The Testing of Frequency Monitors for the Federal Radio Commission

Rule 144 of the Federal Radio Commission of the United States of America requires broadcast stations to maintain their carrier frequencies within fifty cycles per second of the assigned values. To meet this requirement a new and more accurate frequency checking instrument (known as a frequency monitor) was required by each broadcast station. A type test of the different kinds of frequency monitors manufactured was made by the Bureau of Standards. This paper gives a general description of the monitors tested and of the test procedure. Results of the tests are given for ten monitors approved by the Federal Radio Commission.