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Old 29-Oct-2011, 12:16 AM   #1
TheEmrys
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Get 6.2, but 6.1 and 6.3 are weak - normal?

So is this normal? I like my PBS, and I get 6.2 very strong. However, I am unable to consistantly get 6.1 and 6.3 on my Windows Media Center DVR. Is this normal for some sub-channels to be good, while others are poor/inconsistant? Only 6.1 is in HD, but even the built-in signal meter is shows 6.1 and 3 as being extremely poor. Signal is great on the other TV. May need to pursue something through the tuner card manufacturer, but figured there might be a known issue.

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Old 29-Oct-2011, 2:53 AM   #2
MisterMe
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Virtual Channel 6 is not indicated for any station listed on your TV Fool Radar Plot. You also have multiple PBS stations with signals in the green. Please give the call letters [and RF channel] for your problematic PBS station.
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Old 29-Oct-2011, 2:57 AM   #3
TheEmrys
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So sorry, it is Real channel 18, KRMA.
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Old 29-Oct-2011, 4:19 PM   #4
MisterMe
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Quote:
Originally Posted by TheEmrys View Post
So is this normal? I like my PBS, and I get 6.2 very strong. However, I am unable to consistantly get 6.1 and 6.3 on my Windows Media Center DVR. Is this normal for some sub-channels to be good, while others are poor/inconsistant? Only 6.1 is in HD, but even the built-in signal meter is shows 6.1 and 3 as being extremely poor. Signal is great on the other TV. ...
OK. Your issue appears to be totally unrelated to signal strength. There is a broadcast flag in the digital stream of each program. Microsoft's Windows Media Center DVR honors this broadcast flag. Translated into English, this means that Windows Media Center DVR will not record a program that the broadcaster doesn't want recorded. Producers have coronaries at the prospect of recording HD content. There are also reports of the broadcast flag's being set by accident. You might want to call KRMA and ask about recording its HD programming streams.

You may want to read this report to get a feel for what may be happening.
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Old 29-Oct-2011, 6:07 PM   #5
TheEmrys
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That shouldn't affect the signal, should it? How would signal for 6.2 be strong when 6.1 and 6.3 are extremely low?
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Old 29-Oct-2011, 8:48 PM   #6
MisterMe
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Originally Posted by TheEmrys View Post
That shouldn't affect the signal, should it? How would signal for 6.2 be strong when 6.1 and 6.3 are extremely low?
That would depend on how the signal is being measured. Multicast signals are not independent of each other. It is my understanding that they are multiplexed. I have never seen a case where one subchannel could be received, but others were too weak to be viewed. To the contrary, if one comes can be received, then they will all be received. Often, only the subchannel identifications get through when the signal is too weak to be viewed. By your own testament, your TV [which cannot record] has no trouble with any of the subchannels.

Since it is virtually impossible to prevent the recording of a signal that is viewable on a computer, my guess is that Windows Media Center DVR refuses to decode programs whose broadcast flags are set. An undecoded digital program stream probably looks like noise.
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Old 30-Oct-2011, 1:41 AM   #7
GroundUrMast
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What tuner(s) are you using?

If you are using more than one tuner, the Media Center SW may be selecting a different tuner when receiving 6.2 vs. 6.1 or 6.3
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Old 30-Oct-2011, 2:44 PM   #8
Tower Guy
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Originally Posted by TheEmrys View Post
Is this normal for some sub-channels to be good, while others are poor/inconsistant?
It's very abnormal.

The only thing that comes to mind is jitter on the bad subchannels and no jitter on the good one.

Jitter is small changes in the timing of the transmitted bits.
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Old 11-Nov-2011, 2:04 PM   #9
TheEmrys
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We had quite a bit of snow since I noticed this issue, and ended up with signal issues. I went a head and ordered a new antenna, a Winegard 7697 on the advice of a local installer familiar with my neighborhood (in a low spot, apparently, with lots of big trees) and hoped that may impact my issue. Well, it didn't. So, looks like its either a tuner issue, which is a Hauppauge 2250, or a flagging issue.
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