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, the change being an increase or decrease depending on a direction of the time of flight distance signal relative to 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.
111 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, the change being an increase or decrease depending on a direction of the time of flight distance signal relative to 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, the change being positive or negative depending on a direction of the time of flight distance signal relative to 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, the change being an increase or decrease depending on a direction of the fused distance signal relative to the distance estimate signal; and periodically displaying the value of the distance estimate signal on the display.
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Specification