Late one night in 1982, two young college graduates from India sat in the computer lab at Kansas State University and tried to write a software program that could quickly calculate radio tower interference for new cellular telephone systems.

After a few hours crunching code, Rajendra and Neera Singh paid the lab supervisor $42 for their computer time and went home. The next day they sent the results to a friend of a friend: Wayne Schelle, an entrepreneur who was planning to build the nation's first cellular telephone system in the Washington-Baltimore are.

"We were just doing it for fun," Raj Singh said. "But one of Wayne's assistants called back and said, You have just saved us $80,000. Mr. Schelle insists you get paid.' I said, If he really insists, $1,500.' "

Since then it's been a straight shot upward for the Singhs, an extremely private Northern Virginia couple who parlayed that $1,500 into $1 billion in personal wealth and helped make cell phones an icon of the 1990s. They started as engineers to the cellular stars -- including Schelle, Craig McCaw, Nextel's Morgan O'Brien and Airtouch's Sam Ginn -- designing the complex grids of cellular antennas that relay electronic signals to and from mobile telephones.

Then, after working on many of the nation's first generation of cellular telephone systems, the Singhs shrewdly amassed a large portfolio of wireless properties here and abroad to become industry barons in their own right.

In his first interview after more than a decade in business, Raj Singh, 43, attributed his and his wife's success not only to knowing how the airwaves work but also to knowing their worth and possessing "calculated faith," a willingness to take risks based on good information.

In addition to their longtime engineering firm, LCC International Inc., the Singhs are now investing in new markets, including high-speed Internet and phone services through their part-ownership in Teligent Inc., financial news and information through a small start-up venture called Aether Technologies, and their holdings in wireless licenses around the world.

"They were among the first to have a real understanding of the radio spectrum and computer software and were able to bring the two together," said Craig Farrill, one of Singh's first clients and now vice president of strategic technology for Airtouch Communications Inc., a cellular company based in San Francisco. "Raj is a visionary individual, a person who is highly innovative, a nontraditional thinker."

The Singhs are living a life they never envisioned as students. "I wanted to come to this country not so much to make a lot of money, but because I could go to school here and become a professor," Singh said. "And then of course once you come here, then all the cultural influence is to make money."

And to spend it. Weather permitting, Raj Singh likes to water-ski to his office in Old Town Alexandria. And the family is building a ski home in Vail, Colo. But such indulgences, they insist, are recent and few.

"Our lifestyle even to this day hasn't really changed," he said. "We don't have a plane. . . . Sure, I have a ski boat. But it's only recently, really, that I've been buying some gizmos."

Their focus is on their two boys, 10-year-old Hersh and 8-year-old Samir. Neera, 39, is no longer active in the business. She has other jobs, as den mother for Hersh's Cub Scout troop, as room mother in Samir's school. "I'm having a fabulous time," Neera said. "I decided that my children were growing very rapidly and this is the time I'll miss and never get back."

The Singhs also are providing seed money to Marymount College for a telecommunications program and to programs for educating girls in Raj's home village.

Though they are among cellular's wealthiest entrepreneurs, the Singhs' continued success is not assured. Today's wireless industry is glutted with competitors fighting for often-meager profits. Singh's flagship company, LCC International, lost millions of dollars this year from bad loans to wireless companies that cannot pay for the licenses they bought at federal auctions, and many of its Asian customers owe millions of dollars on their payments. LCC recently installed a new chief executive to help revive the company.

Singh is betting much of his fortune on new wireless services, including competitive local phone and Internet services and mobile data applications. But he concedes that the market, and his own technological assumptions, may yet trip him up.

"I'm a believer that market forces are going to end up doing what they're going to do," he said. "So either you can swim against it or swim with it." From Kairoo to Kansas

They both came from India, but from different worlds.

Rajendra Singh Lunayach was the son of a schoolteacher and farmer in Kairoo, a village of 1,500 in the northwestern province of Rajasthan that had no electricity or telephones. Neera Tandon was the daughter of an upper-middle-class college administrator in the larger and more prosperous town of Lucknow, in the northern province of Uttar Pradesh.

They met in Kanpur in 1977, when Raj and a friend knocked on her dorm room door to borrow a pencil and paper during a visit to the Indian Institute of Technology. Raj Singh was home on a break from undergraduate studies at the University of Maine. He had been studying solar energy, but when an experiment in building solar cells from crystals led to a laboratory explosion, he decided chemical engineering wasn't his strong suit.

