Pulse or digital communications – Systems using alternating or pulsating current
Patent
1994-05-06
1996-05-21
Tse, Young T.
Pulse or digital communications
Systems using alternating or pulsating current
375219, 375257, 370 32, 455 41, H04L 114, H04L 2700
Patent
active
055197299
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of transmitting serial data structures in information carrier (hereinafter "transponder") identification systems and a non-contacting electromagnetic transmission system operating in accordance with the method. Furthermore, it relates to a transponder suitable for the method and system.
Identification systems of the wireless type are known, particularly in chipcards and tool identifiers as disclosed in German Patent Specifications Nos. 3 72 18 22, 3 72 16 22, European Patent EP 79 047 and in WO 88/03594. The known identification systems use integrated chips on the transponder side and are disadvantageous because a register for comparing data dissipates energy and comparatively high energy levels are required for data transfer.
Furthermore, a comparatively low level of data security exists and, with respect to some applications, the time required for data transfer and data comparison is comparatively high.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a transponder identification system and a method for transmitting serial data structures which overcomes the disadvantages of the prior art.
Briefly stated, the present invention provides a process for transmitting serial data structures for information carrier identification systems (RF-ID systems), a transmission system working according to this process and an information carrier for contactless, electromagnetic transmission of serial data structures. The identification system has an interface (antenna) and an information carrier (transponder). The transmission process is essentially characterized in that a time-parallel data transmission and comparison between the data emitted by the interface and the data immediately sent back by the information carrier is carried out. The information data carrier has as essential components two appropriately sizeable receiving and emitting inductances and a multiplexer that is connected with a demodulator, a control logic and a non-volatile memory.
According to the invention an identification system comprises an interface module (hereinafter "interrogator") and a transponder. The interrogator realizes data communication between any suitable computer and the transponder. Advantageously, control devices such as a microcontroller, a microprocessor, and a freely programmable logic array, are employed for establishing a data coupling to a computer, for example, and also for supplying required control signals and orders, and serial data inputs and outputs for transmission to the transponder. A data output of a controller in the interrogator, having a serial data structure, is input to a digital comparator which performs bitwise clocked comparison of a detected serial data structure transmitted by the transponder and recovered by an amplitude demodulator with the controller data output. A comparison result is fed into the controller for evaluation. Clock pulses are provided by the controller for clocked operation of the comparison.
Control of the data comparison is possible via a pulse static or edgetriggered flip-flop. A clock edge for S1 is set after a time t.sub.v +t.sub.a, wherein t.sub.v is the signal delay time and t.sub.a is the signal rise time. It is also possible to provide the digital comparator on the interrogator side and/or on a side of the transponder. Hereinafter only the interface version is described.
In the interrogator, data levels High and Low are convened into two frequency levels or phase levels by a frequency shift keying or phase shift keying modulator respectively. A modulated carrier frequency signal T1 drives a resonator circuit via a power driver stage. The carrier frequency signal T1 induces, via a magnetic coupling of a coil of the resonator circuit, an alternating voltage preferably via an input resonant circuit within the transponder corresponding to the carrier frequency signal T1. The input circuit at the transponder is optionally tuned by an integrated capacitor. It is considered within the scope a
REFERENCES:
patent: 4713827 (1987-12-01), Lauffer et al.
patent: 5081670 (1992-01-01), Reum
patent: 5128972 (1992-07-01), Horinouchi et al.
patent: 5258999 (1993-11-01), Wernimont et al.
Brodersen Olaf
Jurisch Reinhard
Peitsch Peter
Micro-Sensys GmbH
Tse Young T.
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