Threshold extension of an f.m. demodulator using a dynamic tracking filter

The paper describes the design and construction of an experimental dynamic tracking-filter demodulator developed as suitable for receiving wideband transmissions of frequency-division-multiplex (f.d.m.) telephony and television from a communications satellite. Some of the design aspects of the demodulator are considered, and a test to determine the effect of noise on the tracking signal is described. The salient features of the demodulator circuit are described in detail, and performance measurements of several demodulators receiving 24-, 60-, 120- and 240-channel telephony transmissions are included, together with results of comparative tests using television signals. The results indicate that this type of demodulator performs at least as well as others currently available, and, owing to its small size and comparative simplicity, has advantages from an economic point of view.