JPS5931018B2 - information transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information transmission device that is attached to a moving body or the like and transmits and receives radio waves without having its own power source.

In order to read information held by a moving object from outside the object, an electromagnetic wave transmitter/receiver device installed on the moving object is irradiated with electromagnetic waves to activate the device and emit electromagnetic waves with modulated components according to the information. Systems for receiving and detecting this have already been developed or are in practical use.

The propagation characteristics of electromagnetic waves differ depending on the wavelength, and a wavelength band suitable for the purpose of use is selected. However, in the above applications, the propagation range is often limited to short distances, so the electromagnetic induction region Long waves, which can be used in the field of radio waves, and microwave waves, which have strong directivity, are used.

The microwave method has the advantage that the setting of the propagation area is more flexible than the long wave method, and the device can be made smaller.

In order to complete information transmission within a short period of time when a moving object passes through a limited space at high speed, it is necessary to convert information into a signal. Among these, the binary code serial transmission method is suitable for high-speed transmission, is easy to process, and has already been used. Many practical means exist.

In addition, in order to make it easier to use even when the mobile body does not have a power source, the information transmission device (hereinafter referred to as the transponder) on the mobile body receives, rectifies and drives the radio waves emitted from the reading device on the ground (hereinafter referred to as the interrogator). The power source is practical.

Below, an example of the configuration of a power-free transponder using code transmission using microwaves and an interrogator for the transponder will be shown.

FIG. 1 shows an example in which the interrogator continuously transmits microwaves.

The interrogator 101 on the ground has a transmitter 1, a transmitter antenna 2, a receiver antenna 3, a receiver detector 4, an FSK modulator 5, and a decoder 6 as main components.

A transponder 102 mounted on a moving body etc. includes a receiving antenna 11,
Rectifier circuit 12, code sending circuit 13, storage device 14, modulated wave oscillator 15, frequency switching circuit 16, clock oscillator 1
7, a transmitting antenna 18, and a modulator 19.

Next, the operation of the apparatus shown in FIG. 1 will be explained.

The radio waves sent out from the interrogator 101 are irradiated onto the transponder 102, and the transponder 102 is driven by the electric power, and the radio wave itself is used by the transponder 102 as a carrier wave for a return radio wave.

Microwaves are generated in the transmitter 1 and continuously enter the receiving antenna 11 of the transponder 102 via the transmitting antenna 2, and are converted into direct current by the rectifier circuit 12, which is used as a driving power source for the transponder 102.

The code sending circuit 13 reads out the binary storage contents including a synchronization signal etc. from the storage device 14 and outputs "l ++
, ! 1 Q 11 serial code string, that is, a binary code string, and in order to obtain oscillation outputs of two types of frequencies corresponding to binary values, the oscillation frequency of the modulated wave oscillator 15 is changed to the frequency switching circuit 16.
The so-called frequency shift key ink (FSX
to do).

A clock signal for logic circuit operation is obtained by a clock oscillator 17.

The response radio wave is re-radiated from the transmitting antenna 18 by passively relaying the reception input as it is, but is mixed with the modulated wave, that is, the FSX output, by the modulator 19 on the way.

That is, this radio wave enters the interrogator from the receiving antenna 3 with the same center frequency as the transmitted wave of the interrogator, but the modulated component by the transponder is detected by the receiving detector 4, and the FSK demodulator 5 converts the FSK signal into the interrogator. Binary values are demodulated.

Since the code of the transponder follows a normal binary code data transmission system, it is processed by the decoder 6 including synchronization detection and error control, and the binary stored information of the transponder is read.

Another configuration example is shown in FIG.

This is similar to the example shown in FIG. 1, but the interrogator's transmission waves are interrupted at fixed timings.

In the interrogator 101, 7 is a timing signal generation circuit, 8 is a transmission control circuit, and the transponder 102 does not have a clock oscillator.
Instead, a timing detection circuit 20 is provided.

Next, the operation of the circuit shown in FIG. 2 will be explained.

This example is basically the same as the example shown in FIG. The code circuit of the entire system is controlled at this timing.

That is, since the transponder 102 uses the timing detection circuit 20 to detect an instantaneous interruption of the received radio wave and uses it as a clock,
The constant cycle of the output of the timing signal generation circuit T is controlled by the transmission control circuit 8, which momentarily interrupts the transmission radio wave and gives it to the transponder as a bit synchronization signal, as well as the clock of the decoder inside the interrogator. The system remains bit synchronized.

There is no need to include a bit synchronization signal in the binary code string sent out by the responder.

