Patent ID: 6876296

Claim:
A communication system, comprising: a first vehicle; a first probe located on the first vehicle, the first probe transmitting a first modulated radio frequency request signal and receiving a first modulated radio frequency response signal in response thereto; a second probe located on the first vehicle, the second probe transmitting a second modulated radio frequency request signal and receiving a second modulated radio frequency response signal in response thereto; a second vehicle spaced from the first vehicle; a tag attached to the second vehicle, the tag displaying a registration of the second vehicle, receiving the first modulated radio frequency request signal and the second modulated radio frequency request signal, transmitting the first modulated radio frequency response signal in response to the first modulated radio frequency request signal, and transmitting the second modulated radio frequency response signal in response to the second modulated radio frequency request signal, the first and second modulated radio frequency response signals each having a transmission delay; and a processor unit connected to the first and the second probe, the processor unit determining a location of the first vehicle relative to the second vehicle using the transmission delay of each of the first and second radio frequency modulated response signals.