Siemens Aktiengesellschaft

Manfred Glehr

Stefan Haimerl

Stephan Heinrich

Reiner Buchner

Thomas R&ouml;hrl

Uwe Ahlig

Armin Fischer

Peter Voelkl

A circuit arrangement () for a photodiode () has a microprocessor () with an output () which emits a pulse-width-modulated voltage signal via a low-pass filter () to the cathode of the photodiode (). The voltage which is applied to the cathode of the photodiode () is detected by an input () of the microprocessor () and is regulated at a nominal value by adjusting the voltage signal at the output () of the microprocessor (). The circuit arrangement () has a particular wide dynamic measurement range.

Circuit arrangement for a photodiode

An antenna transponder configuration, in particular for power transmission and angle measurement is described. The antenna transponder configuration contains a stationary antenna device having at least two concentric coils with different mean radii, the mean magnetic flux in the interior of the coils approximately canceling itself out. At least one of the coils is in this case in the form of a meandering coil. A transponder, which is disposed such that it can rotate, has a configuration of coils that are inductively coupled to the magnetic field of the meandering coil. The transponder and the antenna device are separated from one another by an air gap.

Antenna transponder configuration for angle measurement and data transmission

An interrogation signal is emitted via one or more passenger compartment antennas of a motor vehicle. The transmit power of the emitted interrogation signal is changed until a portable transponder just still receives the interrogation signal if the transponder is located at a previously defined, fixed position. The transmit power which is set in this way is stored for the operation of the anti-theft system.

Method for initializing an anti-theft system for a motor vehicle

In order to identify the position of a movable element, such as a lock bolt, a resonant circuit is subjected to the element or a part that moves with the element. The resonant circuit is thereby damped by the element in a position-dependent manner and oscillates in one end position of the element but is damped too greatly in the other end position. A microprocessor controls the switching on and the respective operating point of a transistor in such a way that switching hysteresis is obtained. The operating point can be automatically readjusted in an adaptation phase.

Apparatus for identifying the position of an element, in particular a

In a method for operating an anti-theft system and an anti-theft system operating according to the method, a stationary transceiver sends a question code signal to a portable transponder, which in turn responds with an answer code signal. The answer code signal is scanned at predetermined scanning times and a piece of code information is demodulated therefrom. If the first bits of the answer code signal are already unreadable, then the scanning time is displaced by a phase angle, and the remainder of the answer code signal is read.

Method for operating an anti-theft system and anti-theft system

In an anti-theft system for a motor vehicle, an oscillating circuit of a transceiver in the motor vehicle is modulated with code information of a portable transponder. A demodulator detects the code information and carries it onward to a computer unit, where it is checked for authorization. Component tolerance or temperature changes can mean that initially no code information will be demodulated, despite a properly functioning transponder. According to the invention, the frequency of the modulated oscillation is then measured and reregulated to a command frequency.

Anti-theft system for a motor vehicle

A device for transmitting data or energy supply from or to a transponder, especially for an anti-theft system in a motor vehicle, includes an antenna oscillating circuit which is induced to oscillate by an exciter variable. The oscillation is transmitted by transformer coupling to a transponder oscillating circuit. In order to make the transmission of energy or data as effective as possible, the current or the voltage in the antenna oscillating circuit is measured and compared with a desired variable. Upon a deviation, a correction value is generated by which the exciter current is increased or the resonant frequency is adapted to the exciter frequency as a consequence of the addition of an impedance to the antenna oscillating circuit.

Device for transmitting data or energy

A device for controlling keyless access to a motor vehicle includes a transceiver to be carried by a user. A distance detecting device measures a distance between the transceiver and a motor vehicle. A transmitting unit being disposed in the motor vehicle and being associated with a tripping device broadcasts a question code signal when the tripping device is actuated. The transceiver has a receiver for receiving the question code signal, and the transceiver has a transmitter for broadcasting an answer code signal only whenever the motor vehicle is located in the immediate vicinity of the transceiver. A receiving unit disposed in the motor vehicle receives the answer code signal from the transceiver and furnishes an unlocking signal to an unlocking unit if the answer code signal matches a set-point code signal.

Keyless access control device

An anti-theft system for a motor vehicle includes a portable transponder carrying code information. A stationary transceiver has an oscillator and an oscillating circuit being excited to oscillate by the oscillator at an oscillation being modulated by the transponder in synchronism with the code information. A demodulator demodulates the modulated oscillation of the oscillating circuit. According to one embodiment, the code information is obtained from the demodulated oscillation by sampling the oscillation at least at one predetermined sampling time. An arithmetic unit compares the code information with command code information and transmits an enable signal to a security unit if a match occurs. The modulated oscillation being shifted by a predetermined phase angle is sampled once again if initially no code information is recognized from the demodulator. According to another embodiment, the modulated oscillation containing the code information is sampled at least at two predetermined times being phase-shifted from one another by a predetermined phase angle and the code information is obtained from voltage values detected at the sampling times. The arithmetic unit compares the code information with the command code information and transmits an enable signal to a security unit if a match occurs.

A method for triggering a plurality of relay exciter coils connected parallel to a common voltage source includes turning each of the coils on and off with relay switching means associated with the coils, and triggering the respective coils to be turned on after reaching a response state thereof with a common clock generator having a given clock ratio, through the relay switching means, for establishing a steady state of a holding current being reduced relative to the response state. The method further includes turning off the coils with a common OFF-switch, keeping the respective relay switching means closed for those coils being intended to continue to be operated in the steady state of the holding current, for establishing a response current rising within a short time within the associated coil, and triggering the coil again with the clock generator having the given clock ratio after a predetermined period of time. A circuit for carrying out the method includes diodes each being connected parallel to a respective one of the coils. Each diode is connected in the blocking direction through a common Zener diode connected in series in the blocking direction to the voltage source. The common OFF-switch is connected parallel to the Zener diode.

Method for triggering parallel relays and circuit for carrying out the

Control device for controlling functions of a motor vehicle for a load dump having a computer for generating at least one control signal that is dependent on the level of the operating voltage feeding the control device. A power supply system generates an operating voltage that is supplied to a threshold switch. As long as the operating voltage is above a limit value in the load dump case, the threshold switch outputs a response signal to an evaluator. The latter then only supplies an output signal and thus reports the load dump case to a computer unit when the response signal lasts longer than a set time span.

Control device for controlling functions of a motor vehicle during a

In a method for generating trigger or ignition pulses that control a periodic event of an internal combustion engine, a precalculation is required of a calculated running time T.sub.n+1 that a crank shaft of the internal combustion engine meets in order to traverse the respectively next of prescribed, constant allowed ranges WB.sub.n. For this precalculation, a real running time TE.sub.n is measured after every traversal of one of the allowed ranges WB.sub.n and the next, following running time is precalculated with an approximation. The precalculated value of this calculated running time T.sub.n+1 is derived from the equation:

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Neutraubling, Germany

Manfred Glehr