Direct conversion FM receiver
US5052050A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1989 |
| Grant date | Sep 24, 1991 |
| Priority date | — |
| Expiry date | Mar 14, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D7/165
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A direct conversion receiver for demodulating an FM signal converted frequency down converts the signal to quadrature related baseband signals (I,Q). These signals are applied by way of respective d.c. blocking capacitors (16, 18) and differentiating circuits (26, 28) to a differential arctan demodulator (20). The action of the differentiating circuits (26, 28) is to remove any d.c. component in the I and Q signals and to perform a frequency shaping which enables the demodulator (20) to recover correctly the modulating information. Measures are disclosed to overcome the effects of 180 degree phase jumps which will occur when the direction of rotation of the phasor reverses and of frequency dependent amplitude scaling introduced into the differentiated signals (I', Q').
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.