JP2021030920A - Rail breakage detection device - Google Patents

Abstract

To provide a technique for a novel rail breakage detection device which has improved detection capability of rail breakages and is not influenced by a train current.SOLUTION: A rail breakage detection device 1 includes a signal generating part 10 which modulates a coded signal with spread spectrum to generate a transmission signal S, and outputs the transmission signal S from a signal input point si of each section Ti to a rail, a signal acquisition detection part 30 which tries modulation with spread spectrum to reception signals Ri1, Ri2 input from signal output points ri1, ri2 of each section Ti, and detects that acquisition of the reception signals Ri1, Ri2 succeeded, and a breakage determination part 50 which judges rail breakage for each section Ti on the basis of a detection result of the signal acquisition detection part 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rail rupture detection device that detects rail rupture.

Conventionally, in railways, detection of rail breakage has been realized as a secondary function of track circuits. The track circuit uses the fact that the reception level of the signal transmitted from the transmitting side of the track circuit decreases on the receiving side due to the short circuit between the left and right rails on the wheelset of the train, and the train is placed in the track circuit. It is a device that detects that the train is on the line. Since the reception level is lowered even when the rail break occurs, the track circuit can detect the rail break secondarily.

In recent years, the development of a train control system using wireless communication between the ground and the vehicle, which has made it possible to reduce costs and realize high-density train operation, has been promoted. In such a system, a track circuit is often not installed because the train position is acquired on the vehicle. Therefore, it is required to separately provide a rail breakage detection device. In order to meet this demand, for example, Patent Document 1 discloses a rail breakage detection device with reduced cost.

Japanese Unexamined Patent Publication No. 2011-225192

The rail breakage detection device using the track circuit as disclosed in Patent Document 1 described above transmits a detection signal to the rail, and detects the rail breakage by lowering the reception level thereof. In this case, a train current much larger than the signal current of the detection signal flows through the track circuit, but the train current is divided into two parallel rails to have substantially the same magnitude and flows in the same direction. In the state where the rail breakage does not occur, the rail breakage detection signal flows back to the parallel rails of the track circuit, so the effect of the train current on the detection signal is the difference between the currents flowing in parallel in the same direction. .. However, when the rail is broken, the train current flows only to the healthy rail where the rail is not broken, and all of this becomes an interfering wave to the detection signal, so the S / N (Signal-to-Noise) ratio deteriorates significantly. However, the ability to detect rail breakage may decrease.

In addition, since the frequency of rail breakage is low, it is conceivable that a relatively long section such as between stations may be set as one detection target section in order to reduce costs. However, in that case, since the attenuation of the detection signal flowing through the rail becomes large, the influence of the noise and the disturbing wave due to the above-mentioned train current becomes stronger, and it is considered that the detection ability of the rail breakage is further lowered.

Further, the rail breakage detection device that detects a decrease in reception level using a track circuit not only detects rail breakage, but also detects the presence of a train, that is, a traveling train. While the frequency of breakage of rails, which are lumps of iron, is extremely low, the detection of running trains is orders of magnitude higher. Therefore, if the rail rupture and the train are not separated, it is possible that the rail rupture detection will be overlooked. Therefore, it is necessary to detect only the rail rupture.

An object to be solved by the present invention is to provide a technique of a new rail rupture detection device having enhanced rail rupture detection capability, which is not affected by train current.

The first invention for solving the above problems is
It is a rail rupture detection device that detects rail rupture in each of a plurality of sections that divide the track on which the train travels.
A predetermined coded signal is modulated by a predetermined multi-frequency utilization modulation method to generate a plurality of transmission signals having different frequencies, and at signal input points defined on rails of each section so that the frequencies are different in the adjacent sections. A signal generator that outputs the transmission signal and
Each received signal input from the signal output point defined on the rail of each section can be demodulated by a demodulation method corresponding to the multi-frequency utilization modulation method, and the received signal can be decoded into the coded signal. A signal capture detection unit that detects that signal acquisition was successful for each section when a predetermined demodulation success condition is reached before reaching the state.
A rupture determination unit that determines rail rupture for each section based on the detection result of the signal acquisition detection unit, and a rupture determination unit.
It is a rail breakage detection device equipped with.

