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Can't recieve certain mux?

  • 04-09-2010 9:02am
    #1
    smithy4mcavan
    Closed Accounts Posts: 34 ✭


    Hi all,

    I live in Cavan and I can recieve freeview from Brougher Mountain. Currently I can recieve mux 1, B, D. Since I recabled the whole aerial and stuck in a diplexer, I seem to have lost Mux A. Can anyone give me a hand on how I can recieve it or any other mux's again?

    Thanks


Comments

  • #2
    MACHEAD
    Registered Users, Registered Users 2 Posts: 499 ✭✭MACHEAD


    Not sure of grouping or channel alocation on Brougher, but check the input groups on your diplexer as you might just be 'filtering out' the missing mux.


  • #3
    smithy4mcavan
    Closed Accounts Posts: 34 ✭smithy4mcavan


    MACHEAD wrote: »
    Not sure of grouping or channel alocation on Brougher, but check the input groups on your diplexer as you might just be 'filtering out' the missing mux.

    Thanks for the reply. I thought it might be filtering certain mux's alright, but the input 1: 47-590 MHz and input 2: 598-862 MHz (UK freeview input 1 and Irish analoge input 2).

    From what I can see its all the mux's should be fine, for example mux 2 (http://www.ukfree.tv/mapsofsignal.php?c=34) is 578MHz AND I still cannot recieve it?

    Just another quick question, I'm using my tv (philips 32pfl) to view mpeg2 channels, would a dedicated reciever be more sensitive for recieving channels, or does it make a difference? I'm thinking of getting the edison argus mini.

    Thanks


  • #4
    lucernarian
    Registered Users, Registered Users 2 Posts: 9,235 ✭✭✭lucernarian


    All muxes from Brougher are in group A I believe. I don't know what could be causing it. Did you try bypassing the diplexer to see if that rules out the problem?


  • #5
    lawhec
    Closed Accounts Posts: 1,757 ✭✭✭lawhec


    The current pre-DSO multiplexes from Brougher...

    Mux 1 - E30 (16QAM)
    Mux 2 - E34 (64QAM)
    Mux A - E23 (64QAM)
    Mux B - E26 (16QAM)
    Mux C - E29 (16QAM)
    Mux D - E33 (16QAM)

    all an ERP of 500W.

    Muxs 1, B & D are all 16QAM multiplexes. Compared to a 64QAM multiplex, they can be received at a lower signal strength & signal to noise ratio at the expense of capacity (if FEC and guard interval are the same).

    This doesn't explain the lack of Mux C though.

    If Mux A has gone, first it's a 64QAM multiplex so requires a stronger signal. Second, a proper masthead combiner will have an insertion loss of around 1db which isn't normally a big deal, but can be crucial in "fringe" areas. The combiner you're using is on one leg covering VHF (Band I & III) and UHF up to channel E35, the other from E37 to E69, so should be fine for a Brougher/Carin Hill combo.

    Cavan town itself is (mostly) line of sight from Brougher Mountain but lies at a distance of around 50km from the transmitter, so it might be no surprise that the weak DTT signals are struggling to get that far even in the absence of interference from other transmitters.

    Assuming that the cable is double screened (preferably copper film & copper braid) and all connections are firm, a bigger aerial could work or alternatively, a low-ish gain masthead amp (14db should be more than enough to) to overcome cable & diplexer losses and tuner noise with an appropriate power supply might bring back in Mux A (and might also bring in Muxs 2 & C too). Normally I would (as would others here) recommend a bigger aerial first, but a masthead amp at first might be worth a shot assuming that the aerial aimed at Brougher is a UHF Group A aerial.

    As for the integrated DTT tuner, from what I've seen there isn't much difference in most tuners these days in regards to sensitivity & selectivity for either integrated or STB tuners. If the TV is MPEG2 only, a Saorview STB (when they become available) should cover Irish & UK DTT (though not necessarily Freeview HD when it become available in NI in 2012.)


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