Blaupunkt-werke Gmbh

Peter Seibold

Karl-Peter Strauss

Reinhard Wieschhoff

To suppress tuning noise interferences, and particularly transients, such as whistles and the like, especially in FM receivers during returning of the receiver, an inter-station retuning muting circuit is, in accordance with the invention, modified by including therein a switchable filter (2) having a low-frequency cut-off (f.sub.g2) which is higher than the frequency of noise interference due to retuning of the receiver, the filter being switched to the higher frequency cut-off level for a period of time (T.sub.E) which exceeds the normal muting time (T.sub.E) of FM receivers.

Circuit and method of suppressing inter-station radio tuning noise

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.

Automotive electronic communication apparatus with theft disabling,

Upon unauthorized removal of a car radio (2) from the chassis (C) of a car, a memory (5) which has a code stored therein is changed and inhibits operation of the car radio. The memory is retained in a predetermined memory state either by continuously receiving data inputs, for example from a potentiometer slider of a potentiometer (6), or data entered into an RAM energized only upon being properly connected in the vehicle. Alternatively, a user may enter a code, for example by operation of station selector buttons (4) of the car radio (2), and upon operating a set code switch (9), which code is destroyed upon removal of the radio, or upon failure to enter the correct code from time to time. The selected code can be encrypted by a preset encrypting memory chip, for example within the memory (5), and the encrypted code displayed, with only the manufacturer knowing the encrypting data, and releasing the encrypting data only to an authorized person, thereby permitting continued use of the radio by the authorized person even though the code word may have been forgotten.

Growing community of inventors

Diekholzen, Germany

Peter Seibold