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RTE 2 and Virgin Media good (SNR 50%) but RTE 1 terrible. (SNR 0%)

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  • 24-04-2021 6:13pm
    #1
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭


    I have a terrestrial signal coming into a Optimuss OS3+ combo box.

    RTE 2 and Virgin Media are working fine and the SNR is showing 50+%.
    However RTE 1 is is very terrible, breaking up all the time, with the SNR settling at about 23%.

    Why is this ?
    They are both coming from the same antenna, on the same cable and going into the same port on the box.


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    #2
    athlone573
    Registered Users Posts: 726 ✭✭✭athlone573


    Fr Tod Umptious wrote: »
    I have a terrestrial signal coming into a Optimuss OS3+ combo box.

    RTE 2 and Virgin Media are working fine and the SNR is showing 50+%.
    However RTE 1 is is very terrible, breaking up all the time, with the SNR showing as 0%.

    Why is this ?
    They are both coming from the same antenna, on the same cable and going into the same port on the box.

    They are probably on different "muxes" or frequencies and your aerial probably handles one better than the other. Which aerial do you have and which transmitter is it pointed towards? If there's a coloured plastic bung in the aerial what colour is it?


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    #3
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    athlone573 wrote: »
    They are probably on different "muxes" or frequencies and your aerial probably handles one better than the other. Which aerial do you have and which transmitter is it pointed towards? If there's a coloured plastic bung in the aerial what colour is it?
    Hi
    I can't get easy access to the aerial right now but I'm almost sure it's a red tip.

    And it's pointing to Knockmoyle


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    #4
    athlone573
    Registered Users Posts: 726 ✭✭✭athlone573


    Fr Tod Umptious wrote: »
    Hi
    I can't get easy access to the aerial right now but I'm almost sure it's a red tip.

    And it's pointing to Knockmoyle

    Try swap it out for a wideband white tip, and have a good evening.


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    #5
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    athlone573 wrote: »
    Try swap it out for a wideband white tip ...

    Why would you do that?


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    #6
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    Fr Tod Umptious wrote: »
    I have a terrestrial signal coming into a Optimuss OS3+ combo box.

    RTE 2 and Virgin Media are working fine and the SNR is showing 50+%.
    However RTE 1 is is very terrible, breaking up all the time, with the SNR settling at about 23%.

    Why is this ?
    They are both coming from the same antenna, on the same cable and going into the same port on the box.

    It's just poor signal, with mux 2 (containing RTE1) being slightly worse off than mux 1, enough to push it over the 'digital cliff'.

    Have you checked anything at all? Start with simple stuff, like the plug on the end of the aerial lead.


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    #7
    athlone573
    Registered Users Posts: 726 ✭✭✭athlone573


    Elvis Hammond wrote: »
    Why would you do that?

    Let me rephrase that
    Put your address into the coverage checker on saorview.ie and see what frequencies your local mast uses. They changed recently so a lot of other websites will be out of date.


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    #8
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    athlone573 wrote: »
    Let me rephrase that
    Put your address into the coverage checker on saorview.ie and see what frequencies your local mast uses. They changed recently so a lot of other websites will be out of date.

    That's not a rephrase, that's completely different advice.

    Anyhow, a group A (red tip) aerial would be suitable for Knockmoyle since Sept. 2019, but it was in group C/D before that (the old freqs. being turned off March 2020, not exactly 'recently').


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    #9
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Elvis Hammond wrote: »
    It's just poor signal, with mux 2 (containing RTE1) being slightly worse off than mux 1, enough to push it over the 'digital cliff'.

    Have you checked anything at all? Start with simple stuff, like the plug on the end of the aerial lead.
    I've checked everything except the connection to the aerial itself, it's hard to get at right now.
    But it was the good signal for some channels and bad for others coming from the same aerial, cable, port etc. that was confusing.


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    #10
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Elvis Hammond wrote: »
    That's not a rephrase, that's completely different advice.

    Anyhow, a group A (red tip) aerial would be suitable for Knockmoyle since Sept. 2019, but it was in group C/D before that (the old freqs. being turned off March 2020, not exactly 'recently').
    Ok that is beginning to make some sense.
    I used to have the combo box in a different room on a less frequently used TV
    I never recall having this issue.
    I would have stopped using the combo box a few months ago.

    I then got rid of Sky about 10 days ago and moved the combo box to the main TV, this issue appears on RTE 1.

    So in the few months between using the combo box, the frequency changed.

    So do I need a white tip ?


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    #11
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    The frequencies changed over a year ago.

    Find out for sure what kind of aerial you have now before talking about changing it.

    Also, can you see which UHF channel nos. or frequencies you're getting Saorview on?


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    #12
    athlone573
    Registered Users Posts: 726 ✭✭✭athlone573


    Fr Tod Umptious wrote: »
    Ok that is beginning to make some sense.
    I used to have the combo box in a different room on a less frequently used TV
    I never recall having this issue.
    I would have stopped using the combo box a few months ago.

    I then got rid of Sky about 10 days ago and moved the combo box to the main TV, this issue appears on RTE 1.

    So in the few months between using the combo box, the frequency changed.

