NEW YORK — Think the digital-TV transition is over? Not quite.
Many viewers have found 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. But as signals in the airwaves, 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 some of the UHF band to cellphone carriers, leaving less space for TV channels. Another portion is planned to be used for emergency services.
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.
More than 50 VHF stations have applied to increase signal power.
The power increase helped WPVI punch through to a lot of viewers, but the station still gets calls.
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, though there had been clues it would happen there too.
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.
TV watchers with indoor antennas had the same problem with VHF stations when they were analog but often suffered through it. They would get a poor, snowy picture and decent sound, and considered that good enough. But because digital is an “all-or-nothing” technology, the weak signal they get on digital isn’t enough to produce a picture at all.
Some TV viewers simply have the wrong antennas. For years, “HDTV” antennas were sold that brought in only UHF.
Andy Couch, a Web developer in Austin, Texas, installed one in his attic and was happy with it until this summer, when the local Fox station, KTBC, disappeared from his set. It had moved its digital signal from UHF to VHF.
“Now I have to get a VHF antenna for just one channel? No thanks,” he said.
Another problem is that FM radio stations can interfere with VHF TV channels.
Improving reception
Here are some suggestions:
• Rescan your converter box or digital TV to make sure it finds all available channels. Some stations moved to new channels after the analog shutdown.
• Make sure you have the right antenna. In most major markets, there are now some stations in VHF. Antennas sold a couple of years ago as “HDTV” models will do a poor job of pulling them in. VHF indoor antennas have telescoping “rabbit ears.” UHF antennas usually have loops of wire. Combined antennas have both, though a new generation of combined antennas come as flat plastic boxes. See the Federal Communications Commission’s antenna page, /consumerfacts /dtvantennas.html
• Learn to use the signal meter in your converter box or digital TV. It’s a scale that can be brought up on screen, telling you how strong a signal you’re getting. That helps a great deal in aiming an antenna.
• Place your indoor antenna near a window, preferably on the side of the building that faces the TV towers.
• If an indoor antenna doesn’t work, consider an outdoor antenna. Purchase and installation could run about $300.
• If you have an outdoor antenna, check that it’s aimed at the towers — old antennas can drift.
• If channels 7 through 13 are hard to get, try installing an “FM filter” on the antenna line to eliminate interference from radio stations.
• Find more tips, go to /consumerfacts /troubleshootguide.html.
