Frequency demodulator for recovering digital signals
US4752742A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 26, 1987 |
| Grant date | Jun 21, 1988 |
| Priority date | — |
| Expiry date | Jun 26, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/1525
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A frequency demodulator for a frequency shift keyed (FSK) signal which is modulated by two-level digital signals. The demodulator includes a logic circuit and a quadrature detector having a local oscillator frequency which is substantially equal to the center frequency of the received signal to produce a baseband signal in a quadrature phase relationship. The two-level digital signal is recovered as an output of the logic circuits depending upon whether the received FSK signal frequency is higher or lower than the local oscillator frequency. The demodulator solves the problems centered about a need for analog circuits which are undesirable, from an integrated circuit implementation standpoint. The demodulator avoids spike noise which deteriorates the error rate performance which is commonly found in the prior art (e.g. U.S. Pat. No. 4,521,892).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.