Abstract: The invention is a process to transmit data between a read/write device and a transponder. The data is transmitted by a change in field strength of an electromagnetic or magnetic field, and the times between sequential field strength changes are evaluated. At least at the beginning of data transmission, the systematic time deviation from the setpoint is determined that arises upon a switching threshold in the field strength changes. A correction value is derived, and the subsequently determined times are changed by the correction value. This correction allows for a greater amount of data to be transferred from the read/write device to the transponder.

Abstract: The invention relates to a device and process for data transmission. The data is transmitted by changes in the field strength of an electromagnetic or magnetic field, and then the times between at least two sequential field strength changes are evaluated. A frequency serving as the time base for evaluating the times between the field strength changes is calibrated at least at the beginning of data transmission so that it has a set relationship to the cycle duration of the field strength changes.

Abstract: In a method for automatically identifying an unknown number of transponders, these transponders are put into a dead state by a collision signal transmitted by the reader. Then, each transponder generates its own random dead time and the transponder with the shortest dead time is the first to transmit its data to the reader, while the other transponders are put into an idle state. When the reader has completely received the data of the first transponder, the idle states of the other transponders end and they generate another dead time for themselves. The entire process is then repeated, i.e., the transponder with the shortest dead time transmits its data to the reader, etc. until all transponders have transmitted their data to the reader individually and successively.

Abstract: A read/write device includes a transmitter for producing an RF signal and a modulator coupled to said transmitter for modulating the RF signal and, finally a data receiver for receiving RF data signals from a portable microchip. The microchip includes a resonant circuit tuned to the RF frequency of the read/write transmitter and a receiver that is coupled to the resonant circuit for detecting the RF signal. There is also provided a charging capacitor capable of storing the electrical energy from the RF signal so that the microchip can be powered during pulse pauses of the RF signal. The microchip includes a memory circuit for storing the identification code of the microchip, and a code generator that is coupled to the memory circuit for generating an RF signal that is modulated with the identification data. A switching element that couples the resonant circuit to the code generator de-tunes the resonant circuit when the identification data is transmitted back to the read/write device.

Abstract: A motion sensor is provided having within a casing a resonant element with a magnet arranged therebeneath and a freely movable ball made from magnetizable material disposed there above. A change in the position of the ball causes a change in the density of the flow of the magnetic lines of force and as a result, a resonance voltage is produced in the resonant element thereby indicating motion. As the motion is detected by electronic means, high sensitivity is assured, and such sensitivity, furthermore, can be adjusted by simple means as required in a given case of application.