Can anyone explain how tuning works? (1 Viewer)

robomonkey

Portal Pro
August 4, 2005
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Good Morning,

Could anyone hep me to understand this, is it like radio? i.e. I kow that anywhere in my local area if I tune my radio to FM99.3 I'll get radio 1, it will also work on 99.1,99.2,99.4,99.5 etc. but the best reception is 99.3, and this changes for different areas, e.g. the county next to me might have a better reception on 99.4.

The reason I ask is because I'd like to manually tune my DVB stations because whenever I do an auto tune, I get different results, it always updates some channels and not others, and randomly finds and looses channels, I think this is due to my ariel.

I only actually watch about 13 channels so it hopefully shouldn't be to hard, I just need to find a list of DVB signals in my area I guess?
 

samuel337

Portal Pro
August 25, 2004
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Melbourne, Australia
Its not actually that easy for DVB.

Firstly, every network has a frequency (can be found in the MP xml file if your country is listed - MP automatically searches those frequencies) and a network ID.

Once you've located that you also have to located the channel ID, along with the video stream ID and the audio stream ID, because each network can transmit more than one channel, each with more than one audio stream.

I can't remember the correct terminology for the above IDs, but unless you have the settings from another source, it would be very hard to manually tune digital TV. If you try autotuning, then going into MP configuration -> TV -> Channels, select a channel and press edit, then go to the DVBT tab, you'll see what I mean.

Sam
 

robomonkey

Portal Pro
August 4, 2005
207
1
ok, maybe thats a bad idea then, I'm about to start using multiple cards, (2/3) will the tuning be the same for each card, so essentially once I've got a good reception for a station I can write the settings down to make sure they're always correct?
 

Taipan

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  • February 23, 2005
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    robomonkey said:
    so essentially once I've got a good reception for a station I can write the settings down to make sure they're always correct?
    Theoretically, yes - the settings (frequencies, PIDs etc) will be the same for all cards.

    But, MediaPortal Autotune doesn't always get the correct values in the first place, particularly for the centre frequency.... :( I know this is the case for some Australian frequencies, and I think that others have discovered the same problem in other countries, too. See here for more information.
     

    Taipan

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    robomonkey said:
    where do you get the correct frequencies from?
    I used a utility called ScanChannelsBDA, but I don't think it will be of any use to you, as it was written for Australian channels.....but it wouldn't hurt to give it a try.....
     

    mzemina

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    Taipan said:
    robomonkey said:
    where do you get the correct frequencies from?
    I used a utility called ScanChannelsBDA, but I don't think it will be of any use to you, as it was written for Australian channels.....but it wouldn't hurt to give it a try.....

    I see it also has source code, I wonder if any of the MP developers have looked at this code to help them out?
     

    jawbroken

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    August 13, 2005
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    There should be information about the correct frequencies for your area on the internet somewhere. I found a site that told me the channel frequencies for various parts of Australia once, I would guess that similar information would be available for you somewhere.
     

    bigj

    Portal Pro
    January 10, 2005
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    My dvbt.xml for UK, Mendip follows.
    I've adjusted the offset to 0 and added 167 to the individual entries,
    this is 'cos multiplex 6 dosn't require the offset. Or so it seems.
    I don't remember where I found the frequencies - but was via google.
    I use this so I don't pick up multiple stations from various transmitters, it also speeds up tuning nicely. You should see the freqs in the logs - can't remember which right now. Also if you export settings - they'll get dumped in ChannelList.xml.

    <?xml version="1.0" encoding="iso-8859-1" ?>




    <dvbt>
    <country name="UK - Mendip" offset="0">








    <carrier frequency="778167" bandwidth="8" />
    <carrier frequency="746167" bandwidth="8" />
    <carrier frequency="802167" bandwidth="8" />
    <carrier frequency="826167" bandwidth="8" />
    <carrier frequency="754167" bandwidth="8" />
    <carrier frequency="842000" bandwidth="8" />
    </country>
    </dvbt>
     

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