Digital frequency-shift keyed demodulator
US4479092A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 20, 1981 |
| Grant date | Oct 23, 1984 |
| Priority date | — |
| Expiry date | Nov 20, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/1563
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
Asynchronous digital frequency shift keyed (FSK) signals are demodulated by using an autocorrelation type demodulator including digital integration. To this end, the autocorrelation function and digital integration are realized by generating integration increments, i.e., area increments, at the digital signal sampling points and accumulating them to obtain the integrated output. This is realized by turning to account a relationship between zero crossings of the received signal, zero crossings of a delayed version of the received signal and polarity of the product of the received signal and its delayed version relative to sampling points of the received digital signal. Specifically, the area increment in an n.sup.th sampling interval is determined by the time interval since the last zero crossing of the received signal before the n.sup.th sampling point, the time interval since the last zero crossing of the delayed signal before the n.sup.th sampling point and the polarity of the product signal at the n.sup.th sampling point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.