JP2000296775A - Transponder for railway by spectrum diffusion communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interrogator of a simple constitution simultaneously reading data from responders. SOLUTION: This transponder for a railway is constituted of an interrogator 1 transmitting an interrogation wave and responders 21, 22,... responding to the interrogation wave and replying data signals. The respective responders 21, 22,... output the same diffusion codes generated by a diffusion code generating circuit 21 lagged in time by a prescribed timing set value with a standard timing signal from the interrogator 1 obtained by a timing adjustment circuit 20 set to the standard according to the data signals. The interrogator 1 detects the diffusion codes included in the signals received from the respective responders by a muitiplier 13 and a correlator 14 in a bulk so as to decode the data signals from the respective responders by a decoder 16 based on the detection results, the standard timing signal, and the respective timing set values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a railway transponder for performing communication using microwaves between an interrogator and a transponder, and in particular, a plurality of transponders in response to an interrogation signal from the interrogator. The present invention relates to a transponder for a railway using a spread spectrum communication method for returning a spread spectrum data signal.

[0002]

2. Description of the Related Art Spread spectrum communication systems generally include:
A method in which a carrier modulated with a spread code (pseudo-noise code) having a sufficiently wider spectrum width than an information signal is modulated with an information signal and transmitted, and the receiving side selectively receives only a signal modulated with the spread code. It is. Since such a communication system selectively receives only a signal modulated by a specific spreading code, it has an excellent confidentiality and a function of removing various interference waves and noise. Also, from these features,
If signals modulated with different spreading codes are used in many communication channels, each channel can share the same frequency band.

When the above spread spectrum communication system is introduced into a communication system using an interrogator and a transponder, a different spread code is assigned to each of a plurality of transponders, so that one data from each transponder is stored. Can be read at the same time with the interrogator.

[0004] When such a communication system is applied to a railway transponder, applications where simultaneous reading of a plurality of transponders is necessary include a case where both an interrogator and a transponder are installed on the ground, and a case where one interrogator or a transponder is used (interrogator or responder). Device on a car and the other (interrogator or transponder) on the ground.

[0005]

However, in the conventional transponder for railways using the spread spectrum communication method, in order for one interrogator to read data of a plurality of transponders at the same time, a plurality of interrogators are required. Since the same number of receiving circuits (correlators) as the transponders are required, there is a disadvantage that the outer shape of the apparatus is increased and the cost is further increased.

The present invention has been made in view of the above points, and a railway transponder based on a spread spectrum communication system which realizes a simple interrogator capable of reading data from a plurality of transponders at the same time. The purpose is to provide.

[0007]

One aspect of the present invention to achieve the above object is to provide an interrogator for transmitting an interrogation signal and a spread spectrum processing when receiving the interrogation signal from the interrogator. A plurality of transponders for returning the data signal to the interrogator, and a transponder for a railway using a spread spectrum communication system, wherein each of the plurality of transponders uses the same spread code in each transponder to generate a spectrum. The spread-processed data signal is returned to the interrogator at a time shifted by a different timing set value for each transponder based on a reference timing signal sent from the interrogator, and the interrogator receives the data signal. Detection of whether or not the signal from each of the transponders includes the spreading code is performed collectively, the detection result, and the reference timing signal and each of the Based on the timing set value, the is obtained so as to recognize the data signal from each transponder.

According to this configuration, each transponder receiving the interrogator signal and the reference timing signal transmitted from the interrogator performs a spread spectrum process on the data signal by using the same spreading code in each transponder. The processed signal is temporally shifted by a timing set value with respect to the reference timing signal and returned to the interrogator. The interrogator that has received the signals returned from each transponder with a time difference detects the spread codes included in each received signal collectively, and based on the detection result, the reference timing signal, and each timing set value,
Recognize the data signal from each transponder. As a result, one signal is returned from the plurality of transponders in response to the interrogation signal.
The reception processing is simultaneously performed by two correlators (corresponding to the spread code detection function of the interrogator).

