New service for personal computers offers direct link to satellite

Personal computer users may soon be hitching their machines to a ''star.'' Actually, the star is a communications satellite. And a Chicago company - Satellite Broadcast Network Inc. (SBN) - has announced that it will begin providing direct satellite broadcast of information to PCs by the end of the year.

Direct satellite broadcast of television has been under consideration for years, but has not become a commercial reality. ''We think that the market for data is separate from video,'' explains William Van Slyck Smith, president of SBN.

For $795 - the same cost as many modems (the black boxes that allow computers to communicate over the telephone) - SBN will provide interested computer users with a one-meter satellite dish antenna, the electronics, and the software necessary to pull large amounts of information right out of the sky.

Essentially, SBN subscribers will be trading the cost of the telephone charges required to extract information from current electronic databases for a one-time investment and a basic monthly charge equivalent to a cable-TV hookup, says Mr. Smith.

Of course, he anticipates much of the information will be available only with a surcharge, as is the case with information services available over the telephone. (Base rates for current information services typically run from $5 to

At this point, the only information SBN has to broadcast is weather data. The company is ''like ABC without 'The Love Boat,' '' Smith acknowledges. They need information to broadcast to attract customers, and customers to attract information broadcasters. But they have nearly concluded negotiations for getting stock quotes, Smith claims. SBN envisages small brokerage firms as some of their first customers.

The company has some high-flying aspirations. Among the applications they see for their service:

* Small branch banks could be equipped with a dish and personal computer to receive mortgage rates and other pertinent financial data.

* Subscribers might be able to receive electronic versions of their favorite newspaper. The system could also prove a less expensive way for newspapers to receive the news wire services, upon which they rely heavily.

SBN's system is capable of delivering tremendous quantities of information. The current standard rate at which information is transmitted over the phone lines is 300 characters per second, a comfortable reading speed. The satellite dish can provide eight channels, each transmitting information at 9,600 characters a second. At such a rate, one channel could transmit all the information contained in this newspaper in about five minutes.

Unlike current computer information services, however, SBN's system will be one-way rather than two-way. That is, information will travel only from the satellite to the computer, not from the computer to the system.

This means that the personal computer user cannot interactively search and sort through the information in the remote computer or send messages to other users. To a certain extent, however, the high data rate of the satellite network can minimize this difference. (When data - say, stock prices - are transmitted over and over again at a high rate, the computer user can pick out specified information in a way that seems interactive, Smith says).

All the information SBN broadcasts will be encrypted (scrambled in a secret code) so that only legitimate subscribers can read it. Each receiver will have a unique identification, so that information can be targeted to specific groups of customers.

The system uses microwaves of 12 GigaHertz, a band planned for direct broadcast video and currently under-utilized. More powerful satellites planned for the near future will allow the use of considerably smaller and less expensive dishes.

With current equipment and prices, satellite distribution is less expensive than using the phone lines with groups of more than 1,000, he calculates. And the costs are virtually independent of the number of subscribers.