Systems and methods for determining the distance between two locations
First Claim
1. A system for determining the distance between a first location and a second location, the system comprising:
- a first distancing unit located adjacent to the first location, the first distancing unit comprisinga first radio frequency transceiver for transmitting a first send data stream as a first send radio frequency signal and generating a first receive data stream from a first receive radio frequency signal, anda first baseband processor circuit that operates based on a first clock signal having a first clock frequency, where the first receive data stream is asynchronous relative to the first clock signal and the first baseband processor circuit comprisesmeans for generating a first data receive signal indicating when the first receive radio frequency signal is received by the first radio frequency transceiver based on the first receive data stream and the first clock signal,means for adjusting the first receive data stream in time when the first receive data stream becomes out of synchrony with the first clock signal by a predetermined amount,means for generating a first skip signal whenever the first receive data stream is adjusted in time;
a second distancing unit located adjacent to the second location, the second distancing unit comprisinga second radio frequency transceiver for transmitting a second send data stream as a second send radio frequency signal and generating a second receive data stream from a second receive radio frequency signal, anda second baseband processor circuit that operates based on a second clock signal having a second clock frequency, where the second receive data stream is asynchronous relative to the second clock signal and the second baseband processor circuit comprisesmeans for generating a second data receive signal indicating when the second receive radio frequency signal is received by the second radio frequency transceiver based on the second receive data stream and the second clock signal,means for adjusting the second receive data stream in time when the second receive data stream becomes out of synchrony with the second clock signal by a predetermined amount,means for generating a second skip signal whenever the second receive data stream is adjusted in time;
first control means for operating the first distancing unit to transmit the first send radio frequency signal to the second distancing unit;
second control means for operating the second distancing unit in response to the first send radio frequency signal to transmit the second send radio frequency signal to the first distancing unit;
coarse timing means for generating a course timing value based on the first data transmit signal and the first data receive signal;
first fine timing means for generating a first fine timing value based on a plurality of first skip signals; and
distance calculating means for calculating a distance value based on the coarse timing value and the first fine timing value.
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Accused Products
Abstract
A distancing system comprising radio frequency transceivers and data processing circuits. The radio frequency transceivers allow data transmission via a high frequency radio signal. The transmission and receipt of these radio signals can be timed to estimate distance. But the data processing circuits operate at local clock frequencies, and one cannot be sure at what point a give radio frequency signal was received to a resolution greater than one-half cycle of the local clock signal. The data processing circuits periodically "skip" to resynchronize with incoming data streams. These skips occur at intervals corresponding to the frequency difference between the local clock frequencies. This frequency difference can be used to pinpoint fairly precisely when a given radio frequency signal was received in a previous half-cycle of the local clock. Distances can thus be calculated based on a coarse timing value generated based on the local clock of one of the distancing units and first and second fine timing values generated based on the skips at one or both of the distancing units.
77 Citations
22 Claims
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1. A system for determining the distance between a first location and a second location, the system comprising:
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a first distancing unit located adjacent to the first location, the first distancing unit comprising a first radio frequency transceiver for transmitting a first send data stream as a first send radio frequency signal and generating a first receive data stream from a first receive radio frequency signal, and a first baseband processor circuit that operates based on a first clock signal having a first clock frequency, where the first receive data stream is asynchronous relative to the first clock signal and the first baseband processor circuit comprises means for generating a first data receive signal indicating when the first receive radio frequency signal is received by the first radio frequency transceiver based on the first receive data stream and the first clock signal, means for adjusting the first receive data stream in time when the first receive data stream becomes out of synchrony with the first clock signal by a predetermined amount, means for generating a first skip signal whenever the first receive data stream is adjusted in time; a second distancing unit located adjacent to the second location, the second distancing unit comprising a second radio frequency transceiver for transmitting a second send data stream as a second send radio frequency signal and generating a second receive data stream from a second receive radio frequency signal, and a second baseband processor circuit that operates based on a second clock signal having a second clock frequency, where the second receive data stream is asynchronous relative to the second clock signal and the second baseband processor circuit comprises means for generating a second data receive signal indicating when the second receive radio frequency signal is received by the second radio frequency transceiver based on the second receive data stream and the second clock signal, means for adjusting the second receive data stream in time when the second receive data stream becomes out of synchrony with the second clock signal by a predetermined amount, means for generating a second skip signal whenever the second receive data stream is adjusted in time; first control means for operating the first distancing unit to transmit the first send radio frequency signal to the second distancing unit; second control means for operating the second distancing unit in response to the first send radio frequency signal to transmit the second send radio frequency signal to the first distancing unit; coarse timing means for generating a course timing value based on the first data transmit signal and the first data receive signal; first fine timing means for generating a first fine timing value based on a plurality of first skip signals; and distance calculating means for calculating a distance value based on the coarse timing value and the first fine timing value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for determining the distance between a first location and a second location, the system comprising:
