A method and apparatus extract a signal component of a measured signal using one of two methods. If the signal component in the measured signal is a periodic signal with a certain well-defined peak-to-peak intensity value, upper and lower envelopes of the measured signal are determined and analyzed to...http://www.google.de/patents/US20030055324?utm_source=gb-gplus-sharePatent US20030055324 - Signal processing method and device for signal-to-noise improvement
