DTV Primer

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Free TV

"Okay, so I'm not giving away a free TV! This is free TV programming you get by putting up an antenna--could be rabbit ears on the top of your TV or an old-fashioned antenna on the roof of your house.

Considering that programming from a cable or satellite service provider may cost you about $10,000 over the life of your new digital TV set, that's still a good deal!

To get this free digital TV, you'll need that antenna and a TV with a digital tuner. The best way to do this is to buy a digital TV with an integral ATSC (digital) tuner. Most all TVs are sold with an NTSC tuner inside, but those analog tuners are going to be totally useless really soon. All TVs bigger than 25" are required to have a digital tuner, and all smaller TVs after March 1, 2007 will also have a digital tuner built in. (Make sure you get a widescreen model.)

Bowtie Antenna

Antennas are now color-coded. To figure out what sort of antenna you'll need, consult www.antennaweb.org and/or www.checkhd.com.

These sites are only for outdoor antennas because there are more unknown factors that determine the quality of indoor antenna reception. The type of house construction, its orientation, the number of windows, etc. all play a factor. And don't expect to get good reception from an indoor antenna located in your basement. Roof antennas are in a much simpler environment.

That doesn't mean that indoor antennas don't work well for many people--they do.

Indoor antennas come in different shapes. Some are passive and others you plug in--those with built-in preamplifiers. The traditional rabbit ears work for VHF channels (2 - 13). Rabbit ear antennas often come with a loop for UHF channels (14 - 69 now, 14 - 51 after the transition ends). There are also UHF antennas sold by themselves, such as the bowtie antenna pictured above.

You need to use the proper antenna type (VHF or UHF) that matches the station's digital channel. Here is a table that shows TV stations' analog channel (the station's "number"), the channel they are now using for their digital broadcast, and their final channel assignment (after the end of the transition).

Note that the digital channel number you punch into your remote control is not the same as the actual digital channel number the TV station is using. Confused? See the discussion below.

New "smart" antennas are in development. These are multi-element phased-array antennas that can detect the direction and strength of a TV signal and electronically aim themselves to get the strongest signal. This sort of antenna will require a special connection that will be showing up on new digital TVs and probably on the digital-to-analog converter boxes that will become available in 2008. With smart antennas, you won't have to get up and manually turn the antenna when you turn to a channel that is being transmitted from a different direction.

It's easier to get a good digital signal than a good analog signal, all other things being equal, so if you can get a good analog picture using your antenna, you should be able to get a great picture from the same station's digital channel once they have "maximized and replicated" their digital coverage.

That has happened for stations that are now broadcasting digitally on the same channel they will be using after the transition ends (February 17, 2009). Other stations are required (until the transition ends) to use only as much power as is needed to reach 80 percent of their analog viewers.

Digital channel numbers

Digital channel numbers are now a little obtuse. While the analog channel still have the same plain number, a broadcast station's digital channels are the regular channel number plus a dot (.) or dash (-) and another number (1, 2, 3, 4, or 5).

Why so?

TV stations are now broadcasting on their old analog channels, as well as on another digital channel. Each channel consists of a 6 MHz block of spectrum, i.e. a range of radio wave (RF) frequencies. See a table of channel radio frequencies.

There are just so many TV channels, starting at channel 2 and going up to channel 69. At the end of the transition, all TV broadcasts will be moved into channels 2 through 51 (called "in-core" channels) and channels 52 through 69 will be turned back in to the government. The channel 52 - 69 frequencies (698-806 MHz) will then be auctioned off for other wireless services or used for additional radio channels for fire, rescue, or emergency response organizations.

While each TV channel can be used for either an analog or digital signal, digital broadcasts are much more efficient than analog transmissions. Using digital video compression protocols, a single high-definition channel (with five times the picture detail) can fit in the same channel space as a standard-definition analog channel.

Or, that also means you can fit five digital standard-definition channels into the same 6 MHz as one analog channel.

Or, unfortunately, many stations are trying to fit HD and SD channels into the same space, resulting in degraded picture quality.

Anyway, the FCC is now in the process of assigning permanent digital channels to all TV stations, to take effect at the end of the transition. Even if a TV station elects to use its analog channel for its digital broadcasts at the end of the transition, it cannot do so now (obviously that channel is being occupied by its analog broadcasts).

So it has been assigned a temporary channel to use for its digital broadcasts until the transition is completed (2/17/09). Here's that link again to the table of channel assignments.

Other stations may want to keep using their temporary digital channel assignment at the end of the transition so they do not have to change any of their digital transmission equipment.

In any case, every station wants to keep its channel number "brand" identity throughout and after the transition, no matter what actual channel their digital broadcast is using. Eg. "Channel 11" wants to keep being "Channel 11," and not "Channel 11" analog, "Channel 37" digital, and "Channel 29" after the transition ends.

Consumers don't want that confusion.

What's a body to do?

Answer: PSIP. Or "Program and System Information Protocol." This is a collection of hidden instructions that the local broadcaster puts in its transmissions, which is read by your digital TV. (It also includes programming information that can be displayed as a program guide by some of the newer digital TVs.)

This protocol will allow the TV station to keep its valuable "branded" analog channel number both during and after the transition, even if the actual digital channel number is something else. Example: after the transition to the new digital TV standard is complete, if a station's old analog channel number was "10" and its new digital channel number is "34," PSIP tells the digital TV receiver to tune to channel 34 when the consumer selects channel "10" with her remote control.

During the transition, each station will have an analog channel and a digital channel, and the latter can either be one high-definition channel or divided into as many as five standard-definition channels (or maybe one lower qualtity HD channel and one or more standard-def channel, but you get the point). So how do you tune in all these different channels that are coming from the same TV station?

PSIP makes it possible. No matter what the frequency the digital channels are actually being broadcast on, you would select the usual analog channel number to tune-in the analog broadcast, and then the same channel number with a ".1" added for the primary digital channel (usually the HD channel), and then ".2," ".3," and so on for the other standard-definition channels (if there are any).

Another example: A TV station's analog channel number is 17, and it is transmitting digitally on channel 48. You would select "17" for the analog programming, "17.1" for the digital HD programming (primary digital channel), and "17.2", "17.3", "17.4", etc. for any other standard-definition "multi-cast" digital channels the station may be operating.

(Some TVs use a dash instead of a dot to separate the numbers. Same difference. Eg. 17-1 instead of 17.1)

Obviously, after the transition to DTV is complete, the analog channel will disappear and the digital channel will occupy the main number (which may or may not be the actual broadcast channel number, but it will be the station's "number." Each station will retain its old familiar identity.