[linux-dvb] [Fwd: Help with recent DVB/QAM problem please.]

Michael Krufky mkrufky at linuxtv.org
Mon Aug 11 21:58:44 CEST 2008

On Mon, Aug 11, 2008 at 3:43 PM, Mark Paulus
<mark.paulus at verizonbusiness.com> wrote:
> Michael Krufky wrote:
>> 2008/8/11 Mark Paulus <mark.paulus at verizonbusiness.com>:
>>> Redirecting to linux-dvb on suggestion from
>>> Video4Linux user.
>>> -------- Original Message --------
>>> Subject: Help with recent DVB/QAM problem please.
>>> Hi all,
>>> Background:
>>> I have a machine in my basement with:
>>> Hauppauge PVR-150 (connected to DCT2524)
>>> Air2PC ATSC/OTA card (connected to antenna in attic)
>>> Avermedia A180 (connected to comcast cable)
>>> Dvico FusionHDTV RT 5 Lite (connectec comcast cable)
>>> Debian using 2.6.24-x64 kernel
>>> Situation:
>>> Up until a week ago, I was able to use azap to tune in
>>> a bunch of mplexids, and get good locks on both the A180 and the Dvico
>>> card.
>>>  However, starting on Monday,
>>> I am not able to get locks on either of my DVB cards.
>>> I have been able, and am still able to get good locks
>>> on my air2pc OTA card.
>>> Can anyone help me figure out why I can't seem to see
>>> anything from my 2 QAM cards?  I've tried running a
>>> dvbscan and neither card can make a good lock.  What
>>> other debugging tools can I use to try to find any QAM
>>> signals?  I've also tried doing a VSB-8 scan on the cable
>>> cards, and also don't get any locks.
>> Mark,
>> It's good that you've moved the thread to the correct mailing list.
>> However, I did already answer you and asked you some questions, to
>> which you have not yet responded....
>> Quoting myself:
>> What variables have changed in your test environment since last Monday?
>> If the answer is "nothing" , then the problem is more than likely due
>> to your cable company moving services around.
>> First, you should confirm that you still have clear QAM available...
>> assuming yes, then I recommend scanning for channels again, using each
>> card.
>> Regards,
>> Mike
> As far as I know, no variables have changed.  The only thing that might
> have been of note is that there seemed to have been a wierd Power Blip, and
> my linux machine was off when I was not expecting it.
> After turning it on, I noticed the problem.  However, it seems wierd
> to me that a power blip would blow both QAM cards, and yet leave the ATSC
> and the PVR-150 alone.  (I also have a PVR-150 attached to a Motorola
> DCT-2524 in that machine).
> My biggest problem I have right now is determining if there is even
> any clear QAM available.  I did a dtvscan -q from both cards, and neither
> card is able to lock anything.  Before last week, I was
> able to get locks on many multiplexes, even those populated completely with
> encrypted PIDs.  (I would do an azap in one window
> to lock a multiplex, then I could do a dvbstream in another window, and run
> tsreader on my winxp box to actually look at a stream.  Encrypted streams
> would show up as read w/nothing to look at.
> Clear streams could be clicked, and would play in VLC, so I could
> see what it is.)
> I will run another dtvscan to make sure things aren't there, but is
> there any other means of determining the state of things QAM?  Somehow my
> Motorola DCT-2524 seems to still see channels and
> work fine, so if Comcast did change something, then they did
> it so that it doesn't affect their STBs.

This is my point, exactly.  Since your provider has provided your STB,
they also have an interface into the STB that allows them to update
software and / or encryption keys, etc.

It is more than likely that your provider has changed the
characteristics of the services on their cable.

You may want to contact your provider directly and ask them what has
changed with your service within the past two weeks.

I've heard similar complaints from other users of your service provider.

Good Luck,


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