Do you use an outdoor antenna or rabbit ears to get your local channels? If you do, then you will need a digital converter to be able to see the new digital signals. If you have purchased a new TV in the last year then the TV should have one already built in to it. If you have an older TV, then you will need a digital converter that can be connected to your existing TV.  

There are some advantages and disadvantages to the new digital technology. The good news is that when the picture is there, it is perfect. No more snowy pictures.The bad news is if you have a weak signal, you get nothing. Again, no more snowy pictures. What you will get instead is a clear message saying something like "No Signal". What this means is that for those people who have been watching a fuzzy picture on the old analog signal will probably get NO PICTURE at all on the new digital signal.

 So what's a person to do if you have trouble receiving the new digital signal?

For starters. do you have a UHF antenna? The digital signal comes on the UHF band. The UHF band is the same band that any channel above 14 currently comes on. Most antennas that have been sold over the last 10 years are rated for both UHF and VHF. How can you tell? The most common UHF antenna looks like  an arrow pointed toward the mast. Some UHF antennas look like a vertical square made of wire mesh. Still not sure? Send me a picture and I can tell you what you have. The type of antenna you have can make a difference. If you live in an area of weak reception, the best type of antenna to use is an 8 bay UHF antenna. This antenna will give you the maximum signal strength. 

Secondly, what type of cable are you using? Coax cable is the best. If you have the old style 300 ohm wire, this should be replaced. This type of cable looks like a flat wire with 2 copper strands inside.

Thirdly, assuming you are using an outdoor antenna, is the antenna pointed correctly? Most antennas are directional meaning the direction they point has an effect on the strength of signal they receive. For the maximum signal, the antenna needs to be pointed toward the transmitter (tower) of the channel(s) you want to receive. Since the pointing of your antenna is more important to pick up the digital signals, I recommend using a rotor that will allow you to rotate the antenna from inside your house. Fine tuning the pointing of your antenna can be the difference between a strong working digital signal and a weak signal that doesn't work.

If you have done all of this and still have problems, maybe you should consider moving. I'm not kidding. For better or worse, the most important factor as far as picking up a digital signal is where you live versus the distance and terrain between you and the transmitter. Radio Shack sells antennas rated in mileage. This means virtually nothing. Admittedly, an antenna rated for 75 miles picks up a (slightly) stronger signal than an antenna that is rated for 45 miles. This doesn't mean that if you live within these distances that your will get an adequate signal. I have been to locations that are 10 miles from the transmitter that receive no signal due to a hill being in the way. I have also been to locations that are 60 miles from the transmitter that receive excellent reception.

Two additional notes. Unless you are hooking up multiple TV's or have an extremely long cable run, in general amplifiers will not help. And unless you live very close to the transmitter, indoor antennas generally don't work very well.