Patent ID: 8900142

Claim:
A method of locating a patient-swallowed pill transmitter, the method comprising: receiving signals from a plurality of antennas disposed about a body of a patient, the signals responsive to a transmitted signal from a pill transmitter swallowed by the patient; identifying phase differences of the received signals based at least partly on mutual inductance between the pill transmitter and at least some of the plurality of antennas; determining an initial estimate of a location of the pill transmitter within the body of the patient based at least in part on linear processing of at least the phase differences of the received signals, wherein the initial linear estimate takes into account an orientation of the pill transmitter with respect to at least some of the plurality of antennas; refining the initial estimate by applying a nonlinear process to the initial linear estimate to produce a nonlinear estimate of the location of the pill transmitter; filtering the nonlinear estimate of the location of the pill transmitter to produce an overall estimate of the location of the pill transmitter, based at least in part on a previously estimated location of the pill transmitter within the body of the patient; and outputting an indication of the overall estimate of the location of the pill transmitter for presentation to a clinician; wherein at least said determining and refining the initial estimate are performed by processing electronics.