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    ViX Beta Tester birdman's Avatar

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    ABM (Terrestrial): Frequency Finder. Birdman's thread

    Quote Originally Posted by abu baniaz View Post
    From ABM 3.1, a new feature will be available in ABM to scan for local masts. This is for changes as well as for adding regions.
    Would it make sense if, when scanning (terrestrial?) channels, the options were:

    1. Allow the (manual) creation of a skip-channel list.
    2. Scan all channels except any in the skip-channel list and save the resulting channels as an active-channels list.
    3. Scan just the channels from my active-channels list.


    1. Is to allow for people picking up unwanted signals from a second transmitter to remove it.
    2. Is for a first scan, or a rescan when frequencies change (which will be happening quite a bit over the next year for 700MHz frequency clearance)
    3. Is to pick up new/removed channels.
    Last edited by birdman; 03-08-18 at 01:31.
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  3. #2
    Moderator Huevos's Avatar

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    Quote Originally Posted by birdman View Post
    Would it make sense if, when scanning (terrestrial?) channels, the options were:

    1. Allow the (manual) creation of a skip-channel list.
    2. Scan all channels except any in the skip-channel list and save the resulting channels as an active-channels list.
    3. Scan just the channels from my active-channels list.


    1. Is to allow for people picking up unwanted signals from a second transmitter to remove it.
    2. Is for a first scan, or a rescan when frequencies change (which will be happening quite a bit over the next year for 700MHz frequency clearance)
    3. Is to pick up new/removed channels.
    This tool has nothing to do with scanning for channels. Its purpose is to create an ABM providers file. Previously that had been a manual process that required us to obtain and incorporate the data into the system file supplied with ABM. That is hard work and also means we have to rely on users to supply data that is out of our reach, and that we cannot verify This tool automates that process. Any user that is having trouble scanning with the system file supplied can now use this tool to create a providers file that is specific to their location. That file can be used by them immediately and it can also be submitted back to us so we can update our system file for the benefit of the collective.

    BTW, all the problems you mentioned above are already handled automatically by a normal ABM scan.
    Last edited by Huevos; 03-08-18 at 02:42.

  4. #3
    ViX Beta Tester birdman's Avatar

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    Quote Originally Posted by Huevos View Post
    BTW, all the problems you mentioned above are already handled automatically by a normal ABM scan.
    They're not handled by a "system scan". There you have to select a transmitter, and the config file needs to have the correct data for it (you can't scan the current channel list).
    So would it make sense to have one scanning method?
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    Moderator Huevos's Avatar

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    Above posts removed from the sticky...

    https://www.world-of-satellite.com/s...annels-regions

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    Moderator Huevos's Avatar

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    Quote Originally Posted by birdman View Post
    They're not handled by a "system scan". There you have to select a transmitter, and the config file needs to have the correct data for it (you can't scan the current channel list).
    So would it make sense to have one scanning method?
    This is the ABM part of the forum which is why we posted this here.

    Regarding "system scan" that is just a generic scan based on, either a single user defined parameter entry, or predefined entries from terrestrial.xml. So if you are importing muxes that don't belong to your region either the tuner config is wrong or the content of terrestrial.xml is wrong.

    Regarding the duplication problem you have 2 choices:
    • either enable DVB-T namespace subnet (so the identical muxes can both be captured)
    • or use ABM or the TerrestrialScan plugin



    The TerrestrialScan plugin does an exhaustive search for all active DVB-T and DVB-T2 muxes. It then removes any duplicate muxes, after which it hands over details of the remaining muxes to "system scan" for those muxes, and just those muxes to be scanned.

    The TerrestrialScan plugin can also make a simple single bouquet of the terrestrial services found, ordered by LCN.

    The big difference between ABM and the TerrestrialScan plugin is that ABM collects all the data it needs from one single transponder making the scan lasts just seconds, whereas the TerrestrialScan plugin does an exhaustive search for muxes and this can take several minutes to complete.

    "DVB-T frequency finder" does a combination of the above. It does an exhaustive search once (taking several minutes) and saves that data for subsequent (fast) ABM scans.

    I got no idea what you mean by "scan the current channels list". The point of a scan is to purge old channels and find current ones. That is what "system scan" does.
    Last edited by Huevos; 03-08-18 at 12:01.

