NEW YORK — Starting in the morning and going into the night, TV stations across the U.S. are cutting their analog signals Friday, ending a six-decade era for the technology and likely stranding more than 1 million unprepared homes without TV service.

The Federal Communications Commission put 4,000 operators on standby for calls from confused viewers, and set up demonstration centers in several cities. Volunteer groups and local government agencies were helping elderly viewers set up digital converter boxes that keep older TVs functioning.

"When you're alone like me, that's my partner," Patricia Bruchalski, 82, said about her TV.

Bruchalski, a pianist and former opera singer who lives in Brooklyn Park, Maryland, got assistance Thursday from Anne Arundel County's Department of Aging and Disabilities and a community organization called Partners in Care. After her converter box was installed, Bruchalski marveled that digital broadcasts seemed clearer and gave her more channels — about 15 instead of the three she was used to.

"You're going to be up all night watching TV now," volunteer installer Rick Ebling told her.

A survey sponsored by broadcasters showed that Americans are well aware of the analog shutdown, thanks to a yearlong barrage of TV ads. But not everyone was sure exactly what it means, or what needs to be done to tune in to digital TV.

Any sets hooked up to cable or satellite feeds are unaffected. Newer, digital TVs that get broadcasts through antennas — and older sets hooked up to converter boxes — should be fine, but they will need to be set to "re-scan" the airwaves, to find stations that move to new frequencies Friday.

Some people might also need new antennas, because digital signals travel differently than analog ones. While an analog station that came in imperfectly might have had static but remained viewable, digital generally comes in all or nothing. Indeed, one of Bruchalski's newly available stations looked pixelated, and Ebling said she might have to get a different antenna.

The shutdown of analog channels frees up the airwaves for modern applications like wireless broadband and TV services for cell phones. It was originally scheduled for Feb. 17, but the government's fund for $40 converter box coupons ran out of money in early January, prompting the incoming Obama administration to push for a delay. The converter box program got additional funding in the national stimulus package.

Research firm SmithGeiger LLC said Thursday that about 2.2 million households were still unprepared as of last week. Sponsored by the National Association of Broadcasters, it surveyed 948 households that relied on antennas and found that 1 in 8 had not connected a digital TV or digital converter box.

Nielsen Co., which measures TV ratings with the help of a wide panel of households, put the number of unready homes at 2.8 million, or 2.5 percent of the total television market, as of Sunday. In February, the number was 5.8 million.

Nearly half of the nation's 1,760 full-power TV stations have already cut their analog signals, though they are mostly in less populated areas.

Even after Friday, low-power analog stations and rural relay stations known as "translators" will still be available in some areas. And about 100 full-power stations will keep an analog "night light" on for a few weeks, informing viewers of the need to switch to digital reception.