Method of receiving frequency-modulated stereo multiplex signals
US4817167A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 15, 1987 |
| Grant date | Mar 28, 1989 |
| Priority date | — |
| Expiry date | Jul 15, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03D1/22
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and a circuit arrangement for receiving frequency-modulated stereo multiplex signals is disclosed in which the channel to be received is converted to the zero IF using negative feedback for reducing the frequency deviation in the IF band. The conversion takes place in a quadrature converter stage, and adjacent-channel selectivity is provided by low-pass filtering the two outputs of the quadrature converter stage, with the slopes of the selectivity characteristics of the two low-pass filters being relatively slight and lying partly in the zero IF band. The amount of the average attenuation of the frequency-modulated stereo subcarrier signal is equal to the amount of the reduction of the frequency deviation of the frequency-modulated main-channel signal. The negative-feedback signal is the demodulated main-channel signal, the amount of negative feedback being determined by an amplifier in the negative-feedback path. If the demodulated stereo multiplex signal is used as the feedback signal, a third low-pass filter is necessary which passes the main-channel signal while suppressing the stereo subcarrier signals as far as possible.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.