If you have ever consulted the on-screen directory to find your favorite cable show, chances are good that you watched Sealevel I/O at work. That's because when the TV Guide Channel needed digital I/O to handle the critical insertion link at all their local cable systems they chose the Sealevel DIO-16 Control Board.

The TV Guide Channel reaches more than 55.5 million American households, and viewers tune in over 100 million times per month-this means the channel outranks CNBC and CNN Headline News in viewership. It presents system-specific program listings for basic, digital, premium and pay-per-view programming. Hourly programming segments offer viewers tune-in information on entertainment, family programming, movies, sports, news and weather. The service is currently carried on more than 2,200 cable systems.

The TV Guide Channel features dynamic video segments, previews and consumer promotions. At prescribed intervals, local cable systems that subscribe to the TV Guide Channel have the option of inserting local advertising into the top half of the screen above the data grid. TV Guide provides a computer and a receiver, which the cable system connects to a satellite dish to download the data grid of programming information plus the video feed of promo segments. When it's time to start playing their local insert segments, a video insertion unit carrying this local advertising sends the host computer a precursor signal via digital I/O to indicate that its ready to take over the top half and insert the locally produced video. At the appropriate time, the host computer sends a signal to start the insertion. When the local insertion is complete the insertion unit sends another signal to the host computer and regular programming resumes.

The Upgrade Challenge

The installed subscriber base had originally been equipped with Amiga Commodore computers. Despite the demise of this manufacturer, that solution worked well for a long time because of a number of factors: the excellent video capabilities of the Amiga units, in-house expertise built up by years of working with these units, and the design stability inadvertently conferred by an out-of-production technology. However, TV Guide staff recognized that it would be necessary to upgrade their systems because replacement units-once widely available on the used market-were becoming increasingly difficult to find. The storage and memory capacity of their decades-old technology had become restrictive and the limited computer processing capability of the obsolete Amiga units hindered future development.

Reliability of the link is important to the revenue stream of the TV Guide Channel and local stations. Downtime results not only in repair costs but in loss of revenue from national and local advertising segments, plus a potential reduction in income from pay-per-view shows sponsored by the cable system.

Implementing the Upgrade

After researching multiple upgrade alternatives, TV Guide Channel engineering selected the combination of a Compaq model AP-500 PC and the Sealevel DIO-16 ISA Bus Relay Sensor I/O Control Board. The DIO-16 provides 16 channels of digital I/O to the PC. Eight isolated inputs are available that provide protection to all connected equipment, and eight reed relay outputs allow the PC to perform on/off of control the attached tape deck and other peripheral equipment. To date over 3000 of the upgraded computers with DIO-16 links have been installed.

Results

The Results "We've been very pleased with the way these units have worked out," says Bill Duwe, director of manufacturing for TV Guide Networks and the person responsible for installing and maintaining the entire hardware set in the field. "Sealevel has been very good on the delivery schedule, and they were accommodating on packaging and marking the cards so that we could work them into our units. They were very responsive as a company."