[net.video] VCRs vs. cable

smb@ulysses.UUCP (Steven Bellovin) (05/16/84)

Can one use a VCR to record a scrambled signal, then play it back later
through the cable company's converter?  Or does the recording process depend
on accurate recognition of sync signals, etc.?

	cable ---> VCR ---> converter/unscrambler ---> TV

I'm aware of other solutions, such as using a block converter between the
cable jack and the VCR; my interest is primarily academic.

fish@ihu1g.UUCP (Bob Fishell) (05/16/84)

(oo)
Two of the major encoding schemes, sine wave encoding and synch inversion,
are not compatible with the synchronization circuitry in a VCR.  The
VCR's servo control, which keeps the heads synchronized with the frames
of the picture, depends on a good, undistorted synch pulse to prevent
rolling and blackouts.  This is what add-on "synch stabilizers" take care
of; they reshape the synch pulse sort of like a Schmitt trigger.
-- 

                               Bob Fishell
                               ihnp4!ihu1g!fish