[mythtv-users] QAM question - cable providers & changing channel mappings?

Steven Adeff adeffs.mythtv at gmail.com
Fri Apr 14 17:28:02 UTC 2006

On 4/14/06, Peter Watkins <peterw at tux.org> wrote:
> Mark J. Small wrote:
> > On April 8, 2006 05:06 pm, Steven Adeff wrote:
> >
> >>On 4/8/06, Mark J. Small <msmall at eastlink.ca> wrote:
> >>>I'm thinking about taking the leap and getting a card that can do QAM
> >>>decoding for my cable system.  My biggest worry is this; what happens
> >>>when the cable system changes its channel map?
> >>>I know that the channel map changed recently on my system,  and there is
> >>>nothing stopping my provider from changing it again next week.
> > I was bored one day, and found the frequencies for all the digital channels
> > using the service menus of my cable box.  I don't have the energy to do it
> > again right now, so it could be that many of the frequencies have changed.
> >
> > My point is that if my cable system does this again, then there is no way for
> > me to know about it until my recordings start to fail.  This would really
> > stick if it happened at the beginning of a 2 week vacation...
> >
> > My cable company is planning on adding several new channels soon, so I really
> > don't know how much the digital channels will jump around.  Failed recordings
> > would really mess up my WAF.
> I've got the same concerns. I've tried to read up on FCC guidelines (I'm
> in the United States) regarding "must carry", etc., and never found
> anything terribly clear. I even wrote the EFF (eff.org) and received a
> nice response saying, basically, the FCC does not have clear guidelines
> for QAM, even regarding channels that are "local" broadcasters.
> My provider (Comcast) has maybe 80-90% of the local ATSC broadcast
> channels also in clear QAM. And hundreds of QAM channels I can't tune,
> presumably encrypted content. Beyond carrying some locals in clear QAM,
> I found a few cable-only channels. Very few clear QAM channels had
> useful PSIP (?) labels.
> I would love to see legislation that clearly required cable providers to
>  - make all local broadcaster's HD/ATSC available in unencrypted QAM
>  - make all "basic tier" channels available in unencrypted QAM
>  - clearly label (PSIP) all unencrypted QAM channels
>  - not change the frequency/aid/vid QAM settings for any channel that
>    they're required to make available in unencrypted QAM without
>    notifying all subscribers (who ask for such notification?) with the
>    exact change, exact date/time of the change -- and provide such
>    notification at least 8 weeks in advance
> As it stands, when I add my 2nd HD card, I intend to use it for QAM only
> for the channels I can't pick up OTA (including the unencrypted
> cable-only channels), and continue using my "silver surfer" antenna and
> ATSC for those I can get OTA -- just to avoid missing a show because of
> cable provider QAM-mapping shenanigans.
> >>if you want cheap entry, the Avermedia A180 works great with kernel
> >>2.6.15 and can be had for ~$70, which I think is the cheapest QAM
> >>capable PCI card available right now.
> > I've been eyeing that one, thanks.
> It looks like a much better card (physically) than the HD3000 -- much
> better connectors, stress relief on the coax jack, etc. But then I think
> the HD3000 is unusually poorly designed for a card w/ a coax jack. But
> my A180 is back in the box. Word is that its kernel drivers conflict
> with the i2c drivers for the Hauppauge PVR-350, and I'm using the
> PVR-350 IR receiver (with lirc_i2c) for my remote. LIRC became
> unreliable (would miss IR events) as soon as I put the a180 in my box
> (FC4 loaded its drivers automatically). So I've removed the a180 and
> have to get another IR dongle working for LIRC to receive my remote
> control's IR commands. I tried for a while to get an old Belkin
> SmartBeam serial dongle to work, but though lirc_serial and lirc_dev say
> they found it, mode2 and irw couldn't see any activity. So I hope to get
> a StreamZap USB receiver working, even if I have to remove the PVR-350
> entirely.
> It would have been far easier to buy another HD3000 and keep using the
> PVR-350's IR dongle; maybe I should have split the difference between
> the $70 a180 and $170 HD3000 and tried the $120 Air2PC HD5000...

the FCC guidelines may not be clear, but they're there and a little
reading will net you the following facts:
1. Only over the air analog broadcasts are required to be carried free
of charge to everyone over cable lines. This was the trade off the
federal government made with the cable companies to allow them to run
cable lines on "government property".
2. Over the air ATSC signals are *NOT* considered "analog", they are
considered "digital" and thus not required to be free and clear on
cable lines.

But, processing these channels would require extra cost at no extra
benefit to cable companies, so most don't bother and just send the HD
signals clean and clear. Some, whom don't get free coffee at work,
decided to take advantage of the law and encrypt all their QAM


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