Sync separator and video signal detector circuits

Television – Synchronization – Sync separation

Patent

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

348695, H04N 508, H04N 516

Patent

active

061542563

ABSTRACT:
A symmetrical clamp clamps the input video signal to a reference voltage during composite sync pulses, so the coupling capacitor discharge current is kept small between composite sync pulses. For startup, the non-symmetrical clamp employs an operational amplifier, diode and controllable current source to charge the coupling capacitor to a minimum desired level, and to discharge the capacitor e.g. when there is a change in DC level so that the output level is too high. A sync slicing detector is also provided, using two comparators. One comparator compares the slicing level with the clamped video and produces a properly sliced composite sync output, while the other compares the clamped video with a small reference voltage and produces a fixed sync output. If the clamped video level drops suddenly, a delayed version of the fixed composite sync output clocks a flip flop, creating a fault signal which discharges a memory capacitor over a time period. When composite sync pulses are again sliced, the output from the first comparator resets the flip flop. The circuit also includes a video signal detector which enables its sync outputs only when it receives a predetermined number of valid lines of video with the frequency of the lines being in a predetermined range and with the last several lines being relatively free of noise. A timer prevents muting of the outputs if the input signal frequency is disturbed only momentarily.

REFERENCES:
patent: 5034815 (1991-07-01), Shibayama
patent: 5274451 (1993-12-01), Koblitz et al.
patent: 5410366 (1995-04-01), Hostetler
patent: 5483289 (1996-01-01), Urade et al.
patent: 5486869 (1996-01-01), Cooper
patent: 5528303 (1996-06-01), Bee et al.
patent: 5619275 (1997-04-01), Tults
patent: 5654764 (1997-08-01), Suh
patent: 5754250 (1998-05-01), Cooper

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Sync separator and video signal detector circuits does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Sync separator and video signal detector circuits, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sync separator and video signal detector circuits will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-1731135

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.