EPG/Prevue Guide Videos

[AriX]

The VBI stuff here and on Wikipedia was from swest77... I believe he either remembered this incorrectly, or it was explained to him badly at TV Guide, because it turns out that this data was never sent over any form of VBI anywhere. It was sent as an audio feed that was on the same transponder as WGN, and later the Prevue Guide backhaul - therefore, only one input was needed, and one card decoded data from one frequency, one card switched audio between the three audio frequencies, and one card overlaid video from another frequency. swest posted about this possibility here.

Just to keep the forum up to date after our chat on IRC, I've gone back to swest's post and can see now that the data was sent through via another audio subcarrier. Makes a lot of sense - especially with the Atari EPG Jr, as it basically was constantly loading from tape! Right so that's the VHS idea out of the window

Right. My belief that the data was relayed via WGN's (and later also via the Prevue C-band backhaul video's) VBI's is information that came to me through suits. And I always just assumed it was true because whenever I looked at WGN's VBI directly in those days, it was visibly jam-packed with truckloads of data.

However, Ari's source isn't a suit, but rather worked deep in the technological trenches of it all. So ever since he found this out, I've simply assumed I was misinformed. In any case, that old "EPG DATA" subcarrier listing I found (from the EPG days) would seem to confirm it. I.e., by the time Prevue Guide rolled around, there were probably 5 audio subcarriers. 1) Left, 2) right, 3) music, 4) 2400 baud data, 5) control (75 or 110 baud, can't remember).

I believe the 2400 baud stream was actually 9600 baud as of some time in the early 90s, and the control stream was 110 baud (because that was the fastest that could be reliably maintained when bit-banging with DSR)

[swest77]

Hmm. I'll reply to that subject in this thread, so we aren't needlessly duplicating things.