Carrier signals

[Bigbear]

When I check signal strengths on my tuner I find a few very strong signals without any content.
Can anyone explain what this is?

Thanks
Bear

[ADTech]

Can anyone explain what this is?

No, since you haven't provided any real retails about what you are observing. There's no such thing as a "carrier signal" with digital broadcasting.

[Bigbear]

I'll try to be more clear. When checking on my DVR I find channels like 13-3 that have signal strengths of 90+, but there is no content. All that is displayed is a blue screen. This is what I'm curious about.

[ADTech]

Without the context of what the actual stations are and what specific DVR you're using, we don't have any information upon which to base any analysis. It could be a confused tuner in the DVR, a station that is transmitting a null channel or whatever.

Unless you KNOW there is supposed to be digital programming on that sub-channel, simply go to your "favorites" list and turn off the phantom channel.

[Bigbear]

Yes I have turned this channel off using my TIVO series 3. When doing a channel strength and cycling through the channels, all show up even the ones turned off.
What I am puzzled about is why would there be such a strong signal without anything being broadcasted. Wouldn't this be costly?

[ADTech]

No, it costs nothing. Sub-channels are not a signal of their own, they're simply another entry in the PSIP data of the ATSC broadcast stream.

Stations always broadcast the exact same number of bits per second of digital data. It makes no difference if the bits contain either actual or null data.

It would help if you actually identified the STATION(s) you're referring to.

[rickbb]

(Not trying to hijack the thread, if this is deemed to be that then mods please remove/move/delete this post.)


I have something similar. When scanning for channels I show a sub channel of 26.4, (virtual 26), for PBS out of Winston Salem.

It shows up on scans with all 3 tuners I've used and the signal meter software for my Hauppauge PCI tuner card shows 100% strength and a SNR of 33+. I get programming on the main channel 26.1 and subs 26.2 and 26.3 just fine.

All the channel guides I've checked, TV Guide, the one that comes with both Windows Media Center and the Hauppauge software all list that sub channel with content that is programmed and broadcasting.

But when tuning in to that sub channel all tuners say "no signal detected". I've just thought that it was an error of some sort. But if others have similar issues, could there be something else?

The PBS main source is in Chapel Hill on virtual channel 4.1, with subs 4.2 and 4.3, no 4.4. Which is why I had thought some error with it being listed in guides but no programming being broadcast.

It was my understanding that channel 26 was just a translator/repeater, the PBS network here in NC has dozens all over the state so everyone can get the UNC-TV network feed.

[ADTech]

Rick,

You do best to contact UNC-TV directly and ask them if they've ever started broadcasting UNC-MX on their OTA network. It's quite possible that they've set up their OTA encoding equipment to add the slot for the fourth programming stream with null data(which would make the additional channel show up in your channel list) but they have not yet made the final improvements necessary to actually carry UNC-MX OTA.

You could always do a TSReader data capture with your Hauppauge card and see what's in their data stream. The last one posted at rabbitears.info is from 2012 and may be out of date.

[rickbb]

Interesting, I downloaded the TSReader program and it does not show a sub channel there. Only the 3, 26.1, .2, .3 channels. No data stream on the "ghost" 26.5 sub channel at all.

But something is making all the tuners think there is some data there. All scans still show it as 26.5 WUNC - DT5.

Weird, I have an email sent off to them, we'll see what the response is.

[ADTech]

You may be in a location where two of the UNC's transmissions are being received and the tuner is compensating (or is confused by) for that by issuing consecutive virtual channel numbers internally. This is a logical concern within the tuner, not a transmission or reception issue.

Can you post the TSReader file as well as a link to your current TVFool plot? You may have to attach the TSR file using the "advanced" post feature.

[Jake V]

You do best to contact UNC-TV directly and ask them if they've ever started broadcasting UNC-MX on their OTA network. It's quite possible that they've set up their OTA encoding equipment to add the slot for the fourth programming stream with null data(which would make the additional channel show up in your channel list) but they have not yet made the final improvements necessary to actually carry UNC-MX OTA.

That makes perfect sense. Here in Washington, DC WFTC-DT had 14.3 and 14.4 showing up with no content. It turned out they were doing periodic tests to put content on those sub-channels. Eventually they added full time content.

[ADTech]

The TSReader data file will show any such null channel, if it's present at the time of capture.

[rickbb]

Should I export it as XML or HTML?

[ADTech]

Export as html to a txt file, IIRC

It's been a while..

[rickbb]

Ok here is the html export file and Radar plot. I had to change the file extension from htm to txt and then zip it up before the site would let me upload.


http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d2c15699c13a677