[0009] As a specific configuration of the railway transponder, each of the transponders has the same receiving unit for receiving the interrogation signal and the reference timing signal transmitted from the interrogator, and the transponders have the same configuration. Generate a spreading code, based on the reference timing signal received by the receiving unit,
In accordance with a data signal synchronized in time by the timing set value, according to a spread code generator that outputs the spread code, and an output signal from the spread code generator,
A modulator for modulating the interrogation signal received by the receiver and returning the interrogator to the interrogator.

Further, the interrogator generates and transmits the interrogation signal and the reference timing signal, a signal receiver for receiving a signal returned from each of the responders, and a signal receiver. An extracting unit for extracting a signal including the spreading code from the signal received at the step S, a reference spreading code generating unit for generating the same reference spreading code as the spreading code used in each of the transponders, Using a reference spreading code generated by the unit, a spreading code detecting unit that detects the spreading code from the signal extracted by the extracting unit, and based on the reference timing signal and each of the timing setting values,
A data signal recognizing unit that determines which of the transponders the detection result of the spread code detecting unit corresponds to and recognizes a data signal from each transponder may be provided.

According to another aspect of the present invention, there is provided an interrogator for transmitting an interrogation signal, and a plurality of data signals which are subjected to spread spectrum processing to the interrogator when receiving the interrogation signal from the interrogator. And a transponder for a railway by a spread spectrum communication system including a transponder, wherein each of the plurality of transponders returns, to the interrogator, a data signal subjected to spread spectrum processing using a different spreading code for each transponder. , The interrogator performs detection on a time-division basis as to whether or not the received signal from each of the transponders includes the spread code, and based on the detection result, converts the data signal from each of the transponders. It is intended to be recognized.

According to this configuration, each transponder that has received the interrogator signal transmitted from the interrogator returns a data signal that has been subjected to spectrum spread processing using a different spreading code in each transponder to the interrogator. The interrogator receiving the signal returned from each transponder recognizes the data signal from each transponder based on the detection result of time-divisionally detecting each spread code included in the received signal. Even if you do this,
The signals returned from multiple transponders in response to the interrogation signal
One correlator (corresponding to the spread code detection function of the above interrogator)
At the same time.

As a specific configuration of the railway transponder, each of the transponders receives a query signal transmitted from the interrogator, and a different spread code for each transponder. A spreading code generator for generating and outputting the spreading code according to the data signal; and a modulation for modulating the interrogation signal received by the receiving unit and returning the interrogator according to the output signal from the spreading code generator. And a unit.

Further, the interrogator generates and transmits the interrogation signal, a signal transmitter, a signal receiver for receiving a signal returned from each transponder, and a signal received by the signal receiver. An extraction unit for extracting a signal including each of the spread codes from a reference spread code generation unit for respectively generating the same reference spread code as each of the spread codes; and a reference spread code generated by the reference spread code generation unit. And a reference spreading code switching unit that sequentially switches and outputs any one of them according to a preset switching control signal, and a reference spreading code that is output from the reference spreading code switching unit. A spreading code detecting unit for detecting each of the spreading codes from the received signal, and determining, based on the switching control signal, which of the transponders the detection result of the spreading code detecting unit corresponds to. No Recognizing the data signal recognizing section data signal, it may be provided with a.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of a railway transponder according to the first embodiment.

In FIG. 1, the basic configuration of the railway transponder according to the first embodiment includes, for example, an interrogator 1 for transmitting an interrogation wave, which is an interrogation signal, and data in response to the interrogation wave from the interrogator 1. And a plurality of transponders 2 ₁ , 2 ₂ …
Consists of One of the features of the present system is that each of the transponders 2 ₁ , 2 _2, ... Replies to the interrogator 1 a data signal in which the same spread code is time-shifted and spread.

