Computation of noise covariance based on EEG

Hi, Francois,
I am studying the source estimation based on ERP. Each trial had a baseline signal of 0.5s, followed by a stimulation of 5s. No other noise signals were collected in the experiment. For a certain subject, can I
(1) extract the baseline signals of all trails, (2) splice all these baseline signals together into a file, and then (3) import the file into brainstrom to calculate the noise covariance?

I would appreciate your reply.

Yes, this is a valid approach described here:

This can be done automatically with just a few mouse clicks. This is what is done in this tutorial:

Thank you very much for your answer. It's very helpful for my research.