Milestone-Proposal:Ampex Videotape Recorder - 1956

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Docket #:2013-11

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Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s fields of interest? (e.g. “the theory and practice of electrical, electronics, communications and computer engineering, as well as computer science, the allied branches of engineering and the related arts and sciences” – from the IEEE Constitution) Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an Electrical Engineering Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Ampex Videotape Recorder - 1956

Plaque citation summarizing the achievement and its significance:

In 1956, Ampex Corporation of Redwood City, California, introduced the world's first practical videotape recorder for television stations and networks to produce and time-shift broadcasts, replacing impractical "kinescope" movie film previously used to record TV. The Emmy®-award-winning Ampex "VTR" analog-video recording standard ruled broadcasting worldwide for 20 years, replaced by smaller, less expensive analog and digital videotape formats and non-tape, computer-based servers.

In what IEEE section(s) does it reside?

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

IEEE Organizational Unit(s) arranging the dedication ceremony:

IEEE section(s) monitoring the plaque(s):

Milestone proposer(s):

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates of the intended milestone plaque site(s):

Stanford University, Green Library, Palo Alto, CA.

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need.

Are the original buildings extant?


Details of the plaque mounting:

How is the site protected/secured, and in what ways is it accessible to the public?

Who is the present owner of the site(s)?

A letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property:

A letter or email from the appropriate Section Chair supporting the Milestone application:

What is the historical significance of the work (its technological, scientific, or social importance)?

Ever since the advent of public television there has been a need to record TV programs. Archiving, delayed transmission to accommodate time zones and editing are some of the reasons for this desire. At the beginning of public television in the middle of the 1940s until 1956 the only means available for the recording of TV was film (movie film). For accommodating transcontinental time zones in the United States it was necessary to record a program for the Eastern Time zone and replay the program at the appropriate time for each time zone across the country. (The same method was used in other countries around the world.) Fortunately, the industry was able to install a transmission line across the country which made it possible to send live programs with pickoff points along the way in various time zones.

The method used was to pick the undelayed televised program off the transmission line and display it on a TV monitor while pointing a movie camera at that monitor, thus making a film record of the program. Next, the film was rushed to a film-developing lab for rapid development and returned to the TV station where the film would be edited and at the appropriate time projected into a TV camera and that video signal broadcast into the surrounding area for local TV sets to receive. Some time zones might have only one hour to record, develop and transmit a program whereas other zones might have three hours for that process.

The negative aspects of this whole scheme were many. To start with, film was very expensive and, of course, it could only be used once. However, it was easy to archive for future needs. Another major drawback was the quality was very poor. For higher quality, 35 mm film was used but for most programs used16mm film. Sometimes a recording was made of a live performance and the developed film mailed to the station that was going to broadcast it. This made for better quality (especially when color broadcasting became available), however, again, this was very expensive.

Several companies worked on the process of trying to record TV onto magnetic recording tape. Some of these companies in the USA were RCA, General Electric, Minnesota Mining and Manufacturing Co. and Crosby Enterprises. In Europe several companies including Bausch Gmbh and BASF were working on the process. Baird TV and BBC in England spent large amounts of money in this pursuit.

In 1951 Ampex Corp., in the United States, started a video recording project which had little enthusiasm from management but was to be a buffer by developing some experience in TV. When one of the other major companies developed the process Ampex would already have some knowledge in television recording. After about a year of development the project was put on the shelf in favor of a project in sound recording for theaters. The project was revived in September 1954 and five engineers and one machinist produced a beautiful TV recorder, which was shown at an NARTB (National Association of Radio and Television Engineers) convention in Chicago on April 24, 1956. The first production recorder was completed and put into service late in 1956. The format used became the standard throughout the world for the next twenty years.

What obstacles (technical, political, geographic) needed to be overcome?

It is easy to understand why it is difficult to record television on magnetic tape compared to recording sound on the same medium. Normally it is considered that the range of frequencies in human audio sound is twenty to twenty thousand cycles per second (Hertz). The frequencies one might find in television signals that are to be recorded using a modulated carrier frequency (either AM or FM) are about one thousand times greater.

The range of wavelengths on the magnetic recording tape of an audio recorder (when running at 15 inches per second) would be 15/20 = .75 inch to 15/20,000 = .00075 inch. Reading such a wavelength with a playback head gap of .00025 would be no problem. The recorded wavelength on recording tape running at 15 inches per second and while recording 20,000,000 cycles per second would be 15/20,000,000 = .00000075 inch. A playback head gap of about one third this dimension (0.25 uinch) would have essentially no output. The logical solution would be to run the tape at a higher speed. To obtain the same short wavelength as was indicated above for the highest audio frequency the tape would have to run at 15,000 inches per second. Of course this is not logical. Even running at 1500 inches per second (125 ft./sec.) would be difficult to do. (A 5000 foot real of tape would last 40 seconds.)

Companies (other than Ampex) were trying this high-speed tape method and even multi-track configurations using frequency division multiplexing were used (from two-track to 10-track). Each of these companies were able to get some degree of success but none came even close to an acceptable picture for television broadcast.

Ampex chose to use a multi-transducer (4 heads on a 2-inch diameter drum) rotating at 240 revolutions per second (providing 1500 inches per second writing speed) to produce a picture within broadcast specifications.

What features set this work apart from similar achievements?

The Ampex Videotape Recorder was the first successful video recorder to be exhibited and to reach the market place. Other recorders that followed the Ampex machine took licenses from Ampex or just coppied their unit illegally.

References to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or citations to pages in scholarly books. At least one of the references must be from a scholarly book or journal article.

Stewart Wolpin, "The Race to Video", Invention & Technology, Fall 1994.

"TV Goes to Tape", Popular Science, Feb. 1960, p. 238.
Ed Reitan, RCA-NBC Firsts in Color Television (commented).
a b c "Charles P. Ginsburg". Memorial Tributes: National Academy of Engineering, Vol. 7. 1994: The National Academies Press, Washington DC.

“The History of Television 1942 to 2000” by Albert Abramson

videotape recorder (VTR), U.S. patent number 2,956,114.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.