The interrogator 1 includes an interrogator generator 10, a timing signal generator 11, antennas 12a and 12c,
A multiplier 13 as an extraction unit, a correlator 14 as a spreading code detection unit, a spreading code generation circuit 15 as a reference spreading code generation unit, and a decoder 16 as a data signal recognition unit
And

The interrogator 10 is composed of the transponders 2 ₁ , 2 ₂ .
Generates a query wave that asks for a response from This question wave,
The signal is transmitted from the antenna 12a to the outside via the timing signal generation circuit 11, and is also transmitted to the multiplier 13.

The timing signal generation circuit 11 generates a reference timing signal which is repeated at a constant cycle, and modulates the interrogation wave from the interrogation wave generator 10 in accordance with the timing signal only when transmitting the reference timing signal to the outside. Otherwise, the interrogator transmits the interrogation wave without performing any processing and transmits the interrogation wave to the outside via the antenna 12a. Also,
The above reference timing signal is also sent to the decoder 16.

Therefore, here, the interrogation wave generator 10,
The timing signal generation circuit 11 and the antenna 12a function as a signal transmission unit. The multiplier 13 removes the interrogation wave included in the reception signal by multiplying the reception signal received by the antenna 12c as the signal reception unit by the interrogation wave from the interrogation wave generator 10, and includes the spreading code. It demodulates data signal components. The signal processed by the multiplier 13 is sent to the correlator 14.

The correlator 14 receives the signal from the multiplier 13 and
The correlation with the reference spreading code sent from the spreading code generation circuit 15 is obtained, and the result is sent to the decoder 16. The spread code generating circuit 15 is a circuit that generates the same reference spread code as the spread code generated in each of the transponders 2 ₁ , 2 ₂ .

The decoder 16 includes a timing signal generation circuit 1
1 and each transponder 2 ₁ , 2 ₂ ...
A decoding process of an output signal from the correlator 14 is performed based on a timing setting value set in advance for each
Reproduce the data signal transmitted from ₁ , 2 ₂ .

Each of the transponders 2 ₁ , 2 ₂ ... Has the same configuration, and includes a timing adjustment circuit 20, a spreading code generation circuit 21, a modulator 22, and antennas 23 a, 23 b, 23.
c. Note that the antennas 23a and 23c may be the same antenna.

The timing adjustment circuit 20 receives a signal transmitted from the antenna 12b of the interrogator 1 (a signal obtained by modulating an interrogation wave according to a reference timing signal) via the antenna 23b, and generates a reference timing signal based on the received signal. Is performed. Then, the demodulated reference timing signal is adjusted according to a preset timing set value,
A timing setting signal for setting the output timing of a signal transmitted from the transponder to the interrogator 1 is generated and sent to the spreading code generation circuit 21.

The spread code generation circuit 21 generates a spread code (pseudo noise code) consisting of a predetermined code sequence, and modulates the spread code according to a data signal synchronized with a timing setting signal from the timing adjustment circuit 20. 22. Here, it is assumed that, for example, when the data signal is “1”, the spread code is output, and when the data signal is “0”, the output of the spread code is stopped. Therefore, the spreading code generation circuit 2
In the case of 1, a signal obtained by spectrum-spreading a data signal using a predetermined spreading code is output in synchronization with the timing setting signal.

The timing set value and the data signal may be externally supplied or may be stored in advance in the timing adjustment circuit 20. Although the output of the spread code is stopped when the data signal is "0", the present invention is not limited to this, and the spread code is different from the spread code output when the data signal is "1". May be output when the spread code is “0”. In this case, the interrogator 1 may perform the data signal decoding process using two correlators or the like corresponding to the respective spread codes.

The modulator 22 is connected to the antenna 12a of the interrogator 1.
A signal (interrogation wave) transmitted from the antenna 23a and received by the antenna 23a is modulated according to a signal (a signal obtained by spectrum-spreading a data signal by a spread code) from the spread code generation circuit 21 and transmitted outside via the antenna 23c. That is, here, the interrogation wave is used as a carrier wave in the spread spectrum communication system. The respective signals transmitted from the antennas 23c of the transponders 2 ₁ , 2 ₂ ... Are received by the antenna 12c of the interrogator 1. Further, the antennas 23a and 23c may be the same.

