| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To give an early warning that an IC card is not inserted or improperly inserted in an ETC on-vehicle unit before a vehicle passes a tollgate. <P>SOLUTION: The bandwidth of a narrow band pass filter 12e is set to a narrow band to extract and detect only a carrier wave out of a carrier wave and a sideband wave included in a radio wave received from an ETC road unit. Whether there is a radio wave sent from the ETC road unit can be detected with high sensitivity, so that an early warning that an IC card is not inserted or improperly inserted in the ETC on-vehicle unit can be given before the vehicle passes a tollgate. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
