The use of a microwave discriminator in the measurement of noise modulation on c.w. transmitters

A circuit incorporating a microwave discriminator is described which is capable of measuring 0.001 c/s r.m.s. frequency deviation in a 70 c/s bandwidth between 1 and 100 kc/s off carrier frequency. The minimum detectable a.m. noise sideband power in the same bandwidth is ¿120 dB at 1 kc/s, decreasing with increasing frequency at 6 dB/octave.