NEW YORK — TV's big switch from analog to digital broadcasts will be complete just a year from now, on Feb. 17, 2009, and many consumers are puzzling over how the shift will affect them: Do they need a new converter box, a new TV, a better antenna?

But it's pretty clear which business interests stand to gain.

Cable and satellite TV companies could see a wave of new subscribers as people with older TVs pass on hooking up converter boxes to older televisions or buying new sets. Local stations are already using some of the extra capacity that digital broadcasting frees up by launching auxiliary TV channels with weather and traffic reports, and they're looking for ways to bring programming to portable devices.

The Federal Communications Commission began the switch some years ago to free up a large chunk of U.S. airwaves, which the government is in the process of auctioning off, a process that will net billions of dollars for public coffers. Making all of the UHF broadcast spectrum above channel 52 available will allow for powerful new wireless services, and possibly for a new network for public safety officials to use during disasters.

Most U.S. TV stations already broadcast digital signals as well as analog. What's happening a year from tomorrow is that they'll switch off the analog signals. No one with cable or satellite service will be affected, nor will anyone who gets stations over the air with a newer TV with a digital tuner.

Those who will be affected are the 13 million or so households that get TV broadcasts exclusively over the air and have a TV more than a few years old — or even a newer TV that's relatively small. Also affected are TVs not connected to cable, even if a home has cable.

A Nielsen Co. study released yesterday found that 16.8 percent of all U.S. households have at least one analog television set that will not work following the switch. And Hispanics are nearly twice as likely as whites to find themselves without TV reception at that point.

Affected households can get a digital converter box, buy a new television or sign up for cable or satellite service or one of the newer cable-like services being offered by phone companies.

A government program said yesterday that on Tuesday it will begin sending out coupons worth $40 each to any U.S. household that requests them to subsidize buying a converter box. Each household is entitled to two coupons for the boxes, which are just coming into stores now and start at $40 or $50, making this option easy and practically free. The government says it has funds for 33 million coupons. To get one, go to www.dtv2009.gov. or call 1-888-DTV-2009 (1-888-388-2009).

All TVs being sold today have digital tuners, which are sometimes called ATSC tuners, after their technical standard (the analog standard was known as NTSC). If your current TV is less than a year old, if the initials "DTV" appear somewhere on its front, or if its screen is rectangular, you're probably OK. If you still have the owner's manual, check there whether the tuner is digital.

The new signal could mean the picture on some televisions will improve, but it doesn't guarantee high-definition visuals. That depends on whether a particular TV is set up to receive high-definition programming and whether a program is broadcast that way.

The switch could give an economic boost to retailers and manufacturers that sell the boxes and new TVs. And cable providers could get a boost over the next year or two from consumers who sign up for new service rather than deal with the other options.

According to a report Sanford C. Bernstein & Co. released yesterday, an estimated 1.4 million households will likely switch to pay TV service as a result of the digital TV transition — enough to significantly lift the growth rates for the cable industry in 2009.

For retailers, Bernstein analysts say, the economic boost is likely to be incremental. The market for the converter boxes is likely to be about $1.4 billion, and for new TVs about $1.7 billion, for a total of $3.1 billion — still a relatively tiny part of the $150 billion U.S. consumer electronics market.

The cost to broadcasters of new digital equipment is relatively small. Tim Thorsteinson of Harris Corp., a major manufacturer of broadcasting equipment, says it costs about $500,000 to upgrade a typical TV station.

The transition comes at a tough point for local TV stations, however, because they are seeing live viewership erode amid a proliferation of ways to watch video — over the Internet, on iPods and DVDs.

Mark Aitken, director of advanced technology at Sinclair Broadcast Group Inc., a major broadcaster based near Baltimore, says digital technology gives TV station owners several ways to hold onto viewers, mainly with high-definition broadcasts, which can be much higher quality for viewers to watch than YouTube videos.

Aitken calls using HDTV broadcasts the "low-hanging fruit" for TV stations to take advantage of.

He points to another big possibility: sending live TV broadcasts to portable devices such as cell phones. Adapting the handsets would be simple technically; the far bigger issue is getting broadcasters, programmers and mobile device makers to agree on a standard.

A preliminary field trial of three competing technologies for portable TV viewing is just about to get under way in San Francisco, Aitken said. The industry could have a candidate for a new mobile TV standard in place by later this year.