Signal quality I get 100% signal strength but 0 to 8 % signal quality on most of the local channels and the signal quality will float up and down. I have a high gain DTV antenna and a mast mount amplifier. I have about 20 ft.run to one TV and fifty ft.to the other with amplifiers at both sets. I have a metal roof but the antenna is mounted on standoffs so it does not sit directly over the roof. I am about 30 miles from the transmitter in mountainous terrain. Can you please tell me what is effecting my signal quality, and how can I improve it?

Try checking the signal strength then run the scan again.
Checking the DTV signal strength
You can check the DTV signal strength to determine if you need to adjust your antenna or digital cable input. The higher the signal strength, the less likely you are to experience picture degradation.To check the DTV signal strength:
1.Press MENU. The on-screen menu opens.

2.Press < or > to highlight Channel, then press v. The Channel menu opens. The DTV signal strength is shown at the bottom of the menu.

3.Press EXIT to close the menu.

Usually, with this problem, it's due to low signal strength. Digital TV needs a good quality DTV antenna. GOOD QUALITY cables and connectors are also a good idea. If you live in a low signal strength area, u may also need an amplified antenna.

Do you have the antenna aimed correctly and the correct antenna for the distance between your location and the stations? Check antennaweb.org and tvfool.com for the directions to the stations you should be able to receive. Antennaweb assumes an external antenna and is very conservative in the station list. TVfool gives the stations you should get with various different types of antennas. Tall trees and buildings will block signal strength so consider the environment around you.

With digital signals, if you do not have enough signal strength for a given tuner, the channel will not come in. An amplifier may help you get the signal, particularly if the signal is shared to several devices. Failure of an amplifier or lightning surge protection can stop the signal from reaching the TV. A surge through the antenna can damage the tuner.

A damaged cable can also be a source of a problem. Check the outside portion of the wire as well as the interior wires. Replace any that have damaged insulation or ends.

For this TV, if you have done a channel scan with the TV set to the Input TV/DTV, and the Signal Source set to Antenna. Turn the antenna and then set the Additional Scan to On. (Menu > TV > Channels > Additional Scan.) Then do another channel scan.

If you need a copy of the manual, see: http://www.vizio.com/m220va.html#support .

Returned product to dealer. That fixed my proble.
Thanks...

Antenna may not be compatible with DTV signals or not aimed correctly.  Go the www.dtvanswers.com and click on the Antennas tab at the top for more info.

yes your signal is very good but it hangs up, the most important is the quality of your picture, cause signal is composed of so many impurities including noise, so dish be orientated once more.thanks.

I found I needed at least 80 percent.