Therefore, here, the antennas 23a,
23b functions as a receiving unit, and the timing adjusting circuit 20
The spread code generation circuit 21 functions as a spread code generation unit, and the modulator 22 and the antenna 12c function as a modulation unit.

Next, the operation of the above-described railway transponder will be described with reference to the timing chart of FIG. First, in the interrogator 1, a reference timing signal as shown in FIG.
And an interrogation wave (not shown) is generated by the interrogation wave generator 10. This interrogation wave is sent to the timing signal generation circuit 11 and is modulated or not modulated according to the reference timing signal and transmitted from the antenna 12a to the outside as it is.

The interrogator 1 transmitted from the interrogator 1 is received by the transponders (here, for example, the transponders 2 ₁ and 2 ₂ ). Each of the transponders 2 ₁ and 2 ₂ returns required data to the interrogator 1 in response to a signal from the interrogator 1.

More specifically, the signal transmitted from the antenna 12a of the interrogator 1 is transmitted to the antenna 23b of each of the transponders 2 ₁ and 2 ₂ .
And a timing adjustment circuit 20 based on the received signal.
Demodulates the reference timing signal. The demodulated reference timing signal is delayed or the like according to the timing setting value, and sent to the spreading code generation circuit 21 as a timing setting signal. Here, different values are set for the respective timing setting values corresponding to the transponders 2 ₁ and 2 ₂ as shown between (A) and (B) and between (B) and (C) in FIG. ing.

The spreading code generation circuit 21 of each of the transponders 2 ₁ and 2 ₂
Then, as shown in FIGS. 2B and 2C, the data signal is synchronized with the timing setting signal from the timing adjustment circuit 20, and a predetermined spreading code is output when the data signal is "1". , "0", there is no output of the spreading code. As a result, a data signal to which a spread code is assigned is transmitted from the spread code generation circuit 21 to the modulator 22. Then, in the modulators 22 of the transponders 2 ₁ and 2 ₂ ,
The interrogator wave received from the interrogator 1 received by the antenna 23a is modulated according to the signal from the spreading code generation circuit 21 and returned to the interrogator 1 via the antenna 23c.

In the interrogator 1, the signals transmitted from the antennas 23c of the transponders 2 ₁ and 2 ₂ are received by the antenna 12c and sent to the multiplier 13. The multiplier 13 removes the interrogation wave included in the reception signal by multiplying the reception signal by the interrogation wave from the interrogation wave generation circuit 10 to perform a demodulation process of a spread code component (data signal component). . The spreading code component demodulated here is transmitted to the transponder 2
A indicates the sum of the _first spreading code and a response unit 2 ₂ of the spreading code. The signal processed by the multiplier 13 is output to the correlator 1
4

The correlator 14 calculates the correlation between the spread code included in the signal from the multiplier 13 and the reference spread code generated by the spread code generation circuit 15 and outputs the detection result. Here, as shown in FIG. 2 (D), a peak corresponding to a correlation value corresponding to one cycle of the spread code of each transponder appears and is output to the decoder 16.

The decoder 16 uses each of the transponders 2 ₁ , 2 ₂ by using a timing window shown in a shaded area in FIG. 2E and set in advance so as to correspond to each of the transponders 2 ₁ , 2 _2. Is decoded. Said timing window, based on the reference timing signal from the timing signal generating circuit 11, the transponder 2 _1, 2 ₂ ... set timing set value (between FIG. 2 (A) (B) and (B )
(See (C))) is a window for detecting a correlation value having a required time width set in accordance with (a).

[0036] Specifically the decoding process of the decoder 16, in a timing window corresponding to the responder 2 _1, the correlation value is high, that is, when the sharp peak occurs, in FIG. 2 (F) as shown, until reaching the next timing window, "1" is output as the received data for the transponder 2 _1, whereas, remains low correlation value, that is, if the sharp peak does not occur "0" Is output. Similarly, the transponder 2 _2, according to the correlation values in the corresponding the timing window, as shown in FIG. 2 (G), is "1" or "0" as received data for the transponder 2 ₂ Is output.

