sheldon wrote on Jun 16th, 2010, 7:14am:Actually it is not
Very not correct.
sheldon wrote on Jun 16th, 2010, 7:14am:read the next page, page 45, and will see that an alternate approach is recommended.
By saving the periods you can apply the PSD.
Again you are wrong. You are very missing point and don't understand point.
You refered
L(Δf) in your append :
http://www.designers-guide.org/Forum/YaBB.pl?num=1276575200/6#6On the other hand, this is an evaluation of
Sφ(Δf) based on well-known Spectrum Estimation Technique which is useful for getting small frequency resolution with small number of samples.
Here evenly spaced time step samples can be used.
http://www.designers-guide.org/Forum/YaBB.pl?num=1242749411Statements which you refered regarding evaluation of
L(Δf) are similar to old day's claim regarding advantage of Shooting Newton of Cadence Spectre compared to HB analysis.
Small frequency resolution requires very long capturing time.
On the other hand, we have to make time step very small so we can not miss jitter.
So if time steps are evenly spaced even for period where jitters are not included,
it is not efficient regarding total time points.
This is a claim of Fourier Integral Calculation in Cadence Spectre.
sheldon wrote on Jun 16th, 2010, 7:14am:The number of FFT samples required to capture the jitter is extremely high
so it is not an efficient tool for this problem.
But FFT of evenly spaced time step sampling data is used in actual instruments.
And it is very practical and useful level.
I can set RBW(Resolution Band Width) 1Hz in my Real Time Spectrum Analyzer based on FFT with practical sweep time.