Recording biological signals using Hilbert transforms
 A method and apparatus for monitoring electrical signals propagated through a living organism. A bipolar electrode is placed in contact with the tissue of the organism. Means is operatively connected to the electrode for performing a Hilbert transform on signals from the electrode. The individual electrodes of the bipolar electrode are preferably spaced-apart a distance d so as to satisfy the equation: .vertline..pi.Bd/v.vertline.<.pi./2. The Hilbert transform can be implemented by performing a Fourier transform on the signal, multiplying the signal by the imaginary number j, changing the sign of the signal at all negative frequencies, and then performing a reverse Fourier transform on the signal. The resulting signal is then displayed. Preferably brush tip electrodes are used for EMG signals although the method and apparatus is also applicable to needle electrodes. 
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Cecil Yunquan Charles A.
Hershler Chen Laszlo