초록 ▼

The location of a vehicle having an assigned serial number is determined at a location remote from the vehicle with a system including a central master station and plural local networks, each having a local master station in a bi-directional communication link with the central master station. Each v

The location of a vehicle having an assigned serial number is determined at a location remote from the vehicle with a system including a central master station and plural local networks, each having a local master station in a bi-directional communication link with the central master station. Each vehicle includes a receiver for Loran-C emissions, a transmitter for modulating a first carrier having a frequency much higher than the Loran-C emissions with pulses having time positions corresponding with and synchronized with Loran-C pulses as the received Loran-C emissions, and a receiver for a second carrier having a frequency much higher than the Loran-C emissions. The first carrier is modulated by vehicle serial number signals. The carriers are transmitted via radio links between the local master station and vehicle. The local master station responds to the first carrier to detect the time difference between pulses modulating the first carrier to determine vehicle position. A data signal transmitted by the local master station to the central master station indicates the vehicle position and serial number. The central master station responds to the data signal to indicate vehicle location and serial number. The central master station transmits an information signal including a vehicle serial number to the local master stations. The central master station derives a voice signal that is converted to an aural signal at the vehicle with the designated serial number. The vehicle includes a receiver for a locally generated vehicle identification signal vehicle condition sensors. Activation of the transmitter on the vehicle is controlled in response to the receiver for the locally generated coded signal and the sensed vehicle conditions, and in response to the serial number signal originating at the central master station.

대표청구항 ▼

A method of locating a vehicle equipped with a receiver for low frequency radio waves in response to first pulses of said low frequency radio wave transmitted to the vehicle from three stations having known locations, the first pulses being transmitted from the stations at precise time intervals so

A method of locating a vehicle equipped with a receiver for low frequency radio waves in response to first pulses of said low frequency radio wave transmitted to the vehicle from three stations having known locations, the first pulses being transmitted from the stations at precise time intervals so that the pulses from the different stations arrive at the vehicle at displaced times, the method comprising receiving the first pulses of the low frequency radio waves at the receiver on the vehicle, transmitting from the vehicle a radio frequency wave modulated by second pulses having displaced time positions synchronized and corresponding with the reception times of the first pulses as received by the receiver, receiving the radio frequency wave at a location displaced from the vehicle, detecting the displaced time positions of the second pulses in response to the radio frequency wave received at the location displaced from the vehicle, and determining the location of the vehicle from the detected displaced time positions.