Circuit arrangement for generating and connecting the ringing signal voltage for subscriber stations of a digital time-division multiplex telephone system

摘要

To achieve a flexible ringing signal concept, the ringing signals and, where appropriate, further non-switching audible tone signals are generated by the digital tone generator (TG) provided primarily for the audible tone switching signals. Different corresponding amplification levels can be switched on the input side and corresponding bias voltages (UV1 to UV3) can be switched on the output side in the amplifier circuits (VSTE, VSTA) of the subscriber connection circuits (SLCA). In order to prevent interference due to changeover operations of this type, switching means (JNT) are provided to smooth the bias voltage jumps, or the changeovers are deferred to times when the ringing voltage makes a zero crossover. <IMAGE>