A new transistor-magnetic FM/FM subcarrier discriminator

Recently there has been sane interest in a phased-locked loop to replace the bandpass filter in the demodulator section of telemetering systems. Carl Gilchrist of the Jet Propulsion Laboratory of the California Institute of Technology has-done some very interesting work with such loops. The techniques applied by Richman in the development of his “quadricorrelator” scheme are also of interest here³. His article appears in the January 1954 Proceedings of the IRE.