TV Calls for Cell Phones
By Marc Weingarten, Thu Jun 27 00:00:00 GMT 2002

As the cell phone market rapidly heads towards saturation, a handful of engineers are seeking out the road less traveled.


As the cell phone market rapidly heads towards saturation, and the existing spectrum groans and strains to keep up with the exponentially growing traffic, a handful of engineers are seeking out the road less traveled. Trawling for untapped pathways that could help ease the burden of the current cell traffic glut, a company called SIGFX has landed upon the idea of using an unused portion of the television broadcast signal as a prime candidate to send and receive cell phone calls.

The advantages of using television signals for cell phone traffic are potentially enormous. For one thing, infrastructure costs would be held to a minimum. Instead of building new cellular towers, carriers could just piggyback onto existing TV towers for services. Cell traffic could provide a new revenue stream for TV station owners, who could also provide cell phone service to under-served “dead zones” in rural areas. “If you don’t have a lot of infrastructure costs, there’s an interesting profit margin,” says SIGFX Chief Executive Officer Dr. Dallas Nash, an engineer who has spearheaded research into TV phone traffic.

An Unlikely Source


Based in Ridgeland, Mississippi – a tiny southern city that’s no one’s idea of a fertile hi-tech incubator – SIGFX may well be on the cusp of a technology that could inalterably change the global telecom landscape. That’s a remarkable feat for a company is well outside the traditional R&D loop. But what’s perhaps even more surprising is the unlikely alliance that has sparked this innovative new approach to telecom. Jimmy Rogers, a veteran insurance executive in Mississippi, had been besotted with the idea of using television signals to carry cell phone traffic since 1995, but despite his persuasive pitch to countless engineers and potential financial partners, he could never convince anyone to back the project without the hard science to support his theory.

“I’d been looking halfway around the world to find someone who would take this on, but no one would consider this being a possibility,” says Rogers, who speaks in the lilting cadences of a true southern gent. “Even Dallas didn’t think it would work.”

Dallas Nash, who has spearheaded the project, is a veteran communications consultant for countless organizations, including the Defense Department. In 1991, Nash sold his company Dataplex, which specialized in database management and image recognition, among other things, to Dallas-based Affiliated Computer Systems. By the mid-nineties, he was financially comfortable, and looking for new challenges.

As it turned out, Rogers and Nash attended the same church, and Rogers had been impressed with a multimedia presentation that Nash had mounted for a new building project. On this basis alone, Rogers in 1996 approached Nash with his concept. Rogers, in fact, had no knowledge of Nash’s extensive hi-tech resume, only that he seemed like a tech-minded fellow. “Jimmy kept saying, ‘this is gonna work,’ but I was skeptical,” says Nash. “I understood the pitfalls, because of my background.”

Think Outside of the Basestation


Among those pitfalls is the fact that TV signals are powerful, while cell phone signals are considerably less so. How could a cell phone not only handle a big TV signal without crashing, but conversely, how could a phone send a signal to the TV receiver that could be properly separated from other signals and then routed?

These were just two of the vexing issues confronting the pair. Nash agreed to try and put together a prototype cell phone that would be able to pick up television signals. Using equipment that he owned, Nash jerry-rigged what he calls “the world’s largest cell phone.” This “phone” consisted of a series of computers and signaling equipment in a van.

“We has some advanced signal processing boxes, some 400 onboard processors,” says Nash. “We also had some special communications equipment that would allow us to manage the signal, and all of that became our cell phone.” Nash drove the tricked-out van 14 miles away from Channel 46, the local TV station that agreed to participate in the experiment, to see if they could relay a signal. Sure enough, after doing this enough times, a faint cell signal eventually materialized. “We thought, ‘hmmm,’ then spent a year fleshing out that ‘hmmm,’” says Nash.

There were countless kinks to be worked out. A massive, Van-sized cell phone is one thing – trying to pack all of that processing power into a handheld device is another. Nash’s current phone prototype contains four small processing chips, enabling the unit to send signals that could be received on UHF or VHF. But a powerful battery is required for all of that processing power

After much trial and error, Dr. Nash landed upon the idea of using a lithium-ion battery to fuel the processors. “The power quotient for this phone is more than a standard cell, but not dramatically so,” says Dr. Nash. “One big advantage of the lithium-ion battery is its moldability. We could build a battery case out if it. Lithium-ion batteries also don’t crack or get fuzzy over time.”

According to Dr. Nash, numerous manufacturing companies have expressed interest in the phone. “This is something new for them,” he says. “This phone doesn’t require them to retool their existing plants, even though the board structure is obviously different. Besides, the handset market needs a new niche at this point.”

Creative Calling Plan


SIGFX has also patented something called a Return Signal Processor, which segregates the weak phone signals from other signals and then routes the calls. According to Dr. Nash, this processor can be built for a fraction of the cost of building a new cell tower.

In order for the TV-cell phone to provide a formidable challenge to traditional cell phones, however, far more capacity will be needed. SIGFX’s initial experiments have used the vertical blanking interval, that thin slice of the spectrum used for services like closed captioning. The vertical blanking interval wouldn’t be able to accommodate more than 60 calls at a time. Far greater capacity will be needed to handle a large volume of calls. Nash hopes that smaller regional stations that don’t operate 24 hours a day might want to provide phone service during downtime.

With this concept in mind, SIGFX has made overtures to Asian territories like Malaysia, South Korea and China – countries that have an excess of TV spectrum capacity but minimal cellular penetration. “There are literally thousands of TV towers in those countries,” says Dr. Nash. SIGFX has entered into what Dr. Nash calls a “memorandum of understanding” with ZTE Corporation, China’s largest telecom company.

Thus far, however, TV-enabled cell phone calls are still only possible in the Mississippi labs of SIGFX. Dr. Nash is still trying to work out the kinks in the phone prototype, as well as the challenges of trying to open up enough of the TV spectrum in various territories that might want to implement it. But there is no shortage of major players waiting for the day that Dr. Nash and his R&D team work it all out. “There are about 76,000 TV towers out there,” says Dr. Nash. “There’s an existing analog communications system out there. We’re just recycling the existing spectrum.”

Marc Weingarten is an LA-based writer whose work appears in Business 2.0, The Los Angeles Times, Smart Business, Entertainment Weekly, The Village Voice, Vibe and San Francisco magazine.