Method to increase accuracy of locating unit in wireless vehicle system

A method for operating a wireless vehicle system comprising:

• transmitting a vehicle-originating signal from a vehicle-side transmitter;
• receiving the vehicle-originating signal via a receiver on a key fob;
• measuring a received signal strength of the vehicle-originating signal;
• retrieving sensitivity data from a memory on the key fob;
• transmitting a reply signal from the key fob, wherein the reply signal includes the measured signal strength data and the sensitivity data;
• receiving the reply signal in a vehicle—side receiver;
• determining in a vehicle—side control unit a correction factor based on the sensitivity data, wherein the correction factor is a value that compensates for a respective sensitivity of the key fob as compared to a benchmark sensitivity;
• and
• calculating in the vehicle—side control unit a distance that the key fob is spaced from the vehicle—side transmitter based on the determined correction factor and the measured signal strength data that was received in the reply signal.

A vehicle passive entry system comprising:

• a key fob including
• a receiver for receiving a vehicle-originating signal, the receiver having a sensitivity based on comparing an expected received signal strength from an LF antenna in a factory controlled environment and a measured received signal strength from the LF antenna in the factory controlled environment;
• a transmitter for transmitting a reply signal;
• a received signal strength indicator (RSSI) for measuring a received signal strength of the vehicle-originating signal;
• a memory storing sensitivity data corresponding to the sensitivity;
• and
• a control unit in electrical communication with the receiver, the transmitter, the RSSI and the memory, wherein the control unit is configured to communicate with the transmitter to direct the transmitter to transmit the reply signal, wherein the reply signal includes the measured received signal strength data and the sensitivity data;
• and
• a vehicle-side transmitter for transmitting the vehicle-originating signal;
• a vehicle-side receiver for receiving the reply signal;
• and
• a vehicle-side control unit in electrical communication with the vehicle-side transmitter and the vehicle-side receiver, wherein the vehicle-side control unit is configured to compensate for the sensitivity unique to the key fob and to calculate distance between the fob and the vehicle-side transmitter based on the sensitivity data and the measured received signal strength in the reply signal.