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Can a SA convert Phase Nosie in dBc/Hz into rms for noise mx

Question asked by tabbott

on Feb 3, 2012
Latest reply on Nov 30, 2015 by evanpan

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During the RF Back to Basics : Part 1 – Signal Analysis Webcast, hosted by Agilent Technologies, on 25 January 2012, we received a great number of real-time questions from a broad audience.

If one person asks - someone else will want to know the answer too - so we have captured various questions and answers and are posting them individually here, in this Forum, for your future reference and immediate enjoyment!

Question: Can the PXA or any SA have the feature to convert the Phase noise in dBc/Hz into rms (e.g. pico second rms) for noise measurement?

Edited by: tabbott on Mar 21, 2012 11:45 AM

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tabbott Feb 3, 2012 3:27 PM
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Answer: Yes, the phase noise measurement application has this capability built in. You can measure the RMS noise in terms of phase deviation (degrees or radians) or in terms of jitter (time). It is available on the X-series signal analyzers (N9068A & W9068A), as well as the PSA signal analyzer (E444xA opt 226).
X-Series: http://cp.literature.agilent.com/litweb ... 5354EN.pdf
PSA: http://www.home.agilent.com/agilent/pro ... SR.GENERAL
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- ANDY_SCHWARZ @ tabbott on Jan 23, 2013 4:30 AM
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  Hello,
  does the PXA phase noise utility take 2*L(f) (i.e double sided noise) into account when calculating the RMS jitter?
  
  I think I remember the PSA only takes L(f) and one has to adjust manually for DSB.
  Can you confirm?
  
  Thanks, Andreas
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  - sleithem @ ANDY_SCHWARZ on Jan 23, 2013 3:19 PM
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    Hi Andreas,
    
    The PXA phase noise application N9068A displays the single sideband noise in the log plot measurement. However, when calculating RMS jitter, phase deviation, etc., the results are mathematically corrected to properly represent the true result (with the factor of 2 included).
    
    You can refer to the N9068A measurement guide for more information about this calculation:
    http://cp.literature.agilent.com/litweb/pdf/N9068-90011.pdf
    
    Best Regards,
    Scott
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    - ANDY_SCHWARZ @ sleithem on Jan 24, 2013 1:12 AM
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      Hello,
      OK thanks for PXA info
      Does the PSA use the same algorithm? (i.e. adjust for factor 2*L(f) when calculating jitter)
      
      Andreas
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      - sleithem @ ANDY_SCHWARZ on Feb 1, 2013 9:08 AM
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        Hi Andreas,
        
        All of Agilent SA's use the same single sideband formula to calculate RMS noise, including PSA and PXA.
        
        Actually, I slightly misspoke in my previous response. It is true that all Agilent SA's use the factor of 2 in the equation. However, they are not calculating the double sideband result. The factor of 2 actually comes from the conversion from peak to RMS deviation.
        
        The total phase deviation can be determined from the amount of power in a single sideband. If you were to double this, it would not be showing you the actual phase deviation. Think about a frequency modulated signal. The spectrum contains symmetrical sidebands with amplitudes based upon Bessel functions. Given a single sideband of a spectrum, it is possible to figure out the peak frequency deviation just by knowing the amplitude of that sideband (it is not necessary to know the amplitude of the mirrored sideband). The confusion usually comes from the fact that we have to integrate the phase noise to get the equivalent result. However, we only need to know the spectral characteristics of a single sideband to determine the total phase deviation.
        
        Agilent's own Bob Nelson recently published an article explaining these measurements in detail, including the equations that are used. There is a detailed derivation of the calculation for phase deviation and an explanation for the factor of 2 that is there. Here is a link to the article: http://mwrf.com/test-amp-measurement-analyzers/demystify-integrated-phase-deviation-results-phase-noise-measurements
        
        You can set this measurement up if you have an Agilent analyzer and a source with adjustable phase deviation. Note that if you set the total peak phase deviation, the analyzer uses the single sideband to calculate the total RMS phase deviation (there is no need to manually adjust the calculated results).
        
        Hope that helps!
        
        Best Regards,
        Scott
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        igouzouasis @ sleithem on Apr 8, 2013 3:49 AM
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        Hi
        
        Regarding the previous posts..
        I, however, have an old 89441A signal analyzer and I know that when choosing the "Phase Modulation" instrument state the plot given is the double sided band. I then have to subtract 3dB to get the SSB.
        When choosing the phase deviation plot (in time domain) the rms phase deviation includes the doubling or not?
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        tabbott @ igouzouasis on Apr 9, 2013 2:03 PM
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        Hi -
        
        The attached file shows the different methods available for measuring phase noise with the 89441A.
        
        Regards -
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        phasenz.pdf89.5 KB
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        igouzouasis @ tabbott on Apr 10, 2013 10:42 AM
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        The question is not about phase noise
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        evanpan @ igouzouasis on Nov 30, 2015 6:56 AM
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        Hi, igouzouasis.
        As for me, I have seldom tried to convert Phase Nosie in dBc/Hz into rms for nois. I wonder have you ever worked it out? Do I need another 3rd party manual toolkit? When it comes to pdf conversion process, I have another question, I wonder have you ever tried to convert pdf to other image files before? As for myself, I am testing the related PDF to PNG converting , PDF to BMP converting , and PDF to JPG converting programs these days. Do you have experience about it? Any suggestion will be appreciated. Thanks in advance.
        
        Best regards,
        Pan
        -------------------------------------------------------------------------------
        *Tags:* convert pdf ; pdf conversion
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        DaveHornbeck @ igouzouasis on Apr 11, 2013 6:56 AM
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        +I, however, have an old 89441A signal analyzer and I know that when choosing the "Phase Modulation" instrument state the plot given is the double sided band. I then have to subtract 3dB to get the SSB.+
        +When choosing the phase deviation plot (in time domain) the rms phase deviation includes the doubling or not?+
        
        All traces in phase demod mode show double sideband data.
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Can a SA convert Phase Nosie in dBc/Hz into rms for noise mx

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