Estimating the elevation of a wireless terminal based on determining the measurement bias of a pressure reference

• US 10,462,282 B1
• Filed: 03/29/2019
• Issued: 10/29/2019
• Est. Priority Date: 03/29/2019
• Status: Active Grant

• Current Assignee: Polaris Wireless Incorporated
• Original Assignee: Polaris Wireless Incorporated
• Inventors: Blaha, Jr., Jerome Arthur, Gordon, Scot Douglas, Lu, Jonathan Shiao-en, Wu, Jeffrey Noel, Zhu, Jian
• Primary Examiner(s): Zewdu, Meless N
• Application Number:
  US16/369,511
• Time in Patent Office: 214 Days
• CPC Class Codes: G01C 5/00 Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels G01C3/20, G01C3/30 take precedence
• CPC Class Codes: G01C 5/06 by using barometric means
• CPC Class Codes: H04M 1/72403 with means for local support of applications that increase the functionality
• CPC Class Codes: H04M 1/72454 according to context-related or environment-related conditions
• CPC Class Codes: H04M 1/725 Cordless telephones user interfaces specially adapted therefor H04M1/724
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion
• CPC Class Codes: H04W 4/021 Services related to particular areas, e.g. point of interest [POI] services, venue services or geofences
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 4/33 for indoor environments, e.g. buildings
• CPC Class Codes: H04W 4/38 for collecting sensor information
• CPC Class Codes: H04W 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]

Abstract

A location engine that estimates the barometric pressure measurement bias of a pressure station reference, such as an airport pressure station, resulting in an improved estimate of the elevation of a wireless terminal. The location engine generates the estimate of bias of barometric pressure by comparing i) the outdoor barometric pressure measured by the airport pressure station at its unknown height above mean sea level (MSL) and ii) the expected outdoor barometric pressure derived from the pressure measurements from an already-calibrated pressure station, while accounting for the known height of the already-calibrated pressure station. The expected outdoor measurements correspond to a derived height above MSL of the airport pressure station. Subsequently, the location engine generates an estimate of the elevation of the wireless terminal by accounting for the estimate of measurement bias of the airport pressure station.

Claims

1. A method of estimating elevation of one or more wireless terminals, the method comprising:

receiving, by a data processing system, a first series of measurements of barometric pressure made at a first pressure reference, wherein the first pressure reference is at a first outdoor location and at an unknown height above a reference level, the unknown height being unknown to the data processing system;

receiving, by the data processing system, a second series of measurements of barometric pressure made at a second pressure reference, wherein the second pressure reference is at a second outdoor location and at a first known height above the reference level, the first known height being known to the data processing system;

generating, by the data processing system, a first estimate of bias of barometric pressure measured by the first pressure reference based on;

(i) the first series of measurements of the barometric pressure made at the first pressure reference,

(ii) the second series of measurements of the barometric pressure made at the second pressure reference, and

(iii) the first known height of the second pressure reference;

receiving, by the data processing system, a first measurement of the barometric pressure made at a first wireless terminal;

receiving, by the data processing system, a subsequent measurement of barometric pressure made at the first pressure reference, wherein the subsequent measurement of the barometric pressure is separate from the first series of measurements and is received after the first series of measurements is received;

generating, by the data processing system, an estimate of the elevation of the first wireless terminal based on;

(i) the first measurement of the barometric pressure made at the first wireless terminal,

(ii) the subsequent measurement of the barometric pressure made at the first pressure reference, and

(iii) the first estimate of the bias.

2. The method of claim 1 further comprising transmitting the estimate of elevation of the first wireless terminal to a location-based application server.

3. The method of claim 1 further comprising generating a first estimate of height of the first pressure reference, wherein the estimate of the elevation of the first wireless terminal is further based on the first estimate of height of the first pressure reference.

4. The method of claim 3 wherein the first estimate of height of the first pressure reference is based on the height of the second pressure reference.

5. The method of claim 1 wherein the first pressure reference is on a first premises and the second pressure reference is off the first premises.

6. The method of claim 5 wherein the first pressure reference is a weather station at an airport and the first premises is that of the airport.

7. The method of claim 1 further comprising obtaining the first known height via real-time kinematics (RTK) positioning at the second pressure reference.

8. The method of claim 1 further comprising:

receiving, by the data processing system, a third series of measurements of barometric pressure made at a third pressure reference, wherein the third pressure reference is at a third outdoor location and at a second known height above the reference level, the second known height being known to the data-processing system;

wherein the generating of the first estimate of the bias of barometric pressure measured by the first pressure reference is further based on;

(i) the third series of measurements of the barometric pressure made at the third pressure reference, and

(ii) the second known height of the third pressure reference.