Singh transferred to Southern Methodist University in Dallas in 1979 after learning that an Indian professor there, Someshwar C. Gupta, was doing interesting radio engineering research in wireless communications. Singh's timing was good: Cellular and paging technologies had been around for years, but changes in regulations were about to make them available to the masses.

At SMU, Singh said, "my specialty was how you take the same amount of spectrum and get the maximum amount out of it." This efficient use of the airwaves would become central not only to his success as a radio engineer, but to the growth of the entire cellular industry. "I didn't completely understand all the implications," Singh said. "I just thought it was interesting."

After getting his doctorate in 1980, Singh went to teach at Kansas State. Neera transferred from the University of Maine to Kansas State, where they were married in 1981.

With $1,000 between them, for 500 shares each at $1 per share, the Singhs formed a private wireless technology consulting company in 1983 and called it LCC Inc. in Kansas. The initials stood for Lunayach Communications Consultants, reflecting Singh's family name. A Business Grows

After forming LCC, the Singhs worked for Schelle long-distance for about a year. He persuaded the couple to move to Washington and even provided them with a furnished apartment, equipped with an IBM computer, at 24th and K streets NW.

"They really were bright, hard-working people," Schelle recalled. "I told him I thought there was a tremendous amount of engineering business for someone of his and Neera's sophistication. But being out in Kansas made it very difficult."

As soon as they arrived, Raj and Neera Singh got busy. He identified and solved the engineering problems and outlined software projects; she handled the programming. "We basically closed ourselves for two months in our house and brought out the first real-world design software" for cellular systems, he said. "I never touched the computer. We didn't have a hard disk, so all night while we sat there and crunched the data, I changed the floppies so I could stay awake."

By this time Schelle (whose chief investor was The Washington Post Co.) had received his FCC construction permit to build a cellular franchise in the Baltimore-Washington area. He hired LCC to decide where the relay antenna towers should go, how many channels should go on each antenna, what frequencies to use and how to cram as much information as possible into a limited amount of airwaves.

Soon other new cellular businesses began to hear about LCC and the way the Singhs were writing sophisticated computer-modeling software that could dramatically reduce the time and cost needed to decide where to place cellular towers.

The Singhs' growing reputation caught the attention of a young entrepreneur named Craig McCaw. Already a minor celebrity in the industry for the way he used his family's cable TV money to snap up cellular licenses nationwide, McCaw surprised the Singhs one day in 1984 by calling to ask for a meeting -- then arriving 10 minutes later. "He said he wanted to see what it was like in our office without a warning," Singh recalled.

McCaw and Singh met again the next day for breakfast at the Jefferson Hotel. The meeting moved to McCaw's suite, stretched until 5 p.m. and marked the beginning of a close friendship. "He and I used to talk all the time," Singh said, recalling that McCaw said their "frictionless minds" could easily understand each other's ideas.

Working for McCaw and several of the regional Bell telephone companies, LCC's business and reputation grew. The company ultimately had a role in designing cellular systems in 28 of the 30 biggest U.S. markets. By 1990 LCC was earning $10 million a year, on sales of $24 million, and employing 100 people.

But as wealthy as the Singhs were becoming, their clients were growing even wealthier by owning the cellular systems LCC was designing. Singh said he was tempted to join the bonanza, but resisted: "We were too small; we couldn't do both. We didn't know how to hire people, borrow money, build companies. . . . So we forgot that business." Clients -- and Competitors

Instead, the Singhs found investment success elsewhere. In 1986 they risked $25,000 on APEX, a company that helped cellular carriers perform instant verifications on customers who were using their cell phones away from their home market area. Four years later, Electronic Data Systems Corp. bought the company for $50 million, netting the Singhs their first multimillion-dollar investment profit.

That sharpened Raj Singh's ownership ambitions.

Once again, Schelle was there to help. Having sold his Washington-Baltimore cellular license, Schelle was among the first to push for a new generation of cellular. It was a digital technology called PCS -- for "personal communications services" -- that would bring fresh competition to the two cellular carriers that had dominated each market. (In January he sold his stake in Sprint Spectrum here, one of the nation's first PCS networks, and announced his retirement.)

As an enticement to have Singh design his proposed PCS system, Schelle in 1989 offered him a stake in the license. "For a while I think he tried to stay very pure as an engineering consultant," Schelle said. "But it's tough. You see all these guys making a lot of money. . . . I could see him change from Raj the professional engineer to Raj the businessman. He became interested in ownership."

