Hughes Signs Contractors for Satellite Service : Broadcasting: Digital Equipment and Network Computing will aid plan to deliver 150 TV channels by 1994.

Hughes Aircraft Co.’s ambitious plan to launch a 150-channel satellite-to-home TV service in 1994 took another step forward with the announcement Thursday that the Los Angeles technology company has signed two key contractors.

Digital Equipment Corp. of Maynard, Mass., the world’s largest supplier of computer networks, was tapped as prime supplier of hardware for the service’s billing system. Network Computing Corp. of Charlotte, N.C., will provide the billing software. The deal has a potential value of as much as $100 million to the two companies over 10 years.

Hughes’ satellite project, which is backed with $500 million from its corporate parent, General Motors Corp., represents its most far-reaching attempt yet to expand its commercial and civilian businesses to offset dwindling Pentagon contracts.

DirecTv, as the system is named, is nothing if not sweeping. The system plans to deliver around-the-clock programming on 150 channels by bouncing video signals from two Earth-orbiting satellites to rooftop receiving stations available to subscribers.

The first satellite is scheduled for launch late next year, and Hughes has said the service is expected to begin in early 1994. The company projects that the system could attract as many as 10 million subscribers by the end of the decade.

But the success of the project is far from certain. The rooftop receivers--which will be about the size of a dinner napkin--will initially cost $700 each, too steep for most consumers. The service is also likely to face competition from a growing array of entertainment and information sources, including cable TV operators and telephone companies.

Nevertheless, Hughes remains committed to the project, even overcoming the loss of its initial three partners in the deal. The service was originally unveiled as Sky Cable in early 1990 as a joint venture of Hughes, National Broadcasting Corp., Cablevision Systems and Rupert Murdoch’s News Corp.

But the partnership fell apart within a year. Hughes decided to go it alone, relying on its expertise in satellite technology and contracting out the remaining portions of the project.

Hughes said it expects to name the first of its programmers within the next two months.