Joseph Charyk, president of Communications Satellite Corp., clearly remembers the heady days of May 1965 when Comsat became the first commercial venture to transmit live television programming across the Atlantic.

The signals were imperfect, but the fact that the United States was seeing Britain live via satellite was considered a technological breakthrough.

The public takes those services for granted today, viewing frequent live coverage of events from all over the world as if they were coming from around the corner.

With the public's acceptance of that process, Comsat's role has expanded, as each day the firm transmits television, telephone, and other communications all over the world. The company is moving into ambitious new ventures, including the development of the nation's first direct satellite-to-home broadcast system.

"The thing that impresses me about the old stuff is that what used to be a remarkable thing is just accepted as routine," Charyk said. "Sadat is assassinated and we get television pictures five minutes later.

"The problem is never the communications. The idea that I can see an event or talk to anyone in the world is now accepted as a routine thing. Fifteen years ago that was unheard of."

Charyk, 61, was among the incorporators of the company when it was formed on Feb. 1, 1963, the year after Congress gave Comsat its private-sector charter in the Satellite Act. He has been a director ever since, and president since March 1963. No one is in a better position to evaluate where the company has been and is going than Charyk, who holds degrees in aeronautics and engineering.

Comsat is in the enviable position of being at the center of the so-called satellite revolution, a dramatic communications breakthrough that among other things has spawned the cable-television boom.

Set up under federal law to provide a focal point for satellite development, Comsat participates in international satellite activities, providing international satellite services through the International Telecommunications Satellite Organization (Intelsat). It is also the nation's representative to the International Maritime Satellite Organization (Inmarsat).

The company's Comstar satellites lease facilites to American Telephone & Telegraph Co. for domestic communications, and to the Navy and commercial customers through another branch, the Marisat system. In addition, the company manufactures products and provides environmental services.

In a recent interview, Charyk explained his enthusiasm about the company's old and, particularly, new activities. Those include the direct broadcast satellite (DBS) venture, through a subsidiary, Satellite Television Corp., and Satellite Business Systems, the billion-dollar fledgling partnership with International Business Machines Corp. and Aetna Life & Casualty; the company's proposed takeover of key pieces of the government's satellite program, and his general view of the firm's direction.

Further evidence of the company's expansion and the shedding of its staid, cash-rich image is that Comsat has just signed a tentative agreement for its largest acquisition, the $57 million purchase of Amplica Inc., a California electronics firm, and has agreed for the first time to provide full-time service to Australia.

Charyk works in a contemporary office at Comsat's L'Enfant Plaza headquarters overlooking the Potomac. His walls and table tops are liberally decorated with models of Comsat's satellites. He smiles and gestures easily as he discusses the company that has been his home for nearly 20 years.

Charyk paints a rosy picture of Comsat's future, and says that although some observers are skeptical, the company's investment of about $200 million in SBS, and its willingness, upon receiving government permission, to put more than $600 million into DBS, will soon pay off. Comsat has been reporting depressed results, including a 33 percent drop in third-quarter earnings announced last week, results attributed to the SBS investment.

"If you take out those things that represent investments in the future, the basic business is quite sound," Charyk said. "We're increasing our basic business. We're making these investments because we think there will be a significant payout down the road. We think this should be our roughest year. Early next year there should be a turnaround."

SBS, the high-technology satellite service for large businesses, has only recently started bringing in revenue, although Charyk said SBS hopes to show a profit in about two years, eight years after it was founded. "The demand is there," he contended. "The job now is installing the equipment and making it work at the prices we've quoted."

In fact, Bradford Peery, a vice president of the investment house, Paine Webber Jackson and Curtis, says SBS has "enormous" earning power and predicts the company will add $4.90 a share in profits to Comsat's stock in 1986, compared with a loss of $3.30 a share this year.

"The real question is not whether SBS will be profitable but a question of how rapidly they can bring in customers," Peery said.

If the Federal Communications Commission gives the green light, the direct satellite-to-home broadcasting system proposed by Comsat would bring three new television networks to homes later this decade. It also represents a sharp change in direction. But like SBS, Comsat can't go it alone in this project either, a fact dictated, according to Charyk, by both financial and marketing considerations.

"Even if we had no difficulty raising all the money, we would want to think twice about doing the whole thing on our own. We have never focused on dealing with the individual homewoner and that's the kind of experience a partner would, hopefully, bring," Charyk said.

A company with marketing expertise to bring the service directly to consumers and another to supply the equipment are likely partners. Although a proposed partnership with Sears, Roebuck & Co. failed last year, some industry sources suggest that Oak Industries, which builds cable equipment and runs subscription television services, and General Electric Co. are likely candidates.

If partners are found, STC could bring the company $7-a-share profits by 1990, Peery predicts, after losses of about $3.60 a share attributed to the venture through 1986.