Multistage selective differential pulse code modulation system
AssigneeKakusai Denshin Denwa Kabushiki Kaisha
InventorHajime Enomoto
Life of this patent
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Abstract
A differential pulse code modulation system, in which an input signal is at first approximated to a stepwise waveform having level changes at a constant number n of sampling points selected in the order of level magnitude from a predetermined number N of samples in the input signal. The remainder of the above approximating operation is secondary followed-up by delta modulation, which uses a variable step level controlled in accordance with the variation feature of the remainder. The differential pulse code modulation output is provided by the above two approximating operations.
Claims6
A multistage selective differential pulse code modulation system comprising:
- a first encoding stage for receiving an input signal for approximating the input signal to a stepwise waveform having n level changes at sampling points selected in the order of level magnitude from a predetermined adjacent N samples in the input signal by developing a first coded output indicative of said stepwise waveform and a remainder corresponding to a difference between said input signal and said stepwise waveform;
- a second encoding stage connected to said first stage for receiving said remainder to encode said remainder by delta modulation, which uses a variable step level controlled in accordance with the level variation feature of said remainder so as to provide a second coded output indicative of successive values of said variable step level of said delta modulation;
- and
- output means connected to said first stage and said second stage to send out said first coded output and said second coded output to indicate said input signal.
Dependencies are inferred from the claim text.