According to the first invention, a transmission signal transmitted to a rail is modulated by a predetermined multi-frequency utilization modulation method to be generated, and demodulation of the reception signal from the rail is attempted to detect whether the signal acquisition is successful. This makes it possible to detect rail breakage. In other words, even if the received signal was not decoded to the original coded signal, the demodulation method corresponding to the multi-frequency utilization modulation method at the time of transmission was able to achieve the demodulation success condition, that is, the signal was successfully captured. With the detection, it can be confirmed that the received signal must be a proper signal. This makes it possible to capture signals even under the influence of noise and interference waves caused by train currents, greatly improving noise resistance and interference resistance characteristics, and realizing a rail breakage detection device with high rail breakage detection capability. it can. In addition, since the transmission signal is output to each of a plurality of sections so that the frequencies are different in the adjacent sections, the signal of the frequency of the transmission signal input to the section is selected and input as the reception signal to be input from each section. Can be done.

The second invention is the first invention.
The rupture determination unit determines the rail rupture based on the undetected section when the undetected section by the signal acquisition detection unit is not sequentially switched along the track.
It is a rail breakage detection device.

According to the second invention, it is possible to distinguish between the undetected success of signal acquisition due to the train presence and the undetected success of signal acquisition due to rail breakage. Even when the train is on the track, the rails are short-circuited by the wheel sets of the train, so the transmission signal is not received and the success of signal acquisition is not detected. Therefore, the undetected section of successful signal acquisition changes sequentially along the orbit. On the other hand, when the rail breaks, the success of signal acquisition is not detected only in the section where the rail breaks. From this, it can be determined that the rail is broken when the section in which the success of signal acquisition has not been detected is not sequentially switched along the track.

The third invention is the first or second invention.
The signal generation unit performs primary modulation in the multi-frequency utilization modulation method by spread coding of the coded signal using a predetermined spreading code, and modulates a predetermined carrier wave with the primary modulated signal. Secondary modulation is performed to generate the transmission signal,
The signal capture detection unit corresponds to the multi-frequency utilization modulation method by despreading and decoding the received signal by demodulating the signal corresponding to the secondary modulation using the diffusion code. Trial demodulation by the demodulation method
It is a rail breakage detection device.

According to the third invention, a transmission signal can be generated by performing spread spectrum modulation as a multi-frequency utilization modulation method for a coded signal.

The fourth invention is the first or second invention.
The signal generation unit uses the multi-frequency by OFDM (Orthogonal Frequency Division Multiplexing) that synthesizes each signal by converting the coded signal into parallel signals for the number of subcarriers and then performing subcarrier modulation and inverse Fourier conversion. The transmission signal is generated by performing primary modulation by a modulation method and performing secondary modulation in which a predetermined carrier is modulated by the primary modulated signal.
The signal capture / detection unit serializes parallel signals for the number of subcarriers obtained by performing Fourier conversion and subcarrier demodulation on the signal obtained by demodulating the received signal corresponding to the secondary modulation. By converting to, the demodulation by the demodulation method corresponding to the multi-frequency utilization modulation method is tried.
It is a rail breakage detection device.

According to the fourth invention, a transmission signal can be generated by performing OFDM modulation as a multi-frequency utilization modulation method for a coded signal.

The fifth invention is the fifth invention in any one of the first to fourth inventions.
An AGC control unit that adjusts the level of the received signal so that the level of the received signal is within a predetermined threshold level range, and when the level change of the received signal satisfies a steep change condition, the received signal of the received signal AGC control unit to stop level adjustment,
It is a rail breakage detection device further equipped with.

