Key location system
AssigneeContinental Automotive GmbH
InventorsThomas Reisinger, Thomas Georgi, Stefan Hammes
Life of this patent
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Abstract
The present disclosure relates to a method and devices for transit-time-based distance measurement and the teachings may be applied to locating keys for a motor vehicle. In one embodiment, a system for detecting the distance between a vehicle and an associated key may include: a transceiver associated with a vehicle; a key for the motor vehicle; and a processor configured to determine an estimated signal transit time between the transceiver and the key based at least in part on a ratio of a length of two time intervals between the transmission or reception of a message between the transceiver and the key.
Claims16
A system for detecting the distance between a vehicle and a key associated with the vehicle, the system comprising:
- a transceiver associated with the vehicle;
- the key;
- and
- wherein either the transceiver or the key transmits two data items to the other of the transceiver and the key;
- wherein the first of the two data items comprises information relating to a first time interval indicating a time difference between transmission of two previously transmitted messages and the second of the two data items comprises information relating to a second time interval indicating a time difference between reception of the two previously transmitted messages;
- and
- a processor configured to calculate an estimated signal transit time between the transceiver and the key based at least in part on a ratio of a length of the two time intervals;
- wherein the processor estimates the signal transit time based at least in part on the determined times and transmits the estimated signal transit time to either the transceiver or the key;
- and
- the processor calculates a distance between the vehicle and the key based on the estimated signal transit time.
A method for determining the distance of a key from a transceiver in a motor vehicle on the basis of an estimated signal transit time between the transceiver and the key, the method comprising:
- transmitting two data items in a first direction from one of the transceiver and the key to the other of the transceiver and the key;
- receiving the two data items and determining reception times for each of the two data items;
- using the respective reception times to determine the estimated signal transit time;
- transmitting a message in return including an indication of the ratio between a first time interval and a second time interval;
- the first time interval indicating a time difference between the transmission or reception of the two data items transmitted in the first direction,
- and the second time interval indicating a time difference between two additional data items transmitted in a second direction opposite to the first direction;
- wherein an estimated signal transit time of at least one user is determined from the indication, transmitted thereto, of the ratio of the lengths of two time intervals and times measured;
- and
- calculating a distance between the vehicle and the key based on the estimated signal transit time.
Dependencies are inferred from the claim text.