METHOD AND APPARATUS FOR LOCATING A MOBILE DEVICE
First Claim
1. A method for locating a mobile device, said method comprising:
- periodically transmitting radio signals via a transmitter;
utilizing said radio signals to time synchronize a mobile device;
transmitting a modulated ultrasound signal via said transmitter, wherein said modulated ultrasound signal includes at least one symbol configured for pulse compression;
in response to the receipt of a demodulated ultrasound signal sent from said mobile device, wherein said demodulated ultrasound signal is derived from said modulated ultrasound signal, extracting transmitter identifier and timing information from said demodulated ultrasound signal;
determining a location of said transmitter based on said transmitter identifier information; and
determining a location of said mobile device based on said timing information and said determined location of said transmitter.
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Abstract
A method for locating a mobile device is disclosed. Initially, a set of modulated ultrasound signals and a set of radio signals are separately broadcast from a group of transmitters. The ultrasound signals include at least one symbol configured for pulse compression. After the receipt of a demodulated ultrasound signal from a mobile device, wherein the demodulated ultrasound signal is derived from the modulated ultrasound signals, transmitter identifier and timing information are extracted from the demodulated ultrasound signal. Timing information include, for example, the arrival time of the demodulated ultrasound signal in relation to the start time of its transmission. After the locations of the transmitters have been ascertained from the transmitter identifier information, the location of the mobile device can be determined based on the timing information and the locations of the transmitters.
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Citations
18 Claims
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1. A method for locating a mobile device, said method comprising:
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periodically transmitting radio signals via a transmitter; utilizing said radio signals to time synchronize a mobile device; transmitting a modulated ultrasound signal via said transmitter, wherein said modulated ultrasound signal includes at least one symbol configured for pulse compression; in response to the receipt of a demodulated ultrasound signal sent from said mobile device, wherein said demodulated ultrasound signal is derived from said modulated ultrasound signal, extracting transmitter identifier and timing information from said demodulated ultrasound signal; determining a location of said transmitter based on said transmitter identifier information; and determining a location of said mobile device based on said timing information and said determined location of said transmitter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for locating a mobile device, said method comprising:
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transmitting a modulated ultrasound signal via a transmitter, wherein said modulated ultrasound signal includes at least one symbol configured for pulse compression; in response to the receipt of a demodulated ultrasound signal, wherein said demodulated ultrasound signal is derived from said modulated ultrasound signal, extracting transmitter identifier from said demodulated ultrasound signal; determining a location of said transmitter based on said transmitter identifier information; and determining a location of said mobile device based on said determined location of said transmitter. - View Dependent Claims (9, 10)
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11. An apparatus for locating a mobile device, said apparatus comprising:
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a radio for transmitting radio signals, and utilizing said radio signals to time synchronize a mobile device; a speaker for transmitting a modulated ultrasound signal, wherein said modulated ultrasound signal is formed by modulating an ultrasound signal having at least one symbol configured for pulse compression; a network interface for receiving a demodulated ultrasound signal sent from said mobile device, wherein said demodulated ultrasound signal is derived from said modulated ultrasound signal; and a processor for extracting transmitter identifier and timing information from said demodulated ultrasound signal; determining a location of said transmitter based on said transmitter identifier information; and determining a location of said mobile device based on said timing information and said determined location of said transmitter. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification