[mythtv-commits] Ticket #13257: Auto-tune of HD channels fails but works when transponders manually added

[MythTV]

#13257: Auto-tune of HD channels fails but works when transponders manually added
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     Reporter:  whpaul.thompson@…         |      Owner:
         Type:  Bug Report - General      |     Status:  new
     Priority:  minor                     |  Milestone:  needs_triage
    Component:  MythTV - Channel Scanner  |    Version:  v29.0
     Severity:  medium                    |   Keywords:
Ticket locked:  0                         |
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 Internet searches reveal that a failure to tune HD channels is not
 uncommon. Having identified the following workaround for PCTV 290e HD
 auto-tuning fail works for me (this is post Crystal Palace (UK) Mar 18
 changes that also required a new wide-band aerial), sharing this may help
 others resolve their own difficulties and perhaps even help developers
 reduce the likelihood of HD channel scan failure.

 Symptoms:
 Post Crystal Palace changes need to retune my MythTV to locate changed HD
 channels. However, MythTV auto-tune fails to pick them up. Neither does
 TVheadend nor w_scan. w-scan does find the MUX/transponder but not the
 channels within. When I insert the 290e into my Windows laptop (running
 PCTV's TVCenter 6.4.9.1033) it finds the new HD channels automatically
 with a reported signal strength of > 80%. The issue is therefore not my
 aerial, too high or too low a signal but something software related on my
 arch linux arm box (4.4.47-1-ARCH armv5tel) common to the autoscan
 detection process in MythTV, TVheadend and w_scan.

 Workaround:
 Autodetect of the HD channels is no longer working (it did before the
 recent Crystal Palace changes). However, manually adding the
 MUXs/transports to MythTV/TVheadend etc '''and specifying that they are
 QAM256 modulation and 8Mhz bandwidth (rather than leaving them both at
 Auto)''' does enable both MythTV and TVheadend to discover the channels on
 the HD MUXes/transportes.

 I don't know why auto-detect does not work nor why specifying the
 modulation and bandwidth manually solves my problem, but am happy to offer
 my setup as a reproducible testbed for any expert willing to investigate
 the matter further.

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Ticket URL: <https://code.mythtv.org/trac/ticket/13257>
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