Patent ID: 6191705
Filing Date: 2001-02-20
Classification: G07B,G08G

Abstract:
In a highway toll collection system where normal transponders carrying specific vehicle identification information are carried on motor vehicles and communicate with a roadside radio frequency (RF) system,said normal transponders being actuatable by a signal from the roadside RF system to record the address of the roadside system at the transponder and transmit the transponder identification information, including a selected class of vehicle, to the roadside RF system,the improvement comprising: a monitor transponder located to receive a detection signal from the roadside RF system;said roadside RF system including receiving means responsive to the transmission of said specific vehicle information from the normal transponder and including means for sending said detection signal to said monitor transponder thereupon; andsaid monitor transponder including means responsive to said detection signal to emit a sensible signal upon receipt of said detection signal.