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    ViX Beta Tester birdman's Avatar

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    Quote Originally Posted by Huevos View Post
    Regarding "system scan" that is just a generic scan based on, either a single user defined parameter entry, or predefined entries from terrestrial.xml. So if you are importing muxes that don't belong to your region either the tuner config is wrong or the content of terrestrial.xml is wrong.
    Over the next year there will be frequency changes at many transmitters. From the day these happen the terrestrial.xml file will be wrong until a new one can be put in place, which currently requires a new Vix release with the new version file (and the user to update to it). Until that happens they will have lost services, unless they do a full scan.
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    Moderator Huevos's Avatar

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    No. Once a new file is on github you can pull it straight into your image using the gui. No build needed.

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    Moderator abu baniaz's Avatar

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    ABM "scanning" and Enigma 2 scanning are different processes.

    ABM uses the provider xml files in /usr/lib/enigma2/python/Plugins/SystemPlugins/AutoBouquetsMaker/providers to obtain tuning data from the stream. For the UK, we have used the same frequency for BBC1 as the home transponder. Some frequency data is missing (DVB T2) and occasionally incorrect. So we add the custom transponders. ABM does not really scan. It tunes to the home frequency and gets the tuning data from there. You can update the config files within ABM provided it is the same version.

    Enigma2 scanning consults the terrestrial.xml in firstly /etc/enigma2/. If not present is uses the system version in /etc/tuxbox/ The idea is a personalised one can be kept in /etc/enigma2. It checks each frequency that is listed for services. Enigma2 scanning does not uses aerial groups like TVs do. (Even for TV's, there are some areas where the frequencies/channels need to be scanned individually owing to clashes.) Yes the xml file need to be correct. Selecting the UK one will scan all of them and generally works for everyone. Where people have clashes, we have listed the areas. This means they can select the their areas and scan only specific frequencies instead of all of them. Prior to splitting by country, it would have been a very long list. Compounded by the fact that the area was selected by the position in the xml file. We changed this too so that the name is used. People can submit changes by pull requests to benefit their neighbours if they want.

    We created and added xml update plugin so that people can fetch the updated file without waiting for an image update. The xml update plugin needs to be installed.

    For DVB-C, there is a function to select frequencies to scan. This would be a good addition to add for EnIgma2 DVB-T scanning. But users will need to know which frequencies/channels to scan. Or just use Terrestrial scan plugin. Explanation above.

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    Moderator abu baniaz's Avatar

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    Quote Originally Posted by Huevos View Post
    No. Once a new file is on github you can pull it straight into your image using the gui. No build needed.
    See here
    https://www.world-of-satellite.com/s...e-xml-updating

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    ViX Beta Tester birdman's Avatar

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    Quote Originally Posted by abu baniaz View Post
    ABM "scanning" and Enigma 2 scanning are different processes.
    Given that they are both trying to produce the same result (a lamedb(5) file) could they not be the same?

    ABM uses the provider xml files in /usr/lib/enigma2/python/Plugins/SystemPlugins/AutoBouquetsMaker/providers to obtain tuning data from the stream. For the UK, we have used the same frequency for BBC1 as the home transponder. Some frequency data is missing (DVB T2) and occasionally incorrect.
    Well, that would explain why on the recent frequency change on Sandy Heath one was spotted (a DVB-T mux) while two were not (DVB-T2 muxes). Although that was doing a system scan (as I don't use ABM).

    So we add the custom transponders. ABM does not really scan. It tunes to the home frequency and gets the tuning data from there. You can update the config files within ABM provided it is the same version.
    Which will break a lot in the next year...

    Enigma2 scanning consults the terrestrial.xml in firstly /etc/enigma2/. If not present is uses the system version in /etc/tuxbox/
    ...as will that.
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    Moderator Huevos's Avatar

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    Now I'm sure you're on a windup... but just in case you're not...

    DVB-T tuners are not normally hardware blindscan capable. Instead they rely on a bandplan. Same for TVs, same for Enigma2 receivers. In the case of Europe that bandplan is in 8 MHz steps between 474 Mhz and 858 MHz inclusive and follows the DVB standard. For Enigma2 that bandplan is written into terrestrial.xml and has been unchanged ever since Enigma2 was created and will still be current after any change in the UK takes place.

    Following this 8 MHz step bandplan (built into Enigma2) it is possible to do a "system scan" and return all channels that are receivable in your location. If for some reason you can't receive any channels that is down to user error (e.g. an incorrectly configured receiver). Any changes to the frequencies allocated on a UK mast are nothing to do with this process. Changes to frequencies locally within this bandplan will not affect a correctly configured receiver's ability to find all the channels available in that area.

