[Efficient extraction of event related potentials by the combination of subspace method and lift wavelet transform]

A new approach is put forward for reducing the number of trials required for the extraction of the brain event related potentials (ERPs). The approach is developed by combining both the subspace methods and lift wavelet transform. First, the signal subspace is estimated by applying the singular value decomposition (SVD) to an enhanced version of the raw data obtained by orthonormal projection of the raw data onto the estimated signal subspace. At the same time, the colored noise is whitened. Next, the ERPs are extracted by lift wavelet construction of the enhanced version. Simulation results show that combination of both the subspace methods provides much better capability than does each of them. The experiments showed that the practical results were good.