Code converters
Номер патента: CA1113609A
Опубликовано: 01-12-1981
Автор(ы): John D. Everard
Принадлежит: Post Office
Опубликовано: 01-12-1981
Автор(ы): John D. Everard
Принадлежит: Post Office
Реферат: A B S T R A C T A digital-to-analogue converter which uses a technique of two-level quantisation in order to generate a pulse density modulated signal which yields the analogue signal when filtered. Standard digital logic adders and registers are used in the conversion of PCM signals to the pulse density modulated signal. The adders and registers are arranged as a feedback loop in which an approximation signal capable of either a "high" or a "low" level is compared repetititively with a PCM signal and the difference is accumulated but at the end of each operation the accumulated total is tested and the value of the approximation signal for the next cycle is chosen so as to reduce the accumulated total. The cycle period is set by a clock and the approximation signal is the pulse density modulated signal. The noise spectrum of the pulse density modulated signal may be adjusted by the addition of an offset signal to the incoming PCM signal. The digital-to-analogue converter is suitable for use in converting linear PCM telephone speech signals into analogue signals.
Code converter and variable length code decoding device and decoding method
Номер патента: KR980006960A. Автор: 히로시 이마니시,마사키 도요쿠라. Владелец: 마쯔시다 덴키 산교 가부시키가이샤. Дата публикации: 1998-03-30.