One LNB-Cable: 2 Tuner-Cards possible with this hardware? (1 Viewer)

heikoh

Portal Pro
September 5, 2007
110
1
Hi everyone,

I've been using MP for a very long time and I am very satisfied with it - Thanks to the Team!!!

I've now upgraded to MP1.0 and now I'm finally using a TV Server config, which is working great with a single tuner setup.

From my early days I have still a SkyStar2 lying in my basement, and I now like to reintegrate it into my HTPC.
The only problem: 1 only have one cable from my LNB going to the HTPC, and there is no way I can add another one.
However, I only intend to watch Germany's most common TV Stations on Astra, they basically are on 2 horizontal transponders (Pro7 Group, RTL Group) and maybe some of the big public tv stations that are also on horizontal transponders.

Now sometimes I want to record two shows on different horizontal transponders at the same time.
Would it be possible to split the horizontal signal with the following hardware.

My only concern is to prevent hardware damage - I don't mind if I can't get some channels any more (e.g. if they are on a low or high horizontal frequency...)

Antennen-Verteiler Sat/BK, 1 Eing. 2 Ausg. - Berlin-Satshop

To prevent damage from one of the receivers, I am thinking of putting one of the following on one of the receivers:
DC-Blocker FR10 - Berlin-Satshop
Or do I have to add 2 of these (one to each receiver)?

Remember: I don't care if some channels cannot be received any more with that configuration.
The price of the components is < 10€, so my only convern is preventing damage from my tuner cards.

Thanks for your suggestions.

Heiko
 

RobNorthcott

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  • October 9, 2007
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    AFAIK you need one LNB (and therefore a separate cable) for each tuner. I'm pretty sure you can't tune two transponders on one LNB, even if they're both the same polarity.

    I'd love to be proved wrong though - I'm in the same situation as you (long cable buried through the house from dish to tuner, really don't want to add another one). At the moment I'm making do with one tuner/LNB and waiting for DVB-T transmissions to start in August...

    Rob
     

    heikoh

    Portal Pro
    September 5, 2007
    110
    1
    Yes, you can tune an infinite number of transponders from one LNB cable - as long as they have the same polarisation and band.
    That's how DISECQ-Switches work.

    I also have a prove of concept with a cheap standalone tuner that has an LNB-in and also an LNB out.
    My HTPC is running behind that standalone tuner.

    As long as my standalone tuner is set to horizontal, I can freely choose which transponder to watch on my HTPC as long as it is horizontal as well.

    Unfortunately, my PCI-Tuner-Card does not have an LNB Out - that's why I'm trying to find a workaround.
     

    WedgeCan

    Portal Member
    July 26, 2006
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    I've successfully tuned two channels on one DVB-S card. When I'm doing this, I see a green check mark in the channel list for other stations that I can receive. -- Of course, MediaPortal realizes that I only have one card installed. I doubt that it'll know to do the same with a second card that is limited to (say) horizontal transponders... but I might be wrong.
     

    heikoh

    Portal Pro
    September 5, 2007
    110
    1
    I doubt that it'll know to do the same with a second card that is limited to (say) horizontal transponders... but I might be wrong.

    Yes, I doubt that as well.
    But that is not so important.

    I intend a configuration like this:

    Code:
    LNB -> PCI-DVB-S-Card #1
           -> PCI-DVB-S-Card #2

    Card #1 will be the master, Card #2 will be slave.
    For example, in TV Server Config, I could map only my 10 most commonly viewed channels to.
    This way, the probability that Card #2 also gets a signal is very high, and if for some reason I'm watching an uncommon channel on Card #1, Card #2 just will display "no signal".

    My only concern here is to prevent hardware damage.
    Does anyone know it that can be prevented with the DC-Blocker mentioned in the 2nd link above?

    Thanks,

    Heiko
     

    WedgeCan

    Portal Member
    July 26, 2006
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    Canada Canada
    heikoh;

    The point I'm trying to make is that you may be able to watch the two channels you're interested in with only one card... and therefore not have any concerns related to damaging your equipment.

    Cheers, WedgeCan
     

    RobNorthcott

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  • October 9, 2007
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    you may be able to watch the two channels you're interested in with only one card
    At the risk of talking rubbish again (!)... With a single tuner you can receive as many channels as you like from one transponder, so if you're lucky and the two (or more) channels you want are on the same transponder you can watch/record them both.

    What heikoh is proposing (and I didn't know about before) is that the LNB itself can receive all transponders of the same polarity at the same time, so if you split the signal from the LNB to two tuners you'd still be limited to either vertical or horizontal transponders, but that would give a much higher chance of two channels being available than when limited to a single transponder.

    I think the problem is that the LNB is powered from the tuner, so if you just connected the cable to two tuners with a Y lead the tuners would damage each other and/or the LNB when they both tried to provide power. It sounds like the "DC blocker" is a device (presumably just a capacitor of the appropriate size) that will let the signal through to the second tuner but block its power.

    If it works I'll be very tempted to get another hybrid tuner now and use the second DVB-S tuner in this way (I was going to stick with one tuner until DVB-T starts being broadcast here at the end of the year).

    Rob
     

    WedgeCan

    Portal Member
    July 26, 2006
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    RobNorthcott;

    The eurika moment happened thanks to your message. And then I understood better what heikoh was trying to say. Sorry for my confusion of the subject.
     

    RobNorthcott

    MP Donator
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  • October 9, 2007
    540
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    Dartmoor, England
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    RobNorthcott;

    The eurika moment happened thanks to your message. And then I understood better what heikoh was trying to say. Sorry for my confusion of the subject.
    Let's hope I got the right idea this time then, or it's the blind leading the blind :)

    Rob

    Edit: The "risk of talking rubbish again" remark was in reference to my first post in this thread, where I thought you had to have one LNB per tuner (which I now know is not true). Just making sure you didn't think it was directed at you...
     

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