Couple of Questions about Prevue Guide

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prevuefan07
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Joined: Tue Aug 19, 2014 9:01 pm

Couple of Questions about Prevue Guide

Post by prevuefan07 » Tue Aug 19, 2014 10:02 pm

I've read the wikipedia article, but still wondered a few things about prevue guide, the 88-93 version.

So, the previews in the top left or top right quarters of the screen were from the satellite feed (based in Tulsa, Ok, right? Basically wherever it first transmits to the satellite for download to then numerous cable companies) and the bottom scrolling half of the screen was from your local cable company. I was wondering, in segments of prevue tonight, how did it know what channel say an HBO movie was on the local cable system, because it could be channel 10 on one system, channel 23 on another, channel 35 on another, so how did it know to put the correct channel for the movie in the ad?

nwgatwcfan
Posts: 105
Joined: Mon Jul 05, 2010 5:52 pm

Re: Couple of Questions about Prevue Guide

Post by nwgatwcfan » Wed Aug 20, 2014 7:01 am

prevuefan07 wrote:I've read the wikipedia article, but still wondered a few things about prevue guide, the 88-93 version.

So, the previews in the top left or top right quarters of the screen were from the satellite feed (based in Tulsa, Ok, right? Basically wherever it first transmits to the satellite for download to then numerous cable companies) and the bottom scrolling half of the screen was from your local cable company. I was wondering, in segments of prevue tonight, how did it know what channel say an HBO movie was on the local cable system, because it could be channel 10 on one system, channel 23 on another, channel 35 on another, so how did it know to put the correct channel for the movie in the ad?
Before the listings are downloaded into the system, the Prevue software would receive the local cable channel lineup. The channel lineup would control channel numbers for both the listings and the upper portion.

A command would be sent through Control Data to advise which network it was being shown and the system would parse and find the channel number and display it on the screen.

Thanks,
Steven.

prevuefan07
Posts: 3
Joined: Tue Aug 19, 2014 9:01 pm

Re: Couple of Questions about Prevue Guide

Post by prevuefan07 » Wed Aug 20, 2014 7:30 pm

Before the listings are downloaded into the system, the Prevue software would receive the local cable channel lineup.
Receive the lineup from where? The office in tulsa where the satellite feed was uoloaded to a satellite for download?
The channel lineup would control channel numbers for both the listings and the upper portion.
Yeah, but it would have to match the right ones to the right prevue's, say if total recall was showing that came from the satellite feed, whereas the channel listings didn't. They would have to be matchedf right?
A command would be sent through Control Data to advise which network it was being shown and the system would parse and find the channel number and display it on the screen.
from the Tulsa Office you mean?

Thanks,
Steven.[/quote]

nwgatwcfan
Posts: 105
Joined: Mon Jul 05, 2010 5:52 pm

Re: Couple of Questions about Prevue Guide

Post by nwgatwcfan » Wed Aug 20, 2014 9:33 pm

Receive the lineup from where? The office in tulsa where the satellite feed was uoloaded to a satellite for download?
The lineups, control data, and listings were sent digitally over the VBI (vertical blank interval) signal from the satellite feed. The satellite receiver would take the data from the VBI and send it using the serial port on the back of the satellite receiver to the back of the Amiga. Originally the data feeds started on WGN-TV satellite channel, then went to Prevue's own satellite feed on Satcom F4 - Transponder 8.
Yeah, but it would have to match the right ones to the right prevue's, say if total recall was showing that came from the satellite feed, whereas the channel listings didn't. They would have to be matchedf right?
They would be matched. The control data handled which side of the screen was displayed in the upper half. I want to say that there is a file on the Prevue disk that held the data for the promo IDs (which my conjecture would be the title and channel ID, and possibly the date/time of the program.) This part I think we are still trying to figure out.
from the Tulsa Office you mean?
Yes. All of the data feeds and software would be created and sent from the Tulsa office. Also, the satellite feed for the promos would also come from the Tulsa office.

Good questions. I wished I had better answers.
Thanks,
Steven.

tin
Posts: 544
Joined: Sat May 08, 2010 9:54 pm

Re: Couple of Questions about Prevue Guide

Post by tin » Sat Aug 30, 2014 6:57 pm

Just to say the data and control streams we now know were actually audio on the audio subcarriers, not VBI, and these were demodulated to serial data by a card physcially inside the Amiga (although the data did feed back out of the card into the serial port, it was only connected to the ISA bus inside the Amiga, to which the Amiga itself is not connected :D ).

The data stream contained coded lineups for each cable system that Prevue Guide worked for, so the box would listen for its custom channel lineup.

The channels were all given short codes and the box would store (and later also cache to disk) the listings for the channels it knew it had in it's lineup. This included regional variations by having seperate channels with differing codes, e.g. FOX015 is seen in the image that AriX had found all those years ago, presumably the 15th variant of FOX. The time offset was handled by the box being coded to it's local timezone and adjusting the listing times accordingly. I think the raw data listings were all adjusted for whatever timezone Tulsa is in AFAIR.

For the upper part (I assume) extra data - programme name, ordering instructions for PPV etc also came across the data stream seperately. The control stream was exceptionally slow (300 baud we think, because of the way it was transmitted into the Amiga) so must only have indicated which promo was running in video on either side of the screen. The Amiga could make the choice of which one (or both) to cover up, and what text to display based on its channel lineup - i.e. if it included one or both of the channels.

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