AM synchronous detecting circuit
US4633187A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1985 |
| Grant date | Dec 30, 1986 |
| Priority date | — |
| Expiry date | Apr 26, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/66
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A demodulating circuit for an amplitude-modulated signal comprises an input terminal to be supplied with an input signal comprising at least a modulated carrier signal amplitude-modulated by an information signal, the modulated carrier signal having a predetermined phase; an oscillator for generating a first demodulating carrier the phase of which is displaced from that of the modulated carrier signal by 90.degree., and a second demodulating carrier which has the same phase as that of the modulated carrier signal; a first synchronous demodulator for demodulating the input signal with the first demodulating carrier; a second synchronous demodulator for demodulating the input signal with the second demodulating carrier; a level detector for detecting the level of a predetermined portion of the demodulated output of the first synchronous detector; a control circuit supplied with the output of the level detector for controlling the oscillator so that the phase of the second demodulating carrier is synchronous with that of the modulated carrier signal; and an output terminal connected to the second synchronous detector for receiving the demodulated information signal from the second syn…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.