[mythtv-users] channel scan missing channels

Michael T. Dean mtdean at thirdcontact.com
Wed Dec 15 00:56:26 UTC 2010

  On 12/14/2010 06:06 PM, Steven Adeff wrote:
> On Tue, Dec 14, 2010 at 3:06 PM, Michael T. Dean wrote:
>>   On 12/14/2010 01:50 PM, Steven Adeff wrote:
>>>>>   On 12/13/2010 04:54 PM, Steven Adeff wrote:
>>>>>> In doing a channel scan on my parents new mythbackend we've noticed
>>>>>> that Myth isn't finding all the channels that we find using the
>>>>>> digital tuner in their HDTV. I've done full scans of "Cable", "Cable
>>>>>> IRC" and "Cable HRC" at QAM-64, 128 and 256. I just can't seem to get
>>>>>> Myth to see the channels. I need to try to create the channel by hand
>>>>>> to see if Myth can tune them, but I'm wondering if anyone else has run
>>>>>> into this before?
>>> anyone have any ideas? there's a few channel's Myth just won't find
>>> that the digital tuners they have *do* find, and they are HD channels
>>> so it would be nice if I could get Myth to tune them.
>> Have you tried to see if any other application using the exact same hardware
>> (the PC and the PC tuners) can find them?  Something like dvbscan?
>>   http://www.mythtv.org/wiki/Dvbscan
>> Could well be tuner sensitivity/interference, etc., so we need to prove that
>> it's actually the software--meaning we need to see some other software that
>> uses the same hardware find those channels.
> I have tried other channel scanners, the problem is, none of them give
> me a usable output since they just show frequencies and sub channels,
> but not the "virtual" channel shown by Myth or the TV's digital tuner.
> On top of that, the mplexid value, which is basically the "channel" to
> the service value's sub channel is not the number shown as the channel
> on the digital tuner. So it makes it basically impossible to figure
> out how to use something like dvbscan/scan to manipulate Myth's
> channel database.
> here's the output from scan,
> http://www.mythtv.org/wiki/Westchester,_CA
> I created the link so as I figure out what channels are what I can put
> them there and hopefully help any others in that area.
> I've tried scanning multiple times, but there are just certain channel
> frequencies that Myth doesn't find/add.
> The cable line has plenty of signal strength and a strong S/N ratio.
> One of the digital tuners doing the scanning uses an output from the
> same splitter that goes to Myth (for the time being as we set Myth up)
> and has no trouble finding these channels.
> And Robert, yes, thank you for your channel scanner work, along with
> whomever helped. I remember trying to add QAM channels to Myth
> compared to doing things the old manual way 4 or 5 years ago, and it
> was not fun. I recently had to rescan my channels due to Comcast
> moving things around and I was up and running almost immediately with
> a proper channel mapping. I just wish Time Warner where my parents
> are, and whom this is for, was as easy...

So what specifically is missing from MythTV?


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