Kristina Schauer followed all the instructions to bring the promised benefits of digital television -- clearer reception and more free channels -- to her Santa Monica condominium.
The 32-year-old stay-at-home mom bought a converter box, hooked it up to her old 17-inch Toshiba set and attached the rabbit-ears antenna. She then scanned for the digital signals that all Los Angeles stations and most nationwide have been transmitting in advance of turning off their analog broadcasts.
But like some Americans who have made the digital TV switch early, Schauer discovered that the new world of digital TV isn't a pretty picture. Hilly terrain, especially in cities such as Los Angeles, and key differences between the two transmission formats have made their over-the-air TV reception worse. Schauer now gets fewer channels than she did before.
"It doesn't feel like an upgrade," she said.
Congress this month delayed the government-mandated switch to all-digital broadcast signals. By pushing it back to June 12 for most of the country, President Obama and Congress hope to give millions of unprepared viewers more time to upgrade their equipment so they don't lose over-the-air programming.
In some cities, households with old sets need to be prepared by Wednesday. To save money, about a quarter of the nation's 1,749 full-power stations have applied for permission to turn off their analog signals on the originally scheduled date.
Stations planning to switch next week include Fox, CBS and ABC affiliates in San Diego; NBC, ABC, CBS and Telemundo affiliates in Santa Barbara; and KJLA and KHIZ, independent stations in Los Angeles.
But widespread concern about those who haven't yet switched has overshadowed the woes of some who have.
"These are people who have taken action early, done everything the government asked them to do, and find themselves . . . with less service than they had before," said Joel Kelsey, a policy analyst at Consumers Union. "This is clearly an issue for a lot of consumers -- many more than the federal government has anticipated."
The switch to digital broadcasts will free up valuable airwaves for public safety officials to improve their communications networks and for wireless companies to offer new services. And for most people, it will produce sharper pictures with better sound. Digital TV also enables broadcasters to transmit four or more programs simultaneously on new sub-channels.
Nearly 9 out of 10 stations will increase the number of viewers who can tune in to their signals, according to federal officials and broadcasters. But the Federal Communications Commission estimates that 11% of full-power TV stations will reach at least 2% fewer people with their digital signals.
For example, the population capable of receiving the digital signal of KCBS-TV Channel 2 will drop to 14.4 million from 16 million -- though only about 15% of those viewers depend on over-the-air signals. The rest won't be affected because they get the station through pay TV.
The reception problems may improve after broadcasters finish the complex transition. By June 12, KCBS will move its digital signal to a better channel with increased power.
"The change in frequency and power will make it easier for many of our viewers who are currently experiencing difficulty with receiving our transitional signal with an over-the-air antenna," KCBS spokesman Mike Nelson said.
Simple fixes, such as buying a new antenna or manually entering station numbers instead of automatically scanning for them, can also improve reception. But there are no guarantees.
"In an ideal world, every consumer would receive the exact same stations for digital service that they currently receive for analog service," said Julius Knapp, chief of the FCC's Office of Engineering and Technology. "Unfortunately, the laws of physics and other factors come into play."
The problem is caused by the so-called digital cliff effect. A weak analog signal can be staticky but still watchable. In contrast, a poor digital signal will cause the picture to freeze up or simply disappear.
A study last year by Centris, a market research firm, predicted that 9.2 million households -- about 54% of those that rely on antennas -- could have trouble receiving digital signals. Because of its large size and hilly terrain, Los Angeles was one of the areas most at risk, the study said.
Eric Marchese, 49, a freelance journalist who lives in Santa Ana, said he received good pictures on the large TV, equipped with a converter box, that sits in his front room. But the small Sony set in his bedroom receives no digital stations.
"They all say all you need to do is go out and pick up a converter box, and you're all set," he said. "It doesn't work that way."