| 摘要 |
To prevent overriding an electronic car radio theft disabling system by connecting an external battery to a car radio prior to theft thereof, the radio includes a measuring circuit (7, 7') measures the impedance of a connected accessory, for example a loudspeaker or loudspeaker system (8), and if the impedance of connected loudspeaker does not match the impedance stored in a memory (5) of the car radio, operation of the radio is inhibited until the appropriate code word-known only to the proper owner-is reinserted.
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