Transcoder for sampled television signals

Abstract

A transcoding arrangement transcodes signals sampled at a first frequency into second signals clocked at a second frequency. The first and second frequencies are selected so that their quotient is the ratio of integers. This results in recurrent blocks of samples having integer numbers of input samples and new output samples. A transcoder uses delay elements to form successively delayed samples of the input signal. Subtractors form difference signals representing the amplitude difference between successive delayed samples. Multipliers coupled to the subtractors multiply the difference signals by a running variable multiplicand to form weighted difference signals. The running variable is related to the effective position of the new sample being formed within a transcoding block of samples. The weighted difference signals are summed in an adder to form the new sample values. In a preferred embodiment of the invention, the ratio of the first and second frequencies is selected to be the ratio of an integer divided by an integer power of two (2.sup.r), which results in blocks of samples in which the number of new samples is 2.sup.r, with the result that the multipliers can advantageously be of the shift-and-add type.