Singh accepted Schelle's offer but backed out three weeks later. "He called me one day and he said he wasn't going to be able to do it," Schelle said. "Some of his clients weren't pleased about him having a piece of the assets."

In one sense, the old-line cellular clients didn't want Singh doing anything that would hasten the emergence of a new generation of competing digital wireless phones. But it was more than that: Singh was an engineer, a consultant. Having an ownership stake in licenses, some clients believed, made Singh less of a consultant and more of a rival.

One such client was Craig McCaw. Faced with losing his biggest customer and offending his good friend, Singh honored McCaw's request that he turn down Schelle's offer.

"I did not especially feel good about it," Singh said. "But because of my respect for Craig and for business reasons, I decided that was the course of action to take. I hold no resentment. At the time I was disappointed, but not bitter."

"It doesn't look good to your clients if you have an equity stake" in other licenses, said McCaw spokesman Bob Ratliffe. "Craig's view is that you can never completely renounce your own self-interest."

McCaw declined to be interviewed for this story.

It wouldn't be the last disagreement between Singh and McCaw.

Morgan O'Brien, a founder of Nextel Communications Inc., came to Singh later in 1989. O'Brien had been driving across the country, buying out mom-and-pop owners of licenses for two-way radio service in hopes of stitching together a new nationwide cellular network. He wondered if Singh could help Nextel (then known as Fleet Call) design its system, which, like PCS, threatened McCaw and the other cellular incumbents.

"Initially I thought no way" would Singh agree to work with Fleet Call, O'Brien said. "But I met him, and his attitude was that he had always done engineering for people who competed against each other."

This time, Singh overcame McCaw's reluctance. "In the end, he said the right thing," Singh said of McCaw. "Craig said, Listen, if they don't work with you, they will work with someone else. I'd rather have them with a friendly consultant than someone else.' "

McCaw does not recall the incident, said his spokesman, Ratliffe. Today, ironically, McCaw is Nextel's biggest shareholder after selling his cellular empire to AT&T Corp. in 1995.

Singh and McCaw had their most bitter confrontation a year ago, in a dispute over a large bloc of airwaves that Singh had acquired in the early 1990s along with Myles Berkman, a successful Pittsburgh cellular and cable investor.

That tale begins in 1985. Xerox Corp. had persuaded the FCC to set aside frequencies in the 18 gigahertz portion of the radio spectrum for a new service to connect copiers and computers inside buildings without wires. But Xerox never developed the technology, and the service was widely considered defunct.

Identifying and seizing control of those frequencies was one of Raj Singh's most brilliant moves, observers say. Few noticed when Singh and the Berkman family applied to the FCC and over a five-year period were awarded licenses for dozens of cities. Once again, Singh's timing was impeccable: In 1993 Congress mandated the auctioning of such airwaves; but the Singhs and Berkmans got theirs -- potentially worth billions -- free of charge.

These licenses today are the chief assets of Teligent (formerly Associated Communications LLC), the company the Singhs and Berkmans recently took public. Teligent aims to provide wireless local phone service and Internet access to businesses nationwide.

That's a far broader use for those airwaves than Xerox had planned. McCaw's lawyers complained to the FCC in July 1996 that Associated's plans for the frequencies would interfere with McCaw's plans for Teledesic, a huge satellite-based Internet and phone project bankrolled by McCaw and Microsoft Corp. Chairman Bill Gates.

"Raj Singh and the Berkmans were very clever in picking up these licenses with nobody noticing, but they seem to be cobbling these licenses together to create a new service that's never received policy review," said Teledesic President Russell Daggatt at the time.

From Singh's point of view, he merely saw an opportunity for free spectrum that nobody else saw: "I simply thought that technologies are moving along in higher and higher frequency bands and this was the lowest frequency band that was available to apply for," he said.

The conflict was resolved in private talks between the companies and the FCC: Teligent would move its licenses to a higher frequency band. But in exchange for moving, the FCC granted the Singhs and the Berkmans four times more spectrum than they had at the lower band, at no charge. Critics called it yet another windfall for the Singhs and Berkmans. But the FCC agreed with Singh's engineers, who argued that the higher frequency posed costly technical challenges that required extra spectrum.