According to the fifth invention, it is possible to improve the detection accuracy of rail breakage by adjusting the level so as to follow the decrease in the level of the received signal. The level of the received signal may decrease due to ballast subsidence due to repeated train passages and changes in the trackbed due to changes over time due to environmental changes. Also, the level of the received signal drops when the train passes. Comparing the two over time, the decrease in the level of the received signal due to the track bed fluctuation is small and the decrease is slow, but the decrease in the level of the received signal when the train passes is after a sharp decrease. It makes a sharp change such as returning to the original level. Therefore, it is determined whether or not the level change (decrease) of the received signal is due to the passage of the train depending on whether or not the level change of the received signal satisfies the steep change condition. The accuracy of demodulation and signal capture success / failure judgment for the received signal is performed by adjusting the level of the received signal so that it falls within a predetermined threshold level range as a follow-up control for a slow decrease in the level of the received signal due to roadbed fluctuations, etc. Can be enhanced.

The block diagram of the rail breakage detection device. The block diagram of the signal generation part. The block diagram of the signal acquisition detection part. An example of rail rupture determination by the rupture determination unit. An example of rail rupture determination by the rupture determination unit. An example of rail rupture determination by the rupture determination unit. The block diagram of the parallel signal generation part in the case of generating a transmission signal using OFDM. The block diagram of the parallel capture detection part in the case of generating a transmission signal using OFDM.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the embodiments described below do not limit the present invention, and the embodiments to which the present invention can be applied are not limited to the following embodiments. Further, in the description of the drawings, the same elements are designated by the same reference numerals.

[Constitution]
FIG. 1 is a configuration diagram of the rail breakage detection device 1 of the present embodiment. The rail rupture detection device 1 is a device that detects rail rupture of each of a plurality of sections Ti (i = 1, 2, ..., N) that divide the track 3 on which the train travels.

One signal input point si and two signal output points ri1 and ri2 are defined in each section Ti. The signal input point s is defined in the center of the section T, and the signal output points r are defined at both ends of the section T. The signal input point s and the signal output point r are electrical contacts between the rail and the rail breakage detection device 1, and signals are input and output to and from the rail via a matching transformer connected between two pairs of left and right rails. Will be done. The rail breakage detection device 1 outputs a transmission signal S to the rail from the signal input point s of the section T in parallel with each of the plurality of sections T, and receives input from the signal output point r of the section T. The rail breakage of the section T is determined based on the signal R.

The rail rupture detection device 1 includes a signal generation unit 10, a signal capture detection unit 30, and a rupture determination unit 50.

The signal generation unit 10 generates a plurality of transmission signals S having different frequencies after modulating the rail breakage detection signal, which is a predetermined coded signal, by spread spectrum, which is one of the multi-frequency utilization modulation methods. , The transmission signal S is transmitted to the signal input points s defined on the rails of each section T so that the frequencies are different in the adjacent sections T.

As shown in FIG. 2, the signal generation unit 10 has a plurality of parallel signal generation units 20-j (j = 1, 2, ..., M: 2 ≦ m ≦ n). The number m of the parallel signal generation unit 20 is not more than the number of sections n. The parallel signal generation unit 20 includes a detection signal generation unit 21 and a modulation unit 29. The modulation unit 29 includes a diffusion code generation unit 22, a diffusion coding unit 23, a carrier wave generation unit 24, and a carrier wave modulation unit 25. The detection signal generation unit 21 generates a rail breakage detection signal which is a coded signal. The diffusion code generation unit 22 generates a pseudo noise code (hereinafter, referred to as “PN code”) which is a diffusion code according to a clock signal (not shown). The diffusion coding unit 23 performs first-order modulation by spread spectrum by multiplying the rail breakage detection signal generated by the detection signal generation unit 21 and the PN code generated by the diffusion code generation unit 22 to perform diffusion coding. Generate a signal. The carrier wave generation unit 24 generates a carrier wave having a predetermined frequency. The carrier wave modulation unit 25 performs secondary modulation for modulating the carrier wave with the spread coded signal by multiplying the spread coded signal generated by the spread code unit 23 and the carrier wave generated by the carrier wave generation unit 24. A modulation signal H (H1, H2, ..., Hm) is generated. The modulated signal H is output to each section T and is used as a transmission signal S. The modulated signal Hx corresponds to the transmission signals Sx, Sm + x, S2m + x, ... (X = 1, 2, ...).

