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EN300220 and phase noise

Discussion in 'Electronic Design' started by Robert Lacoste, Jul 5, 2006.

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  1. Hi all,

    Any EN 300-220 European standard guru out there ?

    I have some difficulties to deduce the maximum phase noise profile of a
    transmitter from this standard in the case of a very narrow bandwidth
    transmitter (say 10KHz bandwidth, operating in a non-standard VHF frequency
    band) :

    - Standard gives a limitation of the transmitted power in the adjacent
    channels (10µW integrated over each adjacent channel). Fine
    - Standard gives a limitation for the spurious emissions (-36/-54dBm under
    1GHz with 100KHz spectrum analyzer bandwidth depending on the frequency).
    Fine.

    But what is the maximum noise or side modulation levels say 2, 3 or 10
    channels away from the carrier ? My first assumption was that the "spurious"
    specification was applicable, but with a 100KHz resolution bandwidth I would
    be measuring the carrier power if I do the measurement even 5 channels away
    from the carrier...

    Any help welcome...

    Friendly yours,
    Robert
     
  2. upda

    upda Guest

    I would say that you should keep your phase-noise below the leve
    where your radiated power is less than -36 dBm when integrated fro
    two channels away and out. On both sides
     
  3. Thanks Daniel, that's effectively a potential interpretation. However I must
    admit, well, that the result in terms of phase noise is quite hard to comply
    with at least with low cost transmitters... and I was hoping to get another
    answer ;+)
     
  4. Joerg

    Joerg Guest

    Hello Robert,
    I don't know your transmitter but if noise from the PLL is a concern
    experiment with the loop bandwidth. If it needs to remain agile you
    might consider two loops, one to do the fast pull-in and the slower one
    to keep the lock.
     
  5. Thanks Joerg. Have you the same understanding of the standard than Daniel
    for such a narrow band transmitter I mean :

    P(Fc-CBW/2 to Fc+CBW/2) < whatever si the nominal autorized in-channel power
    P(Fc+CBW/2 to Fc+3CBW/2) < -20dBm (adjacent channel)
    P(Fc+3CBW/2 to Fc+3CBW/2+100KHz) < -36dBm (application of the "spurious"
    spec starting just after the adjacent channel)

    (with CBW=channel bandwidth and F0 the center frenquency)
     
  6. Joerg

    Joerg Guest

    Hello Robert,
    I am not familiar with that part but AFAIR we had to design to 4nW
    spurious and 250nW adjacent. However, that was under 1GHz. This would be
    more than what you have listed.

    Wish I had it in French or at least in English but if you can plow your
    way through some German this might help:

    http://www.circuitdesign.de/products/tech_info/guide5.asp

    Best would be a brief chat with your EMC lab about what limits they test
    for (or have to test for).
     
  7. upda

    upda Guest

    So Robert, what type of oscillator do you have? PLL? Is it som
    all-in-one radio IC? Just an external coil
     
  8. PLL/VCO/modulator chip with external coil, but trying to use in for a non
    standard application. I know how to optimize its phase noise (or at least
    how to balance it with loop filter, etc), but my question is really to
    understand what's the standard is specifying. I'm in touch with a notified
    body to try to have a definitive answer...

    Thanks for your help,
    R.
     
  9. Joerg

    Joerg Guest

    Hello Robert,
    Way to go. A standard is one thing. But at the end of the day the guys
    in the certified lab decide how they'll measure compliance. Been there a
    lot, and there is absolutely no argueing with them if you think that one
    test or the other is a bit too strict versus the standard.

    Seems you have the loop filter licked. If it's FM then the other thing
    to look out for is the modulator input. You might have to muffle the
    higher spectra a bit, especially if it is a data stream.

    I am pretty sure this won't happen with your experience but in case
    others are following the thread: When called out to find a "cure" for a
    failed compliance test the number one problem I found with transmitters
    was their power supply. Mostly there were remnant switcher spikes, RAM
    banking transients, video sync and all kind of other stuff riding along.
    This resulted in almost perfect AM modulation right onto the carrier.
    You could see a picket fence on the analyzer. It doesn't take a lot to
    blow through -20dbm or -30dBm.
     
  10. Yes Joerg, you're fully right. In fact I got today a prelmiminary answer
    from a notified body, and there seems to be some room for interpretation
    effectively...

    Thanks all,
    Robert
     
  11. Joerg

    Joerg Guest

    Hello Robert,
    If this is for a mass product there would be another advantage. Let's
    say someone questions the compliance. They may not relent at all if you
    counter with lots of technical details and analyzer plots. But if you
    place a paper in front of them with a stamp and some signatures, stating
    that this was tested to the EN 300 200 standard by XYZ S.A., they'll
    probably salute and rest their case.
     
  12. vasile

    vasile Guest

    So, how much is your LO phase noise measured at 10Khz, 100Khz and 1Mhz
    from the carrier, which is the LO frequency and what is the carrier
    frequency and SNR you've got after the PLL ?
    You say non-standard. There are many non standard applications these
    days.
    The specification should tell you clear which shoud be the adjacent
    channel rejection.
    You can't guess. However -20dB suppresion looks very little for me.

    greetings,
    Vasile Surducan
     
  13. Joerg

    Joerg Guest

    Hello Vasile,

    It's -20dBm, not -20dB below carrier. Depending on the power level it
    may not be quite trivial to achieve but feasible.
     
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