Conti Temic Microelectronic Gmbh

Dornier Gmbh

Daimler Chrysler Ag

Dornier System Gmbh

Udo Knepper

Rolf Schuler

Wolfgang Schulter

Walter Ulke

Ralph Speck

Stefan Rau

Wolfgang Voss

Karl-Heinz M&uuml;ller

Heinrich Haas

Franz Lutz

Thomas Oexle

Karlheinz Mueller

Viktor Beyer

In a method for determining the distance between two transmitting and receiving stations, a transmission signal is generated in each station and is transmitted as a series of microwave pulses having a predefined pulse repetition frequency to the other respective station. The coincidence of pulses of the transmission signal sent by the respective station and the signal received by the station is detected in each station as a coincidence event, and the number of pulses transmitted and received by the respective station at the time of the coincidence event is determined. The distance between the stations is then calculated on the basis of the number of the determined pulses.

Method for determining the distance between two transmitting and receiving stations

In a method for securing an object against unauthorized use, an interrogation unit () transmits an interrogation signal (s) and tests whether a response unit (), which is to be carried by an authorized user, responds to the interrogation signal with a response signal (r) that contains as information a code authorized for desecuring a security device (). If so, the security device is desecured. The securing method shall prevent unauthorized persons from establishing a radio link via relay stations between the interrogation unit () and the response unit () for providing the authorized code via this radio link without being noticed by the authorized user. The securing method prevents the desecuring of the security device () if the signal transit time of a signal transmitted as the interrogation signal (s) and received as the response signal (r) by the interrogation unit () during a monitoring time interval (t&#x2013;t) is greater than a prescribed value. The method is carried out in a keyless security system for securing motor vehicles against unauthorized use.

Securing method, interrogation unit and securing system for implementing the securing method

In a procedure for the provision of access authorization for an engine-driven vehicle, if there is an operator request for the provision of access authorization to an engine-driven vehicle, a bidirectional signal transmission using encoded transmission signals and an electronic key will be effected. From transmission units located on or in the vehicle, vehicle signals will be transmitted to the electronic key, and, from the electronic key, key signals will be returned as echo signals to the respective transmission units. The time difference between the vehicle signal and the key signals will be determined and evaluated. The position of the electronic key in relation to the vehicle will be determined by means of successive bidirectional signal transmissions between at least two transmission units and the electronic key as well as by evaluating the time differences; having determined the actual key position, a decision on access authorization to the vehicle will be made.

Procedure for the provision of access authorization to an engine-driven vehicle

A transmitting and receiving part of a pulse Doppler radar, in which the transmitting oscillator, by frequency shifting, is at the same time used as a local (reception) oscillator, and the intermediate-frequency reference frequency is generated coherently with respect to the pulse repetition frequency. Since only one high-frequency oscillator is required, the quality of which does not have to meet very high requirements, a low-price pulse Doppler radar can be implemented.

Transmitting and receiving part of a pulse doppler radar

A sensing circuit is assumed to produce in phase and quadrature Doppler signals. The relative phase of these signals is used to determine the passage of object such that correctly related zero passages in the two signals are counted, and the count state within certain periods of time yields information to check the significance of signals as genuine Doppler signals.

Radar signal progessing

The invention concerns a procedure and a circuit arrangement for a coherent, high-resolution pulse radar applicable to distances from several tens of meters down to less than one meter and which evinces at the same time an accuracy in the cm range; the application is in particular to industrial monitoring operations. Two highly stable pulse sequences are generated in the transmitter and differ only slightly with respect to their pulse repetition frequencies. Both sequences are shaped into microwave pulse bundles and one sequence is processed into transmitter pulses, the other sequence being processed into scanning pulses for a time-expansion procedure. Heterodyning with the scanning pulses takes place in the receiver mixer, the result being a combined formation of intermediate-frequency (IF) and time-expansion. In this manner the signal bandwidth is already decreased by the time-expansion factor in the IF part. This is made possible in that coherent phases are used, i.e., there is an arbitrary but constant time relationship between the rising edge of the controlling pulse and the starting time (initial phase) of the carrier oscillation produced in the microwave oscillator. The oscillators used are microwave resonators driven by extremely short control pulses.

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Langenargen, Germany

Udo Knepper