Digital modem having a monitor for signal-to-noise ratio
US4555790A · kind A · utility
19Cited by
6References
4Claims
0Family size
Inventors
Key dates
| Filing date | Jun 30, 1983 |
| Grant date | Nov 26, 1985 |
| Priority date | — |
| Expiry date | Jun 30, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/38
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The present invention pertains to a digital modem utilizing QAM-type modulation having a signal-to-noise monitor which utilizes some of the components of a standard modem without interfering with its normal operation. The monitor averages the absolute value of the difference between the signal received by the modem and the ideal signal as represented on a typical signal constellation. In order to minimize the effect of phase and amplitude errors the monitor only handles the innermost signals of the constellation and ignores all the other signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.