The carrier wave generation unit 24 generates a carrier wave having a frequency f (f1, f2, ..., Fm) different for each parallel signal generation unit 20. The frequency f (f1, f2, ..., Fm) of the carrier wave generated by each carrier wave generation unit 24 has a frequency band of the modulated signal H (H1, H2, ..., Hm) after modulation by the carrier wave modulation unit 25. In terms of frequency, it is defined so that the frequency band of adjacent modulation signals H and at least a predetermined frequency band Δf are not superimposed. More specifically, the PN codes generated by the diffusion code generation units 22 of the parallel signal generation units 20 have the same code, and the signals of the PN code have the same frequency. Therefore, by setting the frequency fj of the carrier wave in a frequency band Δf wider than the signal frequency bandwidth of the PN code, it is determined that the frequencies of the adjacent modulated signals H do not overlap. Then, each of the signal generation units 10 uses the modulation signal H generated by each parallel signal generation unit 20 as the transmission signal S so that the frequency f of the transmission signal S output to each section T repeats in a predetermined order along the orbit 3. Output to the rail from the signal input point s in section T. In FIG. 2, the modulation signal H1 of the carrier wave of the frequency f1 is output as the transmission signal S in the sections T1, Tm + 1, T2m + 1, ..., And the modulation of the carrier wave of the frequency f2 in the sections T2, Tm + 2, T2m + 2, ... The modulated signal H of m kinds of frequencies fj (j = 1, 2, ..., M) is repeated along the orbit 3 as the transmission signal S, such that the signal H2 is output as the transmission signal S. It is output to each section T.

Returning to FIG. 1, the signal capture detection unit 30 attempts demodulation by spread spectrum for each received signal R input from the signal output point r defined on the rail of each section T, and detects the received signal R as rail breakage. It detects that the signal has been successfully captured when a predetermined demodulation success condition is reached before the signal can be decoded. It is not necessary to decode the rail breakage detection signal from the received signal R.

As shown in FIG. 3, the signal acquisition detection unit 30 has a plurality of parallel acquisition detection units 40-k (k = 1, 2, ..., 2n). Two signal output points ri1 and ri2 are defined in each section Ti, and since the received signals Ri1 and Ri2 are input from each signal output point ri1 and ri2, 2n parallel acquisitions, which is twice the number of sections n, are captured. It will have a detection unit 40 (see FIG. 1). The parallel capture detection unit 40 includes an AGC control unit 41 and a demodulation unit 49. The demodulation unit 49 includes a carrier wave generation unit 42, a carrier wave signal removal unit 43, a diffusion code generation unit 44, a reverse diffusion decoding unit 45, and a synchronous capture unit 46.

The AGC control unit 41 adjusts the level of the received signal R so that the level of the received signal R falls within a predetermined threshold level range. When the level change of the received signal R satisfies the steep change condition, the level adjustment of the received signal R is stopped, and the adjusted value at the time of the stop is maintained as it is. After that, when the steep change condition is no longer satisfied, the level adjustment of the received signal R is restarted from the held adjustment value. The steep change condition is a condition in which the level of the received signal R is considered to have changed sharply. Specifically, when a train travels on track 3, the left and right rails are short-circuited by the wheel sets of the train, so that the level of the received signal R drops significantly in a short time, and the train passes through and is short-circuited by the wheel sets. When is finished, it makes a sharp change such as returning to the original level immediately after. The steep change condition is a condition for determining a steep level change of the received signal when the train passes. A circuit that updates and holds the input signal level at any time, and the difference between the signal level immediately before being held in the circuit and the signal level input this time are compared with a predetermined threshold value, and a difference exceeding the threshold value occurs. In this case, a comparison circuit for determining that the steep change condition is satisfied and a circuit for determining whether or not the steep change condition is satisfied can be configured.

