Extracting Fetal ECG "Expectations" term query

[jonnybgood]

Attached is a paper on Fetal ECG extraction. Adaptive noise cancellation is explained with some derivation.

I cannot understand the statement;



What does it mean by 'expectations'

pg. 5

thanks

 

[Tunelabguy]

The terms in the first equation are random variables (something from probability theory). I think by "Expectations" they mean "Expected Value", which is something that makes sense when applied to random variables.