Method of determining vehicle location from key fob
View Patent ↗A method of indicating a proximity value representative of the distance between a key fob ( 202 ) and a vehicle ( 102 ) includes transmitting ( 304, 406, 504 ) at least one locate signal from the key fob ( 202 ) to the vehicle ( 102 ), transmitting ( 364, 468, 562 ) at least one response signal from the vehicle ( 102 ) to the key fob ( 202 ) in response to the at least one locate signal, performing ( 362, 462, 510 ) RSSI measurements of either the at least one locate signal or the at least one response signal, and displaying ( 318, 412, 514 ) the proximity value on the key fob ( 202 ) based on the RSSI measurements.
1. A method of indicating a proximity value representative of the distance between a key fob system and a vehicle system, comprising:
transmitting an N plurality of locate signals from the key fob, each of the N plurality of locate signals having a different signal strength;
performing RSSI measurements for the N plurality of locate signals received by the vehicle system;
determining a proximity value by the vehicle system based on the N plurality of locate signals received;
determining by the vehicle system the power level optimal for distinguishing proximity using the signal strength of the N received locate signals;
transmitting from the vehicle system the transmit power level for the next key fob transmission along with the RSSI value and the proximity value;
displaying a proximity value on the key based on RSSI measurements;
setting the key fob system transmission power signal strengths of an N+1 plurality of locate signals to that received from the vehicle system and a level greater than that received from the vehicle system; and
transmitting the N+1 plurality of locate signals from the key fob system, each of the N+1 plurality of locate signals having a different signal strength.
2. The method of claim 1 further comprising repeating each of the steps in succession a plurality of times.
3. The method of claim 1 further comprising calculating the proximity value based on at least one of the RSSI values within a preferred range of RSSI values.
4. The method of claim 3 further comprising repeating each of the steps a plurality of times in succession.
5. The method of claim 4 wherein the performing step comprises rejecting RSSI measurements that exceed a maximum rate of change.
6. An apparatus for indicating a proximity value representative of the distance between a key fob system and a vehicle system, comprising:
the key fob system configured for transmitting an N plurality of locate signals to the vehicle system, each of the N plurality of locate signals having a different signal strength
the vehicle system configured to:
perform RSSI measurements of the N plurality of locate signals received by the vehicle system;
determine a proximity value based on the N plurality of locate signals received;
determine the power level optimal for distinguishing proximity using the signal strength of the N received locate signals;
transmit the transmit power level for the next key fob transmission along with the RSSI value and the proximity value; and
a display on the key fob configured for displaying the proximity value based on RSSI measurements;
wherein the key fob system is further configured to:
set the key fob system transmission power signal strengths of an N+1 plurality of locate signals to that received from the vehicle system and a level greater than that received from the vehicle system; and
transmitting the N+1 plurality of locate signals from the key fob system, each of the N+1 plurality of locate signals having a different signal strength.