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Re: [softrock40] Phase Noise of One-Time Programmable Oscillator Modu l es

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  • Kees & Sandy
    I don t think jitter measurement with this old HP54110D is going to work other than provide relative measurement data to use. The only way to use this unit
    Message 1 of 4 , Aug 30, 2007
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      I don't think jitter measurement with this old HP54110D is going to work other than provide  relative measurement data to use. The only way to use this unit (that I can figure out) is to do several waveform "period" measurements which I believe are calculated averages anyway? The period can be measured down to 10ps (last digit seems to be fixed at "0"). So, for a 40m softrock measuring the output (14Mhz) of the first FF to take the triggering into account, I see a range from 70.840ns to 70.880ns or a movement of 40ps for 10 readings. It's not frequency drift because the numbers vary between the two radomly. It may be only scope repeatability error, but measuring something else should tell me that. ....maybe I can estimate something from the initial individual digital "dot" samples before they are averaged. Sloppy measurements to say the least but may provide some useful data from a "relative measurements" view.

      I'm sure someone out there has much better instrumentation and can take repeat data over a long (xx sec?) period of time.

      73 Kees K5BCQ  


      -- k5nwa <k5nwa@...> wrote:

      At 07:43 PM 8/30/2007, you wrote:

      >Looks like a lot of very expensive test equipment. It does explain
      >one thing ....."RMS jitter" is the (much lower number) one sigma
      >jitter. The "P-P jitter" is the full range (I thought all jitter was
      >measured as "P-P jitter" .....but that's apparently before marketing
      >spun it into "RMS jitter").
      >
      >73 Kees K5BCQ

      Others do a FFT and then give you a distribution of noise saying so
      many ps at one Sigma and so many ps at 3 Sigmas.

      Cecil
      K5NWA
      www.softrockradio. org www.qrpradio. com

      "Blessed are the cracked, for they shall let in the light."

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