Thanks for the very thorough response. Based upon what you wrote, I'm afraid that my original post was insufficiently specific, so I'm going to add a little bit more detail.
I'm using a Windows Media Center PC to record shows off of Live TV using a SiliconDust HDHomeRun Dual Tuner. It is hooked up to a directional antenna that I purchased from DennyAntennaService.com which is designed specifically to receive UHF and the portion of the VHF band that remains in use for TV after the digital transmission (called the EZ-HD antenna). The antenna is located in my attic and points in the general direction of the transmission towers to the Northeast, which are visible without obstruction from my house. The HDHomeRun tuners consistently report 100% signal and symbol strength. Even with the 12db attenuator, my signal strength is still roughly 95%.
I never, ever watch live TV. Occasionally, when I'm watching a pre-recorded show, I'll encounter an artifact of some kind, i.e. bottom half of screen goes gray or green for a brief moment, or a small part of the screen will do so, or I'll observe some motion artifacts (duplicate images) on a portion of the screen that's moving. Most shows record just fine, without any issues, but once in a while, maybe once every 5 shows or show, I'll see one of the above. I often do record more than one show at a time, and I've gone back and watched the others at the same moment and do not recall seeing an artifact at the same time in the other recording.
This may well just be par for the course with the broadcasters here in Oregon. For example, today, during the CBS Evening News, I saw a bit of green appear on a child's chin (right before she hugged a horse), and then immediately called a friend who lives in the area and records OTA using his Dish Network with the optional TV Tuner module. He checked his recording and observed the **very same artifact**. I also checked a recording made back in California (using a friend's WMC set-up similar to mine) and found no artifact. So, at least in this particular case, it appears to be a problem with the encoding done by the transmitter and not by anything particular about my set-up.
I've only posted here because I never, ever saw this kind of artifacting when I lived in California. However, there I was in the biggest TV Market in the nation (L.A.), and so I suspect that those stations spend a lot of money making sure that their equipment is perfect.
So, at the outset, I'm just wondering if you guys here ever see such artifacts on the broadcasts, and if so, how often??
However, in response to your offer, I'd definitely open to having a fellow ham come by and see what he can see. I'll PM you.
P.S. I'm pretty sure that I've seen a car with your call sign driving around town. Everytime we do, my wife asks me if I know you.
Originally Posted by LinleyG
Rereading this, I note that I should have said, "... a FREE (i.e. no charge ever) consultation ..."