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On-board communication system, and portable device

  • US 9,950,692 B2
  • Filed: 07/27/2015
  • Issued: 04/24/2018
  • Est. Priority Date: 07/25/2014
  • Status: Active Grant
First Claim
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1. An on-board communication system, comprising:

  • (i) an on-board device that transmits detection signals from a plurality of antennas disposed in a vehicle and (ii) a plurality of portable devices that each receive the detection signals transmitted from the on-board device and transmit response signals corresponding to the received detection signals, the on-board device performing position detection of each of the portable devices based on the response signals transmitted from each of the portable devices, wherein;

    the detection signals are signals received in common by the plurality of portable devices,the on-board device comprises;

    an on-board transmission unit that, prior to transmission of the detection signals, transmits from the antennas a processing start signal for causing reception processing of the detection signals by each of the portable devices to start, and then transmits the detection signals from the antennas, andan on-board reception unit that receives the response signals transmitted from each of the portable devices, andeach of the portable devices comprises;

    a portable reception unit that receives the processing start signal and the detection signals transmitted from the on-board device,a timer unit that measures an elapsed time from when the portable reception unit receives the processing start signal, anda portable transmission unit that (i) when the portable reception unit has received the detection signals, transmits a first response signal that includes information corresponding to the received detection signals, and (ii) when a specified time has elapsed from when the portable reception unit received the processing start signal, transmits a second response signal including the same information as the information included in the first response signal, the specified time being different for each of the plurality of portable devices, whereineach portable device uses the same processing start signal as the basis of the start of timing.

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