TV bandwidth reduction system using a hybrid discrete cosine DPCM

Apparatus for taking the cosine transform of a digital signal, comprising:

• input means for storing digital data:
• means for generating basis vectors;
• means for multiplying, having as inputs the outputs of the means for storing and of the means for generating basis vectors;
• means for summing, having two inputs, one input being the output of the multiplying means;
• means, whose input is connected to the output of the summing means, for accumulating a series of digital numbers, the output of the accumulating means forming the second input to the summing means;
• means, whose input is connected to the output of the accumulating means, for scaling the values of some of the digital numbers;
• means, whose input is connected to the output of the scaling means, for limiting the values of the input digital numbers;
• and
• output means, whose input is connected to the output of the limiting means, for storing the resultant transformed digital numbers.

A discrete pulse code modulator comprising:

• first means for summing, one of whose two inputs accepts digital numbers;
• first means for limiting, whose input is connected to the output of the summing means, which ensures that the digital numbers are within a prescribed value, limited to a predetermined number of bits;
• a means for forward quantizing, whose input is connected to the means for limiting, which quantizes the coefficients of the input signal into K-bit code words;
• means generating a digital word for specifying the number of bits assigned to the coefficients which the code words represent;
• means, having as inputs the outputs of the forward quantizing means and the specifying means, for inversely quantizing the forwardly quantized word;
• second means for summing, one of whose two inputs comprises the output of the inversely quantizing means;
• second means for limiting, whose input is connected to the output of the second summing means, which limits the absolute value of the output so that it is always less than the absolute value of the input value;
• first means, whose input is connected to the output of the second limiting means, for storing the digital words;
• means, whose input is connected to the output of the storing means, and whose output is connected to the first and second summing means, for feeding back part of the output signal to the inputs;
• second means, whose two inputs comprise the outputs from the forward quantizing means and the specifying means, for storing digital words received from its two inputs;
• and
• means, whose input is connected to the output of the second storing means, for converting the input digital word in serial form into a digital word in parallel form.

Apparatus for receiving a differential pulse-code-modulated digital signal in serial form, the signal representing video information comprising frames in a rectangular format, each frame including M parallel vertical stripes, each stripe comprising N scanned lines, the apparatus comprising:

• means for converting the input signal in serial form into an output parallel digital signal;
• means, whose input is connected to the output of the converting means, for demodulating, or decoding, the differential pulse-code-modulated signal;
• means, whose input is connected to the output of the decoding means, for generating the inverse digital cosine transform of the signal at its input;
• means, whose input is connected to the output of the decoding means for storing the video data and information as to the line and stripe in which current data is stored;
• means, whose input is connected to the output of the storing means, for converting the digital data in the storing means into analog data;
• and
• means for timing all said means.