Differential pulse code modulation transmission system

Claim 1

A transmission system comprising: A. a transmitter including: (1) a DPCM coding arrangement for converting an information signal x(n) into a DPCM signal d(n) and including a first difference producer, to a first input of which the information signal x(n) is applied and to a second input of which an estimated version y(n) of this information signal is applied, for generating a first difference signal e(n), (2) a first error reduction circuit for generating a first error reduction signal y(n) which reduces transmission errors and includes a first quantizing device having an input for receiving one of the signals applied to the two inputs of the first difference producer; (3) means coupled to the first quantizing device for producing a first quantization error signal q(n); (4) means for modifying the first quantization error signal q(n) for generating a modified first quantization error signal q(n); (5) adder means for generating the transmitter output signal z(n); (6) means for applying the DPCM signal d(n), the first error reduction signal y(n) and the modified first quantization error signal q(n) to the adder means; B. a receiver including: (1) a receiver input for receiving the transmitter output signal z'(n); (2) a second difference producer, a first input of which is coupled to the receiver input and to which a second error reduction signal y'(n) is applied via a second input, for generating a second difference signal d'(n); (3) a DPCM decoding arrangement to which the second difference signal d'(n) is applied and which has a DPCM decoding arrangement output; (4) a second error reduction circuit for generating the second error reduction y'(n) signal and including a second quantizing device, the input of which is coupled to the DPCM decoding arrangement output; (5) means coupled to the second quantizing device for generating a second quantization error signal q'(n); (6) means for modifying the second quantization error signal q'(n) for generating a modified second quantization error signal q'(n); and (7) means which are coupled, in cascade with the second difference producer, between the receiver input and the DPCM decoding arrangement output and to which the modified second quantization error signal q'(n) is applied for eliminating the modified first quantization error signal q(n) present in the received transmitter output signal z'(n).