Abstract: A method for determining the channel gain between one or more emitter(s) and one or more receiver(s) by using a linear transform, such as a wavelet transform. Provides a fast and robust method for determining the channel gain, the signal being emitted with a very low power since received signals are easily resolved at the receiver. The method is employed in a three dimensional pointing device for a computer improving the possibility of moving the pointer in three dimensions. Information may be obtained about objects positioned in the signal path. May be employed for door openers or for determining the position of a remote control or for reducing “Cross talk” in electrical components.

Abstract: Method for regulating the control signal for adjustment of the optical path between a data disc and a signal pick-up detector system in a data disc drive, where the control signal is regulated as a response to the deviation of the actual reading signals from expected reading signals, and wherein the control signal is regulated in dependence of the tendency of said deviation.