Filter arrangement for an audio companding system
US4704726A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 30, 1984 |
| Grant date | Nov 3, 1987 |
| Priority date | — |
| Expiry date | Mar 30, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G9/025
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A companding system for a television audio apparatus includes a compressor and an expander for stereo difference signals. The compressor provides variable preemphasis of high frequency signal components and the expander provides complementary variable deemphasis. At the receiver, unwanted signals are generated by a mixer that demodulates the stereo difference signal. The unwanted signals can cause mistracking of the expander relative to that of the compressor. A filter to eliminate the effect of these unwanted signals is placed in the expander control circuit, rather than the difference signal path. This eliminates the need and expense of an equalizing filter in the sum signal path.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.