Systems and methods for determining, broadcasting and using reference atmospheric data in a network of transmitters

Abstract

Determining, broadcasting and using reference pressure data in a network of transmitters. Particular embodiments described herein include machines that select atmospheric data from weather stations within a transmitter network, use the selected atmospheric data to determine a reference atmospheric value, and transmit the reference atmospheric value from a transmitter to a mobile device for use in estimating an altitude of the mobile device. The atmospheric data may include any of reference pressures form the weather stations, measured temperatures from the weather stations, or reference temperatures from the weather stations. The reference atmospheric value may include a reference pressure value of a reference altitude, or a reference temperature value.

1 . A method comprising:
 determining a cellular element associated with a transmitter of a transmitter network;   selecting reference data from one or more weather stations, wherein the reference data meets a proximity condition relative to the cellular element;   using the selected reference data to determine a reference value; and   transmitting the reference value from a transmitter of the transmitter network to a mobile device.   
     
     
         2 . The method of  claim 1 , further comprising:
 calibrating a barometric pressure sensor of the mobile device using the reference value.   
     
     
         3 . The method of  claim 1 , further comprising:
 estimating an altitude of the mobile device using the reference value.   
     
     
         4 . The method of  claim 1 , further comprising:
 after transmitting the reference value, determining that a broadcast is scheduled at a first time; and   in response to the broadcast being scheduled at the first time:
 selecting new reference data from the one or more weather stations; 
 using the new reference data to determine a new reference value; and 
 transmitting the new reference value from the transmitter to the mobile device or another mobile device. 
   
     
     
         5 . The method of  claim 1 , further comprising:
 after transmitting the reference value, determining that a broadcast is scheduled at a first time;   in response to the broadcast being scheduled at the first time, determining occurrences of the reference value being valid and being not valid;   in response to the reference value being valid, transmitting the reference value from the transmitter to the mobile device or another mobile device; and   in response to the reference value being not valid:
 generating a new reference value; and 
 transmitting the new reference value from the transmitter to the mobile device or the other mobile device. 
   
     
     
         6 . The method of  claim 5 , wherein the determining of the occurrences of the reference value being valid and being not valid comprises:
 determining a time at which an atmospheric condition in the transmitter network is expected to change by a threshold amount of the atmospheric condition since the reference value was determined, wherein the atmospheric condition is pressure when the reference value is a reference pressure value, and the atmospheric condition is temperature when the reference value is a reference temperature value; and   determining, based on the determined time, an expiration time for the reference value before which the reference value is valid and after which the reference value is not valid, wherein the expiration time is the determined time or a time that precedes the determined time by a threshold amount of time.   
     
     
         7 . The method of  claim 5 , wherein the reference value is a reference pressure value, and wherein generating the new reference value comprises:
 adjusting the reference pressure value by an amount of pressure change that occurred in the transmitter network since the reference pressure value was determined, wherein the new reference value is the result of adjusting the reference pressure value.   
     
     
         8 . The method of  claim 5 , wherein the selected reference data includes selected reference pressures, wherein the reference value is a reference pressure value, and wherein generating a new reference value comprises:
 for each reference pressure of the selected reference pressures that originated from an area in which pressure changed in excess of a threshold amount of pressure since that reference pressure was determined, adjusting that reference pressure by an amount of pressure change that occurred since that reference pressure was determined; and   computing the new reference value using the adjusted reference pressures.   
     
     
         9 . The method of  claim 1 , further comprising:
 after transmitting the reference value, determining occurrences of the reference value being valid and being not valid;   in response to the reference value being valid, transmitting the reference value from the transmitter to the mobile device or another mobile device; and   in response to the reference value not being valid:
 generating a new reference value; and 
 transmitting the new reference value from the transmitter to the mobile device or the other mobile device. 
   
     
     
         10 . The method of  claim 1 , further comprising:
 after transmitting the reference value, determining that a first broadcast is not scheduled at a first time;   in response to the first broadcast being not scheduled at the first time, determining occurrences of the reference value being valid and being not valid;   in response to the reference value being valid, determining if a second broadcast is scheduled at a second time that is after the first time; and   in response to the reference value being not valid:
 generating a new reference value; and 
 determining if the second broadcast is scheduled at the second time. 
   
     
     
         11 . The method of  claim 1 , wherein selecting the reference data further comprises:
 selecting only reference data from each weather station within the cellular element or within a threshold distance from part of the cellular element.   
     
