Circuit arrangement for converting analog signals into PCM signals and PCM signals into analog signals

Claim 1

Apparatus for converting analog signals, particularly pulse amplitude modulated (PAM) signals, into pulse code modulated (PCM) signals and for converting PCM signals into analog signals, in each case utilizing a nonlinear characteristic, comprising: generator means for producing a time varying voltage having a wave shape corresponding to that of said nonlinear characteristic, means for receiving said analog signals to be converted into PCM signals, analog comparator means having inputs connected, respectively, to said generator means output and to said means for receiving said analog signals for comparison and for producing an output signal voltage variable with time in accordance with said nonlinear characteristic, clock-actuated counter means for producing code chains corresponding to the instantaneous amplitude of the output signals from said generator means, output signals being produced from said counter means when said analog comparator means produces an output signal indicating equality between said received analog signal and the output of said generator means, Pcm output register means for producing PCM output signals to a PCM trunk, said PCM output register being connected to receive the output from said counter means, Pcm input register means for receiving and storing incoming PCM signals from the PCM trunk, digital comparator means having inputs coupled, respectively, to an output from said counter means and an output from said PCM input register means and for producing a control signal when there is equality between the output values from said counter means and said incoming PCM signals, first switching means for connecting an output from said generator means to an analog signal output terminal, said switching means having an operating input connected to the output of said digital comparator means so that the appearance of said control signal actuates said switching means.