Patent ID: 8884820

Claim:
A receiving station configured to determine a location of a transmitting device based on reception of short-duration frequency-hopping spread spectrum (FHSS) signals having a duration of as short as ten microseconds, the receiving station comprising: first, second and third antennas; switching circuitry coupled to the antennas and configured to select pairs of the antennas; a surface acoustic wave (SAW) delay line having first and second opposite ends and a plurality of tap outputs; receiver circuitry coupled to outputs of the switching circuitry configured to receive the FHSS signals transmitted by the transmitting device through a selected pair of the antennas, the receiver circuitry configured to hop to particular frequencies based on a known spreading sequence to receive the FHSS signals; processing circuitry arranged to cause the switching circuitry to select the pairs of the antennas and configured to process signals present at the tap outputs to determine a time-difference-of-arrival (TDOA) between the FHSS signals received through the selected pair of antennas; and an inverter coupled between the receiver circuitry and the SAW delay line configured to provide an inverted version of signals received through a second antenna of the selected pair to the second opposite end of the SAW delay line, wherein the receiver circuitry is further configured to inject a non-inverted version of the FHSS signals received through a first antenna of the selected pair into the first opposite end of the SAW delay line and to inject the inverted version of the FHSS signals received through the second antenna of the selected pair into the second opposite end of the SAW delay line to set up an acoustic standing-wave within the SAW delay line, wherein the processing circuitry is further configured to determine the TDOA for each selected pair of antennas by detection of a zero-crossing of the standing wave, wherein the processing circuitry is further configured to provide the TDOAs determined for each selected pair of antennas for use in determining an angle-of-arrival (AOA) of the signals from the transmitting device, and wherein the processing circuitry is further configured to cause the switching circuitry to reverse polarity of the received FHSS signals wherein the non-inverted version of the FHSS signals received through the first antenna of the selected pair is injected into the second opposite end of the SAW delay line and the inverted version of the FHSS signals received through the second antenna of the selected pair is injected into the first opposite end of the SAW delay line.