Intermediate frequency saw filter with nyquist phase modulation correction
US4602288A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 21, 1983 |
| Grant date | Jul 22, 1986 |
| Priority date | — |
| Expiry date | Nov 21, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/62
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The frequency response of an intermediate frequency filter for an intercarrier sound television receiver is modified to provide a substantially constant gain response portion over a predetermined range of frequencies centered about the 45.75 MHz intermediate frequency picture carrier. Picture carrier phase modulation induced by the Nyquist slope of the conventional intermediate frequency response is thereby eliminated over the predetermined frequency range reducing audio "buzz" by decreasing the phase modulation transferred to the 4.5 MHz intercarrier sound signal by the intermediate frequency picture carrier. In a preferred embodiment, the modified intermediate frequency response is established by a surface acoustic wave filter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.