# Good OTA signal - no picture or sound



## CurtE (Apr 1, 2005)

My local OTA FOX channel has no picture or sound - just a blank screen. This just started last night. I have not had any issues receiving this channel (or any of the other major OTAs) in the past on my HR10-250?

My signal is normal - 88%. All other OTA channels have normal signal too with no problems. The guide data shows up in the guide. If I unplug my OTA connection, I get the normal "no signal" message - I plug it back in and the message goes away and my signal is back?

I'm thinking this is an issue on the TV station's end? However, I've check my local area thread on AVS - no one has reported a similar problem yet?


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## TyroneShoes (Sep 6, 2004)

Call the station. There is a known issue with PSIP that can keep certain tuners from displaying audio and video if it is not refreshing properly (certain stations reboot their PSIP server/muxers regularly to help prevent this). Ironically, the HR10 guide does not even use PSIP, but if certain data is not refreshed within PSIP from time to time, some tuners have been known to stop working altogether. If the station is monitoring with a different brand of demodulator (tuner) they might not even realize this is causing a problem, because they will still see their signal return normally.


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## newsposter (Aug 18, 2002)

I had the same problem with abc philly ota. Reboot or 2 cured it.


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## phox_mulder (Feb 23, 2006)

TyroneShoes said:


> Call the station. There is a known issue with PSIP that can keep certain tuners from displaying audio and video if it is not refreshing properly (certain stations reboot their PSIP server/muxers regularly to help prevent this). Ironically, the HR10 guide does not even use PSIP, but if certain data is not refreshed within PSIP from time to time, some tuners have been known to stop working altogether. If the station is monitoring with a different brand of demodulator (tuner) they might not even realize this is causing a problem, because they will still see their signal return normally.


I'd bet most stations aren't even using off the shelf tuners to monitor themselves, I know we are using a fancy industrial model that could care less what PSIP is doing.

In the past, we had a constant problem with our PSIP dropping the video stream and putting two audio streams in, resulting in most consumer level tuners losing both audio and video, so we got in the habit of checking it regularly to fix it, or relying on viewers to call in and complain.

Also, stations will make a minor tweak in the PSIP (or flexicoder setups), and some tuners won't like this, and will display nothing until it they are either rebooted, or the channels rescanned.

Most often a reboot will solve 99% of the problems.

phox


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## newsposter (Aug 18, 2002)

Psip?


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## CurtE (Apr 1, 2005)

Thanks for all the info! It does seem to be a PSIP issue? A few others in my area have posted this problem on the AVS board. Sounds like our FOX station has had this problem before.


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## phox_mulder (Feb 23, 2006)

newsposter said:


> Psip?


Not sure on the exact definition, but it is an integral part of OTA HDTV.

It tells the HDTV recievers what channel they are watching,
as 90% of HDTV is in the UHF range, and the channels most peope are used to are in the VHF range, it renames the channels.

Fer instance, here in Salt Lake, the CBS affiliate is KUTV Channel 2.
Our Digital channel is 36.
PSIP tells the recievers it is watching KUTV 2-1, viewers aren't as confused.

Many stations are doing multiple broadcasts in Digital,
they'll have their HD channel on the "-1", SD channel on "-2", maybe a constant weather forecast on "-3", etc.
The one I know of here that does is KSL, the NBC affiliate, channel 5 (38 digital)
They have their HD on 5-1, standard TV on 5-2 and a weather channel on 5-3.
PSIP is what allows them to do this by allocating how much bandwitch for each subchannel, naming the subchannels, even making it a video stream, audio stream, or both.

PSIP is a computer program, and therefore very likely to crash without warning, so when it does, your reciever doesn't know what it is watching, so it won't show anything until you remap the channels.

It does a lot more, but it's very technical and I don't even understand.
I'm sure there's a Digital TV FAQ somewhere on the internet that goes into more detail.

phox


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## chris_h (Dec 17, 2003)

phox_mulder said:


> PSIP is a computer program, and therefore very likely to crash without warning, so when it does, your reciever doesn't know what it is watching, so it won't show anything until you remap the channels.
> 
> phox


From my favorite acronym finder:
Program and System Information Protocol (Digital TV data standard)

It is the protocol used to send information from the TV station to your home via ATSC. This includes audio and video streams, as well as channel mapping information.

I don't really think of it as a computer program. I agree that there is a computer program running on a computer at the TV station that generated the PSIP data. If that computer program crashes, restarts, or is reset by station personel, you may need to rescan the channel. So I guess in that sense your statement is still true.


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