JPH03181235A - Non-contact data communication system - Google Patents

Abstract

PURPOSE:To improve the reliability of communication by providing a means on a data carrier to convert the transmission energy received from a fixed station unit into the active power together and a means which works with the power supplied from the energy converting means and performs the communication with the electromagnetic waves, and nonvolatile storage means. CONSTITUTION:A reception antenna 20 and a detection rectifying circuit 22 are provided on the side of a data carrier 12 of a reading unit 10. Thus the radio waves transmitted from the unit 10 are received and the active power is produced after the reftification of detection. The carrier 12 is provided with a nonvolatile storage circuit 24 which receives the active power from the circuit 22 and reads out the prescribed data stored previously. The data read out of the circuit 24 are supplied to a code modulator 26 as the modulation signals, and the carrier signal received from a carrier oscillator 28 is FM modulated for example. Thus the crosstalk disturbance can be omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contactless data communication system for transmitting and receiving data between a fixed station unit and a portable data carrier.

[Prior Art] Conventionally, electromagnetic coupling methods, electromagnetic induction methods, microwave methods, optical communication methods, and the like are known as non-contact data communication methods using portable data carriers.

The electromagnetic coupling method uses a magnetic field generated by applying a radio frequency current of several hundred KHz to several MHz to induction coils with cores facing each other at a distance of several millimeters to several tens of millimeters, and communicates between the fixed station unit and the data carrier. I do.

In addition, the electromagnetic induction method uses several hundred K applied to the coil antenna.
The communication medium is a magnetic field generated near the antenna by a medium wave band radio frequency current of Hz, and communication is performed by signals induced in the antenna of the other party.

Further, in the microwave method, communication is performed between a fixed station antenna unit and a data carrier using radiated electromagnetic waves (radio waves) by microwaves of 2.45 GHz, which are allocated for mobile communication among premises radio equipment, as a communication medium.

Furthermore, in the optical communication method, communication is performed by receiving near-infrared light emitted by, for example, an LED using a phototransistor as a communication medium.

[Problem to be solved by the invention] However, among conventional contactless data communication methods, microwave methods and electromagnetic induction methods that allow relatively long-distance communication require batteries to be used as power sources for data carriers. However, there is a lack of electromotive force at low temperatures, battery deterioration at high temperatures, and the complexity of operational management for battery replacement.Furthermore, the package structure of the data carrier has to be modified to make battery replacement possible. Since it cannot be completely sealed, it is almost impossible to use it in railways, transportation, civil engineering and construction, etc., which have harsh operating environments.

In addition, the electromagnetic coupling method has the advantage of eliminating the need for batteries by supplying operating power using electromagnetic induction, but the communication distance is short at most, a few centimeters, and in order to obtain a longer communication distance, it is necessary to The induction coil mounted on the carrier becomes very large, and the original advantage of the data carrier, which is reduced in size by force, is lost.

Furthermore, the optical communication system has the problem that the optical system gets dirty, so it can only be used in limited environments such as office buildings.

The present invention has been made in view of these conventional problems, and is an electromagnetic wave type non-contact technology that eliminates the need for a built-in battery power source in a data carrier and ensures high communication reliability even with weak electromagnetic waves. The purpose is to provide a data transmission method.

[Means for Solving the Problems] First, the present invention provides a fixed station unit that commands data reading and/or data writing, and a data reading and/or data writing of a storage circuit in response to a control command from the fixed station unit. The target is a contactless data communication system equipped with a portable data carrier.

Regarding such a contactless data communication system, the present invention includes a data carrier that includes a conversion means that converts the energy transmitted from the fixed station unit into operating power, and a device that operates using the power supplied from the conversion means and communicates using electromagnetic waves. The device is equipped with a communication means that performs this, and a non-volatile storage means whose stored contents do not disappear even if the power supply is cut off.

