I have my S3 hooked up to a small set top antenna for HD OTA reception. Thursday morning I snapped it on (ch 3.1) and was surprised to find displayed, what appeared to be an XP desktop with someone typing up a Thanksgiving e-mail. This was partially pixelated with parts of the Ch3.1 broadcast. As I watched the broadcast took over the entire picture.

I'm kind of bummed that I didn't think to hit record before changing channels and clearing the buffer. I might have been able to find out which neighbor is using a badly installed TV modulator.

ps, I hadn't known there were HD RF modulators available.

Is it possible it wasn't just some kind of screwup at the TV station?

If you're after decent PC based DVB/ATSC modulators then have a look at Dektek. They even do linux drivers. I'm currently trying to convince my boss to buy me a DVB-T modulator card for testing.