Local channel problem on HR10-250

[CurtE]

I just noticed last night that my HR10-250 is having problems with my local FOX digital channel 21-1 (broadcast on 57). When tuned to 21-1 the screen is black - the guide info is there and current - also there is not an error about "no signal" - if I disconnect the OTA then the signal message pops up - once I reconnect the OTA is the message goes away. I check the signal meter and it looks good (in the 90's like always). All other local OTAs are normal. No problems with the SD version of channel 21 on this HR10-250. Also, no problem with the SD or HD channel 21 on my HR20. I've tried several "reboots" and new OTA channel scan.

Any thoughts?

[bblick2]

I live in upstate SC and the same thing happened to me. At 8:00PM 21.1(FOX) goes out. I have a splitter on my OTA signal, so I switch inputs and get the same results from the OTA going straight into my TV. I switch back to my Tivo and I can get FOXHD from charter but not from my OTA. Strange.

[CurtE]

bblick2:
I'm in the upstate too...Seneca/Clemson area.

I guess it is a WHNS-DT OTA problem...not D* and/or Charter? Our problems appear the same - we can get WHNS-DT via sat and/or cable but not OTA?

I've posted the problem in the AVS forum local area thread...no response yet.

[bblick2]

Equipment malfunction with the PSIP generator caused your
problem. The signal was on channel 57 last night as always. The PSIP
generator is a computer that instructs your HDTV turner to look for our
signal on channel 21.

If you desire more information on other functions of a PSIP
generator, Google PSIP on the internet and there are numerous web sites.

Our signal should be okay now.

Jim Barnes CPBE
Chief Engineer
WHNS-TV
21 Interstate Ct.
Greenville S.C. 29615
office 864 213-2135
cell 864 423-5592
fax 864 297-0728

[CurtE]

Glad they've got it fixed...Thanks!

[TyroneShoes]

...The signal was on channel 57 last night as always. The PSIP generator is a computer that instructs your HDTV turner to look for our signal on channel 21...
That's true, but is not exactly an explanation of why things did not work, as there is no need for PSIP to provide that info to receivers that have already scanned that channel during a period when PSIP was working OK.

When the receiver does an original setup scan, it finds 57 and also finds metadata on that channel that tells the receiver how to remap to 21. That info is kept locally in the receiver in a PROM lookup table. When you tune "21", the receiver refers to the lookup table and physically tunes to 57 without benefit of PSIP, which it doesn't even see until the remap and tuning of the physical channel already occurs.

If there were not an original scan, tuning to 21 would not get you the actual channel without local info (the lookup table created during the scan) to guide it, as it can't get that info without scanning (or magically knowing what physical channel to go to) first. That is why the scan is done, to write the lookup table and facilitate the remap.

Unless the lookup table gets corrupted, a PSIP failure should not interfere with this process unless it somehow rewrites or skunks the receiver's local lookup table (which would never be necessary or on purpose), but apparently something in PSIP (and probably something other than the remap) still can get corrupted, typically on receivers that came about in the last few years only (making life for broadcast engineers that much more difficult). This means that broadcasters can be monitoring their return signal off air and not know they have a PSIP problem, unless they are using a receiver that is prone to this problem (or until the phone rings off the hook).

There are other PSIP failures that can cause this issue, but not a failure of the remap algorithm (assuming the original scan was intact), so the answer given is not exactly the real answer as to why there was a problem.

For instance, if something in the PMT (program map table, which tells the receiver which program identifier is mapped to each video and audio stream) was corrupted, that could indeed have caused the problem, especially when the PMT refreshes on tuning.

The fact that there was no popup on the screen means the HR10 assumed it was tuned to the channel in the lookup table, so I think the HR10 was actually tuning the correct physical channel, but possibly a PMT error caused it to not be able to reconcile the PIDs with the proper video or audio streams. That would account for a black screen with no popup.

[tjperez]

So next year when analog NTSC goes off the air, will stations continue to broadcast on a physical channel different from what they call it? Do they plan to move the DTV signal to the old analog transmitter/channel, or will they start IDing themselves by their physical channel number? I imagine the whole point of shutting down NTSC is so they can free up half of the channels from the current simulcasts.