Matlab根据相噪计算抖动

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来源:http://www.mathworks.cn/matlabcentral/fileexchange/22038-phase-noise-to-jitter/content/Pn2Jitter.m function Jitter = Pn2Jitter(f, Lf, fc) % % Summary: Jitter (RMS) calculation from phase noise vs. frequency data. % % Calculates RMS jitter by integrating phase noise power data. % Phase noise data can be derived from graphical information or an % actual measurement data file. % % Usage: % Jitter = Pn2Jitter(f, Lf, fc) % Inputs: % f: Frequency vector (phase noise break points), in Hz, row or column. % Lf: Phase noise vector, in dBc/Hz, same dimensions, size(), as f. % fc: Carrier frequency, in Hz, a scalar. % Output: % Jitter: RMS jitter, in seconds. % % Examples: % [1] >> f = [10^0 10^1 10^3 10^4 10^6]; Lf = [-39 -73 -122 -131 -149]; % >> Jitter = Pn2Jitter(f, Lf, 70e6) % Jitter = 2.3320e-011 % Comparing fordahl application note AN-02-3{*} and jittertime.com{+} % calculations at fc = 70MHz % Pn2Jitter.m: 23.320ps % AN-02-3 (graphical method): 21.135ps % AN-02-3 (numerical method): 24.11ps % Aeroflex PN9000 computation: 24.56ps % JitterTime.com calculation: 23.32ps % % {*} fordahl Application Note AN-02-3: % "Phase noise to Jitter conversion" % http://fordahl.com/images/phasenoise.pdf % As of 11 May 2007 it also appears here: % http://www.metatech.com.hk/appnote/fordahl/pdf/e_AN-02-3.pdf % http://www.metatech.com.tw/doc/appnote-fordahl/e-AN-02-3.pdf % % {+} JitterTime Consulting LLC web calculator % http://www.jittertime.com/resources/pncalc.shtml % As of 5 May 2008 % % [2] >> f = [10^2 10^3 10^4 10^5 10^6 10^7 4.6*10^9]; % >> Lf = [-82 -80 -77 -112 -134 -146 -146 ]; format long % >> Jitter = Pn2Jitter(f, Lf, 2.25e9) % Jitter = 1.566598599875678e-012 % Comparing ADI application note{$} calculations at fc = 2.25GHz % Pn2Jitter.m: 1.56659859987568ps % MT-008: 1.57ps % Raltron {&}: 1.56659857673259ps % JitterTime: 1.529ps--excluding the (4.6GHz, -146) data point, % as 1GHz is the maximum allowed % {$} Analog Devices, Inc. (ADI) application note MT-008: % "Converting Oscillator Phase Noise to Time Jitter" % http://www.analog.com/en/content/0,2886,760%255F%255F91502,00.html % {&} Raltron web RMS Phase Jitter calculator: % "Convert SSB phase noise to jitter" % http://www.raltron.com/cust/tools/osc.asp % Note: Raltron is restricted to f(min) = 10Hz; % therefore it cannot be used in this example [1]. % % [3] >> f = [10^2 10^3 10^4 200*10^6]; Lf = [-125 -150 -174 -174]; % >> Jitter = Pn2Jitter(f, Lf, 100e6) % Jitter = 6.4346e-014 % Comparing ADI application note{$} calculations at fc = 100MHz % Pn2Jitter.m: 0.064346ps % MT-008: 0.064ps % JitterTime: 0.065ps % % Note: % f and Lf must be the same length, lest you get an error and this % Improbable Result: Jitter = 42 + 42i. % % (A spreadsheet, noise.xls, is available from Wenzel Associates, Inc. at % http://www.wenzel.com, "Allan Variance from Phase Noise." % It requires as input tangents to the plotted measured phase noise data, % with slopes of 1/(f^n)--not the actual data itself--for the % calculation. The app. note from fordahl discusses this method, in % addition to numerical, to calculate jitter. This graphical straight- % line approximation integration technique tends to underestimate total % RMS jitter.) % % [4] Data can also be imported directly from an Aeroflex PN9000 ASCII % file, after removing extraneous text. How to do it: % (1) In Excel, import the PN9000 data file as Tab-delimited data, % (2) Remove superfluous columns and first 3 rows, leaving 2 columns % with frequency (Hz) and Lf (dBc/Hz) data only. % (With the new PN9000 as of April 2006, only the first row % is to be removed, and there are only two columns. % I may take advantage of this in an updated version of this % program,thereby eliminating the need to edit the data), % (3) Save As -> Text (MS-DOS) (*.txt), e.g., a:\Stuff.txt, % (4) At the MATLAB Command Window prompt: % >> load 'a:\Stuff.txt' -ascii % Now Stuff is a MATLAB workspace variable with the % phase noise data, % (5) >> Pn2Jitter(Stuff(:,1), Stuff(:,2), fc); % (assuming fc has been defined) % One 10MHz carrier data set resulted in the following: % Pn2Jitter.m: 368.33fs % PN9000 calculation: 375fs % % Runs at least as far back as MATLAB version 5.3 (R11.1). % % Copyright (c) 2005 by Arne Buck, Axolotol Design, Inc. Friday 13 May 2005 % arne (d 0 t) buck [a +] alum {D o +} mit (d 0 +} e d u % $Revision: 1.2 $ $Date: 2005/05/13 23:42:42 $ % % License to use and modify this code is granted freely, without warranty, % to all as long as the original author is referenced and attributed % as such. The original author maintains the right to be solely % associated with this work. So there. % Bug fixes to resolve problematic data resulting in division by 0, or % excessive exponents beyond MATLAB's capability of realmin (2.2251e-308) % and realmax (1.7977e+308); no demonstrable effect on jitter calculation % AB 18May2005 Fix /0 bug for *exactly* -10.000dB difference in adjacent Lf % AB 24May2005 Fix large and small exponents resulting from PN9000 data % AB 11May2007 Improve documentation, update URLs % AB 5May2008 Verify and update URLs tic %% It's almost nine o'clock. We've got to go to work. L = length(Lf); if L == length(f) % Fix ill-conditioned data. I=find(diff(Lf) == -10); Lf(I) = Lf(I) + I/10^6; % Diddle adjacent Lf with % a diff=-10.00dB, avoid ai:/0 % Just say "No" to For loops. lp = L - 1; Lfm = Lf(1:lp); LfM = Lf(2:L); % m~car+, M=cdr fm = f(1:lp); fM = f(2:L); ai = (LfM-Lfm) ./ (log10(fM) - log10(fm)); % Cull out problematic fine-sieve data from the PN9000. Iinf = find( (fm.^(-ai/10) == inf) | fm.^(-ai/10)<10^(-300)); % Find Inf fm(Iinf) = []; fM(Iinf-1) = []; Lfm(Iinf) = []; LfM(Iinf-1) = []; ai(Iinf) = []; f(Iinf) = []; Lf(Iinf) = []; % Where's the beef? Jitter = ... 1/(2*pi*fc)*sqrt(2*sum( 10.^(Lfm/10) .* (fm.^(-ai/10)) ./ (ai/10+1)... .* (fM.^(ai/10+1) - fm.^(ai/10+1)) )); else disp('> > Oops!'); disp('> > > The f&Lf vector lengths are unequal. Where''s the data?') Jitter = sqrt(sqrt(-12446784)); end % if L toc  

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