Detection of near threshold contrast visual evoked potentials using coherent detection techniques

The detection of near threshold contrast visual evoked potentials was studied using two coherent detection techniques. Both techniques were used to detect the presence of a common but unknown signal on several noisy channels. The first method utilizes the generalized coherence (GC) estimate, while the second method is an eigenvalue based detection method which studies the eigenvalue distribution of the data autocorrelation matrix. Simulation results show the ability of the two methods to detect the steady-state visual evoked potential (SSVEP) at very low SNR corresponding to grating contrasts that are near to psychophysical threshold.