| 摘要 |
In automotive engineering transmitting and receiving stations are usually used in keyless locking systems as electronic key modules or evaluation units for identifying the key module. Deactivation of the locking system is prevented if the key module allocated by means of a clear identification number from the evaluation unit is not in the immediate vicinity of the evaluation unit. The novel method shall determine the distance between two transmitting and receiving stations with high resolution. According to the novel method, a transmission signal (S 1 , S 2 ) respectively is generated in the transmitting and receiving stations ( 1, 2 ) and transmitted as a series of microwave pulses having a predefined pulse repetition frequency (fp 1 , fp 2 ) to the other respective transmitting and receiving station ( 2, 1 ) and received thereby in the form of a received signal. The pulse repetition frequencies (fp 1 , fp 2 ) of the transmission signals (S 1 , S 2 ) vary according to a predefined differential frequency value (fd), which is preferably small in relation to the impulse repetition frequencies. Points of coincidence (t 11 , t 12 , . . . ; t 21 , t 22 ) are determined in the transmitting and receiving stations ( 1, 2 ), corresponding to those moments in time, when the pulses of the transmission signal (S 1 , S 2 ) sent by the respective transmitting and receiving station ( 1, 2 ) and the received signal E 1 , E 2 ) received by the respective transmitting and receiving station ( 1, 2 ) coincide. The distance between the transmitting and receiving stations is then determined from the distance between the points of coincidence.
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