Method and apparatus for determining the angle of departure
An ultra-wideband (“UWB”) communication system comprising a transmitter having two transmit antennas and a receiver having a single receive antenna. Respective selected portions of the UWB signal are transmitted by the transmitter via each of transmit antennas is received at the receive antenna. By comparing the phases of the received signal portions, the phase difference of departure can be determined. From this phase difference and the known distance, d, between the transmit 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 having first and second transmit antennae separated by a distance, d, and adapted to transmit a signal, and a UWB receiver having a receive antenna, a method comprising the steps of:
1.1 using the first transmit antenna to transmit a selected first portion of the signal;
1.2 using the receiver to:
1.2.1 receive, via the receive antenna, the transmitted first portion of the signal; and
1.2.2 develop a first phase value as a function of the complex baseband impulse response of the received first portion of the signal;
1.3 using the second transmit antenna to transmit a selected second portion of the signal; and
1.4 using the receiver to:
1.4.1 receive, via the receive antenna, the transmitted second portion of the signal;
1.4.2 develop a second phase value as a function of the complex baseband impulse response of the received second portion of the signal; and
1.4.3 develop a path difference value, p, as a function of the first and second phase values; and
1.4.4 correcting p as a function of mutual coupling of the first and second transmit antennas.
2. The method of claim 1 further comprising the step of:
1.4.5 develop an angle of departure of the signal transmitted by the transmitter relative to the receiver as a function of d and p.
3. The method of claim 1 further comprising using the receiver to:
1.4.6 determine a first time of flight of the transmitted first portion of signal transmitted from the first transmit antenna to the receive antenna;
1.4.7 determine a second time of flight of the transmitted second portion of signal transmitted from the second transmit antenna to the receive antenna;
1.4.8 determine a distance r between the receive antenna and a mid-point between the first transmit antenna and the second transmit antenna; and
1.4.9 develop an (x,y) Cartesian position of the transmitter relative to the receiver as a function of d, r and p.
4. In an ultra-wideband (UWB) system comprising a UWB transmitter having first and second transmit antennae separated by a distance, d, and adapted to transmit a signal, and a UWB receiver having a receive antenna, a method comprising the steps of:
4.1 using the first transmit antenna to transmit a selected first portion of the signal;
4.2 using the receiver to:
4.2.1 receive, via the receive antenna, the transmitted first portion of the signal; and
4.2.2 develop a first time of arrival as a function of the complex baseband impulse response of the received first portion of the signal;
4.3 using the second transmit antenna to transmit a selected second portion of the signal; and
4.4 using the receiver to:
4.4.1 receive, via the receive antenna, the transmitted second portion of the signal;
4.4.2 develop a second time of arrival as a function of the complex baseband impulse response of the received second portion of the signal;
4.4.3 develop a path difference value, p, as a function of the first and second times of arrival; and
4.4.4 correcting p as a function of mutual coupling of the first and second transmit antennas.
5. The method of claim 4 further comprising the step of:
4.4.5 develop an angle of departure of the signal transmitted by the transmitter relative to the receiver as a function of d and p.
6. The method of claim 4 further comprising using the receiver to:
4.4.6 determine a first time of flight of the portion of the signal transmitted from a selected one of the first and second transmit antennas to the receive antenna;
4.4.7 determine a distance r between the receive antenna and the selected transmit antenna as a function of the first time of flight; and
4.4.8 develop an (x,y) Cartesian position of the transmitter relative to the receiver as a function of d, r and p.
7. A location determination circuit configured to perform the method of claim 1 .
8. An RF receiver comprising a location determination circuit according to claim 7 .
9. An RF transceiver comprising a wireless receiver according to claim 8 .
10. An RF communication system comprising a wireless transceiver according to claim 9 .
11. 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 .