Why can't jitter function use a eyediagromSI object as the input argument y?

https://ww2.mathworks.cn/help/releases/R2024b/signal-integrity/ref/jitter.html says that the input argument y is the amplitude coordinates of the jittery signal, specified as a vector or as an eyeDiagromSI object.

But when I use an eyeDiagromSI object as y, it says Error using jitter (line 94)

Invalid argument at position 1. Value must be of type double or be convertible to double.

How can I measure the jitter of a eye diagram?

Answer 1

[Maneet Kaur Bagga]

Hi,

As per my understanding, the error suggests that "jitter" function expects a numerical data. Please refer to the following as a possible workaround for the same:

• Extract the required amplitude data manually, instead of passing the whole "eyeDiagramSI" object. Refer to the following code snippet for the same.

eyeObj = eyeDiagramSI(signal, sampleRate); % Create the eye diagram object
y = eyeObj.Waveform; % Extract waveform data (assuming it exists)
jitterValue = jitter(y);

• Check if the "jitter" requires additional preprocessing of the "eyeDiagramSI" object using the following command:

methods(eyeObj)

Alternatively you can consider using "comm.JitterAnalyzer" object. Please refer to a following MATLAB Answer for the same :

https://in.mathworks.com/matlabcentral/answers/1933395-how-to-derive-eye-diagram-metrics-in-matlab

Hope this helps!