[mythtv-users] LiveTV issues (root caused to cable signals)

Monkey Pet monkeypet at gmail.com
Sat Sep 1 23:02:09 UTC 2012

On Sat, Sep 1, 2012 at 8:40 AM, Monkey Pet <monkeypet at gmail.com> wrote:

> On Sat, Sep 1, 2012 at 6:01 AM, Michael T. Dean <mtdean at thirdcontact.com>wrote:
>> On 09/01/2012 01:51 AM, Joseph Fry wrote:
>>>>  After re-cabling:
>>>>>> (notice the numbers jump)
>>>>>> [me at mythtv libhdhomerun]$ ./hdhomerun_config 1313E021 get
>>>>>> /tuner0/status
>>>>>> ch=qam:759000000 lock=qam256 ss=76 snq=82 seq=100 bps=38809216 pps=994
>>>>> Those numbers, while clearly better, are still rather low.  I typically
>>>>> see values in the 90's.  I seem to recall ss=76 indicates a power
>>>>> level that would normally be out of spec for digital cable (although
>>>>> it might just work sometimes).
>>>>> First thing, plug the hdhr directly into the outlet using a short
>>>>> piece of
>>>>> quality coax, and see if the values are more reasonable.  If not, call
>>>>> your cable company and ask them to make a service call.  They are
>>>>> responsible for adequate signal levels at the outlet.  If it looks good
>>>>> directly plugged into the outlet, it would point the finger towards
>>>>> your
>>>>> coax or splitters (or cable amp if you using one).
>>>>>  I just don't understand why recording a show works, but LiveTV always
>>>> fail.  That seems odd to me.
>>>>  That is odd.  Do you have fast channel switching enabled?
> It is set to never.
> I might have spoken too soon about the issue not occurring on recordings.
>  Myth lies about the recording times of truncated recordings, so it is hard
> to tell.  I have seen at least one instance of it during a recording.
> Until i get my signal issues look at by the comcast guys, my mythbox is
> useless now, I plan to upgrade to 0.26 to see if the behavior changes.

Now everything is running 0.26-head, as expected I see the same issues.  I
found a better/shorter coax cable and used that instead and my signals are
getting better.

This low signal  issue might be a good test case for the developers.  It
leads to strange mythfrontend behaviors for example, you can easily crash
the frontend by:
1. starting liveTV
2. then pulling the coax on your HDhomerun box.
3. mythfrontend will either crash OR display the max buffering error

I'll file a bug issue for this case.

>> Use quick tuning
>>  - Never
>>  - Live TV only
>>  - Always
>> If enabled, MythTV will tune using only the MPEG program number. The
>> program numbers change more often than DVB or ATSC tuning parameters, so
>> this is slightly less reliable. This will also inhibit EIT gathering during
>> Live TV and recording.
>> in your Input Connections in mythtv-setup, IIRC.
>> Mike
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