In addition, the level of the received signal R may decrease due to ballast subsidence due to repeated train passages and changes in the trackbed due to changes over time due to environmental changes, etc., but this level decrease is compared to when the train passes. , The degree of decrease is small, and the decrease is slow. Therefore, the AGC control unit 41 determines whether or not the level change (decrease) of the received signal R is due to the passage of the train depending on whether or not the level change of the received signal R satisfies the steep change condition, and the roadbed change or the like. The level of the received signal R can be adjusted so as to be within a predetermined threshold level range so as to follow the slow decrease in the level of the received signal R due to the above. This makes it possible to improve the accuracy of demodulation of the received signal R and the success / failure determination of signal capture, and as a result, the accuracy of detecting rail breakage.

The carrier wave generation unit 42 generates a carrier wave having the same frequency as the carrier wave generated by the carrier wave generation unit 24 of the parallel signal generation unit 20. That is, a carrier wave having the same frequency as the carrier wave used when generating the transmission signal S output to the signal input point s in the same section T as the signal output point r of the received signal R input to the carrier wave generation unit 42 is generated. To do. The carrier wave signal removing unit 43 is a functional unit that demodulates the received signal R by multiplying the received signal R output from the AGC control unit 41 and the carrier wave generated by the carrier wave generating unit 42. The carrier signal is removed. The signal after being removed is called a demodulated signal. The demodulation performed by the carrier wave signal removing unit 43 is a demodulation corresponding to the secondary modulation by the carrier wave modulation unit 25 of the parallel signal generation unit 20.

The diffusion code generation unit 44 generates a PN code which is the same diffusion code as the PN code generated by the diffusion code generation unit 22 of the parallel signal generation unit 20 according to a clock signal (not shown). The despread decoding unit 45 multiplies the demodulated signal after the carrier signal is removed by the carrier signal removing unit 43 with the PN code generated by the spreading code generating unit 44 to obtain a PN code for the demodulated signal. Perform the reverse diffusion decoding used. This reverse diffusion decoding can be said to be a trial of demodulation by spread spectrum.

The synchronous acquisition unit 46 outputs a signal indicating the phase of the PN code to be generated to the diffusion code generation unit 44, and is included in the phase of the PN code generated by the diffusion code generation unit 44 and the reception signal R. Synchronous acquisition of the received signal R that matches the phase of the PN code is performed. Specifically, the values of the signals despread-decrypted by the de-diffusion decoding unit 45 are integrated, and the diffusion code generation unit 44 is subjected to such an integrated value (which can be said to be a correlation value) as high as possible. Instructs to shift the phase of the generated PN code. The integration corresponds to a so-called cross-correlation operation. Further, when the integrated value (correlation value) of the despread-decrypted signal satisfies a predetermined peak value condition, the synchronous capture unit 46 detects that the demodulation success condition has been reached and has succeeded in capturing the received signal R. To do. The detection result of the success or failure of signal acquisition is output as the acquisition signal D.

The demodulation success condition is a condition in which the received signal R can be regarded as including the rail breakage detection signal. In the present embodiment, since the rail breakage detection signal is modulated by spread spectrum, the integrated value (correlation value) of the received signal R (more accurately, the signal despread-decoded) and the PN code has a predetermined peak. The condition for successful demodulation is that the value condition is satisfied. Since the PN code is a code having a predetermined length (for example, 64 bits), it is not the entire PN code but a part thereof (for example, when the code length is 64 bits, it is 50% 32 bits and 20% 12). It is said that the predetermined peak value condition is satisfied when the threshold value that can appear as the integrated value (correlation value) is reached when the bits (bits, 10%, 6 bits, etc.) are matched, and the demodulation success condition is reached. Can be determined.

