Data demodulation circuit for FSK modulated RF signal receiver providing wide-band 90.degree. baseband phase shifting
US5446762A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1990 |
| Grant date | Aug 29, 1995 |
| Priority date | — |
| Expiry date | Aug 27, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/1525
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An FSK radio receiver of direct conversion type, which derives baseband in-phase and phase quadrature signals from a received FSK RF signal in respective mixers by applying local oscillator signals to the mixers differing in phase by 90.degree., in which wide-band baseband 90.degree. phase shifting circuits formed of only digital logic elements phase shift the in-phase and phase quadrature signals to enable a demodulated digital data signal to be obtained by subsequent digital processing. In that processing, signals having a frequency that is double that of the in-phase and phase quadrature signals are derived and used to derive the demodulated data signal, ensuring high accuracy of detection and lowering the accuracy required for the local oscillator frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.