Here, the communication means of the data carrier includes code modulation means for modulating a carrier wave signal with data read from the nonvolatile storage means, and spreading modulation means for modulating and transmitting a spreading code sequence using the modulated output of the code modulation means. On the other hand, on the fixed unit side, demodulation means demodulates the received signal using the same spreading code sequence as the spread modulation means of the data carrier, and code demodulation means demodulates the read data from the demodulated output of the spread demodulation means. will be established.

Further, the code modulation and spread modulation means on the transmitting side may be used for communicating the write control signal and the write data to the data carrier in the fixed station unit, and the data carrier side may be provided with spread demodulation and code demodulation means.

[Function] According to the contactless data communication system of the present invention having such a configuration, since electromagnetic waves whose spectrum is spread by pseudo-noise sequences such as the M sequence and the GOLD sequence are used, transmission of data carriers is difficult. A sufficient communication distance can be secured even with low power, and since the data carrier's transmission power is small, sufficient communication can be achieved even with the data carrier's power converted from transmission energy such as electromagnetic waves from the fixed station unit. .

Additionally, since batteries are no longer required, the data carrier can have a completely sealed package structure, making it practical for use outdoors in harsh environmental conditions or in moving objects such as automobiles.

Furthermore, by using different spreading code sequences for each data carrier, highly reliable communication that reliably eliminates interference can be achieved.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention, taking as an example a case where the device is read-only.

In FIG. 1, 10 is a readout unit as a fixed station unit, and 12 is a portable data carrier.

The reading unit 10 includes a power supply oscillator 14 and a power amplifier 1 to supply operating power to the data carrier 12.
6 and a transmitting antenna 18 are provided. Corresponding to the power supply circuit section on the readout unit 10 side, a receiving antenna 20 and a detection rectification circuit 22 are provided on the data carrier 12 side, and receive the transmitted radio wave from the readout unit 10 and output the operating power after detection rectification. is creating.

The data carrier 12 is provided with a storage circuit 24 using nonvolatile memory, and the storage circuit 24 is connected to the detection rectifier circuit 22.
When supplied with operating power, it performs a reading operation of pre-stored predetermined data. The code data read from the storage circuit 24 is supplied as a modulation signal to the code modulator 26, and the carrier wave signal from the carrier wave oscillator 28 is subjected to FM modulation, for example.

That is, as shown in FIG. 2, the carrier wave signal of frequency f is frequency-shifted to (f+Δf) using bit 1 of the read data.
Further, bit 0 performs FM modulation by shifting the frequency to (f-Δf).

Referring again to FIG. 1, the modulated output of code modulator 26 is provided to spreading modulator 30. Referring again to FIG. A spreading modulator 30 performs spreading modulation using a spreading code sequence from a spreading code generator 32.

That is, as shown in FIG. 2, a spreading code sequence indicated by PN is repeatedly transmitted from the spreading code generator 32 to the spreading modulator 30 for an FM modulated signal corresponding to one bit of read data.
given to.

The spreading code generator 32 generates sequence signals such as the M sequence and the Gold sequence, which are known as pseudo-random sequences.

FIG. 3 shows a modulated wave when the code modulated wave obtained from the code modulator 26 is outputted with a Mo sequence and subjected to spread modulation.

That is, the Mo sequence as a spreading code sequence is a bit signal that changes between +1 and -1, and can be generated, for example, by a four-stage shift register 60 and EX-OR gate 46 shown in FIG.

The spreading modulator 30 multiplies the code modulated wave by a Mo sequence generated as a spreading code sequence. Therefore, the Mo series is +1
In the case of , the code modulated wave is output as is, but when it is inverted to -1, the phase of the code modulated wave is inverted by 180° and becomes an opposite phase.

In FIG. 3, the falling and rising edges of the Mo sequence are synchronized with the zero crossing of the code modulated wave, but they do not necessarily need to be synchronized.

Referring again to FIG. 1, the modulated output from spreading modulator 30 is provided to transmit antenna 34 for transmission.

