Pixelation is usually caused by your antenna receiving too little signal strength or the same signal being received from different directions at the same time (multipath). If the signal/s are arriving at your antenna directly and also arriving after being reflected from a building or a mountain, your tuner cannot decipher the competing identical signals. The third possibility is you have too much signal strength for your tuner to work with.
All three possibilities can be resolved by moving your antenna (up/down/right/left/forward/backwards) until the signal becomes dependable. Sometimes it requires a different type of antenna, so post more details for us to work with.
I've used a converter box with an analog TV & indoor antenna since the transition to digital broadcasting in 2009. I have been receiving 42 channels from 12 different TV stations in my area (each station broadcasts multiple channels of different programming).
About a week ago, there was an abrupt change in my reception of ALL these channels. I now have no signal at all (no matter what time of day) on 24 of the channels that I've always been able to receive with good signal strength. On the other 18 channels that I've always been able to receive with good signal strength, the signal strength now varies between 0% & 15%. (Ironically, now, on the channels that I can still receive, even with a signal strength as low as 5%, the programming has very little disruption, pixelation, stuttering, freezing, or loss of audio/visual display. Previously, such a low signal strength would have resulted in constant freezing, pixelation, or no audio/visual display.)
The cause of this is a mystery so far. It's the same TV, the same converter box, same antenna, & same location as before. I did not change any component or connection. Everything appears to be functional/operational. It appears that something is now blocking or reducing the signal from all 12 of the TV stations that I was previously receiving good signals from.
I've done "trouble-shooting". I've talked to the technical support department at the FCC. I've searched the internet for information & resources relating to the possible causes of this. I've not yet found any answers or resolution for this particular issue. (There are no new structures or known physical/electrical sources of interference in my home or neighborhood.)
This change was extremely abrupt, not gradual. It's as though something was turned on a week ago that blocks or severely reduces all TV signals in my area. Since this started, the problem has been constant rather than variable.
I'm still looking for answers. Does anybody have any insight as to possible causes of these particular issues? Any input would be appreciated.
You need to 'rescan' your Converter Box. The Federal Government eliminated all real television channels 37-51 and sold those frequencies to cell phone companies. Prior to this, channels 52-69 were sold and years before that, channels 70-83 were removed. All stations that choose to stay on-air are transitioning to lower number (real) channels 2-36. There are several threads on this forum about the topic: use the key words channel transition in your searches here or with google.
You may have to relocate your antenna to receive the 'new' channels, so be prepared to rescan several times. Note: some of your stations may be operating at reduced power on their new channels until their transmitting antennas can be replaced.