Patent attributes
An apparatus and a method for determining the location of a pointing device in the vicinity of a set of receivers able to receive one or more locating signals transmitted through a medium. The method includes receiving at a receiver a signal that includes a locating signal and an interfering signal, determining an estimated interference signal indicative of the interfering signal included in the signal received, determining a signal indicative of the difference between the received signal and the estimated interference signal, and using the signal indicative of the difference to compute the location of the pointing device on a surface near the set of receivers. One version uses a separate receiver from which to determine the estimated interference signal, while another version uses the received signal at a time when there is expected to be no locating signal present in order to determine the estimated interference signal. An adaptive filter computes the estimated interference signal.
