Patent ID: 7970354

Claim:
A signal filter, comprising: a first vector modulator, a second vector modulator, and a third vector modulator coupled to a microprocessor; an input signal line coupled to the first vector modulator; and a pilot tone generator coupled to the second vector modulator, wherein the pilot tone generator is adjusted to generate a frequency at the center frequency of a radio transceiver receive channel, wherein the first vector modulator is capable of generating a transmit cancellation signal which when combined with the transmit signal results in transmit signal cancellation at and beyond the physical point of signal combination, wherein the third vector modulator is capable of generating an error signal based on an output of the signal filter, wherein the second vector modulator is capable of generating a receive noise cancellation signal based on the transmit signal cancellation generated by the first vector modulator and based on the error signal generated by the third vector modulator which, when combined with the receive hand noise, results in receive band noise cancellation at and beyond the physical point of combination.