FtG (01/20/83)
I saw an image stabilizer advertized by Radio Shack for $60- question, if these things fix vertical stability, do they also allow one to watch pay channels with the vertical synch taken out? Does anyone out there own one of these beasts and can send me info on what it is they are supposed to do? FtG at !rochester
she (01/21/83)
Image stabilizers retail from about $100 on up to $500. I assume standard electronics discounts are available. Major manufacturers include Showtime Video Ventures, Vidicraft, VIP and HMS. The cheaper models offer only one type of image enhancement (vertical sync regeneration) and do not include RF converters (not needed for direct VCR-to-VCR copying).
karn (01/21/83)
The methods used for on-air and cable channel scrambling are quite
different from "copyguard" (TM?), and none that I know of distort vertical
sync - they all work by screwing up horizontal sync. Oak's ON-TV system
uses a sine wave turned off during the vertical interval (to prevent
transmitter overmodulation), while WHT in Newark and most cable systems
use a simple square wave ("posthole") sync suppression scheme. The sound
is usually on an FM subcarrier (like SCA on FM broadcast stations) or a
suppressed-carrier DSB subcarrier (like the stereo difference info in FM
broadcasting).
On a related topic, does anyone have info on HBO's satellite scrambling
scheme? I suspect strongly that they will be going to digital audio
(notice their newly proclaimed stereo ability). I also think that going
digital, even without high speed encryption, will be enough to deter
most "pirates", so there may be some hope for those of you with
knowledge of digital modulation techniques.
Phil