Method and apparatus for determining location using phase difference of arrival
An ultra-wideband (“UWB”) communication system comprising a transmitter and a receiver having two antennas. An UWB signal transmitted by the transmitter is received at each of the antennas. By comparing the carrier phases of the received signals, the phase difference can be determined. From this phase difference and the known distance, d, between the antennas, the Cartesian (x,y) location of the transmitter relative to the receiver can be directly determined.
1. In an ultra-wideband (UWB) system comprising a UWB transmitter adapted to transmit a signal, and a UWB receiver having first and second antennae separated by a first distance, d, a method comprising the steps of:
1.1 using the first antenna to receive the transmitted signal;
1.2 using the second antenna to receive the transmitted signal; and
1.3 using the receiver to:
1.3.1 develop a range, r, between the transmitter and a selected one the first and second antennas;
1.3.2 develop a first phase value as a function of the complex baseband impulse response of the transmitted signal received by the first antenna;
1.3.3 develop a second phase value as a function of the complex baseband impulse response of the transmitted signal received by the second antenna;
1.3.4 develop a path difference value, p, as a function of the first and second phase values; and
1.3.5 develop an (x,y) location of the transmitter relative to the receiver as a function of d, r and p.
2. The method of claim 1 wherein d is less than or equal to one half a wavelength, λ, of the transmitted signal.
3. The method of claim 1 wherein step 1.3.4 is further characterized as:
1.3.4 develop a path difference value, p, as a function of the first and second phase values and of a selected calibration function.
4. A location determination circuit configured to perform the method of claim 1 .
5. An RF receiver comprising a location determination circuit according to claim 4 .
6. An RF transceiver comprising a wireless receiver according to claim 5 .
7. An RF communication system comprising a wireless transceiver according to claim 6 .
8. A non-transitory computer readable medium including executable instructions which, when executed in an RF system, causes the system to perform the steps of a method according to claim 1 .