Returning to FIG. 1, the rupture determination unit 50 determines the rail rupture for each section T based on the detection result of the signal acquisition detection unit 30. When a rail break occurs in a certain section T, the propagation of the transmission signal S is blocked at the rail break portion, so that the signal acquisition of the received signal R in the section T fails. Further, when the train travels on the track 3, the rails are short-circuited by the wheel sets of the train, so that the signal acquisition of the received signal R fails. The rupture determination unit 50 determines that the train has passed when the section T in which the signal acquisition by the signal acquisition detection unit 30 has failed, that is, the section T in which the success of signal acquisition has not been detected is sequentially switched along the track 3. If the switches are not sequentially switched, the rail breakage is determined based on the failure of the signal acquisition.

4 to 6 are examples of rail fracture determination by the fracture determination unit 50. FIG. 4 is an example of the determination result in the normal time when the rail is not broken and the train is not traveling on the track 3, and FIG. 5 is an example of the determination result when the train is traveling on the track 3 when passing through the train. It is an example of the determination result, and FIG. 6 is an example of the determination result when the rail breaks. Further, in FIGS. 4 to 6, in each of the determinations by the fracture determination unit 50 and the detection result of the signal acquisition detection unit 30, the acquisition signals Di1 and Di2 (i = 1, 2) for each section Ti at each time t. ,,,, n) indicates the success or failure of the signal capture detection. In each section Ti, since the positions of the signal output point ri1 and the signal output point ri2 are opposite to each other with respect to the signal input point si, the section Ti can be divided into two with the signal input point si as a boundary. In FIGS. 4 to 6, they are referred to as “first half” and “second half”. In the captured signal Di1 based on the received signal R1 from the signal output point ri1 and the captured signal Di2 based on the received signal R2 from the signal output point ri2, rail breakage or rail breakage or It is possible to determine the passage of a train.

The rupture determination unit 50 determines rail rupture or train passage based on the failure of signal acquisition indicated by the acquisition signal D for each section T.

As shown in FIG. 4, in the normal state, the signal acquisition of the received signal R is successful for all the sections T, and the rupture determination unit 50 determines that "normal (no rail rupture or train passage)".

Further, as shown in FIG. 5, when the train passes, the train travels along the track 3, so that the section T in which the signal acquisition of the received signal R fails is sequentially switched along the track 3 with the passage of time. The rupture determination unit 50 determines that the train has passed.

Further, as shown in FIG. 6, when the rail rupture occurs, the section T in which the signal acquisition of the received signal R fails (in FIG. 6, the first half of the section T2) is only the section in which the rail rupture occurs, and the train. There is no switching with the passage of time that the adjacent section T fails to acquire the signal before and after the signal acquisition fails in the section T as in the case of passing. In addition, the signal acquisition fails continuously in the same section T. The rupture determination unit 50 determines that "the rail ruptures in the first half of the section T2".

[Action effect]
As described above, according to the rail breakage detection device 1 of the present embodiment, the transmission signal S transmitted to the rail is modulated and generated by spread spectrum, and demodulation with respect to the received signal R from the rail is attempted to succeed in signal acquisition. Rail breakage can be detected by detecting whether or not the rail has broken. That is, even if the received signal R is not decoded into the rail breakage detection signal which is the original coded signal, the demodulation method corresponding to the multi-frequency utilization modulation method at the time of transmission can be used to achieve the demodulation success condition. By detecting that the signal has been successfully captured, it can be confirmed that the received signal must be a rail breakage detection signal, which is an appropriate signal. This makes it possible to capture the rail rupture detection signal even if it is affected by noise or interference waves due to train current, greatly improves noise resistance and interference resistance characteristics, and has high rail rupture detection capability. The detection device 1 can be realized. Further, since the transmission signal S is output to each of a plurality of sections so that the frequencies are different in the adjacent sections, the signal of the frequency of the transmission signal S input to the section is selected as the reception signal R to be input from each section. You can enter it. In addition, depending on whether the section where signal acquisition failed, that is, the undetected section where signal acquisition was successful, is sequentially switched along the track, the success of signal acquisition due to the train presence is not detected and the signal acquisition is successful due to rail breakage. Can be distinguished from undetected. Further, the AGC control unit 41 adjusts the signal level of the received signal R so as to follow the decrease in the level of the received signal R, so that the rail breakage detection ability can be improved.

