Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

DTT Trial box (Humax) signal strength meter

  • 06-04-2008 12:54am
    #1
    lucernarian
    Registered Users, Registered Users 2 Posts: 9,235 ✭✭✭


    Hey folks,

    I was trying to work out what sort of amplification I could get away with for a masthead amp here, but seeing as I'm not a professional I don't have a signal strength meter for the incoming signal strength from the aerial.

    Does anyone know exactly if the Humax set top box scale which is in % can be converted into something like dBuV or dBmV??

    I did email Humax some time ago about this but I got no response.


Comments

  • #2
    watty
    Registered Users, Registered Users 2 Posts: 32,417 ✭✭✭✭watty


    Measure length of cable from aerial to receiver. The loss per metre X distance = gain mast head amp should be.

    Assume about 3dB per 10m of cable if decent coax.

    The mast head amp should be 1m to 2m away from aerial to avoid "feedback".

    Any excess gain (esp more than 3dB) will equally boost noise and makes the system more prone to overload.

    If you can get a reasonable analogue picture on an indoor aerial then a mast amp will overload and should be avoided, or else 1/2 way along a very long feed cable (like 50m long).


  • #3
    lucernarian
    Registered Users, Registered Users 2 Posts: 9,235 ✭✭✭lucernarian


    Well all I really want to know is if the signal strength reading on a humax box can be converted in to dBuV...

    The problem is that 2 sets of signals are being received at the aerial and I roughly estimate what with frequency based loss and EIRPs and the distances involved, that one is 26 dB stronger relative to the other. From what I can tell on the TV screen, it looks a fairly accurate guess. So there's a big problem of overpowering one group or underpowering another. And they're on the same aerial, making separate amps impossible.


    Also, I think that amplification above and beyond cable loss can work (up to a resulting signal of 85 or so dBuV) if the SNR is >44 dB (including whatever noise the amp and PSU inserts) but then it's not often that both wanted signal and noise floor are of a low strength.


Advertisement