Method and apparatus for converting C-MAC television signals for transmission over a limited bandwidth medium
US4665427A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 2, 1984 |
| Grant date | May 12, 1987 |
| Priority date | — |
| Expiry date | Mar 2, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N7/083
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A wide-band frequency modulated DBS signal of the type having time sequential compressed chrominance and luminance (video) components is received by an aerial (1), frequency converted in a down converter (2) and applied to the input (4) of a conversion unit. The conversion unit has a tuner (5), i.f. stage (9,10) and a frequency demodulator (11) to produce baseband video which is applied after de-emphasis at (12) to a modulator (27) where the video is amplitude modulate onto a vision carrier from an oscillator (28). The modulated carrier is applied through a vestigial sideband filter (29) and an adder (30) to an output (31). Sound/data bursts present in the DBS signal are recovered in a stage (13) and processed in a processor (14) where the sound/data bursts are expanded to occupy approximately a line period at a bit rate which is an integral sub-multiple of the bit rate for the sound/data bursts in the received DBS signal. The expanded sound/data and clock frequency are digitally modulated in a modulator (32 ) onto a sound carrier from an oscillator (33), the modulated sound carrier being applied through a bandpass filter (34) and the adder (30) to the output (31). The output (31) …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.