Progress‐report on radio dissemination of the national primary standard of frequency

Abstract

The national primary standard of frequency maintained by the Bureau of Standards is made available to the public by means of standard‐frequency transmissions. These are given every Tuesday for four hours, on a frequency of 5,000 kilocycles per second. The primary standard Is made to operate harmonic amplifiers which directly control the transmitting set used for the transmissions. The transmitted waves are held constant throughout each transmission within a few parts in a hundred million. At certain times of day and year, the frequency as received at a distance is observed to vary as much as a part in ten million. This is due to an effect equivalent to a Doppler effect in the ionized upper regions of the atmosphere.