As described above, according to the first embodiment, in response to the signal transmitted from the interrogator 1, each of the transponders 2 ₁ ,
2 ₂ ... is returned temporally staggered data signal the same spreading code to the interrogator 1, it was so as to receive and process their signals from each transponder 2 _1, 2 ₂ ... Interrogator 1, Since the configuration of the interrogator that can read signals from a plurality of transponders at the same time is simplified, the size of the interrogator and the cost of the railway transponder can be reduced.

In the first embodiment, the method of giving the reference timing from the interrogator to the transponder by modulating the interrogation wave is adopted as the way of giving the reference timing, but the present invention is limited to this. Not something. For example, a method of giving a reference timing to the interrogator and the plurality of transponders by wire may be adopted. In this case, the generation source of the reference timing may be an interrogator, a specific transponder, or another device other than these. However, in this method, since the interrogator and the transponder are both connected by wire, the application is limited to the case where both the interrogator and the transponder are installed on the ground.

Further, for example, a method may be used in which a reference timing is given to a plurality of transponders by wire. In this method, the reference timing is not directly given to the interrogator, and the interrogator sets a timing window based on a predetermined timing setting and a correlation result of the received spread code. The source of the reference timing may be one specific transponder or another device.

Next, a second embodiment of the present invention will be described. FIG. 3 is a diagram illustrating a schematic configuration of a railway transponder according to the second embodiment. However, the same parts as those in the configuration of the first embodiment are denoted by the same reference numerals.

In FIG. 3, the basic configuration of the railway transponder of the second embodiment is the same as that of the first embodiment, except that one interrogator 3 and transponders 4 ₁ , 4 ₂ . Consists of However, one feature of the system of the second embodiment is that the transponders 4 ₁ , 4 _2, ... Can return different spreading codes to the interrogator 3 at independent timings.

The configuration of the interrogator 3 is different from the configuration of the interrogator 1 of the first embodiment in that the timing signal generation circuit 11
Are omitted, and each transponder 4 is replaced with the spreading code generation circuit 15.
_1, 4 ₂ ... spreading code generation circuit 30 ₁ as a reference spread code generating section corresponding to, 30 ₂ ..., and the reference is a portion in which a spreading code switching circuit 31 as a spreading code switching unit. The configuration of the interrogator 3 other than the above is the same as the configuration of the interrogator 1.

Each of the spread code generating circuits 30 ₁ , 30 ₂ ... Generates the same reference spread code as the spread code used in the corresponding transponders 4 ₁ , 4 ₂ .
Output to 1. The spreading code switching circuit 31 sequentially switches one of the reference spreading codes sent from each of the spreading code generating circuits 30 ₁ , 30 ₂ ... In a time-division manner in accordance with a preset switching control signal, and outputs it to the correlator 14. At the same time, the switching control signal is output to the decoder 16.

The configuration of each of the transponders 4 ₁ , 4 ₂ ... Differs from the configuration of each of the transponders 2 ₁ , 2 ₂ ... Of the _first embodiment in that the timing adjustment circuit 20 and the antenna 23 b are omitted. . The configuration of each of the transponders 4 ₁ , 4 ₂ ... Other than the above is the same as the configuration of each of the transponders 2 ₁ , 2 ₂ .

Next, the operation of the second embodiment will be described with reference to FIG.
This will be described with reference to the timing chart of FIG. First, an interrogation wave is generated by the interrogation wave generator 15 of the interrogator 3 and the antenna 1
The message is transmitted from 2a to the outside. Then, the transmitted interrogation waves are received by transponders (here, for example, transponders 4 ₁ and 4 ₂ ), and each transponder 4 ₁ and 4 ₂ transmits required data in response to the interrogation waves. Reply to interrogator 3.

