Communications transmission system

In a communications transmission system of the type in which pulse modulated analog signals and digital signals are transmitted between subscriber stations over a transmission medium, the improvement therein in which a subscriber station comprises:

• a speech microphone
• a speech receiver;
• a data input for receiving data;
• a data output for emitting data;
• a station output for connection to the transmission medium;
• a station input for connection to the transmission medium;
• a pulse modulator having a first input connected to said microphone, a second input and an output;
• a sub-channel multiplexer having a first input connected to said pulse modulator, a second input, a third input, and an output connected to said station output;
• a buffer memory having a first input connected to said data input, a second input and an output connected to said second input of said sub-channel multiplexer;
• a data clock pulse recognition circuit having an input connected to said data input, and an output;
• a synchronous word generator having an input connected to said output of said data clock pulse recognition circuit, and an output connected to said third input of said sub-channel multiplexer;
• a data word generator having a first input connected to said output of said data clock pulse recognition circuit, a second input and an output connected to said station output;
• a delay circuit connection to said station input;
• a sub-channel demultiplexer having a first input connected to said station input via said delay circuit, a second input, a first output connected to said data output, and a second output;
• a switch having a first input connected to said second output of said sub-channel demultiplexer, a second input, and an output;
• a pulse demodulator having a first input connected to said output of said switch, a second input, and an output connected to said speech receiver;
• a data word comparator including an input connected to said station input, a first output connected to said second input of said switch and said second input of said buffer memory, and a second output;
• and a bit and word clock pulse generator including a first input connected to said station input, a second input connected to said second output of said data word comparator, a first output connected to said second input of said data word generator, and a second output connected to said second inputs of said pulse modulator and said pulse demodulator.