JPS5779742A - Spare device for frequency division multiplexer - Google Patents

Abstract

PURPOSE:To simplify the constitution, by taking the ratio of present use circuits and spare circuits used for a frequency division multiplexing line as N to 1. CONSTITUTION:A signal in frequency division and multiplex is given to an input terminal 3, and a demodulated signal is outputted from a terminal 10 through a supergroup demodulation section 5, group demodulation section 6, and switching circuit 9. On the other hand, a part of the frequency division multiplex signal is inputted to a low pass filter 15 in a spare and monitor circuit, and converted to further high frequency sections of monitored frequency sections of monitored frequency band with a demodulation section 16. This is further converted to the basic group band at a demodulation section 18. Band pickup for each supergroup and each group is made by changing the frequency of carrier applied to the section 16. The monitor of present use circuit is made at a monitor circuit 11 at all times and an alarm signal is outputted to a control circuit 12 at failure. In this case, the switching circuit 9 changes over the present use circuit to a spare circuit and the basic group signal of a band pass filter 19 is outputted from the output terminal 10.