The Establishment of the Japanese Radio-Frequency Standard

This paper describes the standard frequency equipment established at this laboratory. A valve-maintained tuning fork of Elinvar steel, made by H. W. Sullivan Co., Ltd., London, has been taken as the working standard. Some of the important characteristics of its frequency variation have been measured and adjustments have been made in order to minimize the variations which have been observed. The absolute value of its frequency has been measured through a long series of tests and the follwing value obtained as the mean frequency: 999.770 cycles per sec. at 36.0 deg. Cent. The precision of measurement is estimated as being well within one part in one million, but, because of the effect of atmospheric pressure, the constancy of maintenance is a few parts in one million. Two stages of multivibrators multiply the standard frequency by one thousand and the calibration can be made with an accuracy of one part in several hundred thousand. In order to determine the constancy of maintenance of the standard, a piezo-electric oscillator has been calibrated from time to time over a period of five months ond the results have been satisfactory.