Regarding the configuration example shown in FIG.
1, filed as Japanese Patent Application No. 54-22323, and the example shown in Figure 2 was also filed as Japanese Patent Application No. 54-22322, dated February 27, 1978.

In the example shown in FIG. 1, the interrogator is characterized by supplying drive power to the transponder and carrier wave for return radio waves, but the information transmission method of the transponder is normal wireless data transmission having an independent clock.

In the example shown in Figure 2, bit synchronization is provided by periodic momentary interruptions in the interrogator; however, if the period of interruption becomes longer, the rectified output of the transponder will decrease, and if the interruption is made shorter, the interrogator's strong radio waves will be occupied. When the frequency bandwidth is widened and the transmission speed is high, one drawback is that the reception of radio waves from the transponder is significantly interfered with.

For example, in the case of several tens of Kbps, reception is affected over a width of IMH2 or more under practical isolation conditions between transmitting and receiving antennas.

This invention was made in order to eliminate the drawbacks of the above-mentioned ones, and the transmitting wave of the interrogator is modulated with a sine wave of a constant frequency or a waveform close to this without intermittent, and the response is to receive this modulation. After demodulation, the device side shapes the signal waveform, detects the timing, and generates a clock signal.In addition, when relaying input radio waves without power, an amplitude limiting circuit is installed at the stage before modulation, and responsive transmission is performed. It has an added function to make the radio wave carrier wave a constant output.

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 101 is an interrogator, and 102 is a responder.

In the interrogator 101, 1 is a transmitter (having a modulation function)
, 2 is a transmitting antenna, 3 is a receiving antenna, 4 is a receiving detection section,
5 is an FSX demodulator, 6 is a decoder, 9 is a sine wave oscillator, 1
0 is a clock circuit.

In addition, in the transponder 102, 11 is a receiving antenna;
is a rectifier circuit, 13 is a code sending circuit, 14 is a storage device, 15 is a modulated wave oscillator, 16 is a frequency switching circuit, 18 is a transmitting antenna, 19 is a modulator, 20 is a clock signal generation circuit, 21 is a detection circuit, 22 is a waveform shaping circuit, and 23 is an amplitude limiting circuit.

Next, the operation of the circuit shown in FIG. 3 will be explained.

Microwaves generated by a transmitting section 1 having a modulation function are irradiated to a transponder via a transmitting antenna 2, then continuously enter a receiving antenna 11, and are supplied to various parts within the transponder as DC power by a rectifier circuit 12. .

The code sending circuit 13 reads the binary storage contents including the synchronization signal etc. from the storage device 14, and reads out the binary storage contents including the synchronization signal and the like.

A serial code of 0'' is used, and two modulation frequencies corresponding to this are FSKed by the frequency switching circuit 16.

Here, two frequencies are associated with two values and 7) NRZR
Z method There is an RZ method that inserts a third frequency for each bit, but there is no problem in using either method.

In addition, the oscillator may have one dedicated to each frequency, and any of the various methods used in general data transmission, such as adopting a digital signal modulation method other than FSK, can achieve the purpose, but known techniques Therefore, detailed explanation will be omitted.

However, it goes without saying that minimizing the power consumption of the transponder is an important condition for maintaining the functionality of this device.

The clock for the logic circuit operation is obtained by the clock signal generation circuit 20, and its period is given from the radio wave transmitted by the interrogator.

That is, the transmitter 1 of the interrogator has a modulation function, and receives the output of the sine wave oscillator 9 at the frequency (or 1/2) of the clock of the transponder 102 and sends out a modulated wave.

In the transponder, this is detected by the detection circuit 21 to obtain a sine wave, but as it is, accurate timing cannot be obtained, so
After the waveform shaping circuit 2 uses a so-called clipper circuit, for example, to sharpen the rising and falling edges, the clock signal generating circuit 2
0, for example a comparator.

A pulse having the repetition frequency of the sine wave (or twice that frequency) is obtained and used as a clock.

On the other hand, the response radio wave is a passive relay of the received input and re-radiated from the transmitting antenna, but on the way it is mixed with the modulated wave subjected to FSX by the modulator 19.

Sunawa. Then, secondary modulation is added.

However, when it is sent out from the interrogator, it has already been modulated and, for example, in the case of amplitude modulation, it is further modulated in the transponder, resulting in complex modulation, which may sometimes produce unnecessary components. Therefore, before modulation, the amplitude control circuit 23 will be provided.

Question - The greater the degree of modulation of the transponder, the easier it is to detect the timing of the transponder, but in order to limit the amplitude, the degree of modulation must be appropriate.

