Method and apparatus for modeling time relationships between clocks

Patent metadata

Field	Value
Publication number	US-9810766-B2
Application number	US-201615185567-A
Country	US
Kind code	B2
Filing date	Jun 17, 2016
Priority date	Aug 17, 2011
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

An example method includes identifying a link that is one of a plurality of links of a wireless locating system, the link being defined by at least a reference signal source, a first receiver unit, and a second receiver unit; determining a reliability metric for signal transmission via a link based on first link data, the link data describing first reference signal events for the link; and modifying the reliability metric based on second link data describing second reference signal events for the link, wherein modifying the reliability metric includes: determining whether the second link data is consistent with the first link data; adjusting the reliability metric using a first function when the second link data is consistent with the first link data; and adjusting the reliability metric using a second function different than the first function when the second link data is inconsistent with the second link data.

First claim

What is claimed is:

1. A method comprising:
identifying a link that is one of a plurality of links of a wireless locating system, the link being defined by at least a reference signal source, a first receiver unit, and a second receiver unit;
determining, via a processor, a reliability metric for signal transmission via a link based on first link data, the link data describing first reference signal events for the link; and
modifying, via the processor, the reliability metric based on second link data describing second reference signal events for the link, wherein modifying the reliability metric includes:
determining whether the second link data is consistent with the first link data;
adjusting the reliability metric using a first function when the second link data is consistent with the first link data; and
adjusting the reliability metric using a second function different than the first function when the second link data is inconsistent with the second link data.

2. A method as defined in claim 1 , wherein the first function is a linear function and the second function is an exponential function.

3. A method as defined in claim 1 , wherein:
adjusting the reliability metric using the first function when the second link data is consistent with the first link data includes adjusting the reliability metric to indicate the link being more reliable; and
adjusting the reliability metric using the second function when the second link data is inconsistent with the first link data includes adjusting the reliability metric to indicate the link being less reliable.

4. A method as defined in claim 1 , wherein:
the first link data describing the first reference signal events is defined by at least first time stamps describing times at which the first receiver unit received reference signals transmitted by the reference signal source; and
the second link data describes second reference signal events; and
the second link data is defined by at least second time stamps describing times at which the first receiver unit received reference signals transmitted by the reference signal source.

5. A method as defined in claim 4 , wherein determining the reliability metric includes calculating a first standard deviation for the first time stamps.

6. A method as defined in claim 5 , wherein determining whether the second link data is consistent with the first link data includes determining that the second link data is consistent with the first link data when a second standard deviation calculated for the second link data is the same or less than the first standard deviation.

7. A method as defined in claim 5 , wherein determining whether the second link data is consistent with the first link data includes determining that the second link data is inconsistent with the first link data when a second standard deviation calculated for the second link data is greater than the first standard deviation.

8. An apparatus comprising processing circuitry configured to at least:
identify a link that is one of a plurality of links of a wireless locating system, the link being defined by at least a reference signal source, a first receiver unit, and a second receiver unit;
determine a reliability metric for signal transmission via a link based on first link data, the link data describing first reference signal events for the link; and
modify the reliability metric based on second link data describing second reference signal events for the link, wherein modifying the reliability metric includes:
determining whether the second link data is consistent with the first link data;
adjusting the reliability metric using a first function when the second link data is consistent with the first link data; and
adjusting the reliability metric using a second function different than the first function when the second link data is inconsistent with the second link data.

9. An apparatus as defined in claim 8 , wherein the first function is a linear function and the second function is an exponential function.

10. An apparatus as defined in claim 8 , wherein the processing circuitry is configured to:
adjust the reliability metric using the first function when the second link data is consistent with the first link data by adjusting the reliability metric to indicate the link being more reliable; and
adjust the reliability metric using the second function when the second link data is inconsistent with the first link data by adjusting the reliability metric to indicate the link being less reliable.

11. An apparatus as defined in claim 8 , wherein:
the first link data describing the first reference signal events is defined by at least first time stamps describing times at which the first receiver unit received reference signals transmitted by the reference signal source; and
the second link data describes second reference signal events; and
the second link data is defined by at least second time stamps describing times at which the first receiver unit received reference signals transmitted by the reference signal source.

12. An apparatus as defined in claim 11 , wherein the processing circuitry is configured to determine the reliability metric by calculating a first standard deviation for the first time stamps.

13. An apparatus as defined in claim 12 , wherein the processing circuitry is configured to determine whether the second link data is consistent with the first link data by determining that the second link data is consistent with the first link data when a second standard deviation calculated for the second link data is the same or less than the first standard deviation.

14. An apparatus as defined in claim 12 , wherein the processing circuitry is configured to determine whether the second link data is consistent with the first link data by determining that the second link data is inconsistent with the first link data when a second standard deviation calculated for the second link data is greater than the first standard deviation.

15. A wireless locating system comprising:
a plurality of receiver units including a first receiver unit and a second receiver unit; and
a location processing agent, the location processing agent configured to at least:
identify a link that is one of a plurality of links of the wireless locating system, the link being defined by at least a reference signal source, the first receiver unit, and the second receiver unit;
determine a reliability metric for signal transmission via a link based on first link data, the link data describing first reference signal events for the link; and
modify the reliability metric based on second link data describing second reference signal events for the link, wherein modifying the reliability metric includes:
determining whether the second link data is consistent with the first link data;
adjusting the reliability metric using a first function when the second link data is consistent with the first link data; and
adjusting the reliability metric using a second function different than the first function when the second link data is inconsistent with the second link data.

16. A wireless locating system as defined in claim 15 , wherein the first function is a linear function and the second function is an exponential function.

17. A wireless locating system as defined in claim 15 , wherein the processing circuitry is configured to:
adjust the reliability metric using the first function when the second link data is consistent with the first link data by adjusting the reliability metric to indicate the link being more reliable; and
adjust

Assignees

• Zih Corp

Inventors

• Boyd Robert W

Classifications

• G01S5/021

  Calibration, monitoring or correction (G01S5/0252 takes precedence) · CPC title

• G01S5/10 Primary

  Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements {, e.g. omega or decca systems}(G01S5/12 takes precedence {; beacons and receivers cooperating therewith G01S1/306, G01S1/308}) · CPC title

• H04L5/0048

  Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091) · CPC title

• H04W24/08

  Testing, {supervising or monitoring} using real traffic · CPC title

• G01S5/06 Primary

  Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence) · CPC title