The transmission radio waves from the data carrier 12 are transmitted to the reading unit 10
is received by the receiving antenna 36 and provided to the spreading demodulator 38. Since the received signal to the spreading demodulator 38 is the spreading modulated wave shown in FIG.
The FM modulated signal can be demodulated by generating the same spreading code sequence, for example, the Mo sequence, from the spreading code generator 32 of the data carrier 12 and multiplying them together. Spreading code generator 40 is synchronously controlled by delay synchronization circuit 42 . That is, the delay synchronization circuit 42 synchronously controls the code sequence generation timing of the spreading code generator 40 so that the spreading code sequences of the 12 data carriers and the received spreading code sequence are simultaneously generated.

The demodulated output from the spreading demodulator 38 is given to the code modulator 44, where the read data consisting of bits 0 and 1 is demodulated by FM demodulation, and is received from the reading unit 10 by the computer system performing information collection processing. The code data is output.

The contactless data communication system of the present invention shown in FIG. When the data carrier 12 is brought into an operating state, predetermined read data is read out from the storage circuit 24 of the data carrier 12, subjected to FM modulation and further spread modulation, and sent out. The reading unit 10 receives the transmitted radio wave from the data carrier 12 side, performs spread demodulation and code demodulation, and then reads the read data, and checks the response of the vehicle equipped with the data carrier 12 from the ID code obtained as the read data, for example. be able to.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

In FIG. 5, the readout unit 10 is provided with a power supply oscillator 14, a power amplifier 16, a spreading demodulator 38, a spreading code generator 40, and a code demodulator 44, similar to the embodiment shown in FIG. The difference from the embodiment shown in FIG. 1 is that instead of providing a transmitting antenna 18 and a receiving antenna 36, a transmitting/receiving antenna 18 is provided, and the output of the power amplifier 16 and the spreading demodulator are connected via a directional coupler (circulator) 48. 3
It is characterized in that 8 human power is connected to the antenna 18.

Further, as a spreading demodulator 38, the received spreading modulation signal and the spreading code sequence from the spreading code generator 40 are transmitted to a surface acoustic wave element (S
A convolver is used which generates a spread demodulated output by inputting the signal to the AW (AW), and the use of the convolver eliminates the need for the delay synchronization circuit 42 shown in FIG.

On the other hand, on the data carrier 12 side, an antenna 20 for both reception and transmission is provided, and the antenna 20 is connected to the detection rectifier circuit 22 via a directional coupler (circulator) 50.
and the output of the spreading modulator 30. Also, instead of providing the carrier wave oscillator 28 for the code modulator 26 in FIG. 1, the frequency of the received signal for power supply from the reading unit IO is multiplied and supplied to the code modulator 26 as a carrier wave signal. A multiplier circuit 52 is provided, and by providing the multiplier circuit 52, a carrier wave oscillator is not required. The multiplier circuit 52 outputs the power supply frequency signal received by the antenna 20 as it is, or doubles or triples it and outputs it as a carrier signal to the code modulator 26 . The rest of the memory circuit 24, spreading modulator 30, and spreading code generator 32 are the same as those in the embodiment shown in FIG.

FIG. 6 is an embodiment configuration diagram showing another embodiment of the present invention. In this embodiment, a Reed-Solomon code is used as a spreading code sequence, and the carrier frequency used for code modulation on the data carrier side is It is characterized by whipping the communication band to spread the communication band.

In FIG. 6, a carrier wave oscillator 28 provided in the data carrier 12 generates frequencies fl, f2, . f3゜...fn
carrier waves can be switched and output.

The spreading code generator 32 generates a control voltage of an oscillation frequency that whips frequencies f1 to fn in order according to a Reed-Solomon code.

Therefore, the code modulator 26 is given a carrier wave that is whipped over n frequencies f1 to fn according to the Reed-Solomon code, and this carrier wave is sent to the storage circuit 24.
The signal is modulated by the data bits from the source and output to the spreading modulator 30. In this embodiment, spreading modulator 30 functions simply as an amplifier.

On the other hand, the configuration of the readout unit 10 is the same as that of the embodiment shown in FIG.
A sequence of the same whipping frequency as that whipped with ~fn is generated, synchronized with the transmitting side of the data carrier 12 by the delay synchronization circuit 42, and applied to the spreading demodulator 38 to perform spreading demodulation, and finally to the code demodulator 44. Demodulates the read data and outputs it to the outside.

The method of spreading the communication band by sequentially changing the carrier wave oscillation frequency and frequency whipping according to the Reed-Solomon code shown in FIG. 6 is advantageous when the data carrier 12 is mounted on a mobile object such as a car. It is. In other words, in mobile radio, a dead zone occurs approximately every λ/4 wavelength due to multiple reflections and combinations of radio waves, but because the carrier frequency changes rapidly relative to the speed of the information code sequence, so-called frequency diversity occurs. As a result, dead areas in mobile wireless communication can be eliminated.

FIG. 7 is an embodiment configuration diagram showing another embodiment of the present invention, and in this embodiment, operating power is supplied from the reading unit 10 to the data carrier 12 by an optical communication system. Features.

That is, the reading unit 10 is provided with a light source 56 driven by a power source 54, and the light from the light source 56 is received by a solar cell 58 to generate operating power for the data carrier 12. Of course, the solar cell 58 can generate operating power not only from the light from the light source 56 of the reading unit 10 but also from natural light such as sunlight. The other configurations are the same as the embodiment shown in FIG.

FIG. 8 shows another embodiment of the present invention, in which the data carrier 1
It is characterized in that it enables both data writing and data reading between the two.

In FIG. 8, a write/read unit 100 is provided as a fixed station unit, and in addition to the configuration of the read unit 10 shown in FIG. device 60, carrier wave oscillator 62
and an adder 64. That is, the code modulator 60 frequency-modulates the carrier wave signal from the carrier wave oscillator 62 using the write control signal and the write data, the adder 64 adds it to the transmission signal for power supply, and the signal is sent from the circulator 48 to the antenna 18. It is transmitted to the data carrier 12.

A code demodulator 65 is provided on the data carrier 12 side for data writing, and demodulates a write control signal and write data from a signal received by the antenna 20 obtained via the circulator 50, and outputs the write control signal and write data to the control circuit 24-1. The data is written to the nonvolatile memory 24-2 via the . Of course, for a read command to the nonvolatile memory 24-2, a read control signal is given to the control circuit 24-1 using the same system as when writing, and based on this read control signal, the control circuit 2
4-1 reads read data from the specified address of the nonvolatile memory IJ 24-2, performs FM modulation with the code modulator 26, spread modulates it with the spread modulator 30, and transmits it to the write/read unit 100 side. become.

The embodiment of FIG. 8 is applicable when the transmission power of the write/read unit 100 is sufficiently large.

FIG. 9 is a configuration diagram showing another embodiment of the present invention, and this embodiment is designed so that data can be written to the data carrier 12 even if the transmission power of the write/read unit 100 is not so large. It is characterized by what it did.

That is, in the embodiment shown in FIG. 9, spread spectrum communication is used in the transmission system for the write control signal, write data, and read control signal from the write/read unit 100 shown in FIG. 8 to the delta carrier 12. It is characterized by the application of technology.

In FIG. 8, a spreading modulator 66 is provided following the code modulator 60, and the FM modulation signal from the code modulator 60 generates a spreading code sequence from a spreading code generator 68, for example, M
o sequence is spread modulated and transmitted to the data carrier 12.

In this way, spread spectrum communication is also used for communication from the write/read unit ↑00 to the data carrier 12, so even if the transmission power of the write/read unit 100 is small, a sufficient communication distance to the data carrier 12 can be maintained. can be secured.

On the other hand, a spreading demodulator 70 and a spreading code generator 72 are provided following the directional coupler 50 on the data carrier 12 side.
After spreading and demodulating the received signal, it is applied to the code demodulator 65,
The write control signal, write data, or read control signal is demodulated.

