摘要 |
A keyless entry system comprising a transmitter and a receiver. The transmitter increases a first number stored in the volatile memory according to rules, and transmits the first number by radio. The receiver receives the first number, and if the first number is greater than a second number stored in a memory, outputs a signal to indicate being authenticated as correct and updates the second number to the first number. Further, each time increase in the first number becomes a multiple of a predetermined number, the transmitter writes into a non-volatile memory a third number equal to the predetermined number plus the first number. When the first number in the volatile memory is erased due to the exchange, etc., of the battery, the transmitter reads out the third number from the non-volatile memory and writes the third number as the first number into the volatile memory. |