Patent ID: 8384584

Claim:
A method for locating a transponder (MT) with a remote locator (RL), the method comprising: transmitting, by the RL, an interrogation signal including an interrogation sequence that is encoded with a specific identifier associated with the MT; capturing, by the MT, samples associated with the interrogation signal with a receiver in the MT; determining, by the MT, that the captured samples correspond to the interrogation signal encoded with the specific identifier associated with the MT, and if the interrogation signal is determined to be encoded with the specific identifier associated with the MT: determining, by the MT, a quantized Doppler measurement associated with the interrogation signal, adjusting, by the MT, transmission characteristics of a transmitter in the MT with the quantized Doppler measurement such that twice the quantized Doppler measurement is effectively subtracted from the carver frequency and cadence of the transmitter, selecting, by the MT, a reply sequence for transmission, encoding, by the MT, a Doppler compensation factor in a coded message for transmission in at least a portion of the reply sequence, and transmitting, by the MT, the reply sequence with the coded message as a reply signal; capturing, by the RL, samples associated with the reply signal with a receiver in the RL; determining, by the RL, that the captured samples correspond to the reply signal from the MT; and when the reply signal is determined to be from the MT: extracting, by the RL, the Doppler compensation factor from the coded message associated with the reply signal, determining, by the RL, a Doppler shift associated with the reply signal using the Doppler compensation factor extracted from the coded message, and determining a direction from the RL to the MT based on the determined Doppler shift associated with the reply signal.