Close but no cigar!
WNAC's HD signal is fed through encoders at the studios and then digital microwave to the transmitter. WNAC's HD is received via equipment at the studios in Provdience.
The most likely cause is the local commercials are fed through an upconverter, that the audio also goes through (for lip sync). The most common upconverter has a known bug where the audio will literally drop out when it has an error in the audio stream. A simple reboot or audio switch will correct the problem.
*- An upconverter takes a normal non HD feed, and makes it "HD Ready" by either stretching the picture or the black bars on the sides.
> Believe it or not, I bet I know what this is!
> If I'm not mistaken, several of those stations have their
> switching contracted out, and the signals are then fed back
> to the X-mitter via a digital phone line. Occasionally, a
> mistake or bad weather will cause a line to be bad or
> disconnected.
> How do I know this?
> A few years back I was watching WBZ TV and they were having
> the same trouble, even through their 11p newscast. They
> later explaned that a digital line had been cut and that was
> the reason.
>
> Probably a similar case here.
> -G.
> > I am watching American Idol on Fox 64HD and all the local
> > breaks have no audio. All there local commercials, there
> > local news teases had no audio. I wonder if the techs in
> > the control room knew that was going on. I get Fox64HD
> > perfectly at my house. American Idol in HD came in
> > perfectly, crystal clear and sounded great in stereo.
> > Anyone else find this too be?
> >
>