More specifically, in the spread code generation circuit 21 of each of the transponders 4 ₁ and 4 _2, a spread code having a code sequence different from each other is generated, and the spread code is generated by the modulator 22 according to the data signal. Is output to FIG. 4 (A) (B)
Shows respective data signals input to the spreading code generation circuit 21 of each of the transponders 4 ₁ and 4 ₂ . Here, as in the case of the first embodiment, it is assumed that the spread code is output when the data signal is "1" and the spread code is not output when the data signal is "0". Then, in the modulators 22 of the transponders 4 ₁ and 4 ₂ , the interrogator 1 received by the antenna 23 a from the interrogator 1 is modulated according to the signal from the spreading code generation circuit 21, and is interrogated via the antenna 23 c. Reply to 3.

In the interrogator 3, signals from the transponders 4 ₁ and 4 ₂ are transmitted to the antenna 12 in the same manner as in the first embodiment.
c and is sent to the multiplier 13, where the multiplier 13
The interfering wave included in the received signal is removed, and the spread code component (data signal component) is demodulated. The diffusion code component to be demodulated herein is as shown the sum of the responder 4 ₁ spreading code and the responder 4 ₂ spreading codes. And a multiplier 1
The signal processed in 3 is sent to the correlator 14.

In the correlator 14, the correlation between the spread code included in the signal from the multiplier 13 and the spread code sent from the spread code switching circuit 31 is obtained. It is assumed that the switching operation of the spreading code switching circuit 31 follows a time period, for example, as shown in FIG. More specifically, if a signal from the multiplier 13 contains a spread code while the spread code is being sent from the spread code switching circuit 31 to the correlator 14, as shown in FIG. , A peak corresponding to one cycle of the spread code is output to the decoder 16 as a correlation value. The same operation as described above is performed while the spread code is being sent from the spread code switching circuit 31 to the correlator 14.

In the decoder 16, when the correlation value from the correlator 14 becomes high (a sharp peak is generated), the decoder 16 shown in FIG.
As shown in (E), the decoded data is “1” for a period corresponding to one cycle of the spread code, and when the correlation value remains low, the decoded data is “0”. Then, the decoded data described above, in accordance with switching control signals from spreading code switching circuit 31 as the reception data corresponding to the responder 4 ₁ or responder 4 _2, are outputted from the decoder 16 to the outside. That is, while the switching control signal indicates that the spreading code switching circuit 31 is outputting a spreading code, FIG.
As shown in (F), during which the decoded data is output as reception data corresponding to the responder 4 _1, the diffusion code switching circuit 31 that outputs a spreading code indicated by the switching control signal As shown in FIG. 4 (G),
It said decoded data is output as reception data corresponding to the responder 4 _2.

As described above, according to the second embodiment, each of the transponders 4 ₁ , 4 _2, ... Replies to the interrogator 3 at independent timings the data signals that have been spectrum-spread by different spreading codes. Even if the signals from the transponders are read simultaneously by the interrogator 3 and time-division-processed in accordance with the switching control signal, the configuration of the interrogator 3 can be simplified. Therefore, as in the first embodiment, The size of the interrogator and the cost of the railway transponder can be reduced.

[0051]

As described above, according to the present invention,
In response to the signal transmitted from the interrogator, a plurality of transponders return the data signal obtained by spreading the same spreading code in time and spectrum spreading to the interrogator, and the signals from the respective transponders are interrogated. , The interrogator capable of simultaneously receiving and processing signals from a plurality of transponders can be realized with a simple configuration, so that the interrogator can be downsized and the cost of the railway transponder can be reduced. Can be.

Also, a plurality of transponders may return data signals spread spectrum by different spreading codes to the interrogator, and the interrogators may receive signals from the transponders in a time-division manner. Since the configuration of the interrogator can be simplified, the same effect as described above can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a railway transponder according to a first embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the first embodiment.

FIG. 3 is a diagram showing a schematic configuration of a railway transponder according to a second embodiment of the present invention.

FIG. 4 is a timing chart for explaining the operation of the fourth embodiment.