It should be noted that the applicable embodiments of the present invention are not limited to the above-described embodiments, and of course, they can be appropriately changed without departing from the spirit of the present invention.

(A) Multi-frequency utilization modulation method In the above-described embodiment, the multi-frequency utilization modulation method used when generating the transmission signal S is modulation by spread spectrum, but as another modulation method, for example, OFDM (Orthogonal Frequency Division). Multiplexing (Orthogonal Frequency Multiplexing) may be used. In this case, in the rail breakage detection device 1 (see FIG. 1) of the above-described embodiment, each parallel signal generation unit 20 of the signal generation unit 10 is connected to the parallel signal generation unit 20A shown in FIG. 7, and each of the signal capture detection units 30. This can be realized by replacing the parallel capture detection unit 40 with the parallel capture detection unit 40A shown in FIG.

As shown in FIG. 7, the parallel signal generation unit 20A in the rail breakage detection device using OFDM includes a detection signal generation unit 21 and a modulation unit 29A. The modulation unit 29A includes an OFDM modulation unit 26 that primaryly modulates the rail breakage detection signal generated by the detection signal generation unit 21, a carrier wave generation unit 24, and a carrier wave modulation unit 25. The OFDM modulation unit 26 converts a rail breakage detection signal, which is a serial signal generated by the detection signal generation unit 21, into parallel signals for a predetermined number of subcarriers, and a plurality of parallel signals, respectively. It has a subcarrier modulation unit that modulates and generates a subcarrier signal, and an IFFT unit that performs inverse Fourier transform on a plurality of subcarrier signals to synthesize them.

Further, as shown in FIG. 8, the parallel capture detection unit 40A includes an AGC control unit 41, a demodulation unit 49A, and a capture detection unit 48. The demodulation unit 49A includes a carrier wave generation unit 42, a carrier wave signal removal unit 43, and an OFDM demodulation unit 47 that attempts demodulation corresponding to the primary modulation by the OFDM modulation unit 26 of the parallel signal generation unit 20A. The OFDM demodulation unit 47 includes an FFT unit that performs Fourier conversion on a signal whose carrier wave has been removed by the carrier wave signal removal unit 43 to reproduce it as a plurality of subcarrier signals, and a subcarrier demodulation unit that demodulates each of the plurality of subcarrier signals. It has a unit and a P / S conversion unit that converts the demodulated parallel signal into a serial signal and outputs it to the capture / detection unit 48.

The capture detection unit 48 compares the signal demodulated by the OFDM demodulation unit 47 with the rail breakage detection signal which is a coded signal, and detects that the signal capture of the received signal R is successful when the demodulation success condition is reached. To do. The demodulation success condition is, for example, the degree of matching between the demodulated signal and the rail breakage detection signal (which can also be called the demodulation rate). Specifically, the entire rail breakage detection signal, which is a coded signal of a predetermined length, matches. (That is, the demodulation rate is 100%), but the demodulation success condition is that a part of the rail breakage detection signal is demodulated, such as the demodulation rate is 50% or more, 20% or more, 10% or more, and so on. It may be determined that the value has been reached. When the capture detection unit 48 determines that the demodulation success condition has been reached, it determines that the signal capture has been successful, and outputs a capture signal D indicating the determination result.

