[mythtv-users] Slave backend part 2

Mike Perkins mikep at randomtraveller.org.uk
Fri Oct 23 14:49:30 UTC 2020 

So I built my slave backend, loaded it with Debian Buster and added the deb-multimedia repo.

Installing the backend is a pain, since it insists on installing a database server, which of course 
is not required for a slave. (This also happened when updating the master; it mucks about with the 
database password in config.sys. Beware.)

Added my Hauppauge Nova-T USB tuner, created a source and attempted to scan. Nothing! I can see on 
the display that there is signal but the message is always the same, whatever the channel: Timed 
out, no signal.

Adding in some debug tracing gives me a stream of which the following is a snippet:

2020-10-23 15:28:07.492726 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- end
2020-10-23 15:28:07.492790 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 39 mplexid(0)
2020-10-23 15:28:07.492883 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 599500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 606500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:07.492899 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Tuning to 606500000Hz
2020-10-23 15:28:08.326998 I  DVBChan: wait_for_backend: Status: Signal,
2020-10-23 15:28:08.327022 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:08.327072 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:11.332313 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 39 offset 1 mplexid(0)
2020-10-23 15:28:11.587085 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 606500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 606625000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:11.587102 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:11.587151 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:14.590891 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): transport_tune_complete: 
wait_until_complete 0
2020-10-23 15:28:14.591025 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): Channel 39 offset 1 -- 
Timed out, no signal
2020-10-23 15:28:14.591045 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- begin
2020-10-23 15:28:14.884806 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- end
2020-10-23 15:28:14.884864 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 40 mplexid(0)
2020-10-23 15:28:14.884975 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 606500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 613500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:14.884998 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Tuning to 613500000Hz
2020-10-23 15:28:15.715051 I  DVBChan: wait_for_backend: Status: Signal,
2020-10-23 15:28:15.715082 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:15.715137 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:18.721037 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 40 offset 1 mplexid(0)
2020-10-23 15:28:18.991130 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 613500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 613625000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:18.991148 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:18.991197 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:21.994333 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): transport_tune_complete: 
wait_until_complete 0
2020-10-23 15:28:21.994455 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): Channel 40 offset 1 -- 
Timed out, no signal
2020-10-23 15:28:21.994474 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- begin
2020-10-23 15:28:22.284838 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- end
2020-10-23 15:28:22.284900 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 41 mplexid(0)
2020-10-23 15:28:22.284988 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 613500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 620500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:22.285003 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Tuning to 620500000Hz
2020-10-23 15:28:22.285178 I  DVBChan: wait_for_backend: Status:
2020-10-23 15:28:22.285198 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:22.285248 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:25.289546 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 41 offset 1 mplexid(0)
2020-10-23 15:28:25.289627 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 620500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 620625000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:25.289641 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:25.289686 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:28.293252 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): transport_tune_complete: 
wait_until_complete 0
2020-10-23 15:28:28.293378 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): Channel 41 offset 1 -- 
Timed out, no signal
2020-10-23 15:28:28.293399 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- begin
2020-10-23 15:28:28.321404 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- end
2020-10-23 15:28:28.321477 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 42 mplexid(0)
2020-10-23 15:28:28.321590 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 620500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 627500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:28.321606 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Tuning to 627500000Hz
2020-10-23 15:28:29.163021 I  DVBChan: wait_for_backend: Status: Signal,
2020-10-23 15:28:29.163046 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:29.163097 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:32.166000 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): ScanTransport Tuning to 
Channel 42 offset 1 mplexid(0)
2020-10-23 15:28:32.431106 I  DVBChan[16](/dev/dvb/adapter0/frontend0):
Old Params: 627500000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
New Params: 627625000 auto 0 auto auto 7 8 auto n v fec: auto msys: UNDEFINED rolloff: 0.35
2020-10-23 15:28:32.431123 I  DVBChan[16](/dev/dvb/adapter0/frontend0): Tune(): Frequency tuning 
successful.
2020-10-23 15:28:32.431173 I  DTVSigMon[16](/dev/dvb/adapter0/frontend0)::SetChannel(-1, -1):
2020-10-23 15:28:35.434978 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): transport_tune_complete: 
wait_until_complete 0
2020-10-23 15:28:35.435110 I  ChannelScanSM(/dev/dvb/adapter0/frontend0): Channel 42 offset 1 -- 
Timed out, no signal
2020-10-23 15:28:35.435131 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- begin
2020-10-23 15:28:35.716704 I  DVBSigMon[16](/dev/dvb/adapter0/frontend0): Stop() -- end

Sorry about the length, but the selection is important. I /know/ that there are transmissions (here) 
on channels, 39, 40 and 42, yet the scanner finds NOTHING. (My MBE is using these channels!)

A close look at the channel frequencies reveals the problem: they are nothing like the published 
values. Channel 39 is being scanned at 606500000Hz but I know that it should be 618200000Hz. Channel 
42 is scanned at 627500000Hz whereas it should be 642000000Hz.

I am using the Europe-west table as I am in the UK. My master backend has been successfully tuned 
this way in the recent past. Has something recently changed?

-- 

Mike Perkins

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