The other configurations are the same as the embodiment shown in FIG.

Also, the data carrier 1 from the write/read unit 100
Assuming that the communication to No. 2 is downlink and the opposite direction is uplink, different spreading code sequences are used for uplink and downlink spread spectrum communication. For example, if the uplink is the Mo sequence, the downlink is the M1 sequence to prevent interference.

[Effects of the Invention] As explained above, according to the present invention, since electromagnetic waves whose spectrum is spread by pseudo-noise sequences (PN sequences) such as the M sequence and the Gold sequence are used, the transmission power of the data carrier is reduced. Even if the distance is small, a sufficient communication distance can be ensured.

In addition, since the data carrier requires less transmission power,
It is sufficient to generate operating power from transmission energy such as electromagnetic waves from the fixed station side to enable communication from the data carrier.

Furthermore, since there is no need to incorporate a battery into the data carrier, the package structure of the data carrier can be completely sealed, ensuring use outdoors under severe environmental conditions or in moving objects.

Furthermore, by using different spreading code sequences for each data carrier, highly reliable communication that reliably eliminates interference can be achieved.

Further, by multiplying the frequency of the received signal to generate a carrier wave without providing a carrier wave oscillator in the data carrier, it is possible to eliminate the need for an oscillator that consumes a large amount of power, and further reduce the power consumption of the data carrier.

[Brief explanation of drawings]

FIG. 1 is an embodiment configuration diagram showing a read-only embodiment of the present invention; FIG. 2 is a detailed explanatory diagram of the present invention; FIG. 3 is a detailed explanatory diagram of the present invention; Explanatory diagram of the Mo sequence generator used in the invention; Fifth
．． 6. FIG. 7 is a block diagram showing another embodiment of the present invention which is read-only; FIGS. 8 and 9 are block diagrams showing other embodiments of the present invention which are writable and readable. 10: Read unit 100: Write/read unit 12: Data carrier 14: Power supply oscillator 16: Power amplifier 18. 20. 34. 36: Antenna 22, detection rectifier circuit 24: Storage circuit 21-1: Control circuit 24 -2: Non-volatile memory 26.60: Code modulator 28.62: Carrier wave oscillator 30.66: Spreading modulator 32.40.68 + Spreading code generator 38.70 + Spreading demodulator 44: Code demodulator 45: Shift register 46, EX-OR gate 48.50: Directional coupler 52: Multiplier circuit 54: Power supply 56: Light source 58: Solar cell (circulator)

Claims (1)

[Scope of Claims] (1) A fixed station unit that commands data reading and/or data writing, and a data carrier that reads data and/or writes data in a storage circuit in response to a control command from the fixed station unit. In the contactless data communication system, the data carrier includes a conversion means for converting transmission energy from the fixed station unit into operating power, and a communication device operated by the power supplied by the conversion means to perform communication using electromagnetic waves. (2) A non-contact data communication method characterized by comprising: a non-volatile storage means whose stored contents do not disappear even if the power supply is cut off; code modulation means for modulating a carrier wave signal with the read data of the code modulation means, and spreading code modulation means for modulating and transmitting a spreading code sequence using the output of the code modulation means, the fixed station unit transmits the received signal to the data carrier. 2. The contactless data according to claim 1, further comprising a spreading demodulating means for demodulating using the same spreading code sequence as the spreading modulating means, and a code demodulating means for demodulating the read data from the demodulated output of the spreading demodulating means. Communication method. (3) A code modulation means for modulating a carrier wave signal from a code sequence of a write control signal and write data in the fixed station unit, and a spreading modulation means for causing the output of the code modulation means to be modulated with a spreading code sequence and transmitted. and the communication means for the data carrier includes spreading demodulation means for demodulating the received signal with the same spreading code sequence as the spreading modulation means of the fixed station unit, and a spreading demodulation means for demodulating the write control signal or 2. The contactless data communication system according to claim 1, further comprising code demodulation means for demodulating the code string of the write data.