Digital TV gets a step closer

Vouchers to help pay for conversion to hit the mail

Experts said consumers should also be careful when shopping for antennas. While some companies are labeling their antennas as "digital" or "HDTV," any antenna that can receive both VHF and UHF signals will work for receiving digital signals.

Another concern raised by communications officials is that some converters won't be able to receive analog signals transmitted by so-called "low-power" stations, which will be allowed to continue broadcasting in analog after next February.

They suggest consumers consider boxes that can pass analog signals through to the TV set. Boxes with this capability are noted on the list of converter boxes posted on the NTIA's Web site where consumers can apply for coupons.

Even with a converter box, however, some viewers might find themselves without a picture. Unlike analog signals - which can be watched in varying degrees of clarity, digital signals are all or nothing.

Some people who now receive a poor analog signal will receive a much clearer picture when they switch to digital, while others will see nothing but static.

"We refer to it as the `cliff effect,'" said Kelly Williams, the senior director of engineering for the NAB. "Your picture remains perfect until you slide off the cliff."

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