Band-pass filter circuit
US4361894A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1980 |
| Grant date | Nov 30, 1982 |
| Priority date | — |
| Expiry date | Aug 18, 2000 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A band-pass filter circuit comprising a band-pass filter for removing noise modulation components from an input signal comprising a carrier sine wave, a phase detector for detecting a phase difference between input and output signals of the band-pass filter, a loop filter supplied with the output from the phase detector, and automatic control means for effecting control by the output from the loop filter so that a difference between the frequency of the input sine wave and the center frequency of the band-pass filter is reduced to zero. For carrier recovery in a burst mode, the loop filter is selected for each particular case so that high-speed pulling-in is possible even if a narrow-band filter is employed as the band-pass filter for the removal of noise components. Also, high-speed and high-precision pulling-in is achieved when many bursts of different frequencies are applied in one frame period. Further, when common and individual frequency variations occur at the same time, high-speed pulling-in is also achieved for each burst.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.