| CPC G01S 11/02 (2013.01) [H04W 64/00 (2013.01)] | 6 Claims |
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1. A distance estimation system comprising:
a portable terminal; and
a communication device;
wherein the portable terminal includes:
a transmitting circuit and a receiving circuit performing data transmission and reception with the communication device by transmitting radio waves to the communication device and receiving the radio waves from the communication device; and
a microcomputer, by executing a control program stored in a first non-transitory storage medium, configured to control the transmitting circuit and the receiving circuit;
wherein the communication device includes:
a communication module coupled to an antenna and performing the data transmission and reception with the portable terminal by transmitting, via the antenna, the radio waves to the portable terminal and receiving, via the antenna, the radio waves from the portable terminal; and
a collation electronic control unit (ECU), by executing a control program stored in a second non-transitory storage medium, configured to:
control the communication module;
determine a phase shift amount from a reference phase following a predetermined generating rule;
generate measuring data by applying the phase shift amount determined under the predetermined generating rule;
generate a plurality of the measuring data at a plurality of different frequencies; and
control the communication module of the communication device to transmit the plurality of the generated measuring data to the portable terminal;
wherein the microcomputer of the portable terminal, by executing the control program stored in the first non-transitory storage medium, is configured to:
acquire, in response to the receiving circuit receiving the plurality of the measuring data from the communication device, a phase of the radio wave from each of the plurality of the measuring data;
determine, according to the predetermined generating rule, a phase for distance estimating purpose for each of the plurality of measuring data based on the acquired phase; and
transmit the phases for distance estimation purpose, which are determined from the plurality of the measuring data, to the communication device through the transmitting circuit;
wherein the collation ECU of the communication device, by executing the control program stored in the second non-transitory tangible storage medium, is configured to
generate at least two sets of combinations, each set including the phase for distance estimating purpose at one of the plurality of different frequencies and the phase for distance estimating purpose at a different one of the plurality of different frequencies;
estimate a distance between the portable terminal and the communication device based on a phase difference between the two phases for distance estimating purpose included in each of the at least two sets of combinations; and
adopt the estimated distance when a difference between the distances respectively calculated based on the at least two sets of combinations of the phases for distance estimating purpose is within a predetermined range, and does not adopt the estimated distance when the difference between the distances respectively calculated based on the at least two sets of combinations of the phases for distance estimating purpose is out of the predetermined range.
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