si2168/dvbsky - blind-scan for DVB-T2 with PLP fails

[Hurda <hurda@chello.at>]

[-- Attachment #1: Type: text/plain, Size: 3558 bytes --]

Hello.

I think I came across a bug in either of the drivers si2168 and dvbsky regarding
blind-scanning DVB-T2-frequencies.

HW: Technotrend CT2-4400v2 (afaik based on or the same as DVBSky T330)
     demod: Si2168-B40
     tuner: Si2158-A20
OS: Ubuntu 15.04 (kernel 3.19)

In Austria, the DVB-T2-service "SimpliTV" is currently airing up to four
muxes, next to one or two DVB-T-muxes.
In my region, the frequencies are 490MHz, 546MHz, 690MHz, 714MHz for DVB-T2,
and 498MHz for DVB-T.
These numbers might be of interest when reading the logs.

The peculiar aspect of these T2-muxes is that they're aired on PLP 1 without
there being a PLP 0. I think this is also the root of my problem.


When doing a blind-scan using w_scan 20140727 on Ubuntu 15.04 (kernel 3.19),
w_scan does not find any of these four DVB-T2-muxes.
It just finds the DVB-T-mux.

Logs:
media-tree_dmesg_lsusb.txt http://pastebin.com/0ixFPMSA
media-tree_w_scan.txt http://pastebin.com/yyG3jSwj

The found transponder:
initial_v3_media_build_trunk.conf http://pastebin.com/LmFQavpy
initial_v5.conf http://pastebin.com/Jx6kymVt

I also tried a fresh checkout from git.linuxtv.org as of last weekend and the
most recent w_scan version (20141122).

As you can see, w_scan tries to tune(?) the DVB-T2-frequencies, but
ultimately doesn't find anything on them.


Then I tried the DVBSky-linux-driver[1] (media_build-bst-20150322.tar.gz)[2]
from their site, which is using a binary called sit2 for this card.
Using this driver, w_scan found all four DVB-T2-muxes and the DVB-T-mux.
Additionally, it found the DVB-T2-muxes during the DVB-T-scan.

Logs:
media_build-bst_dmesg_lsusb.txt http://pastebin.com/vJeDMxtu
media_build-bst_w_scan.txt http://pastebin.com/yhwAYjen

Found transponders:
initial_v3_bst.conf http://pastebin.com/ECKQvRWX
initial_v5_bst.conf http://pastebin.com/CbhY6Hpz

Of course, doing a channel-scan using dvbv5-scan on these transponders worked
too:

dvbv5_sit2.conf http://pastebin.com/3W52bbhv
dvbv5_sit2.log http://pastebin.com/nc66PTkt

Afterwards, I tried to do a channel-scan with the same initial tuning-file
using the opensource-driver, which also worked:

dvbv5_si2168.conf http://pastebin.com/A6FbqUL1
dvbv5_si2168.log http://pastebin.com/ewyVPJR2

This should verify that tuning PLP 1 without there being PLP 0 is not the issue.


Additionally, if you compare the two channel-lists, you find interesting
differences:

The scan with si2168 has AUTO for "MODULATION" and "INVERSION" for
DVB-T2-channels, and for "CODE_RATE_LP" and "INVERSION" for DVB-T-channels.

The scan with sit2 has the respective values in the channel-list.

The dvbv5-scan-logs also differ, as using sit2 also displays the signal quality
during tuning.


I know that there were changes regarding DVB-T2-scanning[3], but as the blog-
article specifically mentions si2168 and w_scan to be fully dvbv5-compliant
and good for using with DVB-T2, I thought you should know about this
particular problem.


In the attachment I've packed the previously linked logs, for archival reasons.


Thank you for your attention.

[1] http://www.dvbsky.net/Support_linux.html
[2] http://www.dvbsky.net/download/linux/media_build-bst-150322.tar.gz
[3] http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html

PS: Interesting comments regarding auto-detection for si2168:
http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html?showComment=1427233615765#c8591459871945922951
http://blog.palosaari.fi/2014/09/linux-dvb-t2-tuning-problems.html?showComment=1427234034259#c6500661729983566638 


[-- Attachment #2: si2168_dvb-t2_blindscan_logs.zip --]
[-- Type: application/octet-stream, Size: 69039 bytes --]