Characterizing and using building weather profile parameters

Patent metadata

Field	Value
Publication number	US-10064017-B2
Application number	US-201715487215-A
Country	US
Kind code	B2
Filing date	Apr 13, 2017
Priority date	Jun 17, 2016
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

Determining building weather profile parameters, and correcting an estimated altitude of a receiver using the building weather profile parameters. Systems and methods for estimating an altitude of a receiver using building weather profile parameters may identify one or more weather profile parameters for a building, determine an initial estimate of a receiver's altitude at a floor inside the building, and use the initial estimate and the identified weather profile parameters to determine a corrected estimate of the receiver's altitude at the floor.

First claim

The invention claimed is:

1. A method for estimating an altitude of a receiver using building weather profile parameters, the method comprising:
identifying one or more weather profile parameters for a building;
determining an initial estimate of an altitude of a receiver at a floor inside the building; and
using the initial estimate and the one or more weather profile parameters to determine a corrected estimate of the altitude of the receiver at the floor by:
determining a first value by dividing a first product by a second product,
wherein the first product is determined by multiplying an acceleration due to gravity, a molar mass of dry air, and a measured indoor pressure, and
wherein the second product is determined by multiplying a universal gas constant and a reference outdoor temperature;
determining a second value by multiplying the first value by the initial estimate of the altitude of the receiver;
determining a third value by multiplying a first weather profile parameter, an inverted temperature difference and a second weather profile parameter;
determining a difference of the second value and the third value;
determining a fourth value by adding a third weather profile parameter to the difference;
determining a third product by multiplying the first weather profile parameter and the inverted temperature difference;
determining a fifth value by subtracting the third product from the first value; and
determining the corrected estimate of the altitude of the receiver by dividing the fourth value by the fifth value.

2. The method of claim 1 , wherein identifying the one or more weather profile parameters for the building comprises:
determining indoor pressures at different altitudes of the building;
determining indoor temperatures at the different altitudes of the building;
for each of the different altitudes, determining a pressure difference between the determined indoor pressure and a corresponding outdoor pressure for that altitude;
for each of the different altitudes, determining a temperature difference using the determined indoor temperature and a corresponding outdoor temperature for that altitude;
storing the determined pressure differences and the determined temperature differences;
generating the one or more weather profile parameters for the building using the determined pressure differences and the determined temperature differences; and
storing the one or more weather profile parameters.

3. The method of claim 2 , wherein the pressure differences and the temperature differences are determined by:
determining an outdoor pressure;
determining an outdoor temperature;
for each of the different altitudes, determining the corresponding outdoor pressure for that altitude using the determined outdoor pressure; and
for each of the different altitudes, determining the corresponding outdoor temperature for that altitude using the determined outdoor temperature.

4. The method of claim 2 , wherein determining the pressure differences and the temperature differences comprises:
determining a first indoor pressure and a first indoor temperature at a first altitude of the different altitudes when a first receiver is at the first altitude;
determining an outdoor pressure and an outdoor temperature;
generating, using the outdoor pressure and the first indoor pressure, an estimate of the first altitude;
identifying an expected altitude of a first floor of the building at which the first receiver is located when the first receiver is at the first altitude;
determining a first altitude difference between the expected altitude of the first floor and the estimate of the first altitude;
using the first altitude difference to determine a first pressure difference between the first indoor pressure and a first outdoor pressure for the first altitude;
determining a first outdoor temperature for the first altitude using the outdoor temperature;
inverting the first indoor temperature and inverting the first outdoor temperature;
determining a first temperature difference between the inverted first indoor temperature and the inverted first outdoor temperature;
determining a second indoor pressure and a second indoor temperature at a second altitude of the different altitudes when a second receiver is at the second altitude;
generating, using the outdoor pressure or another outdoor pressure and the second indoor pressure, an estimate of the second altitude;
identifying an expected altitude of a second floor of the building at which the second receiver is located when the second receiver is at the second altitude;
determining a second altitude difference between the expected altitude of the second floor and the estimate of the second altitude;
using the second altitude difference to determine a second pressure difference between the second indoor pressure and a second outdoor pressure for the second altitude;
determining a second outdoor temperature for the second altitude using the outdoor temperature or another outdoor temperature;
inverting the second indoor temperature and inverting the second outdoor temperature; and
determining a second temperature difference between the inverted second indoor temperature and the inverted second outdoor temperature.

5. The method of claim 4 , wherein the first receiver and the second receiver are the same receiver.

6. The method of claim 2 , wherein generating the one or more weather profile parameters for the building comprises:
generating a linear fit representing the determined pressure differences as a function of altitude;
estimating a plurality of fit parameters using the linear fit, wherein a first fit parameter represents the slope of the linear fit and a second fit parameter represents the y-intercept of the linear fit; and
determining the one or more weather profile parameters for the building using the plurality of fit parameters.

7. The method of claim 1 , wherein the first weather profile parameter represents an amount of air that passes through a surface boundary of the building, the third weather profile parameter represents HVAC performance of the building, and the second weather profile parameter represents air leakage of the building as a function of the height of the building.

8. The method of claim 6 , wherein identifying the one or more weather profile parameters for the building comprises:
identifying two or more sets of fit parameters, wherein each set of fit parameters includes the first fit parameter and the second fit parameter;
generating two or more ratios using the two or more sets of fit parameters and two or more temperature differences;
determining the first weather profile parameter by averaging the two or more ratios; and
determining the third weather profile parameter and the second weather profile parameter by fitting a line to a distribution of each of the two or more sets of fit parameters.

9. The method of claim 8 , wherein the y-intercept of the fitted line corresponds to the third weather profile parameter, and the slope of the fitted line corresponds to the second weather profile parameter.

10. The method of claim 1 , wherein identifying the one or more weather profile parameters for the building comprises:
determining an estimated position of the receiver;
identifying the building using the estimated position; and
identifying, after identifying the building, the one or more weather profile parameters from a database,
wherein the one or more weather profile parameters are stored in the database in association with one or more of a time, a date, an altitude, or a building identifier.

11. The method of claim 1 , wherein determining an initial estimated

Assignees

• Nextnav Llc

Inventors

• Han Guiyuan
• Dormody Michael
• Wolf Thomas
• Pattabiraman Ganesh

Classifications

• G01W1/06

  giving a combined indication of weather conditions (catathermometers for measuring "cooling value" related either to weather conditions or to comfort of other human environment G01W1/17; computers per se G06) · CPC title

• G01C5/00 Primary

  Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels (G01C3/20, G01C3/30 take precedence) · CPC title

• H04W4/04 Primary

  Electricity · mapped topic

• G01C5/06

  by using barometric means · CPC title

• H04W4/30

  Services specially adapted for particular environments, situations or purposes · CPC title