Carrier Supplies for L-Type Multiplex

T h e L-type multiplex operates by frequency-division and thus requires a source of carrier power for each channel or group of channels transposed from one frequency band to another. Specifically, this means a carrier source for each channel, group, and supergroup modulator. These carrier frequencies m u s t be resupplied at the receiving terminal also; and since the system is single-sideband with carrier suppressed, they must be resupplied with extreme frequency accuracy to prevent undue frequency shift in the channels. This is accomplished by accurately synchronizing these carriers to a received pilot which is derived from the carrier supply at the transmitting end.