Operators

Thresholding

Threshold a signal and creates events.

A minimum threshold T_min and maximum threshold T_max must be specified. All time points whose amplitude lie between these two threshold : $$T_{min} < x < T_{max}$$ will be selected.

Events will be created for each of the thresholded parts.

You can see the amplitude distribution across all channels and time points by clicking on the Amplitude Distribution button.

Teager Energy Operators

The Teager Energy Operator (TEO) is a non-linear operator. It has been used in EEG to detect interictal epileptic discharges or action potential. See : Neural action potential detector using multi-resolution TEO - J.H. Choi and T. Kim.

The discrete time TEO can be expressed as : $$ Phi(x(n)) = x^2(n) - x(n-1)x(n+1) $$

The k-TEO is a generalization of the TEO : $$ Phi_k(x(n)) = x^2(n) - x(n-k)x(n+k) $$

The k parameter must be choosed according to the type of detection wanted and the sampling frequency of the signal.

The MTEO operator is a parallel association of several k-TEO operators with differents values of k, followed by a maximum filter.

Note

An IED detector based on the MTEO operator is available in micMac in the Detectors/Epileptic Spike menu, although it has not been tested thoroughly.