Gps-calibrated pedometer

Abstract

A system is provided that is configured to be transported, carried or worn by a user, such as a portable personal training device or sports watch. The system comprises a global navigation satellite system (GNSS) receiver arranged to obtain the location and/or speed of the user and a pedometer for counting steps made by the user. Data from the GNSS receiver is used to calibrate the pedometer each time the user is determined to travel a distance greater than a predefined distance value during a period of time in which signals obtained by the GNSS receiver meet the one or more accuracy and/or reliability criteria.

1 . A system configured to be transported, carried or worn by a user, comprising:
 a global navigation satellite system (GNSS) receiver arranged to obtain at least one of the location and speed of the user;   a pedometer for counting steps made by the user; and   a processor coupled to the GNSS receiver and the pedometer, the processor being arranged to:
 determine the distance travelled by the user during a first time period using locations and/or speeds obtained by the GNSS receiver, wherein during the first time period signals obtained by the GNSS receiver meet at least one of an accuracy and reliability criterion; 
   calculate a calibrated distance per step associated with the first time period using the determined distance travelled during the first time period and the counted number of steps made during the first time period;   determine the distance travelled by the user during a second time period using the counted number of steps made during the second time period and the calibrated distance per step associated with the first time period, wherein during the second time period signals obtained by the GNSS receiver do not meet said at least one of an accuracy and reliability criterion; and   determine the distance travelled by the user during a third time period using the counted number of steps made during the third time period and the calibrated distance per step associated with the first time period, wherein during the third time period signals obtained by the GNSS receiver meet the at least one of an accuracy and reliability criterion, but have not met said at least one of an accuracy and reliability criterion for a predetermined period of time,   
       said processor being further arranged to:
 re-calculate the calibrated distance per step each time the user is determined to travel a distance greater than a predefined distance value during a period of time in which signals obtained by the GNSS receiver meet the at least one of an accuracy and reliability criterion. 
 
     
     
         2 . The system of  claim 1 , wherein the at least one of an accuracy and reliability criterion is selected from the group consisting of: satellite availability; satellite signal strength; and estimated position errors. 
     
     
         3 . The system of  claim 1 , wherein the predefined distance value is between 200 and 2000 meters. 
     
     
         4 . The system of  claim 1 , further comprising data storage means for storing at least one of the calculated calibrated distance per step and the determined distance travelled during the first time period. 
     
     
         5 . The system of  claim 4 , wherein the stored calibrated distance per step is replaced by a new calibrated per step each time it is recalculated. 
     
     
         6 . The system of  claim 1 , wherein the pedometer comprises an accelerometer. 
     
     
         7 . The system of  claim 6 , wherein the pedometer comprises footpad sensor. 
     
     
         8 . (canceled) 
     
     
         9 . The system of  claim 1 , wherein said predetermined period of time is between 2 and 10 seconds. 
     
     
         10 . The system of  claim 1 , wherein the system is a portable personal training device. 
     
     
         11 . The system of  claim 10 , further comprising a housing with a strap for securing the device to a user. 
     
     
         12 . A method of determining a distance travelled by a user using a system transported, carried or worn by the user, the system comprising: a global navigation satellite system (GNSS) receiver arranged to obtain at least one of the location and speed of the user; and a pedometer for counting steps made by the user, the method comprising: determining the distance travelled by the user during a first time period using locations and/or speeds obtained by the GNSS receiver, wherein during the first time period signals obtained by the GNSS receiver meet at least one of an accuracy and reliability criterion;
 calculating a calibrated distance per step associated with the first time period using the determined distance travelled during the first time period and the counted number of steps made during the first time period;   determining the distance travelled by the user during a second time period using the counted number of steps made during the second time period and the calibrated distance per step associated with the first time period, wherein during the second time period signals obtained by the GNSS receiver do not meet said at least one of an accuracy and reliability criterion; and   determining the distance travelled by the user during a third time period using the counted number of steps made during the third time period and the calibrated distance per step associated with the first time period, wherein during the third time period signals obtained by the GNSS receiver meet the at least one of an accuracy and reliability criterion, but have not met said at least one of an accuracy and reliability criterion for a predetermined period of time,   the method further comprising:   re-calculating the calibrated distance per step each time the user is determined to travel a distance greater than a predefined distance value during a period of time in which signals obtained by the GNSS receiver meet the at least one of an accuracy and reliability criterion.