Patent ID: 8170509

Claim:
An apparatus for detecting a relative phase difference between an incident signal and a reflected signal, the apparatus comprising: a plurality of phase shifters adapted to apply first phase shifts to a representation of the incident signal and to a representation of the reflected signal in order to produce a plurality of first phase shifted signals, and to apply second phase shifts to the representation of the incident signal and to the representation of the reflected signal in order to produce a plurality of second phase shifted signals; a plurality of combiners, operatively coupled to the plurality of phase shifters, and adapted to combine different pairs of the plurality of first phase shifted signals in order to produce a plurality of first combined signals, and to combine different pairs of the plurality of second phase shifted signals in order to produce a plurality of second combined signals; and additional circuitry, operatively coupled to the plurality of combiners, and adapted to detect amplitudes of the plurality of first combined signals in order to produce a plurality of first amplitude signals, to detect amplitudes of the plurality of second combined signals in order to produce a plurality of second amplitude signals, and to compare the plurality of first and second amplitude signals in order to produce a digital signal that indicates a region of a reference circle within which the relative phase difference occurs.