Monitoring the Standard Frequency Emissions

The method and equipment used in monitoring the standard frequency emissions are described in this paper. The emissions are continuously recorded in terms of the primary standard of frequency maintained by the Bureau of Standards. By means of selector circuits and frequency multipliers the received signal is heterodyned with the appropriate harmonic of the primary standard. The beat frequency is then recorded on a recording potentiometer by means of a circuit arrangement which produces a potential difference that is proportional to the frequency difference. The records show that the emissions have been in agreement with the primary frequency standard within two parts in one hundred million at practically all times, and the absolute value of the frequency transmitted is rarely in error by as much as one part in ten million.