The gradual falling out between Singh and McCaw was now complete, something Singh says he regrets. "I think we both had some hard feelings on the Teledesic matter," he said. "But then, of course, he's the founder and creator of the Teledesic concept. And me being a big player in Teligent, we had to take sides. But I have great respect for him and I consider him a friend." From Engineer to Financier

In 1990, just as he began acquiring the Teligent licenses, Singh also bought his first cellular license -- a franchise in Mexico's Yucatan Peninsula that he purchased with Berkman. And the more work LCC got doing engineering abroad, the more Singh received offers to buy stakes in international cellular properties.

"I would say that 1990 was a transition point," Singh recalled. "Many of our customers were asking, Why don't you come with us and invest in these countries?' From 1980 to 1990 was more professional, personal growth. And 1990 onward was more financial growth."

To insulate Singh the licensee from Singh the engineer, and to raise cash for further overseas ventures, Singh in 1994 sold much of his LCC stake to the Carlyle Group, a Washington investment bank, and with Carlyle formed Telcom Ventures to invest in cellular properties abroad. Telcom Ventures, and the Singhs privately, then spent heavily on wireless properties -- a cellular concession in India; stakes in licenses in Portugal, Venezuela, Colombia, Honduras and Argentina; and, in 1992-94, two-way dispatch licenses in Mexico and Brazil, like those Nextel was buying in the United States.

The Singhs have since sold many of those investments, gaining $229 million from the $46 million invested since 1991, according to Telcom Ventures President Rahul Prakash. Included in that total is $134 million that the Singhs gained by selling Brazil's largest wireless communications network to Nextel in October 1996.

Today Singh has his feet firmly planted in both camps -- owning and operating wireless services and engineering other people's systems.

With Teligent, Singh is betting that the demand for high-speed, high-capacity data networks by downtown and suburban businesses will be the next wireless bonanza. His engineering team also is working on "third generation" wireless applications, such as mobile personal computing and wireless video conferencing.

"The good thing about the Internet and video telephone is, they require more bandwidth," Singh said, referring to the capacity of electronic pipelines. He sees the evidence in his own home: "My son spends more time on the Internet than I've spent on a computer my whole life." CAPTION: SINGH'S CLIENTS

The people Raj Singh and LCC have done business with over the years would fit comfortably in a Who's Who of the cellular industry. Wayne Schelle: The Baltimore entrepreneur built the nation's first cellular system in the Baltimore-Washington area. Last month, he sold his stake in Sprint Spectrum and retired. CRAIG McCAW: One of the pioneers of cellular, he sold McCaw Cellular Communications Corp. to AT&T Corp. in 1995 and today is assembling a new group of wireless, satellite and local telephone companies. He is the largest investor in McLean-based wireless provider Nextel Communications Inc. McCaw was among Singh's biggest engineering clients and a longtime friend, but Singh's moves toward owning wireless properties ultimately strained their business and personal relationship. MORGAN O'BRIEN: The founder of Nextel Communications, he bought out two-way radio licenses to put together a nationwide cellular system and went to Singh to have him help design it. CAPTION: THE SINGH EMPIRE

Raj Singh is chief executive of Telcom Ventures. Here is a look at the company's holdings and what they are worth: Publicly traded companies: - Teligent Inc. (33 percent of company), $541 million. - LCC International Inc. (58 percent), $102 million. Private holdings, total estimated value $430 million - Wireless Ventures of Brazil (19 percent) - Wireless Ventures of Venezuela (100 percent) - Infonet of Venezuela (50 percent) - Portatel cellular of Mexico (30 percent) - Avantel of Columbia (12 percent) - Aether Technologies, Owings Mills, Md. (22 percent). - Other investments of less than 5 percent, including Omnipoint Communications Inc., Teledesic Corp. CAPTION: RESUME Rajendra Singh Age: 43 Position: Chief executive of Telcom Ventures, which owns major stakes in a variety of wireless ventures. Education: PhD in electrical engineering from Southern Methodist University. Family: Wife, Neera, and two sons Home: In Mount Vernon Drives: Mercedes Benz Favorite books: J.R.R. Tolkien's "The Lord of the Rings" and Daniel J. Boorstin's "Creators" and "The Discoverers." CAPTION: Rajendra and Neera Singh, co-founders of LCC International Inc., used their knowledge of cell phone technology to build a $1 billion stake in the industry in only 10 years. CAPTION: EXPONENTIAL GROWTH (This chart was not available)