FREQUENZMULTIPLEX-SIGNALUEBERTRAGUNGSEINRICHTUNG

摘要

A frequency multiplexer technique is established that permits a high channel density within the speech frequency bandwidth. The frequency signals from a large number of sub stations are transmitted back to the central exchange in relation to a base reference frequency. The substation receives (G) the incoming reference signal that is processed through a bandpass filter (BP). A programmable frequency divider (T) operates on the signal to produce the required frequency for transmission (fn). A phase locked loop (PLL) detects any erroneous condition in the frequency.