[Explanation of symbols]

1, 3 Interrogators 2 ₁ , 2 ₂ ..., 4 ₁ , 4 ₂ ... Transponders 10 Interrogator generators 11 Timing signal generators 12 a, 12 b, 12 c, 23 a, 23 b, 23 c Antennas 13 Multipliers 14 Correlators 15, 21, 30 ₁ , 30 ₂ ... Spreading code generating circuit 16 Decoder 20 Timing adjusting circuit 22 Modulator 31 Spreading code switching circuit

Claims (6)

[Claims] 1. A spectrum comprising: an interrogator for transmitting an interrogation signal; and a plurality of transponders for returning a data signal subjected to spread spectrum processing to the interrogator when receiving an interrogation signal from the interrogator. In the railway transponder by the spread communication method, each of the plurality of transponders, a data signal subjected to spread spectrum processing using the same spread code in each transponder,
On the basis of the reference timing signal sent from the interrogator, the interrogator replies to the interrogator at a time shifted by a different timing setting value for each transponder, and the interrogator receives the response from each of the transponders. The detection of whether or not the signal includes the spreading code is performed collectively, and based on the detection result, the reference timing signal and each of the timing setting values, the data signal from each of the transponders is recognized. A transponder for railways using the spread spectrum communication method. 2. Each of the transponders receives a query signal and a reference timing signal transmitted from the interrogator, and each of the transponders generates the same spreading code. A spreading code generator that outputs the spreading code in accordance with a data signal synchronized with a time shift by the timing set value with respect to the received reference timing signal, and an output signal from the spreading code generator. The transponder for a railway according to the spread spectrum communication method according to claim 1, further comprising: a modulator that modulates an interrogation signal received by the receiver and returns the interrogator to the interrogator. 3. A signal transmitter for generating and transmitting the interrogator and the reference timing signal, a signal receiver for receiving a signal returned from each responder, and the signal receiver. An extraction unit for extracting a signal including the spreading code from the signal received in the step; a reference spreading code generating unit for generating a reference spreading code identical to a spreading code used in each of the transponders; A spreading code detecting unit that detects the spreading code from the signal extracted by the extracting unit using a reference spreading code generated by the extracting unit; and a spread code detecting unit that detects the spread code based on the reference timing signal and each of the timing setting values. 3. A data signal recognizing unit that determines which of the transponders the detection result of the unit corresponds to and recognizes a data signal from each transponder. Railway for the transponder by the spread spectrum communication system. 4. A spectrum comprising: an interrogator for transmitting an interrogation signal; and a plurality of transponders for returning a data signal subjected to spread spectrum processing to the interrogator when receiving an interrogation signal from the interrogator. In the railway transponder by the spread communication method, each of the plurality of transponders returns a data signal subjected to spectrum spread processing using a different spreading code for each transponder to the interrogator, and the interrogator receives the data signal. Detecting whether or not the signal from each of the transponders includes each of the spread codes in a time-division manner, and recognizing a data signal from each of the transponders based on the detection result. A transponder for railways using the diffusion communication method. 5. Each of the transponders receives a query signal transmitted from the interrogator, generates a different spread code for each of the transponders, and converts the spread code into a data signal. A spreading code generating unit that outputs a response signal to the interrogator according to an output signal from the spreading code generating unit. A transponder for a railway according to the spread spectrum communication method according to claim 4. 6. A signal transmitting section for generating and transmitting the interrogation signal, a signal receiving section for receiving a signal returned from each of the transponders, and a signal received by the signal receiving section. An extraction unit for extracting a signal including each of the spread codes from a reference spread code generator that generates the same reference spread code as each of the spread codes; and a reference spread code generated by the reference spread code generator. A reference spreading code switching unit that sequentially switches and outputs any one of them according to a preset switching control signal; and a reference spreading code that is extracted by the extracting unit using a reference spreading code output from the reference spreading code switching unit. A spreading code detection unit that detects each of the spreading codes from the received signal, based on the switching control signal, determines which of the transponders corresponds to the detection result of the spreading code detection unit. data from Railway transponder by spread spectrum communication system according to claim 4 or 5, characterized in that it comprises a recognizing data signal recognizing section No..