    If you want to speed up searching you can limit your search to a handful of transponders known to be active in a certain area. This is what the additional areas in terrestrial.xml allow. This also eliminates scanning junk from other areas. But it requires regular maintenance to ensure the data in the terrestrial.xml file corresponds with the current situation at each location. And as we can only make changes in terrestrial.xml once we are aware of the changes at the location, sometimes terrestrial.xml lags the current situation at each location. There is no way to get around this on any device, and would require insider information or a time machine to get us into the future to collect the data so we can update the data in terrestrial.xml at the instant it changes (and a method to push it to all users).

    From the above you can see that any process that speeds up scanning relies on pre-gathered data (which can become stale). Same for "system scans", same for ABM scans. In the case of "system scans" we created the "xmlupdate" plugin, and in the case of ABM we created "DVB-T frequency finder" so that the data can be collected and used in the shortest possible time. In the case of ABM it is a matter of seconds between collecting the data and using it.

    BTW, of course "system scan" and ABM processes can't be the same. One is a channel scanner, the other is a bouquet maker.
    Last edited by Huevos; 04-08-18 at 15:18.

  14. #12
    ViX Beta Tester birdman's Avatar

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    Quote Originally Posted by Huevos View Post
    If you want to speed up searching you can limit your search to a handful of transponders known to be active in a certain area. This is what the additional areas in terrestrial.xml allow. This also eliminates scanning junk from other areas. But it requires regular maintenance to ensure the data in the terrestrial.xml file corresponds with the current situation at each location.
    That's what I've been saying. And with the 700MHz clearance overt the next year that data is going to be frequently out of date for transmitters.
    So I was wondering if being able to save the list of currently-used channels and just use those for a quick-scan we could do away with maintaining the transmitter data completely.

    And as we can only make changes in terrestrial.xml once we are aware of the changes at the location, sometimes terrestrial.xml lags the current situation at each location. There is no way to get around this on any device, and would require insider information or a time machine to get us into the future to collect the data so we can update the data in terrestrial.xml at the instant it changes (and a method to push it to all users).
    The data is available - but you'd need to know to update the file, and users to download it, on the particular day.

    BTW, of course "system scan" and ABM processes can't be the same. One is a channel scanner, the other is a bouquet maker.
    I wasn't suggesting that. I was suggesting that ABM's scan (to find channels) be the same as the system one. What it then does with the result is unrelated.
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    Moderator abu baniaz's Avatar

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    ABM (Terrestrail ): Add HD channels/regions

    What are you defining as "channels"? Frequencies or Services?

    What is the point in saving what is valid/current to reuse when it is no longer valid/current.

    People need to scan the valid frequencies.

  16. #14
    ViX Beta Tester birdman's Avatar

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    Quote Originally Posted by abu baniaz View Post
    What are you defining as "channels"? Frequencies or Services?
    Frequencies (muxes).

    What is the point in saving what is valid/current to reuse when it is no longer valid/current.
    So there is no need to have an maintain a config file of transmitter data.

    People need to scan the valid frequencies.
    Only at the start and at any change. From then on they just re-use the ones they've saved.
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    Although I currently don't use DVB-T/T2, I was just looking into what changes would happen for Winter Hill over next few years....

    At the moment, Winter Hill uses:
    RF channel 50 (706MHz)
    RF channel 59 (778MHz)
    RF channel 54 (738MHz)
    RF channel 58 (770MHz)
    RF channel 49 (698MHz)
    RF channel 37 (602MHz)
    RF channel 55 (746MHz)
    RF channel 31 (554MHz)

    Finally from mid 2020, Winter Hill will be using:
    RF channel 32 (562MHz)
    RF channel 34 (578MHz)
    RF channel 35 (586MHz)
    RF channel 29 (538MHz)
    RF channel 31 (554MHz)
    RF channel 37 (602MHz)
    RF channel 55 (746MHz)
    RF channel 56 (754MHz)

    Now looking at terrestrial.xml, the general UK (all regions) one covers all RF channels so that should still work come 2020 but the Winter Hill specific entry obviously doesn't mention some of the lower frequencies Winter Hill will eventually be using!

    Sources:
    Digital UK Coverage Indicator (select Detailed view)
    DigitalUK - 700MHz clearance info
    UHF Channel/Frequency Guide (maybe a little out-of-date but appears correct)
    Last edited by bbbuk; 05-08-18 at 10:24.

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