jmsellens@watmath.UUCP (John M Sellens) (08/13/84)
This query has its roots in pay TV, but has nothing to do with unauthorized reception etc..... Up here in Canada, pay TV is an extra service that you pay for on top of your regular cable TV charge (which I understand may not be the case in (some parts of) the US). The pay staions are on converter channels (i.e. not ordinary UHF or VHF frequencies). You must set up your magic boxes as follows: -----> converter -----> decoder ----> TV which makes it hard to use your TV's built-in cable converter (since you always have to keep it on channel 3 or 4). My question is: how hard would it be to make a small box that strips one channel out of the incoming signal for input to the decoder, then takes the output from the decoder and splices it back in to the other signals: -----> split ----all channels except the pay channel-> join ------> TV | ^ pay channel only | converted to ch 3 | | | ----------------> decoder ---------------------- Notes: decoder expects one channel coming in on channel 3. the 'join' would take a signal on channel 3 and move it back where it started (e.g. 26) the 'split' removes the scrambled 26 from all the other channels, converts it to channel 3, and sends it to the decoder. I envisage a small little box, with some (possibly inconvenient) way of setting the channel that you want to decode. Of course this whole idea falls apart when we start talking about more than one channel. Any comments?? Thanks! John M Sellens UUCP: {decvax|utzoo|ihnp4|allegra|clyde}!watmath!jmsellens CSNET: jmsellens%watmath@waterloo.csnet ARPA: jmsellens%watmath%waterloo.csnet@csnet-relay.arpa
lauren@vortex.UUCP (Lauren Weinstein) (08/14/84)
All sorts of games can be played with stripping out some channels, processing them (e.g. through your legal decoder) changing output channels, then reinserting back into the primary cable feed. There are many varieties of converters (single channel and "block") for moving channels around. HOWEVER: 1) By and large, you won't find most of these devices down at your local Radio Shack. This sort of equipment is widely stocked by wholesale cable TV supply companies, who may or may not be interested in dealing with you as an individual. Usually not. 2) The equipment can get expensive. Not so much the converters themselves (though they ain't cheap) but because... 3) ... the RE-INSERTING of signals, unlike splitting off of signals, can be a royal pain and may involve large investments in special sideband traps, filters, and other equipment, depending on how "crowded" your cable is with channels and what channels you are attempting to combine. Adjacent channel and other interference, resulting in herringbone and other fascinating effects, is very common in these situations. Many cable companies can't even get this right, which explains part of the reason for much lousy cable service. I have a very elaborate cable setup here, and know various people (some of them local (L.A.) TV broadcast engineers with similar systems. Most of us have given up on recombining signals, at least on our systems. The overall investment in equipment and ongoing time to keep everything aligned just isn't worth the hassle for us. A/B switches are much easier to setup and maintain, even though they aren't as convenient to use. --Lauren--