9. The method of claim 1 wherein the second pressure reference is a second wireless terminal.

10. The method of claim 1 wherein measurements in the first series of measurements and measurements in the second series of measurements are correlated in time.

11. The method of claim 1 wherein measurements in the second series of measurements are made over at least one diurnal cycle.

12. A method of estimating elevation of one or more wireless terminals, the method comprising:

receiving, by a data processing system, a first series of measurements of barometric pressure made at a first pressure reference, wherein the first pressure reference is at a first outdoor location and on a first premises;

receiving, by the data processing system, a second series of measurements of barometric pressure made at a second pressure reference, wherein the second pressure reference is at a second outdoor location, off the first premises, and at a first known height above the reference level, the first known height being known to the data processing system;

generating, by the data processing system, a first estimate of bias of barometric pressure measured by the first pressure reference based on;

(i) the first series of measurements of the barometric pressure made at the first pressure reference,

(ii) the second series of measurements of the barometric pressure made at the second pressure reference, and

(iii) the first known height of the second pressure reference;

receiving, by the data processing system, a first measurement of barometric pressure made at a first wireless terminal;

receiving, by the data processing system, a subsequent measurement of barometric pressure made at the first pressure reference, wherein the subsequent measurement of the barometric pressure is separate from the first series of measurements and is received after the first series of measurements is received;

generating, by the data processing system, an estimate of the elevation of the first wireless terminal based on;

(i) the first measurement of the barometric pressure made at the first wireless terminal,

(ii) the subsequent measurement of the barometric pressure made at the first pressure reference, and

(iii) the first estimate of the bias.

13. The method of claim 12 further comprising transmitting the estimate of elevation of the first wireless terminal to a location-based application server.

14. The method of claim 12 wherein the first pressure reference is a weather station at an airport and the first premises is that of the airport.

15. The method of claim 12 further comprising obtaining the first known height via real-time kinematics (RTK) positioning at the second pressure reference.

16. The method of claim 12 further comprising:

receiving, by the data processing system, a third series of measurements of barometric pressure made at a third pressure reference, wherein the third pressure reference is at a third outdoor location and at a second known height above the reference level, the second known height being known to the data-processing system;

wherein the generating of the first estimate of the bias of barometric pressure measured by the first pressure reference is further based on;

(i) the third series of measurements of barometric pressure made at the third pressure reference, and

(ii) the second known height of the third pressure reference.

17. The method of claim 12 wherein the second pressure reference is a second wireless terminal.

18. A method of estimating elevation of one or more wireless terminals, the method comprising:

receiving, by a data processing system, a first series of measurements of barometric pressure made at a first pressure reference, wherein the first pressure reference is at a first outdoor location and between a first known height and a second known height above a reference level;

receiving, by the data processing system, a second series of measurements of barometric pressure made at a second pressure reference, wherein the second pressure reference is at a second outdoor location and at the first known height above the reference level;

receiving, by the data processing system, a third series of measurements of barometric pressure made at a third pressure reference, wherein the third pressure reference is at a third outdoor location and at the second known height above the reference level;

generating, by the data processing system, a first estimate of bias of barometric pressure measured by the first pressure reference based on;

(i) the first series of measurements of the barometric pressure made at the first pressure reference,

(ii) the second series of measurements of the barometric pressure made at the second pressure reference,

(iii) the third series of measurements of the barometric pressure made at the third pressure reference,

(iv) the first known height of the second pressure reference, and

(v) the second known height of the third pressure reference;

receiving, by the data processing system, a first measurement of barometric pressure made at a first wireless terminal;

receiving, by the data processing system, a subsequent measurement of barometric pressure made at the first pressure reference, wherein the subsequent measurement of the barometric pressure is separate from the first series of measurements and is received after the first series of measurements is received;

generating, by the data processing system, an estimate of the elevation of the first wireless terminal based on;

(i) the first measurement of the barometric pressure made at the first wireless terminal,

(ii) the subsequent measurement of the barometric pressure made at the first pressure reference, and

(iii) the first estimate of the bias.

19. The method of claim 18 further comprising transmitting the estimate of elevation of the first wireless terminal to a location-based application server.

20. The method of claim 18 wherein the first pressure reference is on a first premises, and the second and third pressure references are off the first premises.