Step filter for estimating distance in a time-of-flight ranging system
First Claim
1. A method of estimating a distance between a mobile node and a base station, said method comprising:
- providing a display on the mobile node;
providing a time of flight subsystem including circuitry incorporated in the mobile node and the base station and generating a time of flight distance signal by periodically transmitting a time of flight signal between the mobile node and the base station and measuring the time taken for transmission of the time of flight signal therebetween;
providing an accelerometer on the mobile node and generating an accelerometer signal therewith;
initializing the value of a distance estimate signal based on the time of flight distance signal;
detecting a human step based on variances in the accelerometer signal;
changing the value of the distance estimate signal by a predetermined quantum only upon detection of a human step, wherein the value of the distance estimate signal is increased by the predetermined quantum responsive to the time of flight distance signal being greater than the distance estimate signal and wherein the value is decreased by the predetermined quantum responsive to the time of flight distance signal being less than the distance estimate signal; and
periodically displaying the value of the distance estimate signal on the display.
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Accused Products
Abstract
A ranging system includes a time of flight subsystem including circuitry incorporated in a mobile node and a base station for generating a TOF signal between the mobile node and the base station, measuring the time taken for transmission of the TOF signal, and generating a TOF distance signal based on the measured time. An accelerometer, mounted in the mobile node, generates an accelerometer signal. A distance filter generates the distance estimate. The filter is configured to (i) initialize the value of a distance estimate signal based on the TOF distance signal, (ii) detect a human step based on variances in the accelerometer signal, and (iii) change the value of the distance estimate signal by a predetermined quantum only upon detection of the human step, the change being positive or negative depending on a direction of the TOF distance signal relative to the distance estimate signal.
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Citations
21 Claims
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1. A method of estimating a distance between a mobile node and a base station, said method comprising:
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providing a display on the mobile node; providing a time of flight subsystem including circuitry incorporated in the mobile node and the base station and generating a time of flight distance signal by periodically transmitting a time of flight signal between the mobile node and the base station and measuring the time taken for transmission of the time of flight signal therebetween; providing an accelerometer on the mobile node and generating an accelerometer signal therewith; initializing the value of a distance estimate signal based on the time of flight distance signal; detecting a human step based on variances in the accelerometer signal; changing the value of the distance estimate signal by a predetermined quantum only upon detection of a human step, wherein the value of the distance estimate signal is increased by the predetermined quantum responsive to the time of flight distance signal being greater than the distance estimate signal and wherein the value is decreased by the predetermined quantum responsive to the time of flight distance signal being less than the distance estimate signal; and periodically displaying the value of the distance estimate signal on the display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system that provides an estimate of the distance between a mobile node and a base station, said system comprising:
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a display disposed on the mobile node; a time of flight subsystem including circuitry incorporated in the mobile node and the base station for generating a time of flight signal between the mobile node and the base station, measuring the time taken for transmission of the time of flight signal, and generating a time of flight distance signal based on the measured time; an accelerometer, mounted in the mobile node, for generating an accelerometer signal; a distance filter for generating the distance estimate, the distance filter configured to (i) initialize the value of a distance estimate signal based on the time of flight distance signal, (ii) detect a human step based on variances in the accelerometer signal, and (iii) change the value of the distance estimate signal by a predetermined quantum only upon detection of said human step, wherein the value of the distance estimate signal is increased by the predetermined quantum responsive to the time of flight distance signal being greater than the distance estimate signal and wherein the value is decreased by the predetermined quantum responsive to the time of flight distance signal being less than the distance estimate signal; and wherein said system is operable to periodically display the value of the distance estimate signal on the display. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of estimating a distance between a mobile node and a base station, said method comprising:
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providing a display on the mobile node; providing a time of flight subsystem including circuitry incorporated in the mobile node and the base station and generating a time of flight distance signal by periodically transmitting a time of flight signal between the mobile control node and the base station and measuring the time taken for transmission of the time of flight signal therebetween; providing a radio signal strength subsystem including circuitry incorporated in the mobile node and the base station and generating an SSI distance signal based on a strength of a radio signal received by one of the mobile node and the base station; providing an accelerometer on the mobile node and generating an accelerometer signal therewith; fusing the SSI distance signal and the time of flight distance signal to generate a fused distance signal; initializing the value of a distance estimate signal based on the fused distance signal; detecting a human step based on variances in the accelerometer signal; changing the value of the distance estimate signal by a predetermined quantum only upon detection of a human step, wherein the value of the distance estimate signal is increased by the predetermined quantum responsive to the fused distance signal being greater than the distance estimate signal and wherein the value is decreased by the predetermined quantum responsive to the fused distance signal being less than the distance estimate signal; and periodically displaying the value of the distance estimate signal on the display.
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Specification