    So do I need a white tip ?
    I don't think you necessarily need a white tip but it would do no harm.
    As Mr. Hammond says check all the cables, connectors etc to make sure there's a good connection and no power cables running alongside. The fact that it works OK on RTE2 suggests you should be able to get it working on RTE1 also without major rewiring, fingers crossed.


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    #13
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Elvis Hammond wrote: »
    The frequencies changed over a year ago.

    Find out for sure what kind of aerial you have now before talking about changing it.

    Also, can you see which UHF channel nos. or frequencies you're getting Saorview on?
    Ok, I misread March 2020 as March 2021

    RTE 1 is giving a frequency of 498.0 MHz
    RTE 2 is 474.0 MHz


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    #14
    Johnboy1951
    Registered Users Posts: 13,999 ✭✭✭✭Johnboy1951


    Fr Tod Umptious wrote: »
    Ok that is beginning to make some sense.
    I used to have the combo box in a different room on a less frequently used TV
    I never recall having this issue.
    I would have stopped using the combo box a few months ago.

    I then got rid of Sky about 10 days ago and moved the combo box to the main TV, this issue appears on RTE 1.

    So in the few months between using the combo box, the frequency changed.

    So do I need a white tip ?

    Have you tried the box back in its original position where it worked?
    Does it still work there?


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    #15
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Johnboy1951 wrote: »
    Have you tried the box back in its original position where it worked?
    Does it still work there?

    Have not tried that.
    I could, but it would take a bit of time.


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    #16
    dxhound2005
    Registered Users Posts: 20,731 ✭✭✭✭dxhound2005


    Fr Tod Umptious wrote: »
    Ok, I misread March 2020 as March 2021

    RTE 1 is giving a frequency of 498.0 MHz
    RTE 2 is 474.0 MHz

    Those are the Mullaghanish frequencies.

    http://www.2rn.ie/wp-content/uploads/2019/09/2RN-DTT-Television-Transmission-Network-Sept-2019-Rev.1.2.pdf


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    #17
    athlone573
    Registered Users Posts: 726 ✭✭✭athlone573


    Forget what I said about a wideband aerial.
    You should check though that your aerial is pointing in the right direction (if you can't see the antenna,a compass may be useful).


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    #18
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    dxhound2005 wrote: »
    Those are the Mullaghanish frequencies.

    http://www.2rn.ie/wp-content/uploads/2019/09/2RN-DTT-Television-Transmission-Network-Sept-2019-Rev.1.2.pdf
    I think that worked.
    I did a manual scan on the Knockmoyle channels on that list and now RTE 1 etc are coming in much better, SNR 50+%.

    Thanks to all for the help with this.

    Good evening.


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    #19
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    Was your aerial install a DIY job? Knockmoyle's signal is vertically polarised, & this isn't always taken into account by DIYers.


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    #20
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Elvis Hammond wrote: »
    Was your aerial install a DIY job? Knockmoyle's signal is vertically polarised, & this isn't always taken into account by DIYers.
    Yes , it's up in the attic, lying down horizontal.

    I suppose I should go up and stand it up vertical ?


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    #21
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    Yes, the aerial elements should be vertical for Knockmoyle. I'd also try keeping it horizontal & aligning on Mullaghanish, to compare signals, & wherever it's pointing, avoid walls, anything metallic or containing water, & be aware there may be signal 'sweet spots' & 'dead spots', that vary with frequency.


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    #22
    Ten Pin
    Registered Users Posts: 2,816 ✭✭✭Ten Pin


    Yes , it's up in the attic, lying down horizontal.

    I suppose I should go up and stand it up vertical ?

    Boom stays horizontal, elements vertical...
    imgE.jpg

    Raise aerial off the attic "floor" as it may be slightly blocking signal reception.


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    #23
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    Apologies for digging up an oldish thread of my own but I have a problem with RTE 1 and all the stations on Channel 36 (Knockmoyle)

    All was good up to a few weeks ago, my antenna was pointed vertically to Knockmoyle which I have LOS to and tuned to Channels 33 and 36.

    But the the SNR on RTE 1 started to drop, down in the 20% range.

    I though it might have had to do with the good weather we were having a nd the high pressure, but RTE2 and the other stations on Channel 33 were still working fine.

    Now RTE1 and the others on 36 have have fallen over that threshold for the signal to even work

    When I check the signal strength on the STB ( Optimuss OS3+) the SNR for Channel 36 is 0%

    I don't have any neighbors to do a comparison with.

    Am I missing something, has something changed ?



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    #24
    Elvis Hammond
    Registered Users Posts: 491 ✭✭Elvis Hammond


    More than likely the problem is at your own end. I'd say it's still the case that the signal getting to your receiver was always borderline, & a small drop has made it unusable.

    Rather than try to find a cause, it might just be easier to build in some margin, say by moving the aerial outside.



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    #25
    Fr Tod Umptious
    Registered Users Posts: 15,061 ✭✭✭✭Fr Tod Umptious


    https://www.boards.ie/discussion/comment/117962989#Comment_117962989

    Thanks

    I went up to the attic and adjusted the antenna location, pointed it more directly to Knockmoyle.

    SNR is now up to 70+% on Channel 36.

    Over the weekend I'll get the antenna off the floor of the attic and get it elevated on the joints.



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