HD Antennas - receiving HD (UHF) over the air with an Antenna

Courtesy of Doug Finck (WPXT, and WPME): Note: Technical information included.

Channels 2-13 are currently referred to as VHF (very high frequency) and are lower in frequency than channels 14-69, which are the UHF (ultra high frequency). VHF channels go further on less power. For instance, channel 6 has a power output of about 360,000 watts. Our channel 51 puts out 3,000,000, almost 10 times the power. But channel 6's signal goes further and is easier to receive than our higher-powered signal.

In 2009, when all stations have to convert to digital, the government is also removing channels from the spectrum. From a regulatory perspective, they are taking all channels above 51. The remaining channels (2-51) will be licensed to broadcasters for digital transmission. To receive those channels, you would want an antenna designed to receive those frequencies (remember, receiving the frequency has nothing to do with the type of modulation being used…analog or digital). So, a VHF antenna will be fine for the lower frequencies, whereas a UHF antenna will be necessary for the higher frequencies.

Stations were given second frequencies to use during the conversion process. The overwhelming majority of stations received UHF frequencies. Because of the nature of digital signals, it turns out that VHF signals, and particularly VHF signals below channel 8, are particularly susceptible to interference (a computer operating near the TV can obliterate a signal), most TV broadcasters decided to stay with their new UHF frequencies and turn in their VHF signals. But because of the decades of branding that stations have had (WCSH will always be thought of as channel 6), the new digital system added a tricky element, the PSIP code which sends information to the digital TV. Each station has to send out a PSIP code to tell the new digital TV how to work, and, more importantly, how to label each station.

So our station, WPXT, analog channel 51, is broadcasting in digital on channel 43. But the PSIP code labels us as WPXT, channel 51. Your digital TV receives our signal at the frequency you used to call 43, but treats it as channel 51. For WCSH, who broadcasts digitally on channel 42 (I think), the PSIP displays it as channel 6. So to receive WCSH clearly, you need a UHF antenna, even though the label will tell you it is channel 6.

The "digital" antennas are nothing more than a combination UHF/VHF antenna, reduced in size to be less obtrusive. As I mentioned before, after the conversion, WMTW and WCBB will continue to operate as VHF stations (even though they will broadcast digitally) while the rest of the stations will be UHF (even though WCSH and WGME will still be displayed as channels 6 and 13….VHF channels…respectively).