David W. Allan



Keeping time, or more precisely, keeping accurate time, has been the focus of David W. Allan’s career. He developed a device to automatically remove systematic timing errors from quartz-crystal oscillators used for generating the United States’ official time. He also created a dual-mixer time-difference measurement system with sub-pico-second precision for comparing atomic clocks. His GPS common-view timing receiver has been used to transfer time from timing centers around the world to the International Bureau of Weights and Measures for generating coordinated universal time (UTC) as the world’s official time. His “smart-clock” method for enhancing GPS civil signals has been instrumental in synchronizing cell phone towers. The Allan Variance, Modified Allan Variance, and the Time Variance, which he developed, have become international standards for designing and constructing time and frequency equipment.

An IEEE Life Senior Member, Allan is president of Allan's TIME, Fountain Green, UT, USA.

Further Reading

David W. Allan oral history