DTV growing pains continue

NEW YORK | Think the digital TV transition is over? Not quite.

Many viewers have found that they can’t pick up certain stations after the switch, even with the right TVs or converter boxes. The stations are still trying to figure out ways to help them tune in.

The main problem is that when the last major stations turned off their analog TV on June 12 to broadcast entirely in digital, some of them moved their digital signals from the UHF frequency band (channels 14 to 69) to VHF (channels 2 to 13). To most viewers, these channels are just different numbers on the remote. As signals in the airwaves, however, they have very different characteristics.

VHF hadn’t been used much for digital signals, and there were indications that there would be problems with the switch, partly because viewers had inadequate indoor antennas. Still, the switch went ahead.

Since then, at least 20 VHF stations have asked the Federal Communications Commission to move their digital signals back to UHF, and more would like to do so. However, the government has sold off some of the UHF band to cell phone carriers, leaving less space for TV channels. Another portion is planned to be used for emergency services, which was another reason for the digital TV transition.

Philadelphia’s ABC affiliate, WPVI, switched its digital signal to channel 6 on June 12, and got thousands of calls per day from viewers who couldn’t find the station on their sets anymore.

Within a week, WPVI got emergency permission from the FCC to quadruple its transmission power. It could do that because the closest station that also uses channel 6, in Binghamton, N.Y., also wanted to increase its power, which meant it wouldn’t be overwhelmed by the stronger signal from Philly. In other cases, however, increasing power is a complicated proposition involving several stations. More than 50 VHF stations have applied to increase their signal power.

The power increase helped WPVI punch through to a lot of viewers, but the station still gets calls every day. Hank Volpe, director of engineering at WPVI, says he understands the loss of the station’s UHF slot, “but I would have loved to have a UHF channel to play with.”

Mark Colombo, a TV enthusiast and electrical-engineering student who maintains an online database of the country’s TV stations, said “everyone who had any sense” knew that broadcasting digitally on channel 6 or lower would yield terrible reception. Those channels are susceptible to interference from household electronics, spark plugs in passing cars and distant thunderstorms.

What was more surprising was that channels 7 to 13 also had problems, although there had been clues it would happen there, too. WVUE in New Orleans, a Fox station, turned off its analog signal in December, before most other stations, and moved its digital signal to channel 8. The reaction was immediate.

“We fielded thousands of phone calls,” said Al Domescik, WVUE’s director of engineering. “We did everything we could. We talked to people on the phone. We sent technicians out to people’s houses. We brought antennas to people’s houses. We just kept beating our heads against the wall for months.”

In June, the station started simulcasting on UHF, which mollified most viewers.

WVUE’s experience was repeated more than six months later, when Chicago’s ABC station, WLS, tried to move its digital signal to channel 7. It says it got nearly 7,000 calls from viewers about reception problems in the week after the transition. Nearly half of the homes visited by the FCC in WLS’ service area in late June had inadequate indoor reception.

WLS tried doubling its output power, but it wasn’t enough. Now the FCC is letting it move to UHF channel 44.

TV consultant Peter Putman said a lot of reception problems for digital VHF channels can be attributed to the fact that VHF antennas need to be large. The long rods on an outdoor antenna are for VHF reception, and it’s difficult to make a compact indoor antenna with good VHF performance.

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