A technique for measuring FM noise in microwave oscillators

Previous methods of analyzing the low-frequency noise spectrum of microwave oscillators have employed the usual scanning-type spectrum analyzer or an arrangement of fixed-tuned filters. The visual presentation of the spectrum analyzer makes high accuracy difficult, while a series of filters does not provide the necessary frequency discrimination. The present system makes use of a chart recorder to present noise level versus frequency as a continuous plot from 0 to 16,000 cycles.