     
         12 . The method of  claim 1 , wherein selecting the reference data further comprises:
 selecting only reference data from the nearest n weather stations to part of the cellular element.   
     
     
         13 . The method of  claim 1 , wherein the reference data is selected based on an age or a quality in addition to the proximity condition, and selecting the reference data further comprises:
 selecting only reference data with an age that is below a threshold age value, selecting only the n most-recently provided reference data, selecting only reference data with a quality that is above a threshold quality value, or selecting only the n highest-quality reference data.   
     
     
         14 . The method of  claim 1 , wherein if none of the reference data meet the proximity condition, the method comprises:
 determining a new cellular element; and   selecting second reference data that meet the proximity condition relative to the new cellular element.   
     
     
         15 . The method of  claim 1 , wherein the selected reference data includes selected reference pressures, the reference value is a reference pressure value of a reference altitude, and the method further comprises:
 receiving, at the mobile device, the reference pressure value that was transmitted by the transmitter;   determining occurrences of the reference pressure value being valid and being not valid at a current time;   in response to the reference pressure value being valid:
 determining a first representative reference pressure value using the reference pressure value received from the transmitter; and 
 using the first representative reference pressure value, the reference altitude, and a pressure value measured by a pressure sensor of the mobile device to estimate an altitude of the mobile device; and 
   in response to the reference pressure value being not valid:
 determining a new reference pressure value by adjusting the reference pressure value received from the transmitter based on changes in pressure in the transmitter network; 
 determining a second representative reference pressure value using the new reference pressure value; and 
 using the second representative reference pressure value, the reference altitude, and the pressure value to estimate the altitude of the mobile device. 
   
     
     
         16 . The method of  claim 15 , wherein determining occurrences of the reference pressure value being valid and being not valid comprises:
 receiving, from the transmitter, an expiration time of the reference pressure value; and determining that the reference pressure value is valid in response to the current time being before the expiration time, and determining that the reference pressure value is not valid in response to the current time being after the expiration time; or   determining a time at which pressure in the transmitter network is expected to change by a threshold amount of pressure since the reference pressure value was determined; determining, based on the determined time, the expiration time for the reference pressure value before which the reference pressure value is valid and after which the reference pressure value is not valid, wherein the expiration time is the determined time or a time that precedes the determined time by a threshold amount of time; and determining that the reference pressure value is valid in response to the current time being before the expiration time, and determining that the reference pressure value is invalid in response to the current time being after the expiration time.   
     
     
         17 . The method of  claim 15 , wherein determining a first representative reference pressure value comprises:
 selecting, from m received reference pressure values, the n most-recently determined reference pressure values, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and computing the first representative reference pressure value by combining the n selected reference pressures;   selecting, from m received reference pressure values, the n reference pressure values having the longest validity times, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and computing the first representative reference pressure value by combining the n selected reference pressures; or   selecting, from m received reference pressure values, the n reference pressure values from n respective transmitters that are closet to an estimated location of the mobile device, wherein m is greater than n, and wherein the n reference pressure values include the reference pressure value received from the transmitter; and computing the first representative reference pressure value by combining the n selected reference pressures.   
     
     
         18 . The method of  claim 15 , wherein determining a new reference pressure value comprises:
 adjusting the reference pressure value by an amount of pressure change that occurred since the reference pressure value was determined, wherein the new reference pressure value is the result of adjusting the reference pressure value;   determining an estimated position of the mobile device; determining an expected amount of change in pressure between the estimated position of the mobile device and a previous estimated position of the mobile device at which the reference pressure value was received; and adjusting the reference pressure value by the expected amount of change in pressure, wherein the new reference pressure value is the result of adjusting the reference pressure value; or   determining an estimated position of the mobile device; determining an expected amount of change in pressure between the estimated position of the mobile device and the transmitter; and adjusting the reference pressure value by the expected amount of change in pressure, wherein the new reference pressure value is the result of adjusting the reference pressure value.   
     
     
         19 . One or more non-transitory machine-readable media embodying program instructions that, when executed by one or more machines, cause the one or more machines to implement the method of  claim 1 . 
     
     
         20 . The method of  claim 1 , wherein the cellular element is a location of the transmitter, a coverage area of the transmitter, a cell sector of the transmitter, or a beam of the transmitter.