Urban terrain geolocation system
First Claim
1. A system for locating a moveable target inside a structure in an urban area, wherein the area is characterized by a feature size, said system comprising:
- at least one transmitter for transmitting an electromagnetic signal into the urban area from a predetermined location, with said signal having a wavelength, λ
, longer than said feature size, wherein a signal path distortion of said signal is caused by said structure and is characterized by said signal wavelength, λ
;
a receiver positioned on said moveable target in the structure for receiving said electromagnetic signal from said transmitter, wherein said received electromagnetic signal includes phase information indicative of the location of the target relative to said transmitter and dependent on said signal path distortion; and
means for using said phase information in said electromagnetic signal to calculate the location of the target.
1 Assignment
0 Petitions
Accused Products
Abstract
A system for tracking a moveable object such as a soldier in an urban environment includes a receiver that is positioned on the movable object and a plurality of signal transmitters. The transmitters are mutually dispersed at known locations within the urban environment and each transmitter is configured to generate a low frequency electromagnetic signal capable of penetrating into buildings in the urban environment. At the receiver, phase related information and the receiver location information are extracted from received signals and used to determine the location of the receiver. Phase related ambiguities can be eliminated by a processor to find the real receiver position using an algorithm such as the maximum likelihood method (MLM) algorithm. Once the real receiver position is calculated, it can be transmitted to a central location using a low probability of intercept (LPI) waveform to prevent hostile parties from intercepting the location of the soldier.
29 Citations
21 Claims
-
1. A system for locating a moveable target inside a structure in an urban area, wherein the area is characterized by a feature size, said system comprising:
-
at least one transmitter for transmitting an electromagnetic signal into the urban area from a predetermined location, with said signal having a wavelength, λ
, longer than said feature size, wherein a signal path distortion of said signal is caused by said structure and is characterized by said signal wavelength, λ
;
a receiver positioned on said moveable target in the structure for receiving said electromagnetic signal from said transmitter, wherein said received electromagnetic signal includes phase information indicative of the location of the target relative to said transmitter and dependent on said signal path distortion; and
means for using said phase information in said electromagnetic signal to calculate the location of the target. - View Dependent Claims (2, 3, 4, 5, 6, 7)
an oscillator mounted on said target for measuring a phase for said signal; and
a processor for using said phase to calculate the location of the target.
-
-
5. A system as recited in claim 4 wherein said processor is positioned on the target.
-
6. A system as recited in claim 4 wherein said processor is positioned at a distance from the target, and said system further comprises a transmitter positioned at the target for transmitting said phase information to said processor via a signal having a Low Probability of Intercept (LPI) waveform.
-
7. A system as recited in claim 6 wherein said Low Probability of Intercept (LPI) waveform is a burst using a wide bandwidth spread spectrum.
-
8. A system for locating a moveable target in a structure within an urban area, said system comprising:
-
a plurality of transmitters dispersed at predetermined locations, with each said transmitter configured to transmit an electromagnetic signal having a wavelength, λ
, into the structure wherein said wavelength λ
, is longer than 150 meters to allow each said signal to penetrate the structure, wherein a signal path distortion of said signal is caused by said structure and is characterized by said signal wavelength, λ
;
a receiver positioned on said target for receiving each said signal from said transmitters, wherein each said received signal includes phase information indicative of the location of the target relative to each respective said transmitter and dependent on said signal path distortion; and
means for using said phase information in said signals to calculate the location of the target. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A method for locating a moveable target in a structure within an urban area, said method comprising the steps of:
-
transmitting signals into the urban area from a plurality of dispersed, predetermined locations, with each said signal having a wavelength, λ
, wherein said wavelength λ
is longer than 150 meters to allow each said signal to penetrate the structure, wherein a signal path distortion of said signal is caused by said structure and is characterized by said signal wavelength, λ
;
receiving said signals at said target, said received signal including phase information indicative of the location of the target relative to each said predetermined transmitting location and dependent on said signal path distortion; and
using said phase information in said signals to calculate the location of the target. - View Dependent Claims (18, 19, 20, 21)
-
Specification