| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an in-vehicle device remote control system capable of increasing the number of multiplexing, by improving the reply interval accuracy of the response signal of a portable device. <P>SOLUTION: The portable device includes: an amplitude limiting circuit 57a for limiting the amplitude of a received ASK signal, when an ASK modulated interrogation signal transmitted from the in-vehicle device is larger than a predetermined value; an automatic gain control amplifier 57b for amplifying a received signal to fixed amplitude; a detection circuit 57c for performing an envelope detection; and a waveform-shaping circuit 47d for outputting the detection signal of the detection circuit as a pulse signal corresponding to the interrogation signal and is provided with a delay multiplex communication system which starts to transmit a signal subjected to spread spectrum modulation of a direct spread system, after a predetermined delay interval different in each portable device with the specific pulse of the pulse signal as a reference time, and is a means for correcting the delay time, when an amplitude-limiting circuit 57a detects that amplitude is limited. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
