The Status of Frequency Standardization

The measurement of frequency, hitherto of laboratory interest only, has become of first-rank importance in reducing radio interference. This has come about through the increasing use of all available radio channels particularly at broadcasting and higher frequencies. While an accuracy of one half per cent was satisfactory five years ago, accuracies a thousand times as good are now sought. The piezo oscillator is meeting the needs of this situation in large part. Much effort is being devoted to making the piezo oscillator as constant as possible. Commercially available piezo oscillators, without temperature control, are generally reliable to about 0.03 per cent, just barely enough to meet the Federal Radio Commission's requirement of one-half kilocycle. In order to reach greater accuracy, considerable work is being done on the primary standards of frequency, to insure the highest constancy and accuracy. The Bureau of Standards and other organizations are engaged on a cooperative program to attain an accuracy of 0.001 per cent. Comparisons with other nations show that the national laboratories of the larger countries are already in agreement to about 0.003 per cent. Temperature controlled piezo oscillators will probably allow the holding of station frequencies so close that several stations can broadcast on the same frequency without heterodyne interference. Use of these or equivalent devices is vital to the maximum utilization of the very high frequencies; the separation of 0.