In a stolen or missing-vehicle location network for use with a vehicle-equipped VHF-frequency transmitter-receiver transponder assembly and comprising vehicle transponder-activating VHF antenna towers controlled from a network operations control center to enable the transponder to transmit periodic vehicle-coded reply signals from the vehicle, usable by a VHF direction-finding vehicle to locate the missing vehicle, a method of providing supplemental GPS vehicle position information over the VHF network to the direction-finding vehicle, that comprises:
- integrating a GPS receiver within the vehicle VHF transponder assembly such that, upon demand from the operations center, the GPS receiver receives from the GPS satellite constellation on a GPS frequency, the GPS coordinate information of the missing vehicle at that time;
- providing said received GPS coordinate information to said VHF transponder transmitter to enable the same, upon demand initiated in response to the sensed departure of the vehicle from a pre-set geofencing area established therefore, to transmit said coordinate information at said VHF frequency to said network, together with the vehicle code;
- and,
- under command of said network control operations control center, up-link-transmitting said coordinate information from the vehicle VHF transmitter to said VHF antenna towers and thence to said tracking vehicle to provide a starting location for said direction-finding.