[mythtv-users] : Re: Artifacts [solved]

jam at tigger.ws jam at tigger.ws
Sun Dec 23 13:23:14 UTC 2018

> On 23 Dec 2018, at 6:41 pm, mythtv-users-request at mythtv.org wrote:
>> Hi
>> because some of our channels have been playing games with their names I dropped all channels and rescanned.
>> All good EXCEPT many channels, specially HD channels, are plagued with artifacts and chirps and squeeks typical of poor signal quality.
>> I checked frequency in sql table channelscan_dtv_multiplex and they are identical.
>> I restored old db with mythconverg_restore.pl and problem is totally gone.
>> What can I say or not say to the db that will affect tuning. The stations are correct just apparant signal strength is bad.
>> I stress NO hardware or software changes or conections are changed in any way ONLY mythconverg DB changes.
>> Whatcould be happening?
>> James
> Was the old table created with the same tuner - its possible that a 
> field set previously to auto might need a parameter. The easiest check 
> is compare all the old and new tuning parameters.
Interedting and may well be of interest:

I live equidistant-ish to 3 transmitters and in range of another two

Perth - Willetton https://www.txaustralia.com.au/tvcoverage

Each scan is different. Trick was to scan (say) 5 times add the results and delete not-good channels.
One transmitter site did not yield best results on every channel!

So a chance good scan once upon a time, was just luck.


PS a note to any developers who may be bored :-)

1) it would be nice to be able to see signal-strengths a la scanning to easily select WHICH channels to prune
2) It would be nice to be able to edit channel frequencies and match frequencies to channels eg

scan choose a frequency of 663. 250000 instead  of 663 500000
sql fiddling to get a list of frequency vs chan

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