(B) Signal input point s and signal output point r
Further, in the above-described embodiment, the signal input point s is defined in the center of the section T, and the signal output points r (r1, r2) are defined at both ends of the section. However, the following may be used. That is, a signal input point s is defined at one end of both ends of the section T, and a signal output point r is defined at the other end. In this case, as shown in FIGS. 4 to 6, it is not possible to determine the rail fracture by dividing the section T into “first half / second half” with the signal input point s as the boundary.

1 ... Rail breakage detection device 10 ... Signal generation unit 20 ... Parallel signal generation unit 21 ... Detection signal generation unit,
29 ... Modulation unit 22 ... Diffusion code generation unit, 23 ... Diffusion coding unit 24 ... Carrier wave generation unit, 25 ... Carrier wave modulation unit 30 ... Signal acquisition detection unit 40 ... Parallel acquisition detection unit 41 ... AGC control unit 49 ... Demodulation unit 42 ... Carrier wave generation unit, 43 ... Carrier wave signal removal unit 44 ... Diffusion code generation unit, 45 ... Reverse diffusion decoding unit, 46 ... Synchronous capture unit 50 ... Breakage determination unit S (Si) ... Transmission signal, R (Ri1, Ri2) ... Received signal 3 ... Orbit, T (Ti) ... Section s (si) ... Signal input point, r (ri1, ri2) ... Signal output point

Claims (5)

It is a rail rupture detection device that detects rail rupture in each of a plurality of sections that divide the track on which the train travels.
A predetermined coded signal is modulated by a predetermined multi-frequency utilization modulation method to generate a plurality of transmission signals having different frequencies, and at signal input points defined on rails of each section so that the frequencies are different in the adjacent sections. A signal generator that outputs the transmission signal and
Each received signal input from the signal output point defined on the rail of each section can be demodulated by a demodulation method corresponding to the multi-frequency utilization modulation method, and the received signal can be decoded into the coded signal. A signal capture detection unit that detects that signal acquisition was successful for each section when a predetermined demodulation success condition is reached before reaching the state.
A rupture determination unit that determines rail rupture for each section based on the detection result of the signal acquisition detection unit, and a rupture determination unit.
Rail breakage detection device equipped with. The rupture determination unit determines the rail rupture based on the undetected section when the undetected section by the signal acquisition detection unit is not sequentially switched along the track.
The rail breakage detection device according to claim 1. The signal generation unit performs primary modulation in the multi-frequency utilization modulation method by spread coding of the coded signal using a predetermined spreading code, and modulates a predetermined carrier wave with the primary modulated signal. Secondary modulation is performed to generate the transmission signal,
The signal capture detection unit corresponds to the multi-frequency utilization modulation method by despreading and decoding the received signal by demodulating the signal corresponding to the secondary modulation using the diffusion code. Trial demodulation by the demodulation method
The rail breakage detection device according to claim 1 or 2. The signal generation unit uses the multi-frequency by OFDM (Orthogonal Frequency Division Multiplexing) that synthesizes each signal by converting the coded signal into parallel signals for the number of subcarriers and then performing subcarrier modulation and inverse Fourier conversion. The transmission signal is generated by performing primary modulation by a modulation method and performing secondary modulation in which a predetermined carrier is modulated by the primary modulated signal.
The signal capture / detection unit serializes parallel signals for the number of subcarriers obtained by performing Fourier conversion and subcarrier demodulation on the signal obtained by demodulating the received signal corresponding to the secondary modulation. By converting to, the demodulation by the demodulation method corresponding to the multi-frequency utilization modulation method is tried.
The rail breakage detection device according to claim 1 or 2. An AGC control unit that adjusts the level of the received signal so that the level of the received signal is within a predetermined threshold level range, and when the level change of the received signal satisfies a steep change condition, the received signal of the received signal AGC control unit to stop level adjustment,
The rail breakage detection device according to any one of claims 1 to 4, further comprising.

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