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first and second distancing units located adjacent to the first and second locations, respectively, where the first and second distancing units each comprise a radio frequency transceiver for transmitting send data streams as send radio frequency signals and generating receive data streams from receive radio frequency signals, and a baseband processor circuit that operates based on a local clock signal having a local clock frequency, where the receive data streams are asynchronous relative to the local clock signal and the baseband processor circuit comprises means for generating a data receive signal indicating when the receive radio frequency signals are received by the radio frequency transceiver based on the receive data streams and the local clock signal, means for adjusting the receive data streams in time when the receive data streams become out of synchrony with the local clock signal by a predetermined amount, means for generating a skip signal whenever the receive data streams are adjusted in time; first control means for operating the first distancing unit to generate a first send radio frequency signal, where the first send radio frequency signal forms a first receive radio frequency signal at the second distancing unit; second control means for operating the second distancing unit in response to the first receive radio frequency signal to transmit a second send radio frequency signal, where the second send radio frequency signal forms a second receive radio frequency signal at the first distancing unit; coarse timing means for generating a course timing value based on the local clock signal of the first distancing unit, a data transmit signal generated at the first distancing unit when the first distancing unit transmits the first send radio frequency signal, and a data receive signal generated at the first distancing unit in response to the second receive radio frequency signal; first fine timing means for generating a first fine timing value based on a plurality of skip signals generated at the second distancing unit; second fine timing means for generating a second fine timing value based on a plurality of skip signals generated at the first distancing unit; and distance calculating means for calculating a distance value based on the coarse timing value, the first fine timing value, and the second fine timing value. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A system for determining the distance between a first location and a second location, the system comprising:
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first and second distancing units located adjacent to the first and second locations, respectively, where the first and second distancing units each comprise a radio frequency transceiver for transmitting send data streams as send radio frequency signals and generating receive data streams from receive radio frequency signals, a baseband processor circuit that operates based on a local clock signal having a local clock frequency, where the receive data streams are asynchronous relative to the local clock signal and the baseband processor circuit comprises means for generating a data receive signal indicating when the receive radio frequency signals are received by the radio frequency transceiver based on the receive data streams and the local clock signal, and computing means for generating a frequency difference value indicative of a frequency difference between the local clock frequencies of the baseband processor circuits of the first and second distancing units; first control means for operating the first distancing unit to generate a first send radio frequency signal, where the first send radio frequency signal forms a first receive radio frequency signal at the second distancing unit; second control means for operating the second distancing unit in response to the first receive radio frequency signal to transmit a second send radio frequency signal, where the second send radio frequency signal forms a second receive radio frequency signal at the first distancing unit; coarse timing means for generating a course timing value based on the local clock signal of the first distancing unit, a data transmit signal generated at the first distancing unit when the first distancing unit transmits the first send radio frequency signal, and a data receive signal generated at the first distancing unit in response to the second receive radio frequency signal; first fine timing means for generating a first fine timing value based on the frequency difference value generated by the computing means of the first distancing unit; and distance calculating means for calculating a distance value based on the coarse timing value and the first fine timing value. - View Dependent Claims (20, 21)
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22. A method of determining the distance between first and second locations comprising the steps of:
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locating first and second distancing units adjacent to the first and second locations, respectively, where the first and second distancing units each comprise a radio frequency transceiver for transmitting send data streams as send radio frequency signals and generating receive data streams from receive radio frequency signals, and a baseband processor circuit that operates based on a local clock signal having a local clock frequency, where the receive data streams are asynchronous relative to the local clock signal and the baseband processor circuit comprises means for generating a data receive signal indicating when the receive radio frequency signals are received by the radio frequency transceiver based on the receive data streams and the local clock signal, means for adjusting the receive data streams in time when the receive data streams become out of synchrony with the local clock signal by a predetermined amount, means for generating a skip signal whenever the receive data streams are adjusted in time; operating the first distancing unit to generate a first send radio frequency signal, where the first send radio frequency signal forms a first receive radio frequency signal at the second distancing unit; operating the second distancing unit in response to the first receive radio frequency signal to transmit a second send radio frequency signal, where the second send radio frequency signal forms a second receive radio frequency signal at the first distancing unit; generating a course timing value based on the local clock signal of the first distancing unit, a data transmit signal generated at the first distancing unit when the first distancing unit transmits the first send radio frequency signal, and a data receive signal generated at the first distancing unit in response to the second receive radio frequency signal; generating a first fine timing value based on a plurality of skip signals generated at the second distancing unit; generating a second fine timing value based on a plurality of skip signals generated at the first distancing unit; and calculating a distance value based on the coarse timing value, the first fine timing value, and the second fine timing value.
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Specification