DIRECTIONAL PRUNING OF TRANSMITTERS TO IMPROVE POSITION DETERMINATION

• US 20140266911A1
• Filed: 03/13/2014
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: NextNav, LLC
• Original Assignee: NextNav, LLC
• Inventors: Sendonaris, Andrew, Krasner, Norman F.
• Granted Patent: US 9,964,647 B2
• Time in Patent Office: Days
• US Class Current: 342/458
• CPC Class Codes: G01S 11/04 using angle measurements
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence
• 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 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308

Abstract

Described are systems and methods for estimating a position of receiver using ranging signals from different regions in a network of transmitters. In some embodiments, each ranging signal that exceeds a quality criterion is assigned to one of several defined regions based on a characteristic of that ranging signal. A maximum number of ranging signals per region may be selected and used during trilateration.

Claims

1. A computer-implemented method for estimating a position of a receiver using a network of transmitters, the method comprising:

identifying a set of transmitters from the network of transmitters;

associating each transmitter from the set of transmitters with at least one of three or more groups of transmitters based on geographic information associated with of that transmitter; and

determining an estimated position of the receiver using at least one range measurement corresponding to at least one transmitter in each of the three or more groups that includes a transmitter from the set of transmitters.

2. The method of claim 1, wherein the geographic information associated with include an estimated azimuth relating to a location of the transmitter.

3. The method of claim 2, wherein each of the three or more groups corresponds to a different range of azimuths, and each transmitter is associated with a particular group of the three or more groups when the azimuth relating to that transmitter falls within the range of azimuths corresponding to that particular group.

4. The method of claim 1, wherein the geographic information associated with include a location of the transmitter.

5. The method of claim 4, wherein each of the three or more groups corresponds to a different geographic region, and each transmitter is associated with a particular group of the three or more groups when the location relating to that transmitter falls within the geographic region corresponding to that particular group.

6. The method of claim 1, wherein each of the three or more groups corresponds to a different geographic region in the network of transmitters.

7. The method of claim 1, the method comprising:

determining, for each of the three or more groups, the number of transmitters associated with each group;

determining, when the number is less than the integer M, the estimated position using range measurements corresponding to each of the transmitters in that group; and

determining, when the number is equal to or greater than an integer M, the estimated position using at least M range measurements corresponding to at least M of the transmitters in that group.

8. The method of claim 1, the method comprising:

determining, for each of the three or more groups, the number of transmitters associated with each group;

determining, when the number is equal to or less than an integer M, the estimated position using range measurements corresponding to each of the transmitters in that group; and

determining, when the number is greater than the integer M, the estimated position using a selection of M range measurements corresponding to a selection of M transmitters in that group, wherein a value of a quality metric for each of the M transmitters is at least equal to each value of the quality metric for the unselected transmitters in that group.

9. The method of claim 8, wherein each value of the quality metric relates to at least one of:

an estimated range error related to that transmitter;

a trilateration weight related to that transmitter;

an estimated distance between the transmitter and an initial estimate of the receiver'"'"'s position; and

an angle of incidence related to that transmitter.

10. The method of claim 1, wherein the method comprises:

identifying one or more preferred transmitters with a value of a quality metric that is above a threshold level of the quality metric; and

determining the estimated position of the receiver using a range measurement corresponding to a preferred transmitter from each of the three or more groups that includes at least one of the preferred transmitters.

11. The method of claim 10, wherein the method comprises:

identifying each non-preferred transmitter with a value of the quality metric that is below the threshold level of the quality metric, wherein the estimated position of the receiver is determined without using range measurements corresponding to any of the non-preferred transmitters from each of the three or more groups that includes at least one of the preferred transmitters.

12. A system comprising one or more processors that perform the method of claim 1.

13. A non-transitory machine-readable medium embodying program instructions adapted to be executed to implement the method of claim 1.