Polarization sensitive synthetic aperture radar system and method for local positioning
First Claim
1. A method of determining the position of a device relative to a landmark, comprising:
- transmitting a pulse from the device, the pulse having a particular polarization;
receiving a return signal over a period of time, the return signal including a reflected pulse from the landmark, the receiving including preferentially receiving signals having the particular polarization; and
processing the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark;
wherein the reflected pulse from the landmark has a polarization substantially the same as the particular polarization, and the return signal includes components not having the particular polarization; and
wherein the method includes transmitting the pulse at a first position of the device, separating the received return signal into multiple portions, and determining from the multiple portions a first plurality of range candidates, each range candidate representing a possible range to the landmark.
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Accused Products
Abstract
A positioning system includes a passive, isotropic reflecting landmark at a fixed position and a device. The device transmits an electromagnetic pulse having a circular polarization and receives a return signal over a period of time. The return signal includes a reflected pulse from the reflecting landmark. The processes the return signal to isolate the reflected pulse from the return signal and to determine a range from the device to the reflecting landmark. The reflecting landmark includes a first passive reflector, a second passive reflector, and a static structure configured to statically position the second passive reflector at an angle relative to the first passive reflector. The device optionally moves in a particular direction while receiving the return signal, detects a Doppler shift in the reflected pulse portion of the return signal, and determines an angle between the particular direction and a straight line between the device and the landmark.
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Citations
15 Claims
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1. A method of determining the position of a device relative to a landmark, comprising:
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transmitting a pulse from the device, the pulse having a particular polarization; receiving a return signal over a period of time, the return signal including a reflected pulse from the landmark, the receiving including preferentially receiving signals having the particular polarization; and processing the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark; wherein the reflected pulse from the landmark has a polarization substantially the same as the particular polarization, and the return signal includes components not having the particular polarization; and wherein the method includes transmitting the pulse at a first position of the device, separating the received return signal into multiple portions, and determining from the multiple portions a first plurality of range candidates, each range candidate representing a possible range to the landmark. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of determining the position of a device relative to a landmark, comprising:
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transmitting a pulse from the device, the pulse having a particular polarization; receiving a return signal over a period of time, the return signal including a reflected pulse from the landmark, the receiving including preferentially receiving signals having the particular polarization; and processing the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark; wherein the reflected pulse from the landmark has a polarization substantially the same as the particular polarization, and the return signal includes components not having the particular polarization; wherein; the transmitting includes transmitting the pulse multiple times, each transmission of the pulse having a respective transmission beam pattern with a null over a different respective range of angles; the processing including; determining from the return signals from the multiple pulse transmissions a first set of range candidates, each range candidate representing a possible range to the landmark, each range candidate having an associated range of angles, and analyzing the range of angles associated with each range candidate to produce a reduced set of range candidates that are consistent with one or more potential landmark positions. - View Dependent Claims (11, 12)
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13. A method of determining the position of a device relative to a landmark, comprising:
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transmitting a pulse from the device, the pulse having a particular polarization; receiving a return signal over a period of time, the return signal including a reflected pulse from the landmark, the receiving including preferentially receiving signals having the particular polarization; and processing the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark; wherein the reflected pulse from the landmark has a polarization substantially the same as the particular polarization, and the return signal includes components not having the particular polarization; wherein; the transmitting includes transmitting a series of pulses; the receiving includes (A) receiving the series of pulses at a plurality of distinct locations having a predefined separation distance therebetween and generating a series of received pulse data sets corresponding to at least a subset of the received pulses, each received pulse data set having received pulse data from receiving a respective pulse at each two or more of the plurality of distinct locations, and (B) combining the pulse data within each pulse data set to produce a combined return signal having a receive pattern null in an associated range of angles; the processing including; determining from the combined return signals a first set of range candidates, each range candidate representing a possible range to the landmark, and determining for each range candidate angle-related signal strength data comprising a plurality of amplitude values associated with a respective plurality of angle ranges; and analyzing the angle-related signal strength data associated with at least one of the range candidates to produce a reduced set of range candidates that are consistent with one or more potential landmark positions.
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14. A method of determining the position of a device relative to a landmark, comprising:
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transmitting a pulse from the device, the pulse having a particular polarization; receiving a return signal over a period of time, the return signal including a reflected pulse from the landmark, the receiving including preferentially receiving signals having the particular polarization; and processing the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark; wherein the reflected pulse from the landmark has a polarization substantially the same as the particular polarization, and the return signal includes components not having the particular polarization; wherein; the receiving includes receiving the pulse at a plurality of distinct locations having a predefined separation distance therebetween and generating received pulse data for at least two of the plurality of distinct locations at which the pulse is received; combining the received pulse data multiple times, using a plurality of phase offsets, to produce multiple combined return signals, each having a receive pattern null in an associated range of angles; the processing includes determining from the combined return signals a first set of range candidates, each range candidate representing a possible range to the landmark, and determining for each range candidate angle-related signal strength data comprising a plurality of amplitude values associated with a respective plurality of angle ranges; and analyzing the angle-related signal strength data associated with at least one of the range candidates to produce a reduced set of range candidates that are consistent with one or more potential landmark positions.
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15. A positioning system, comprising
a passive, isotropic reflecting landmark at a fixed position; - and
a device configured to transmit an electromagnetic pulse, the pulse having a particular polarization;
the device further configured to receive a return signal over a period of time, the return signal including a reflected pulse from the landmark, and to process the return signal so as to isolate the reflected pulse from the return signal and to determine a range from the device to the landmark;wherein the reflecting landmark is configured to reflect the electromagnetic pulse so as to produce the reflected pulse with a polarization substantially the same as the particular polarization; and and wherein the device is configured to transmit the pulse at a first position of the device, to separate the received return signal into multiple portions, and to determine from the multiple portions a first plurality of range candidates, each range candidate representing a possible range to the landmark.
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Specification