automated w_scan, duplicated channels and signal strength filtering

linux-dvb Jelle de Jong 2 participants 3 messages Oct 31, 2008 – Nov 1, 2008 Media (V4L/DVB)

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Jelle de Jong

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2008-10-31 19:53 UTC #0 lore raw

Hello everybody,

I am using a tool called w_scan [1] to automate scanning for dvb-t signals, this kind of works, but its still not enough to be usable for non computer literate people. I got the following issues:

When a scan is completed it list all found channels, in the file, (see attachment) however this also include duplicated channels with other frequencies and strange channels that are from local unusable broadcast.

The issue here is that signal strength is not used to filter out duplicated channels, only the best strongest signal should come in the channel list, and channels without identifiers should be removed.

How can we do this? Is somebody able to fix these issues?

Thank in advance for any repose,

Best regards,

Jelle

[1] http://wirbel.htpc-forum.de/w_scan/index2.html

ps. I can't find any contact info for the developer of w_scan.

Nederland 1(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:7011:7012:1101 Nederland 2(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:7021:7022:1102 Nederland 3(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:7031:7032:1103 TV Rijnmond(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:7041:7042:1104 Radio Rijnmond(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7112:1111 Radio 1(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7122:1112 Radio 2(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7132:1113 3FM(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7142:1114 Radio 4(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7152:1115 Radio 5(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7162:1116 Radio 6(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7172:1117 Concertzender(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7182:1118 FunX(Digitenne):474000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_1_2:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_4:HIERARCHY_NONE:0:7192:1119 [001f]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3011:3012:31 [0020]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3021:3022:32 [0021]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3031:3032:33 [0022]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3041:3042:34 [0023]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3051:3052:35 [0024]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3061:3062:36 [0025]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3071:3072:37 [0026]:498000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:3081:3082:38 Nederland 1(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:7011:7012:1101 Nederland 2(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:7021:7022:1102 Nederland 3(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:7031:7032:1103 TV West(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:7041:7042:1104 Radio West(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7112:1111 Radio 1(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7122:1112 Radio 2(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7132:1113 3FM(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7142:1114 Radio 4(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7152:1115 Radio 5(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7162:1116 Radio 6(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7172:1117 Concertzender(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7182:1118 FunX(Digitenne):722000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_AUTO:FEC_AUTO:QAM_AUTO:TRANSMISSION_MODE_AUTO:GUARD_INTERVAL_AUTO:HIERARCHY_AUTO:0:7192:1119

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wk

2008-11-01 10:23 UTC #1 lore raw

Hello Jelle,

Quoted 4 lines

When a scan is completed it list all found channels, in the file, (see attachment) however this also include duplicated channels with other frequencies and strange channels that are from local unusable broadcast.

That's most probably what your provider sends inside NIT (network information table).
w_scan reads it's informations from there. Sometimes these informations are wrong.

Quoted 7 lines

The issue here is that signal strength is not used to filter out duplicated channels, only the best strongest signal should come in the channel list, and channels without identifiers should be removed.
How can we do this? Is somebody able to fix these issues?

It's not possible to use signal information since nearly every dvb cards sends other information for signal strength,
please read the discussion regarding SNR/strength some days ago here on the list. From application point of view
the signal strength information doesnt contain any useful data as long it's not standardized and reliable across all frontends. Therefore i decided not to use signal strength. Otherwise some frontends would not work.

Signals without identifiers will not be removed, since some of them have their channel names inside EIT information or
inside private data (i.e. Prmiere) and deleting these channels would make other users really unhappy. ;)
Most of these channels are encrypted, so try to avoid them with -E 0 . But channels without video *and* audio will be removed instead.

Quoted 4 lines

[1] http://wirbel.htpc-forum.de/w_scan/index2.html
ps. I can't find any contact info for the developer of w_scan.

email contact is included in the header of each source file. Nevertheless, should be inside README too, you're right.

Regards,
Winfried

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Jelle de Jong

author

2008-11-01 18:41 UTC #2 lore raw

Quoted 34 lines · wk

Hello Jelle,
Quoted 4 lines
When a scan is completed it list all found channels, in the file, (see attachment) however this also include duplicated channels with other frequencies and strange channels that are from local unusable broadcast.
That's most probably what your provider sends inside NIT (network information table).
w_scan reads it's informations from there. Sometimes these informations are wrong.
Quoted 7 lines
The issue here is that signal strength is not used to filter out duplicated channels, only the best strongest signal should come in the channel list, and channels without identifiers should be removed.
How can we do this? Is somebody able to fix these issues?
It's not possible to use signal information since nearly every dvb cards sends other information for signal strength,
please read the discussion regarding SNR/strength some days ago here on the list. From application point of view
the signal strength information doesn't contain any useful data as long it's not standardized and reliable across all frontends. Therefore i decided not to use signal strength. Otherwise some frontends would not work.
Signals without identifiers will not be removed, since some of them have their channel names inside EIT information or
inside private data (i.e. Prmiere) and deleting these channels would make other users really unhappy. ;)
Most of these channels are encrypted, so try to avoid them with -E 0 . But channels without video *and* audio will be removed instead.
Quoted 2 lines
[1] http://wirbel.htpc-forum.de/w_scan/index2.html

Quoted 7 lines

Quoted 2 lines
ps. I can't find any contact info for the developer of w_scan.
email contact is included in the header of each source file. Nevertheless, should be inside README too, you're right.
Regards,
Winfried

Thank you Winfried for both creating the program and to response and clear op my questions.

I followed the SNR/strength messages and read the thread again, I was hopping some drivers where already using some system that could be used, like polling the capabilities of the frontends. I would also suggest some way of translating the dB to a min(0)(red) and max(100)(green) value so a decimal number can also be used for representation.

I was also hopping w_scan was going into debian sid repositories, I would like this for my users, maybe I can find some time next year to fix this.

Sadly it seems my usability issues can not be fixed in an easy way, lets hope SNR support and some logic using it during channel scanning will be coming soon :-p. I can donate 40 euro, dutch stroopwafels, or some plushy tux mascots for some extra motivation.

Thanks in advance,

Jelle

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