Propagation time measurement device and electronic key system
First Claim
1. A propagation time measurement device that measures a propagation time of a transmission signal from when the transmission signal is transmitted, through wireless communication, from a base station to a terminal to when the transmission signal is returned to the base station from the terminal, wherein a plurality of continuous waves having different frequencies are combined to generate the transmission signal, the propagation time measurement device comprising:
- a correlation computation unit that generates a plurality of correlation values by performing a correlation computation on each of the continuous waves and a reception signal that is returned from the terminal and received by the base station; and
a propagation time measurement unit that measures the propagation time from a phase of the correlation value generated for each continuous wave in the correlation computation.
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Accused Products
Abstract
A propagation time measurement device measures a propagation time of a transmission signal from when the transmission signal is transmitted, through wireless communication, from a base station to a terminal to when the transmission signal is returned to the base station from the terminal. Continuous waves having different frequencies are combined to generate the transmission signal. The propagation time measurement device includes a correlation computation unit that generates correlation values by performing a correlation computation on each of the continuous waves and a reception signal that is returned from the terminal and received by the base station. A propagation time measurement unit measures the measurement time from a phase of the correlation value generated for each continuous wave during the correlation computation.
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Citations
8 Claims
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1. A propagation time measurement device that measures a propagation time of a transmission signal from when the transmission signal is transmitted, through wireless communication, from a base station to a terminal to when the transmission signal is returned to the base station from the terminal, wherein a plurality of continuous waves having different frequencies are combined to generate the transmission signal, the propagation time measurement device comprising:
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a correlation computation unit that generates a plurality of correlation values by performing a correlation computation on each of the continuous waves and a reception signal that is returned from the terminal and received by the base station; and a propagation time measurement unit that measures the propagation time from a phase of the correlation value generated for each continuous wave in the correlation computation. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An electronic key system in which a transmission signal is transmitted, through wireless communication, from a vehicle to an electronic key and returned to the vehicle from the electronic key, wherein a plurality of continuous waves having different frequencies are combined to generate the transmission signal, the electronic key system comprising
a propagation time measurement device that measures a propagation time of the transmission signal from when the vehicle transmits the transmission signal to the electronic key to when the transmission signal returns to the vehicle from the electronic key, wherein the propagation time measurement device includes a correlation computation unit that generates a plurality of correlation values by performing a correlation computation on each of the continuous waves and a reception signal that is returned from the electronic key and received by the vehicle, and a propagation time measurement unit that measures the propagation time from a phase of the correlation value generated for each continuous wave in the correlation computation.
Specification