Method and apparatus for error reduction in digital information transmission systems
US3999129A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 16, 1975 |
| Grant date | Dec 21, 1976 |
| Priority date | — |
| Expiry date | Apr 16, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/66
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for reducing idle channel noise, cross talk and quantizing error noise in a digital information transmission system designed for operation over a predetermined frequency spectrum and having an analog-to-digital converter, an information transmission medium, and a digital-to-analog converter all located between a transmitting station and a receiving station. A controlled noise signal having an amplitude lying in the range from about 1/4 to 1/2 of the magnitude of a quantizing interval of the ADC and DAC and a frequency content concentrated at (n+1/2) times the ADC and DAC sampling frequency but outside the system frequency spectrum is added to the analog information input signals prior to conversion to digital form. The injected controlled noise signal predominates whenever the amplitude of spurious noise signals is less than the amplitude of the controlled noise signal and the level of the input to the ADC is near a quantizing interval transition point so that the subsequent analog output signals from the DAC have frequencies concentrated outside the frequency spectrum of the system. The DAC output signals are subsequently filtered by a post sampling filter h…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.