Adaptive-filter single-bit digital encoder and decoder and adaptation control circuit responsive to bit-stream loading
US4940977A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 8, 1988 |
| Grant date | Jul 10, 1990 |
| Priority date | — |
| Expiry date | Apr 8, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/022
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An adaptive single-bit encoder and decoder has its adaptive function determined by dynamically dividing the message frequency band into delta-sigma and delta modulation regimes of operation. In a practical embodiment this is accomplished by varying the corner frequency of a variable-frequency low-pass filter in a leaky integrator so that below the corner frequency the operation is that of delta-sigma modulation and above the corner frequency the operation is that of delta modulation. An adaptation control circuit removes the clock signal component from the encoded bit stream to provide an analog signal representative of bit stream information or loading for use in generating the control signal. The analog signal is peak rectified, smoothed, and (optionally) non-linearly processed to provide the control signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.