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: A anti-theft security system and process for securing merchandise. The security system comprises a base station that has a low frequency (LF) stage having a LF receiving and transmitting unit attached to the base station. Attached to the LF stage is an antenna for generating an electromagnetic field. In addition a plurality of merchandise security labels are each attached to a piece of merchandise. Each security label comprises a LF stage having a LF transmitter and receiving unit operating on the same frequency as the base station LF stage. When a security label enters the field transmission region of the base station the base station a bidirectional signal transmission takes place between the base station and at least one of the security label transponders. If the base station detects an active LF stage on the one of the security labels then an alarm will sound.

Abstract: A reading device and one or more associated transponders are used for non-contact identification of persons or objects. When a transponder is moved into the vicinity of the reading device, the reading device receives and evaluates data sent from the transponder. To provide the maximum distance between the reading device (or the antenna thereof) and the transponder, an automatic tuning device is employed to adjust a resonant circuit of the reading unit to match or approximately match a resonance frequency (fo) of the transponder by tuning the reading unit to a preset frequency which matches the frequency (fo) of the transponder. The tuning unit compensates for external influences caused by the environment in which the reading unit is installed, thereby preventing the resonant circuit of the reading unit from deviating from the optimum resonance frequency of 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: A rolling truck consisting of a metal container on whose bottom are provided castors and at least one brake gear, where the bottom has a contact area between the castors on the opposite sides for placing the rolling truck on a conveyor belt. A transponder is arranged on the bottom of the rolling truck, and the transponder is mounted on a plastic spacer at a distance from the bottom of the rolling truck, and outside the contact area of the bottom of the rolling truck. This reduces the distance between the transponder and the floor where the antenna of an RF reader is installed, and thus reduces the size and power required for the transponder.

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: An access control system for controlling access of individuals to an area having at least one programmed data carrier. Each programmed data carrier is assigned to an individual and has a programmed memory including a predetermined number of active bits within a bit allocation map defining authorization data specific to the individual. The programmable memory also has control data including an entry representative of the predetermined number. A stationary reading device is installed adjacent to the area for receiving the control and authorization data from the data carrier. The stationary reading device has uninitialized and unprogrammed programmable reader memory. A central evaluation unit includes check data and is coupled to the stationary reading device. The control data programs the reader memory so that the reading device recognizes the predetermined number and relays authorization data unaltered to the central evaluating unit.

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: An electronic seal for a casing records the time of changes in the seal state. A sealing strip is fixed in the casing and is formed as a safety loop. A monitoring device is located in the casing and attached to the sealing strip. The monitoring device generates time values which are recorded when changes in the seal state occur.

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.

Abstract: A control system is provided having stationary check points which are contactlessly read by a data collector and verified. The data so read can be stored and transmitted by a transmitter to a central unit, where the data so received are centrally evaluated. Together with the data of the check point being read, the time at which the respective check point is read is transmitted to the central unit as well. If all data are received by the central unit, it transmits back a verification entry, and the data are subsequently stored in a memory together with such verification entry. If no verification entry is received, the data are automatically and continually retransmitted to the central unit until the verification entry is received by the receiver in the data collector. In addition, the data collector has a random generator capable of establishing which individual check points are to be successively called on by the security guard.