Patent ID: 7327802

Claim:
An apparatus, comprising: a transmitter configured to send a transmitter signal associated with a frequency; a receiver associated with the frequency; an antenna coupled to the transmitter and the receiver; and a signal cancellation circuit coupled to the transmitter, the receiver and the antenna, the signal cancellation circuit configured to phase shift by substantially 180 degrees a first portion of the transmitter signal that does not include a reception signal to produce a phase-shifted signal, the signal cancellation circuit configured to combine the phase-shifted signal with a second portion of the transmitter signal to produce a combined signal, the second portion of the transmitter signal being associated with a reflection of a third portion of the transmitter signal from the antenna, the first portion, the second portion and the third portion of the transmitter signal being different from each other, and where the signal cancellation circuit is further configured to execute a training sequence including generating a detector signal based on an amplitude of the training sequence of the transmitter signal, modifying a first amplitude of the first portion of the transmitter signal based on the detector signal, and modifying a second amplitude of the first portion of the transmitter signal such that the second amplitude of the first portion of the transmitter signal is substantially equal to an amplitude of the second portion of the transmitter signal.