System for the quantization of signals

Claim 1

In a system for the quantization of signals having a transmitter section and a receiver section, the transmitter section having quantizing means, a difference producer and filter means, wherein an input signal and a first quantized output signal which is derived from the quantizing means and functions as a feedback signal are applied to the difference producer, and a signal derived from the output signal of the difference producer is applied to the quantizing means, the latter serving to quantize the level of the signal derived from the output signal of the difference producer in a plurality of quantizing levels in order to produce said first quantized output signal, filter means being connected in the path of the input signal for relatively influencing the spectrum of the quantizing noise with respect to the spectrum of the input signal, the improvement comprising said quantizing means being adapted for providing a second quantized output signal in response to the signal derived from the output signal of the difference producer and the receiver section comprising a first network having a first transfer function and having applied thereto a first received signal which is proportional to the first output signal of the transmitter section, a second network having a second transfer function for relatively influencing the spectrum of a second received signal which is proportional to the second output signal of the transmitter section applied thereto, said second network influencing the spectrum of said second received signal in a manner which is similar to the manner in which the said filter means influences the spectrum of the quantizing noise in the transmitter section, summing means for combining the output signal of the first network with the output signal of the second network to provide a receiver section output signal, the transfer functions of the first and second networks being so determined relative to the transfer function of the transmitter section that on combining the received signals the quantizing noise in the first received signal is cancelled by that portion of the quantizing noise in the second received signal which is proportional to the quantizing noise of the first quantized output signal of the quantizing means.