The DTV Transition’s Dirty Little Secret

FCC says only 74% of stations will be operating in the UHF band after the DTV cut-off date.

The DTV Transition’s Dirty Little Secret
If you've installed an HDTV antenna, there's a good chance you'll be tweaking its position on February 17, 2009.
Jason Knott · September 19, 2008

The government has done a great job informing the general public about the upcoming transition to digital broadcasts on February 17, 2009.

But tens of thousands of consumers, who followed all the government advice and bought the converter boxes, will still wake up that winter day to find several channels have turned to “snow.”

And for some, there’s not much they can do about it until that day.

Be Ready to Tweak Some Antennas

About 90 percent of all digital TV broadcasts are currently in the UHF band. According to the Federal Communications Commission (FCC), only 74 percent of stations will be operating in the UHF band after the cut-off date. Click here to see where your city stands. (pdf)

Another 24 percent will be switching into the High VHF band, while the remaining 2 percent will be in the low VHF band. (Note: These numbers have been rounded.)

What does this mean for integrators? It could mean thousands of customers who relied on custom installers to prepare them for the transition with an HD antenna might be screaming into the telephone or flooding your email that day because they don’t realize they need to adjust their HD antenna.

It also means that on February 17, 2009 you’d better be “all hands on deck” for simply going out and tweaking antennas, if you’ve installed a lot of HD antennas. Wipe the calendar clean of new installations that week.

Digital Broadcasts to Move to VHF Frequency

Here’s what’s going on: After the analog shut-off, some stations will move their digital broadcast frequency from UHF to the now-vacant VHF frequency that they were previously using for analog.

One reason broadcasters are doing this is because it requires less power to broadcast VHF. In other words … it’s cheaper.

WABC in N.Y. will move its digital channel currently in UHF to its “old” frequency of channel 7 — High VHF, 174-180MHz. Some stations are making the switch early so customers can “find” their over-the-air signals. And Wilmington N.C. has already adopted the DTV transition.

Some stations are tweaking their frequency locations, but after February 17, 2009 all of these changes are permanent. The FCC ruling is considered final. (pdf) So the “channels” or frequencies of TV channels do not change after the DTV transition. The channels remain 6 MHz wide and are exactly as they were before for well over 50 years.

The only difference is that the UHF band shrinks after the cut-off date, topping out at 700MHz. Channels 52 through 69 will no longer be active for TV. These frequencies are being auctioned by the government for other uses.

Therefore, the “new” UHF band will be 470 MHz to 700 MHz, about 100MHz smaller than the UHF band as it exists today. 

The VHF bands remain the same: low VHF (channels 2 to 6) will be between 54 MHz and 88MHz, while High VHF (channels 7 to 13) will be in the 174 MHz to 216MHz range. Regardless of band assignments, all full-power TV stations will broadcast digitally after the February transition.

FCC Explains

Here is the FCC’s explanation from its Web site:

What are the channel assignments for digital television?

Under the FCC spectrum plan, we have provided most existing broadcasters with access to a 6 MHz channel for digital broadcasting within a core digital TV spectrum, i.e., TV channels 2 to 51. Because of the limited availability of spectrum and the need to accommodate all existing facilities with minimal interference among stations, however, during the transition some broadcasters would be provided DTV channels outside of this core spectrum (channels 52 to 69). These broadcasters would have to move their DTV operations to a channel in the core spectrum when one became available. Broadcasters whose existing NTSC channels were in the core spectrum could move their DTV operations to their NTSC channel at some time in the future. Broadcasters whose DTV transition channel and existing NTSC channel were both outside of the core area could obtain a new DTV channel when channels in the core spectrum are recovered.  After the transition period (2006), the VHF channels (2-13) will remain available for DTV and the analog TV service will end on all channels.

Another thing that could add some confusion among your clients is the use of “virtual channel” tags. This is being done to maintain “branding” of the TV channel.

For example, WCBS in the New York market is and has been known as Channel 2 (analog) and Channel 2 (DTV) but its actual DTV channel is currently UHF 56 (with a frequency of 723 MHz).

But, after the DTV transition, the UHF band will not go higher than UHF 52. So WCBS will change to UHF Channel 33 but still be referred to as Channel 2.

So all in all, the DTV transition will be smoother for some than others.

  About the Author

Jason has covered low-voltage electronics as an editor since 1990. He joined EH Publishing in 2000, and before that served as publisher and editor of Security Sales, a leading magazine for the security industry. He served as chairman of the Security Industry Association’s Education Committee from 2000-2004 and sat on the board of that association from 1998-2002. He is also a former board member of the Alarm Industry Research and Educational Foundation. He is currently a member of the CEDIA Education Action Team for Electronic Systems Business. Jason graduated from the University of Southern California. Have a suggestion or a topic you want to read more about? Email Jason at [email protected]

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