Doug Lung /
05.23.2008 12:00 AM
Washington Post Calls DTV Transition ‘Not as Easy as Advertised’
The Washington Post ran a number of interesting stories about the DTV transition this week. I received multiple copies of Kim Hart’s article Digital TV Transition Not as Easy as Advertised
that outlined problems viewers were having receiving DTV, even if they had acceptable analog reception.
The story references the Centris study of DTV reception problems, which I’ve discussed before in RF Report. Respected antenna and transmission engineer Dr. Oded Bendov is quoted as saying, “about half the viewers who now receive analog channels would not receive all of their digital replacements and that viewers more than 40 miles from a broadcast tower would probably need new equipment.”
The story includes comments from David Donovan, president of the Association for Maximum Service Television cautioning that viewers may have to position their antennas more precisely than they had to with analog signals.
Viewers mentioned in the article include a 26-year-old medical student who used rabbit ears with tin foil on them for analog reception, and a 77-year-old retired engineer who receives 24 analog stations, but lost five of them after switching to digital even after installing an antenna in his attic. He wants to put up a larger rooftop antenna, but said his condominium association won’t allow it.
The article highlights a problem with DTV education efforts—there isn’t enough focus on the antenna. The set of rabbit ears shown in the article may have provided adequate analog VHF reception, even if the signal fluttered when planes flew by or people moved around the room. At UHF DTV channels, a set of rabbit ears is likely to have an unpredictable directional pattern with many sharp peaks and deep nulls. The viewer probably would have had much better luck with Silver Sensor style log-periodic antenna with a preamplifier, or one of the new Antennas Direct indoor antennas described here last week. The retired engineer would probably have successful reception with a roof-mounted antenna, but in the attic the antenna will be affected by wiring, aluminum backed insulation, and ducting. It is also unlikely there’s enough room to optimize the antenna position. To receive both Baltimore and Washington, D.C. stations, a rotor may be needed. An indoor antenna with a preamplifier looking out a window in the direction of the transmitter sites may work better.
The Washington, D.C. area is a tough one for TV reception. Terrain blocks or significantly reduces signal strength in many areas. While most of the TV stations transmit from towers in the northwest part of the city, the urban locations make it impossible for stations to erect towers tall enough to get over the terrain. The main difficulty I’ve had trying to watch DTV on my laptop in the D.C. area is the “wrong side of the street/wrong side of the building” problem. Downtown, there are enough reflections and most stations can be received with a little care in positioning the antenna. I’ve found reception was difficult in hotels near Dulles Airport, where there aren’t as many buildings to reflect the signals around terrain blockage.
By the way, Kim Hart’s blog
has more reports of DTV reception problems where viewers had adequate analog reception, not only in Washington, D.C. but in other markets.