[mythtv-users] What does ATSC poor signal look like? or is thePCnot up to it?

[Misty P]

Andre Newman wrote:

> On 16 Apr 2009, at 17:42, Misty P wrote:
>> Have your friend watch TV with myth, and then when he notices
>> picture wonkyness, kill the femon process.  Look at the results.
>> (Word to the wise: pump femon's output to a file!)  You'll see
>> something along the lines of this:
>>
>> ~$ femon -a 0
>> FE: Samsung S5H1409 QAM/8VSB Frontend (ATSC)
>> status SCVYL | signal 0127 | snr 0127 | ber 00000000 | unc 00000000
>>> FE_HAS_LOCK
>> status SCVYL | signal 0127 | snr 012c | ber 00000000 | unc 00000000
>>> FE_HAS_LOCK
>> status SCVYL | signal 0127 | snr 0127 | ber 00000000 | unc 00000000
>>> FE_HAS_LOCK
>
> I read somewhere that the HVR950 doesn't report ber but unc should be
> useful (maybe the ber thing was a older driver) I'm guessing that unc
> is uncorrected, ie packets that the FEC couldn't correct?

I believe that's correct regarding unc, but don't quote me on it.  (It 
doesn't come with a man page -- garrrgh!)

Don't know if the HVR-950 reports ber or not.  My Hauppauge 1250, 1600, and 
1800 all report both, so I would be surprised if the 950 didn't.  (Yes, I 
have and use all three with myth!)

>> The upshot is to scan the log file and see if you have sections
>> where either the lock drops out or you have ber and/or unc errors.
>> If you do, then everything is working fine and you have signal
>> degredation.  If not, then the signal is fine and you have a problem
>> elsewhere.
>
> Great stuff, just what I have been trying with analysing the transport
> streams but real time is much more meaningful.

Oh yeah, it's much easier in real time!  Besides, if you just look at the 
resultant transport stream, all you know is that you lost data.  You don't 
know *where* you lost that data.

Femon is also really useful for playing around with antenna 
positioning/aiming, since that's the next logical step if you find you have 
signal degredation.