OTA: how can I get a different signal then everyone else?

[newsposter]

Tuesday night guys over at AVS were saying that fox Philly wasn't in HD until well into the 8pm hour. However, my HDtivo picked up the station in perfect HD with no glitches for all of AI and House. These guys presumably :) know what they are doing with their tvs so it's not like they were newbies stuck on the SD station.

So to you engineers out there, is it truly possible that they were receiving a different signal from philly than me? Or their tvs couldn't handle something as well as mine etc and kicked it to SD? This doesn't make sense though.

I dont mean to criticize them or say they are wrong because it's not something you would make up, but I simply dont see how it's possible. And I'm dying of curiosity.


start of situation if you care:

http://www.avsforum.com/avs-vb/showthread.php?p=9634713&&#post9634713

[TonyD79]

Are you sure you were getting HD and not a zoomed or stretched picture?

Don't look at the output of the HR10 for evidence because it will say 1080i if that is what you are set to.

[newsposter]

positively..AI looked the same as it did all other weeks..wonderful (now content is another story) Also as I watch cops OTA i know what the non Hd looks like.

The guys over there were specifically saying they had a 4:3 pic

"OTA I had 4:3 til about 8:40"

[Dssturbo1]

well they certianly could be getting different signal strenghts but no their tvs would not kick down to sd, it would pixalte or lose the pic if the signal was poor but there are no digital sets that will downgrade to an sd pic.

more likely even though they "presumably: :) know what their doing, their sets were on the sd channel or maybe their stb/displays/tuners were set to sd output.

[newsposter]

i hate to accuse them of not knowing what they are doing. I must prefer questioning how come my TV was perfect :)

I got an A in avoidance in skool

[TyroneShoes]

If two receivers are looking at the same signal, they will see the same signal. If WHYY-DT was broadcasting in 4:3 SD, everyone tuned to WHYY-DT would get that, and if they were 16:9 HD, everyone would get that. It is impossible for a single station to provide more than one signal as the primary ".1" channel, and 4:3 SD and 16:9 HD are two separate signals, so assuming there is only one stream (no sub-channels) available, it would be impossible for different receivers to be receiving different signals from the same station.

There is one possibility, though, but extremely small. IF WHYY was broadcasting a sub-channel with the SD program on it, and there was a PSIP issue, such as extraneous or corrupted data in the PAT (program allocation table, which maps the subchannels so the receiver can distinguish between them) it is possible that some receivers would interpret the SD sub-channel as the main ".1" channel, while others interpreted the HD stream normally. Two HR10's would likely not see different signals in that case, but tuners from two different manufacturers just might, although that is highly unlikely. It is also unlikely that an O&O FOX station has a sub-channel running (we are under a mandate not to do that, currently) but there may be some engineering experimentation going on that would create a sub for testing purposes.

Other than that it seems to be a real mystery.