In addition, when the interrogator transmission wave is FM (PM), the amplitude is originally constant, and if the transponder is AM, there is no need to limit the amplitude, but when the transponder is FM, the frequency deviation , mutual interference occurs between the transponders, and adjustments must be made between them.

The transmission wave of the interrogator is AM, and the transponder is FM (PM).
), the amplitude limit may be considered more easily.

Each of the above circuits constituting the transponder can be achieved using known techniques for ordinary radio equipment and data transmission equipment, so individual explanations will be omitted.

The radio waves emitted by the transponder have the same center frequency as the interrogator transmission wave, and enter from the receiving antenna 3, and the modulated components by the transponder are generated by the known homodyne reception method or sidebands due to modulation of various parts within the transponder. Detection can be performed using a superheterodyne method that separates and detects waves.

In the figure, all of the components having the reception detection function are referred to as the reception detection section 4.

The FSK demodulator 5 detects the binary state of the detection output, and the decoder 6 reads the binary stored information held by the transponder using a normal data transmission method including synchronization detection error control.

The lock necessary for the decoding process is generated by a clock circuit 10 in response to the output of a sine wave oscillator 9.

There is a method to obtain timing from a sine wave, such as the so-called zero crossing method, which is similar to the timing detection in the transponder described earlier, and since the method is well known, it is generally referred to as a clock circuit in the figure.

The clocks of the code transmission systems in the interrogator and transponder have a close correlation with each other, and a reliable bit period can be obtained.

Even if the transmission speed is low, the occupied frequency bandwidth of the interrogator transmission wave can be made sufficiently narrow because it is modulated by a sine wave.In the case of AM using an ideal sine wave, the width is twice the oscillation frequency. It is well known that there is.

When the oscillation waveform is distorted, harmonics are generated and the band becomes wider, but the interference to the receiving system can be calculated from the degree of attenuation relative to the fundamental wave.

Even if it is not a perfect sine wave, it can be considered as a sine wave with different harmonic content, such as a rectangular wave, a triangular wave, or a pulse wave, and these variations are of course included in the scope of the claims. be.

In the present invention, the interrogator is installed on the ground and the transponder is installed on the moving object, but it can be easily inferred that even if the device location is reversed, the function can be maintained based on the same principle and structure. Of course, it is included within the scope of the claims.

In addition, although the antenna is shown as having separate transmitting and receiving antennas for the interrogator and the transponder, it is also possible to use the transmitting and receiving antennas together using known technology.Furthermore, the transmitting and receiving antennas are not one each, but multiple radio waves are transmitted for each circuit in the antenna. Even if the invention is received, it has the same function and is considered to be the same as the present invention.

According to this invention, the wireless source mobile information transmission device becomes a high-performance device that can automatically identify the unique numbers of freight cars, automobiles, etc. from the ground, and since it uses digital technology, it can be mass-produced. It is inexpensive and has a wide range of uses.

In addition, the present invention provides high-speed code while increasing reception stability in a sensitive wireless data transmission system in which radio waves are irradiated to a moving object moving in front of it at high speed and the modulation state in the reflected wave is detected. Ensure bit synchronization of transmission.

Furthermore, the present invention has the effect of shortening the code string by omitting the bit synchronization signal.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are block diagrams showing an example of a conventional powerless information transmission device, and FIG. 3 is a block diagram showing an embodiment of the present invention. In the figure, 101 is an interrogator, 102 is a responder, 1 is a transmitter,
4 is a receiving section, 5 is an FSK demodulating section, 6 is a decoder, 7 is a timing signal generation circuit, 9 is a sine wave oscillator, 10 is a clock circuit, 12 is a rectifier circuit, 13 is a code sending circuit, 1
4 is a storage device, 17 is a clock oscillator, 19 is a modulator,
20 is a timing detection circuit or a clock signal generation circuit;
21 is a detection circuit, 22 is a waveform shaping circuit, and 23 is an amplitude limiting circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A rectifier circuit that converts high-frequency current induced in the antenna into direct current, a storage device that stores information in binary codes, and a code sending circuit that reads out the contents of this storage device and sends it out as a series of brigadier codes. a detection circuit for detecting a modulated signal from input to the antenna; a waveform shaping circuit for the detected signal;
A transponder is constituted by a clock signal generation circuit that generates a fixed-period timing signal, and a modulation function that modulates the received radio wave by passing the received radio wave through an amplitude limiter using the second brigadier train. a transmission function for transmitting a radio wave modulated with a sine wave of a constant frequency; a reception detection function for receiving a radio wave returned from the transponder at the same carrier frequency as the transmitted radio wave and reading out a binary code; An information transmission device in which an interrogator is constructed of a sine wave and a clock circuit that generates a clock signal of the same frequency.