Connect with us

RF carriers separation calculation (gsm)

Discussion in 'Electronic Design' started by Steve Sousa, Sep 24, 2009.

Scroll to continue with content
  1. Steve Sousa

    Steve Sousa Guest


    The problem is what is the necessary channel separation to transmit several
    gsm signals on the same medium (direct intensity modulation on an optic
    I have searched all over books, google, I've read the etsi docs but i can't
    find it. I've even asked teachers and got nowhere!
    I'm looking for some sort of "guard-band" spec i can use, imagine the usual
    BW plot, a rectangle:

    ----------- -----------
    | | | | | |
    --------------------- how close? ---------------------
    -bw/2 fc bw/2 -bw/2 fc bw/2

    Say i have a gsm signal with a BW of 24 MHz and carrier at 890-914. How
    close can i set another carrier? 866-890 seems too close, but i don't want
    to pull a number from the air and say "MHz between them is fine", there has
    to be some sort of calculation/rule/norm that applies, my understanding from
    ITU-R is that from 470 MHz to 2450 MHz transmitter tolerance for mobile
    stations is 500 KHz, but I'm not sure this is it. I know that the first
    channel is not used, so that would give 200 KHz. Or do i have to estimate
    some sort of filter crossing bw/2 at -3db and some maximum attenuation at
    some harmonic beyond that, like radio-amateurs use (something around -50db?)
    What if one is gsm and the other a different modulation?

    Suggestions for a more appropriate group are welcome.

    Thank you.

    I know you'll ask, this is not homework but it is part of my studies, an
    extra-curricular activity that i now see might be way above my head.

    Best Regards

    Steve Sousa
  2. JosephKK

    JosephKK Guest

    You might start here:
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day