System and method for robust navigation and geolocation using measurements of opportunity

• US 9,588,218 B2
• Filed: 09/30/2011
• Issued: 03/07/2017
• Est. Priority Date: 09/30/2010
• Status: Active Grant

• Current Assignee: Parsons Corporation (New Port Group Holdings, Inc.)
• Original Assignee: Echo Ridge, LLC
• Inventors: Kennedy, Joseph P., Carlson, John
• Primary Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US13/250,134
• Publication Number:
  US 20120081248A1
• Time in Patent Office: 1,985 Days
• Field of Search: 342/464, 3423572-35723, 455/456.5
• US Class Current: 1/1
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 5/0242 Determining the position of transmitters to be subsequently used in positioning G01S5/0289 takes precedence
• CPC Class Codes: G01S 5/02525 Gathering the radio frequency fingerprints
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks

Abstract

A system and method to opportunistically capture and use measurements on a priori unknown radio signals, not intended for radio navigation or geolocation, to improve navigation/geolocation position estimation yield and accuracy.

Claims

1. A method of locating an agent, comprising the steps of:

a. surveying an RF environment by monitoring a range of RF frequencies;

b. receiving a plurality of RF signals of opportunity (SoOP), at an agent, wherein the RF SoOP is an ambient radio frequency (RF) transmission that is not intended for navigation, position or timing for positioning purposes, and wherein the SoOps are transmitted from a communication system different than the communication system of the agent;

c. in a processor, performing ranging measurements on the received RF SoOPs, wherein the ranging measurements are based on a known sequence transmitted in the SoOPs;

d. in a processor, classifying the received RF SoOPs according to a predetermined criteria of parameters;

e. in a processor, ranking the classified received RF SoOps; and

f. in a processor, determining a location of the agent as a function of the performed ranging measurements and the ranking of the received SoOPs;

wherein the RF received SoOPs include at least one synchronized signal and at least one and unsynchronized signal and wherein at least one of the received RF SoOPs is transmitted from a first transmitter of unknown location.

2. The method of claim 1 further comprising the step of:

g. determining a location of the first transmitter as a function of the received RF SoOPs.

3. The method of claim 1 wherein the step of performing ranging measurements includes determining the time difference of arrival of a signal from least two transmitters.

4. The method of claim 1 wherein the parameters include at least one of:

(i) whether the location of the transmitter of the RF SoOP is known;

(ii) the bandwidth of the received RF SoOP;

(iii) the power of the received RF SoOP; and

(iv) the GDOP contribution of the received RF SoOP.

5. The method of claim 1 wherein the performed ranging measurements are sent to a distributed platform, and steps (c)-(f) are performed at the distributed platform.

6. The method of claim 1 wherein the steps of (a)-(c) are performed at a plurality of agents, and step (f) determines the location of at least one of the agents.

7. The method of claim 1 wherein the steps (a)-(c) are performed by a single agent having a receiver which is in motion for at least while receiving a plurality of the RF SoOPs.

8. The method of claim 1 wherein the agent does not have a priori knowledge of the plurality of received RF SoOPs.

9. A method of locating an agent, comprising the steps of:

a. performing an initialization step to determine the location of a first transmitter of a signal of opportunity (SoOP), comprising;

(i) surveying the RF environment by monitoring a range of RF frequencies using a first plurality of agents, each agent having a receiver and having a coarse location;

(ii) receiving a plurality of SoOPs at each agent, wherein a SoOP is an ambient radio frequency (RF) transmission that is not intended for navigation, position or timing for positional purposes and is transmitted from a communication system different than the communication system of the agent;

(iii) at each agent, using a processor, making a ranging measurement for a first SoOP, wherein the ranging measurement is based on a known sequence transmitted in the SoOP and wherein the first SoOP is transmitted from the first transmitter of unknown location;

(iv) at a first agent, receiving the ranging measurement for the first SoOP from a plurality of agents

(v) at a first agent, using a processor, determining the location of the first transmitter associated with the first SoOP as a function of the ranging measurements for the first SoOP;

(b) performing a mapping step to determine the location of a second agent, comprising;

(i) surveying the RF environment by monitoring for a range of RF frequencies using a second plurality of agents, each agent having a receiver and including a second agent at an unknown location;

(ii) receiving a second SoOPs at each agent of the second plurality of agents;

(iii) at each second agent, making a timing measurement for the second SoOP;

(iv) at the second agent, receiving the timing measurement for the second SoOP from the second plurality of agents; and

(v) at the second agent, using a processor, determining the location of the second agent as a function of (a) the timing measurements for the second SoOP, and (b) and the determined location of the first transmitter.

10. The method of claim 9 wherein the first agent uses GPS to determine its coarse location.

11. The method of claim 9 wherein the ranging measurements include at least one of time of arrival information, demodulated bits, extracted bit sequence timing, frequency offset, and timing relative to a common standard.

12. The method of claim 9 wherein the first agent uses an inertial measurement unit to determine its coarse location.

13. The method of claim 9 wherein the agents communicate with each other through at least one of WiFi access points to the internet, through a service provider link (cellular), or via ad-hoc wireless connections.

14. The method of claim 13 wherein the communication between agents including relative ranging information between agents.

15. A method of locating an agent, comprising the steps of:

a. surveying the RF environment by monitoring a range of RF frequencies transmitted;

b. receiving a first plurality of RF signals at an agent at a first coarse location;

wherein at least one of the first plurality of received signals is a signal of opportunity (SoOP) wherein the SoOP is an ambient radio frequency (RF) transmission that is not intended for navigation, position or timing for positioning purposes transmitted from a transmitter of unknown location from a communication system different than the communication system of the agent;

c. performing ranging measurements on the first plurality of received RF signals, wherein the ranging measurements for the SoOPs are based on a known sequence transmitted in the SoOP;

d. receiving a second plurality of RF signals at the agent at a second coarse location, wherein at least one of the second plurality of received signals is transmitted from a transmitter of unknown location;

e. performing ranging measurements on the second plurality of received RF signals; and

f. determining a location of the agent as a function of the performed ranging measurements of the first and second plurality of received RF signals;

wherein the first and second plurality of received RF signals include at least one synchronized signal and at least one and unsynchronized signal.

16. The method of claim 15 wherein the agent moves from the first coarse location to the second coarse location and the second coarse location is determined as a function of the first coarse position and an inertial measurement unit on the agent.