Документация

% Initialize system parameters
Fs = 10000;             % Sample rate
Rs = 100;               % Symbol rate (Sps)
sps = Fs/Rs;            % Number of samples per symbol
SNR = 30;               % Signal to noise ratio (dB)
Trise = 1/(5*Rs);       % Rise time of the NRZ signal
Tfall = 1/(5*Rs);       % Fall time of the NRZ signal
frameLen = 5000;        % Number of symbols in a frame

% Set up the pattern generator
src = commsrc.pattern('SamplingFrequency', Fs, ...
                      'SamplesPerSymbol', sps, ...
                      'RiseTime', Trise, ...
                      'FallTime', Tfall) %#ok

% Generate NRZ signal
message = generate(src, frameLen);

% Create an comm.AWGNChannel System object.
% Set the NoiseMethod property of the channel to 'Signal to noise ratio
% (SNR)'. The commsrc.pattern object generates unit power signals; set the
% SignalPower property to 1 Watt.
channel = comm.AWGNChannel('NoiseMethod', 'Signal to noise ratio (SNR)',...
  'SNR', SNR, 'SignalPower', 1);

% Add AWGN
received = channel(message);

% Create an eye diagram and display properties
eyeObj = comm.EyeDiagram(...
    'YLimits', [-1.5 1.5], ...
    'SamplesPerSymbol', sps, ...
    'SampleRate', Fs, ...
    'SampleOffset', 0.004*Fs, ...
    'DisplayMode', '2D color histogram', ...
    'ColorScale', 'Logarithmic') %#ok

% Update the eye diagram object with the noisy NRZ signal
eyeObj(received);

% Plot the time domain signal
t = 0:1/Fs:15/Rs-1/Fs; idx = round(t*Fs+1);
hFig = figure('Position', [0 0 460 360]);
plot(t, received(idx));
title('Noisy NRZ signal');
xlabel('Time (sec)');
ylabel('Amplitude');
grid on;

% Manage the figures
hFig.Position = [10 10 hFig.Position(3:4)];
eyeObj.Position = [hFig.Position(1)+hFig.Position(3)+10 hFig.Position(2) ....
                   eyeObj.Position(3)*0.75 eyeObj.Position(4)*0.75];

histEdges = -0.1/Rs:1/(10*Fs):0.1/Rs; hFigPdf = figure;

% Obtain PDF of random jitter generated by the combined jitter object. Set
% random jitter standard deviation to 1% of symbol time.
jitterSrc = commsrc.combinedjitter('SamplingFrequency', Fs, ...
  'RandomJitter', 'on', 'RandomStd', 0.01/Rs);
jitter = generate(jitterSrc, 1e6);
rjPdf = histc(jitter, histEdges);
rjPdf = rjPdf / sum(rjPdf);
subplot(221);
plot(histEdges*1e3,rjPdf);
grid on;
title('Random Jitter');
xlabel('Time (ms)');
ylabel('PDF');

% Obtain PDF of periodic jitter. Set jitter amplitude to 5% of symbol time
% and jitter frequency to 3 Hz.
set(jitterSrc, 'RandomJitter', 'off', 'PeriodicJitter', 'on', ...
    'PeriodicAmplitude', 0.05/Rs, 'PeriodicFrequencyHz', 3);
jitter = generate(jitterSrc, 1e6);
rjPdf = histc(jitter, histEdges);
rjPdf = rjPdf / sum(rjPdf);
subplot(222);
plot(histEdges*1e3,rjPdf);
grid on;
title('Periodic Jitter');
xlabel('Time (ms)');
ylabel('PDF');

% Obtain PDF of random and periodic jitter
jitterSrc.RandomJitter = 'on';
jitter = generate(jitterSrc, 1e6);
rjPdf = histc(jitter, histEdges);
rjPdf = rjPdf / sum(rjPdf);
subplot(223);
plot(histEdges*1e3,rjPdf);
grid on;
title('Periodic and Random Jitter');
xlabel('Time (ms)');
ylabel('PDF');

% Obtain PDF of ISI and random jitter
jitterSrc.PeriodicJitter = 'off';
jitterSrc.DiracJitter = 'on';
jitterSrc.DiracDelta = 0.05/Rs*[-1 1];
jitter = generate(jitterSrc, 1e6);
rjPdf = histc(jitter, histEdges);
rjPdf = rjPdf / sum(rjPdf);
subplot(224);
plot(histEdges*1e3,rjPdf);
grid on;
title('ISI and Random Jitter');
xlabel('Time (ms)');
ylabel('PDF');

close(hFigPdf);
hide(eyeObj);

% Attach the jitter object to the pattern generator
src.Jitter = jitterSrc;
% Generate only random jitter with standard deviation 0.3 ms.
src.Jitter.DiracJitter = 'off';
src.Jitter.RandomJitter = 'on';
src.Jitter.RandomStd = 0.3e-3;

% Generate NRZ signal with random jitter and add AWGN
reset(src);
release(channel);
message = generate(src, frameLen);
received = channel(message);

% Plot the jittered noisy NRZ signal with the noisy signal
t = 0:1/Fs:15/Rs-1/Fs;
idx = round(t*Fs+1);
figure(hFig);
hold on;
plot(t, received(idx), 'r');
title('Noisy and Jittered NRZ signal');
xlabel('Time (sec)');
ylabel('Amplitude');
grid on;

close(hFig)

