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Explanation for ocean expression for phase noise

lahsivece

Hi ,


What does 5 in the phase noise expression  means ?

Phase\ Noise\;\ dBc\/Hz = phaseNoise(5 "pss_fd" ?result "pnoise")

Does it mean 5th harmonic relative to pss fundamental frequency ?
 What does pss_fd means ?

Thanks & Regards

Vishal

  • The 5 means 5th harmonic relative to the PSS fundamental, and pss_fd means PSS Frequency Domain results (as opposed to Time Domain results).

  • Thank you , Andrew !

    Suppose I run a pss pnoise simulation where pnoise is set to look at phase noise around the 5th harmonic of pss fundamental frequency (relative  5 in this case) but I plot for say 7th harmonic

    phaseNoise(7 "pss_fd")

    It's giving me some absurd result . It should not give me any thing because phase noise was calculated around the 5th harmonic only and not 7th. What do I make out of it ?

    Regards

    Vishal

  • That's not surprising. The actual noise computation is only done in the output frequency range you gave when running the pnoise analysis, and so measuring the noise at a different frequency makes no sense. In fact the harmonic number passed as the first argument to pnoise is the harmonic to measure the magnitude of the large signal output (from the PSS results). What it then does is divide the output noise by that magnitude so that the noise is relative to the carrier; plotting this in dB means it will then be in dBc. Specifying the wrong harmonic means that you are outputting the noise at the frequency range you simulated at, but divided by the magnitude of the wrong harmonic of the PSS large signal output. So it will be scaled incorrectly - or put another way, you're scaling it correctly for that harmonic but the numerator is the wrong noise. Take your pick - it's wrong either way you look at it!

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