Hi!
You need to use the following lines for eye diagram object:
'DisplayMode','2D color histogram', ...
and
'OversamplingMethod','Input interpolation', ...
Also, make sure that your values are biased to zero (signal has no DC component). Fastest way to remove DC is:
DC=mean(data);
data=data-DC;
Eye plot example below:
eyeObj = comm.EyeDiagram('SampleRate', Fs,...
'SamplesPerSymbol', samples_per_bit, ...
'EnableMeasurements',true,'DisplayMode','2D color histogram', ...
'SymbolsPerTrace', 2, ...
'OversamplingMethod','Histogram interpolation', ...
'ColorScale','Linear', ... %Choose between Logarithmic / Linear
'ShowGrid',true,...
'YLimits',[1.1*min(data) 1.1*max(data)]);
set(gcf,'color','w');
eyeObj(data); %plot the eye with the above defined parameters
eyestats = measurements(eyeObj);
