2020-07-06, 09:10 AM
(2020-07-03, 04:13 PM)Graham Wrote:(2020-07-03, 03:15 PM)hawkeye100 Wrote: Does the order of channels change often (in anyone's experience) and is it likely to cause similar issues in future or will nextPVR handle it?
NextPVR should find channel numbers during the scan and channels should be the same as on a TV e.g. 1 for BBC1 and 3 for ITV and so on
But NextPVR can struggle to get info during a scan if the signal is weak. That appears to be what is happening here.
NextPVR should handle changes during future scans but results may not be as expected if the signal is weak.
I think I have found the root of the problem, thanks to TSCapture and the Hauppage Digital Signal Quality checker (and Graham's help). In case it helps others, or in case I am off the mark my findings are below:
We receive signal/channels on 5 or 6 frequencies - 5 most likely from the transmitter the aerial is pointing at, and a rogue frequency that seems to be coming from much further away (but in that approximate direction).
This latter frequency is transmitting a duplicate block of channels to one from 'our' transmitter, though has a weak and intermittent signal (many unrecoverable errors, perhaps dependent on weather).
When the rogue frequency (C24 498000000) is present during a channel scan it allocates those channels default numbers e.g. BBC1 to 1 etc and the duplicate block on the 'local' transmitter (C48 690000000) gets a set of much higher channel numbers. (is that simply because 498 is lower number than 690, despite latter being stronger?)
Then when the distant rogue frequency disappears, and an EPG update occurs, the default channels it has been allocated in the TV Guide are emptied.
This all happens because when scanning for channels (on nextPVR and TSCapture) if I choose the 'local' transmitter (from where we have historically received signal) then no channels are found as it only scans a subset of frequencies which exclude those from which we actually receive channels. Consequently we have to scan all locations/frequencies (Auto-Default in nextPVR).
It may even be that our channels are not in fact coming from that local transmitter but from others in whose catchment we also fall (we live towards the edge of several).
When choosing a transmitter to scan, presumably there is a config file/setting somewhere with the relevant frequencies - can this be edited? Maybe Freeview info is out of date if the config is automatically populated from somewhere central. (Some comments on the Freeview site suggest their info may not be up to date in places.)
A solution appears to be to scan the channels to find those we want, delete the others (especially any from the rogue transmitter), and then not re-scan for channels again for as long as possible.
Next step is to find out how to map channels to more sensible numbers, regardless of frequency.
Helpful URLs have been:
Explanation of codes used by Freeview when searching by frequency (though also on some Freeview pages, once you have transmitter details)
https://www.dipolnet.com/tv_channels_pal_bg-dk__bib02.htm
Freeview website with transmitter details
https://ukfree.tv/section/TV_Transmitters
https://www.hauppauge.com.sg/pages/support/support_digital_signal_monitor.html
https://www.tscapture.com/