% Make a copy of the eye diagram object and reset
eyeObjJitter = clone(eyeObj);
release(eyeObjJitter);
reset(eyeObjJitter);

% Update the eye diagram object with the noisy, jittered signal
eyeObjJitter(received);

% Bring up the previous eye diagram for comparison
show(eyeObj);
show(eyeObjJitter);
eyeObj.Name       = 'Eye Diagram without Jitter';
eyeObjJitter.Name = 'Eye Diagram with Jitter';
eyeObjJitter.Position = [eyeObj.Position(1)+eyeObj.Position(3) eyeObj.Position(2) ...
                         eyeObj.Position(3) eyeObj.Position(4)];

% Enable vertical histogram overlay, and therefore measurements
eyeObjJitter.EnableMeasurements = true;
eyeObjJitter.Position = eyeObjJitter.Position + [0 0 0 eyeObjJitter.Position(4)*0.75];
eyeObjJitter.OverlayHistogram = 'Jitter';

% Need to step the input again for histograms to be collected:
eyeObjJitter(received);

% Also export the plotted horizontal histogram with the jitterHistogram
% method
horHist = jitterHistogram(eyeObjJitter);
hide(eyeObj);

eyeObjJitter.OverlayHistogram = 'Noise';

% Also export the plotted vertical histogram, with the noiseHistogram
% method
verHist = noiseHistogram(eyeObjJitter);

eyeObjJitter.OverlayHistogram = 'None';
reset(eyeObjJitter);
release(eyeObjJitter);

% Set the jitter parameters
src.Jitter.RandomStd = 0.1e-3;

% Set jitter hysteresis value, measurement delay, and color scale
eyeObjJitter.Hysteresis = 0.1;
eyeObjJitter.MeasurementDelay = 6/Rs;
eyeObjJitter.ColorScale = 'Linear';

% Set up the square root raised cosine filter.
b = rcosdesign(0.5, 6, sps);
b = b / sum(b);
transmitFilter = dsp.FIRFilter('Numerator', b);

% Run simulation
frameLen = 1000;
numFrames = 20;
lastSymbol = 0;
lastJitter = 0;

release(channel);
% Generate jittered signal
message = generate(src, frameLen*numFrames);
% Add ISI and noise
messageISI = transmitFilter(message);
received = channel(messageISI);

for k = 1:800
  % Update the eye diagram object with the signal
    eyeObjJitter( received( 1+(k-1)*10*2*sps : k*10*2*sps ) );
end

% Also export the displayed measurements with the measurements method:
meas = measurements(eyeObjJitter) %#ok<NOPTS>

% For a detailed explanation of the measurements, please refer to the
% documentation (type "doc comm.EyeDiagram" on the command line). Note that
% since the simulation was run using less than 20000 symbols, the results
% are not very accurate.

Fs = 10e9;
Rs = 100e6;
sps = Fs/Rs;
Trise = 2e-9;
Tfall = 2e-9;

% Create a pattern generator object
srcObj = commsrc.pattern( ...
    'SamplingFrequency', Fs, ...
    'SamplesPerSymbol', sps, ...
    'DataPattern', 'PRBS31', ...
    'RiseTime', Trise, ...
    'FallTime', Tfall);
srcObj.Jitter.RandomJitter = 'on';
srcObj.Jitter.DiracJitter = 'on';
srcObj.Jitter.DiracDelta = [-1e-9 1e-9];

% Create an eye diagram object
eyeObj = comm.EyeDiagram(...
    'SampleRate', Fs, ...
    'SamplesPerSymbol', sps, ...
    'YLimits', [-1.75 1.75], ...
    'EnableMeasurements', true, ...
    'MeasurementDelay', 6e-9);

% Set the range of standard deviation for the random jitter
stdVec = (300:50:500)*1e-12;

% Set simulation parameters
frameLen = 1000;
numFrames = 100;
cnt = 1;

% Main loop
for randStd = stdVec
    % Set the random jitter standard deviation and reset the eye diagram
    % object
    srcObj.Jitter.RandomStd = randStd;
    hide(eyeObj);
    reset(eyeObj);
    release(eyeObj);

    % Update the eye diagram object with the jittered and noisy source
    x = generate(srcObj, frameLen*numFrames);
    r = awgn(x, 40);
    eyeObj(r);

    meas(cnt) = measurements(eyeObj);

    % Adjust the eye center to the middle of the time axis
    timeOffsetSamps = 2*eyeObj.SamplesPerSymbol - Fs*meas(cnt).EyeDelay;
    eyeObj.SampleOffset = round(timeOffsetSamps);

    cnt = cnt+1;
end

hide(eyeObj);
hide(eyeObjJitter);

hFig = figure;
plot(300:50:500, [meas.HorizontalOpening], 'b-*');
hold on;
plot(300:50:500, [meas.RandomJitter], 'r-*');
hold on;
plot(300:50:500, [meas.DeterministicJitter], 'g-*');
legend('Horizontal opening', 'Random jitter', 'Deterministic jitter', 'Location', 'northwest');
title('Measurement comparison for noisy NRZ signal');
xlabel('Standard deviation of random jitter (ps)');
ylabel('Time (s)');
grid on;

eyeObj.ShowBathtub = 'Horizontal';
eyeObj.BathtubBER  = [0.5 10.^-(1:3:13)];
show(eyeObj);