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How do I measure signals in the GHz range?

Discussion in 'Electronic Equipment' started by Saul Bernstein, Oct 2, 2008.

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  1. Hello,

    I've got a storage oscilloscope here with a bandwith of 6 GHz. Unfortunately
    only the default probes with 500 MHz bandwidth are included.

    Now I would like to measure signals in the range of 2.5 gigabit per second.
    Thus, I am looking for suitable probes with sufficient high bandwidth. But I
    think bandwidth is not all there is to consider. There is also the question
    whether to use active or passive probes and probably impedance and
    capacitance will also play a mayor role.

    In addition, the signals I would like to measure on the board are routed
    differentially (selfevident at the frequencies!), so that differential probe
    would surely be the suitable choice here. But wouldn't it be possible to
    measure asymmetrically to ground potential, anyway?

    Guys, how do I find the right solution for my task? Unfortunately I'm an
    absolute newbie in measurement technique so pardon me for bothering you. I
    already hit some books but I couldn't find out, anyhow.

    Thanks for support. Saul
  2. René

    René Guest

    Though I never tried GHz range stuff, I did use the resistive probe as

    And cheap too :)
  3. Guest

    What's so "self-evident" about it? Your sat TV receiver works at 12GHz
    and is 100% unbalanced.

    You don't say what the measurements are supposed to be for. When
    working with data at these rates, the correct tool these days is a
    BERT, or J-BERT, not a scope.

    Unless your "scope" is a BERT with a missing personality module...
  4. larwe

    larwe Guest

    Heterodyne the 2.5GHz signals down to 200MHz or so ;)
  5. [F'up2 was missing --- fixed]

    Pardon the French, but that's nonsense. Nothing in a sat receiver works
    at 12 GHz. That's self-evident if you take just a quick look at the
    antenna cable --- no way a 12 GHz signal can survive 10+ meters of that
    coax cable and connectors.

    The only place 12 GHz take place in a sat TV setup is in the LNB (for
    those who don't know: that's the gadget at the end of that arm, near the
    center of the dish). From there onwards the signal is in the 1..2 Ghz
    range, at most.
  6. Guest

    You're right, I meant the LNB. But there's nothing self-evident about
    going differential at a certain frequency.
    And I consider the antenna and LNB to be part of the receiver. :)
    If a signal won't survive in a coax, it won't survive any better just
    because you use two...
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