METHODS AND APPARATUS FOR ENCODING AND CONSTRUCTING SIGNALS

摘要

Methods and apparatus for encoding electrical signals for transmission in a narrow frequency band or at a low bit rate are described together with methods and apparatus for constructing signals from encoded signals. A succession of first signals representing the durations of sub-divisions, for example, half cycles of the signal to be encoded are generated as is a succession of second signals representing the shape of the subdivisions. each pair of first and second signals may then be replaced by one of a limited number of symbols. After an operations such as transmission to a remote location or removal or addition of symbols, the symbols are translated back in to first and second signals. Whether transmitted or from a store, the first and second signals are used to construct analogue signals having sub-divisions of duration derived from the first signals and shapes derived from the second signals.