[mythtv-users] No longer tune some channels - gives LaG_

Dave Alverson davemyth at test.xetron.com
Fri Apr 27 02:45:50 UTC 2007


My myth box recently stopped tuning some channels on the AirStar  
HD5000 connected to cable.  Its been getting about 20 channels of  
clear QAM, but now it can't  tune any of the channels on one  
frequency - the rest are fine.  From the description of the tuning  
letters from the FAQ, it looks like LaG_ means it sees PAT frames but  
doesn't think they are good.  I have a Sony HDTV and it still gets  
the channels that myth cant; it can pick them up at the remapped  
channel (eg 5.1) and the actual channel, which is what my myth setup  
has (105.1), so the channels haven't moved.

I grabbed dvbsnoop to see what it could tell me:

[root at dvr .azap]# azap -r -c channels.conf "WLWT"
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
tuning to 681000000 Hz
video pid 0x0021, audio pid 0x0022
status 00 | signal 0000 | snr 0000 | ber 00000000 | unc 0000ffff |
status 1f | signal 0000 | snr fe0c | ber 00000000 | unc 0000ffff |  
FE_HAS_LOCK
status 1f | signal 0000 | snr fe17 | ber 00000000 | unc 00000000 |  
FE_HAS_LOCK

[root at dvr .azap]# dvbsnoop -n 1 0x00
dvbsnoop V1.4.00 -- http://dvbsnoop.sourceforge.net/

------------------------------------------------------------
SECT-Packet: 00000001   PID: 0 (0x0000), Length: 44 (0x002c)
Time received: Thu 2007-04-26  18:52:35.972
------------------------------------------------------------
   0000:  00 b0 29 10 0f d5 00 00  00 11 e0 70 00 06 e0  
60   ..)........p...`
   0010:  00 01 e0 20 00 03 e0 30  00 04 e0 40 00 05 e0 52   ... ... 
0... at ...R
   0020:  00 21 e2 10 00 12 e0 80  5a fe 46  
c0               .!......Z.F.

PID:  0 (0x0000)  [= assigned for: ISO 13818-1 Program Association  
Table (PAT)]
Guess table from table id...
PAT-decoding....
Table_ID: 0 (0x00)  [= Program Association Table (PAT)]
section_syntax_indicator: 1 (0x01)
(fixed): 0 (0x00)
reserved_1: 3 (0x03)
Section_length: 41 (0x0029)
Transport_Stream_ID: 4111 (0x100f)
reserved_2: 3 (0x03)
Version_number: 10 (0x0a)
current_next_indicator: 1 (0x01)  [= valid now]
Section_number: 0 (0x00)
Last_Section_number: 0 (0x00)

     Program_number: 17 (0x0011)
     reserved: 7 (0x07)
     Program_map_PID: 112 (0x0070)

     Program_number: 6 (0x0006)
     reserved: 7 (0x07)
     Program_map_PID: 96 (0x0060)

     Program_number: 1 (0x0001)
     reserved: 7 (0x07)
     Program_map_PID: 32 (0x0020)

     Program_number: 3 (0x0003)
     reserved: 7 (0x07)
     Program_map_PID: 48 (0x0030)

     Program_number: 4 (0x0004)
     reserved: 7 (0x07)
     Program_map_PID: 64 (0x0040)

     Program_number: 5 (0x0005)
     reserved: 7 (0x07)
     Program_map_PID: 82 (0x0052)

     Program_number: 33 (0x0021)
     reserved: 7 (0x07)
     Program_map_PID: 528 (0x0210)

     Program_number: 18 (0x0012)
     reserved: 7 (0x07)
     Program_map_PID: 128 (0x0080)

CRC: 1526613696 (0x5afe46c0)
==========================================================

I just upgraded to MythTV 0.20.1-156 from atrpms, and that didnt  
help.  I'm on FC6 and the kernel is 2.6.19-1.2895.fc6 - a few months  
old.

What type of checks are there to see if the PAT is valid and are  
those checks in myth or the driver for the card?



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