What is “Analog Pass-Through”?

The transition from analog over-the-air television broadcasts to only digital signals is scheduled to happen on February 17, 2009, just seven months from now (or Labor Day, if you’re in Wilmington, NC). Let’s just recap the key points; you’ll only be affected by this transition if you use an antenna to get your TV signals. Cable and satellite subscribers shouldn’t see any change in their service as a result of this transition(though you may see changes in your service for other unrelated reasons). The federal government has a rebate coupon program (http://www.ntia.doc.gov/dtvcoupon/index.html) that covers $40 of the cost for converters up to two TVs per household.

A converter takes the new digital signal — which you can receive on your existing antenna — and converts it to a signal that your old TV can receive (typically on Channel 3 or Channel 4, just like with older VCRs and game consoles). But here’s the problem; some television stations will still broadcast only analog signals after February 17, 2009.

How can that be? Aren’t all stations supposed to switch to digital? Actually, only the full-power stations have to switch. There are thousands of low-power stations across the country that are not yet required to switch (though many of them may do so anyway). About half of these low-power stations are local, community broadcasters, and some of these may even carry programming from one of the major networks. The other half are “repeater” stations, which help broadcast television signals into rural areas that get weak reception from the main transmitter.

As a result, there is good reason to want to be able to still receive analog signals. Unfortunately, many converter boxes only process the digital signals. If you want to watch analog broadcasts as well, you have to set up an antenna switch or splitter so that your television can get the analog signals as well. The broadcasters have been encouraging the converter box manufacturers to create models with an “analog pass-through” feature. This means that you run one wire from your antenna to the converter box, and then one wire from the converter to your television. The converter will receive the digital signal and translate it into an analog signal (typically Channel 3 or 4) that your television can receive. But it also passes through any analog signals received by the antenna, which your TV can then receive normally on their assigned channel.

This makes installation and operation much simpler. To watch digital broadcasts, you put your TV on Channel 3 or 4 (depending on how you’ve set your converter box) and use the converter remote to change channels. To watch analog channels, just use your TV’s remote as you always have.

A number of manufacturers have come out with converters that have the analog pass-through feature. I have not tested any of them, but two you might want to investigate are the Zenith DTT901 and the Radio Shack DTX9950.