Diversified doppler for single platform geolocation
First Claim
1. A method of determining a location of a radio frequency (RF) emitter using an RF receiver located on a single moving platform, the method comprising:
- A. receiving, by the receiver, an RF signal transmitted by the emitter over a period of time;
B. measuring, by the receiver, frequency of arrival (FOA) data of the RF signal over the period of time, the FOA data comprising a Doppler-shifted frequency of the emitter, a location of the receiver, and a velocity of the receiver;
C. determining an estimate of a frequency of the emitter based on the measured FOA data and an estimate of the location of the emitter, wherein the estimated frequency of the emitter includes an estimate of a frequency drift and further wherein the estimate of the frequency of the emitter is calculated with a particle filter which preferentially weights particles having a frequency drift that best corresponds to a model of an expected emitter frequency drift;
D. resampling the weighted particles; and
E. determining an updated estimate of the location of the emitter based on the estimate of the frequency of the emitter.
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Accused Products
Abstract
The described invention allows for rapid geolocation of one or more RF emitters using a single moving collection platform. Inaccuracies of conventional frequency of arrival (FOA) geolocation methods are overcome by solving simultaneously for emitter location and a potential emitter drift associated with an observed emitter frequency. Certain embodiments may utilize particle filtering algorithms to recursively update multimodal state densities that are typical of solutions involving both unknown emitter location and nonstationary emitter carrier drift. Moreover, certain properties of particle filters may be exploited to provide a geolocation solution given a complex multimodal state space composed of emitter location and a non-stationary emitter frequency required for FOA.
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Citations
25 Claims
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1. A method of determining a location of a radio frequency (RF) emitter using an RF receiver located on a single moving platform, the method comprising:
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A. receiving, by the receiver, an RF signal transmitted by the emitter over a period of time; B. measuring, by the receiver, frequency of arrival (FOA) data of the RF signal over the period of time, the FOA data comprising a Doppler-shifted frequency of the emitter, a location of the receiver, and a velocity of the receiver; C. determining an estimate of a frequency of the emitter based on the measured FOA data and an estimate of the location of the emitter, wherein the estimated frequency of the emitter includes an estimate of a frequency drift and further wherein the estimate of the frequency of the emitter is calculated with a particle filter which preferentially weights particles having a frequency drift that best corresponds to a model of an expected emitter frequency drift; D. resampling the weighted particles; and E. determining an updated estimate of the location of the emitter based on the estimate of the frequency of the emitter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system for determining a location of a radio frequency (RF) emitter comprising:
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a receiver located on a platform, the receiver adapted to receive an RF signal transmitted by an emitter over a period of time; and a processor in communication with the receiver adapted to; measure frequency of arrival (FOA) data of the received RF signal over the period of time, the FOA data comprising a Doppler-shifted frequency of the emitter, a location of the receiver, and a velocity of the receiver; determine an estimate of a frequency of the emitter based on the measured FOA data and an estimate of the location of the emitter, wherein the estimated frequency of the emitter includes an estimate of a frequency drift and further wherein the estimate of the frequency of the emitter is calculated with a particle filter which preferentially weights particles having a frequency drift that best corresponds to a model of an expected emitter frequency drift; resample the weighted particles; and determine an updated estimate of the location of the emitter based on the estimate of the frequency of the emitter. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification