Digital/analog subterminal

Claim 2

In a digital transmission system for transmitting a pulse train of recurrent frames divided into a plurality of channels each including a plurality of information digits; a digital/analog terminal for one of said channels comprising: means for deriving frame and digit synchronization pulses from said pulse train; means responsive to at least some of said digit synchronization pulses during each frame, for generating quantizing control pulses; counting decoder means for deriving an analog output signal voltage, the amplitude of which is a function of the time required to obtain numerical coincidence between the number of quantizing control pulses generated during a frame and the incoming digital number in said one channel; and/or counting encoder means, for deriving a digital number for insertion in said one channel which is equal to the total number of quantizing control pulses that are generated during a time interval which is a function of the amplitude of an analog input signal voltage.

Claim 3

In a digital transmission system for transmitting a pulse train of recurrent frames divided into a plurality of channels each including a plurality of information digits; an intermediate digital/analog terminal for one of said channels, comprising: means for recovering frame and digit synchronization pulses from said pulse train; quantizing counting means responsive to at least some of said digit synchronization pulses for generating quantizing control pulses; means for decoding the quantizing control pulses to obtain channel and sampling control signals; coincidence means for determining coincidence between the incoming digital number in said one channel and the number of digits of said quantizing control pulses during a frame to obtain a time variable coincidence signal which is proportional to the number of said quantizing control pulses; decoder means for deriving an analog output signal which is a function of the period of said time variable coincidence signal; encoder means for deriving, following the period of said sampling signal, a time variable control signal, the period of which is a function of the amplitude of an analog input signal; register means for storing the instantaneous count of said quantizing control pulses occurring during the period of said time variable control signal to generate outgoing information digits representative of the total of said instantaneous count; means timed by said channel control signal for inserting said outgoing information digits in said pulse train.

Claim 4

In a digital transmission system for transmitting a pulse train of recurrent frames divided into a plurality of channels each including a plurality of information digits; an intermediate digital/analog terminal for one of said channels, comprising: means for recovering frame and digit synchronization pulses from said pulse train; quantizing counting means responsive to at least some of said digit synchronization pulses for generating quantizing control pulses; means for decoding the quantizing control pulses to obtain channel and sampling control signals; coincidence means for determining coincidence between the incoming digital number in said one channel and the number of digits of said quantizing control pulses during a frame to obtain a time variable coincidence signal which is proportional to the number of said quantizing control pulses; decoder means for deriving an analog output signal which is a function of the period of said time variable coincidence signal; encoder means for deriving, following the period of said sampling signal, a time variable control signal, the period of which is a function of the amplitude of an analog input signal; register means for storing the instantaneous count of said quantizing control pulses occurring during the period of said time variable control signal to generate outgoing information digits representative of the total of said instantaneous count; means timed by said channel control signal for inserting said outgoing information digits in said pulse train.

Claim 5

A digital/analog subterminal for a selected channel in a digital transmission system which transmits a pulse train of recurrent frames divided into a plurality of channels each including a plurality of information digits in which one of said digits identifies the polarity of the analog signal and the balance the amplitude of said analog signal, the total number of digits per frame being greater than the total number of quantizing levels of the analog signal; said digital/analog subterminal comprising: means for recovering digit and frame synchronization pulses from said pulse train; quantizing counter means resPonsive to at least some of said digit and frame synchronization pulses for generating quantizing control pulses during each frame; means for determining coincidence between the incoming digital number in said one channel and the number of the digits of said quantizing control pulses during a frame to obtain a time variable coincidence signal, the signal period being proportional to the instantaneous amplitude of an analog output signal; decoder means for deriving said analog output signal, the amplitude of which is proportional to the period of said time variable coincidence signal, and the polarity of which is responsive to the state of said one digit; encoder means for deriving a time variable control signal, the period of which is proportional to the amplitude of an analog input signal; register means for storing the instantaneous count of said quantizing control pulses occurring during the period of the time variable control signal to generate information digits representative of the instantaneous amplitude of said analog input signal; polarity generating means for generating an additional digit representing the instantaneous polarity of said analog input signal; and means for gating said information digits and said additional digit into said selected channel.

Claim 6

A digital/analog subterminal for a selected channel in a digital transmission system which transmits a pulse train of recurrent frames divided into a plurality of channels each including a plurality of information digits in which one of said digits identifies the polarity of the analog signal and the balance the amplitude of said analog signal, the total number of digits per frame being greater than the total number of quantizing levels of the analog signal; said digital/analog subterminal comprising: means for recovering digit and frame synchronization pulses from said pulse train; quantizing counter means resPonsive to at least some of said digit and frame synchronization pulses for generating quantizing control pulses during each frame; means for determining coincidence between the incoming digital number in said one channel and the number of the digits of said quantizing control pulses during a frame to obtain a time variable coincidence signal, the signal period being proportional to the instantaneous amplitude of an analog output signal; decoder means for deriving said analog output signal, the amplitude of which is proportional to the period of said time variable coincidence signal, and the polarity of which is responsive to the state of said one digit; encoder means for deriving a time variable control signal, the period of which is proportional to the amplitude of an analog input signal; register means for storing the instantaneous count of said quantizing control pulses occurring during the period of the time variable control signal to generate information digits representative of the instantaneous amplitude of said analog input signal; polarity generating means for generating an additional digit representing the instantaneous polarity of said analog input signal; and means for gating said information digits and said additional digit into said selected channel.