Low distortion filters for separating frequency or phase modulated signals from composite signals
US4747140A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 24, 1986 |
| Grant date | May 24, 1988 |
| Priority date | — |
| Expiry date | Dec 24, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B1/1646
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A circuit for separating FM signals from a composite signal utilizes a comb filter having successive frequency response nulls which span the frequency spectrum of the FM signal to be separated. The comb filter response is phase linear and defines the pass-band of the desired signal. A nonideal or phase nonlinear bandpass filter can be cascaded with the comb filter to attenuate out of band signals. The cascade combination of the comb filter and nonlinear bandpass filters is a cost effective substitute for the conventional, complicated phase linear bandpass filter having a boxcar frequency response traditionally used to separate FM signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.