% XPCJITTERTEST: Tested using TCP/IP connection with No Graphics.
close all; clear all; clc; % Start with a clean environment
MICRO = 1e-6; NANO = 1e-9; % Parameter constants
MEGA = 1e6; GIGA = 1e9; % Parameter constants
tClkFrq = 2.8*GIGA; % Theoretical clock frequency (Hz)
tSampleRate = 250*MICRO; % Theoretical sample rate (sec)
tg=xpc; % Create target object
tg.load('xpcJitterTest'); % Download model to target PC
tg.SampleTime = tSampleRate; % Set sample rate (sec)
tg.StopTime = 11; % Set stop time (sec)
+tg; % Start jitter model
pause(12) % Wait until the run ends.
tStart = 1; % Start computing statistics at 1 sec
tOffSet = tStart/tg.SampleTime+1; % Index for time offset
t = tg.TimeLog(tOffSet:end)-tStart; % Simulation Time
pJitterCnt = tg.OutputLog(tOffSet:end,1); % Clock Jitter (Counts)
ccJitterCnt = tg.OutputLog(tOffSet:end,2); % Clock Jitter (Counts)
mClkFrq = tg.OutputLog(tOffSet:end,3); % Clock Frequency (Hz)
pJitter = pJitterCnt/mean(mClkFrq)/MICRO; % Period Jitter (usec)
ccJitter = ccJitterCnt/mean(mClkFrq)/MICRO; % Cycle-Cycle Jitter (usec)
if mean(mClkFrq)* NANO < 1.0 % Determine clock scale (GHz or MHz)
clkScale = MICRO; clkFrqLabel = 'MHz';
else
clkScale = NANO; clkFrqLabel = 'GHz';
end
% Display statistics.
disp(['Clock Frequency (' clkFrqLabel ') : ' num2str(mean(mClkFrq)*clkScale,'%8.3f')]);
disp(['Period Jitter Mean (usec) : ' num2str(mean(pJitter),'%8.3f')]);
disp(['Period Jitter SDev (usec) : ' num2str(std(pJitter),'%8.3f')]);
disp(['Period Jitter Max (usec) : ' num2str(abs(max(pJitter)),'%8.3f')]);
disp(['Cycle-Cycle Jitter Mean (usec): ' num2str(mean(ccJitter),'%8.3f')]);
disp(['Cycle-Cycle Jitter SDev (usec): ' num2str(std(ccJitter),'%8.3f')]);
disp(['Cycle-Cycle Jitter Max (usec): ' num2str(abs(max(ccJitter)),'%8.3f')]);
% Plot jitter signals.
figure(1); clf;
subplot(2,1,1); plot(t,pJitter,'b',[t(1) t(end)],[tSampleRate tSampleRate]/MICRO,'r','LineWidth',2);
legend('Measured','Ideal','Location','SouthEast');
set(gca,'XLim',[t(1) t(end)]); set(gca,'YLim',[248 252]);
grid on; xlabel('Time (sec)'); ylabel('\musec'); title('Period Jitter');
subplot(2,1,2); plot(t,ccJitter,'b',[t(1) t(end)],[0 0],'r','LineWidth',2);
legend('Measured','Ideal','Location','SouthEast');
set(gca,'XLim',[t(1) t(end)]); set(gca,'YLim',[-2 2])
grid on; xlabel('Time (sec)'); ylabel('\musec'); title('Cycle-Cycle Jitter2');
% Plot jitter statistics.
figure(2); clf;
subplot(2,3,[1 4]); axis([0 10 0 10]); set(gca,'Visible','off');
h=text(-2, 9,'Period Jitter MEAN (\musec):'); set(h,'FontSize',12); h=text(7, 9,num2str(mean(pJitter), '%12.3f')); set(h,'FontSize',12);
h=text(-2, 8,'Period Jitter STD (\musec):'); set(h,'FontSize',12); h=text(7, 8,num2str(std(pJitter), '%12.3f')); set(h,'FontSize',12);
h=text(-2, 7,'Period Jitter MAX (\musec):'); set(h,'FontSize',12); h=text(7, 7,num2str(abs(max(pJitter)), '%12.3f')); set(h,'FontSize',12);
h=text(-2, 3.5,'Cycle-Cycle Jitter MEAN (\musec):'); set(h,'FontSize',12); h=text(7, 3.5,num2str(mean(ccJitter), '%12.3f')); set(h,'FontSize',12);
h=text(-2, 2.5,'Cycle-Cycle Jitter STD (\musec):'); set(h,'FontSize',12); h=text(7, 2.5,num2str(std(ccJitter), '%12.3f')); set(h,'FontSize',12);
h=text(-2, 1.5,'Cycle-Cycle Jitter MAX (\musec):'); set(h,'FontSize',12); h=text(7, 1.5,num2str(abs(max(ccJitter)),'%12.3f')); set(h,'FontSize',12);
subplot(2,3,[2 3]); hist(pJitter,1000); ylabel('Period Jitter')
subplot(2,3,[5 6]); hist(ccJitter,1000); ylabel('Cycle-Cycle Jitter')
% figure(2); clf;
% subplot(2,1,1); hist(pJitter,1000); xlabel('\musec'); ylabel('Period Jitter')
% subplot(2,1,2); hist(ccJitter,1000); xlabel('\musec'); ylabel('Cycle-Cycle Jitter')
% Plots the cycle-cycle jitter PSD.
figure(3); clf;
psd(spectrum.periodogram,ccJitter,'Fs',1/tSampleRate);
