Abstract: Disclosed is a digital encoding apparatus related to CVSD techniques which provides an improved signal. The apparatus includes a comparator, comparing an analog input signal to a reconstructed analog signal and for generating the digital outputs in a manner similar to the CVSD technique. An integrating means, receives a slope control signal and the digital outputs to generate the reconstructed analog signal. The slope control signal, according to the present invention, is generated in a slope control means which includes means responsive to n digital outputs from serial clock cycles for generating an m-dimensional digital vector signal, and means responsive to the m-dimensional digital vector signal for generating the slope control signal. The m-dimensional digital vector signal is converted to an analog slope control signal by generating a scalar product of the m-dimensional digital vector signal with an m-dimensional weighting vector.