Method for angle of arrival determination on frequency hopping air interfaces
A method for calibrating an antenna and signal processing system enabling angle of arrival (AOA) determination for a frequency hopping signal, in which a calibration coefficient is determined in response to one or more calibration signals injected into the system at one or more of the frequencies in the hopping sequence and proximate in time to reception of the communication signal. The calibration coefficients are reflective of a frequency and time dependent parameter of a path between the antenna and wireless location sensor. The AOA is determined as a function of the calibration coefficient and the radio frequency energy of the received communication signal. Several embodiment of the method are illustrated.
1. A method of determining an angle of arrival of a frequency hopping communication signal comprising the steps of:
obtaining a frequency hopping sequence of the communication signal;
receiving the communication signal over multiple hops of the same frequency;
injecting a calibration signal at one frequency of the frequency hopping sequence of the signal in response to receipt of said communication signal;
determining a calibration coefficient C 1 for said one frequency; and,
determining the AOA of the signal based on the hops of the communication signal having said one frequency and the calibration coefficient C 1.
2. The method of claim 1 wherein said frequency hopping sequence is comprised of N frequencies f i where i=1 to N.
3. The method of claim 1 wherein the step of injecting a calibration signal is proximate in time to receiving the communication signal.
4. The method of claim 1 wherein the one frequency is determined as a function of an average frequency of the hopping sequence.
5. The method of claim 1 wherein the one frequency is the first frequency in the frequency hopping sequence.
6. The method of claim 1 wherein the one frequency is arbitrarily chosen from the frequency hopping sequence.
7. The method of claim 1 wherein the one frequency is determined as a function of a first moment of the frequencies in the frequency hopping sequence.
8. A method of determining an angle of arrival of a frequency hopping communication signal comprising the steps of:
obtaining a frequency hopping sequence of the communication signal;
injecting a calibration signal at one frequency of the frequency hopping sequence of the communication signal in response to receipt of said communication signal;
determining a calibration coefficient C 1 for said one frequency;
storing said calibration coefficient C 1 ;
receiving the communication signal over multiple hops of the same frequency; and,
determining the AOA of the signal based on the hops of the signal having said one frequency and the calibration coefficient C 1.
9. The method of claim 8 wherein the step of injecting a calibration signal is initiated periodically.
10. The method of claim 8 wherein the step of injecting is triggered in anticipation of receiving said communication signal.
11. The method of claim 8 wherein said frequency hopping sequence is comprised of N frequencies f i where i=1 to N.
12. The method of claim 8 wherein the step of injecting a calibration signal is proximate in time to receiving the communication signal.
13. The method of claim 8 wherein the one frequency is determined as a function of an average frequency of the hopping sequence.
14. The method of claim 8 wherein the one frequency is the first frequency in the frequency hopping sequence.
15. The method of claim 8 wherein the one frequency is arbitrarily chosen from the frequency hopping sequence.
16. The method of claim 8 wherein the one frequency is determined as a function of a first moment of the frequencies in the frequency hopping sequence.