning lessons and sharing them with others. So when I learn a lesson, a share it. I put it on my website so that others can benefit.

Donley:

Mm-hmm (affirmative).

Allan:

Got rid of shoulder pain. Got rid of a heart attack. Got rid of strokes, high blood pressure and several other things. I used to wear glasses. So lots of fun things I've learned.

Donley:

Mm-hmm (affirmative). Well, that's great wisdom to live by, and I'm getting to the end, we're getting to the end of what we had planned to talk about. Do you have any final thoughts or words of wisdom?

Allan:

Um, years ago I encountered a book that talked about competition versus cooperation, and as I have studied the Bible, I've learned a truth from John 14 that is not taught in any religion as far as I know that He says, "if you love me, you keep my commandments." And then later on He says, "whosoever it is keeps my commandments, he it is that loveth me." And in logic, if A implies B and B implies A, it's an identity, so you learn that the first law of heaven is love, which is equivalent to obedience, that this now is a definition of obedience that's very different than we typically think of. It's not about duty, I gotta do it, but rather, I want to do it because it makes me feel good, it makes my Creator happy because I'm pleasing Him, I'm serving mankind, and so forth. So the idea of learning that love is the motivation of heaven and should be our motivation has become a fundamental tenant for me. And I feel the world's problems could be solved if everybody lived the law of love.

Donley:

Mm-hmm (affirmative).

Allan:

Love God and then thy neighbor. And so, this cooperation rather than competition changes into the oneness so that everybody's time and talents can be used optimally. It reminds me of the AT1 time-scale algorithm, which generates time for the United States. Because everybody's different. Everybody has a different mission. And they can work cooperatively together to bring a much greater good than if they tried to say, "look what I did, and I did it all by myself." It’s often a lesson in being humble and learning from others versus ego -- thinking we know it all. I know I am extremely grateful for the many lessons I have learned from family, friends, and colleagues and especially from on High.

Donley:

Mm-hmm (affirmative).

Allan:

The ego often gets in the way.

Donley:

Mm-hmm (affirmative). Okay. Well, this has been a great joy and honor for me to come here and conduct this interview. Thank you very much for your time and for welcoming me into your home.

Allan:

Well, what a delight it is to have you in our home. You're a dear friend, and it's been wonderful to get acquainted again.

Donley:

Okay. Well, thanks very much.