Digital FSK demodulator with offset cancellation
US5394109A · kind A · utility
10Cited by
2References
5Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Feb 17, 1994 |
| Grant date | Feb 28, 1995 |
| Priority date | — |
| Expiry date | Feb 17, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/1525
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A digital FSK demodulator includes a quadrature phase detector for detecting space and mark tones used in FSK signals. Due to its inherent characteristics, a telephone loop in which the demodulator is used produces unequal amplitudes in detected mark and space tones. The inequality or offset must be cancelled so that a proper timing signal can be recovered from the FSK signal. The demodulator includes a digital compensation circuit for off-hook and on-hook offset cancellation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.