JP2007168677A - Train detector - Google Patents

Abstract

A transmission detection signal is reliably matched by simply matching the phase of a spread signal generated in a transmission unit and the spread signal generated in a reception unit without requiring a synchronization acquisition unit or synchronization holding unit in the reception unit. To detect.
A transmitter 1 and a receiver 2 generate a PN code string based on a synchronization signal corresponding to the frequency of a commercial power supply 12, and a transmitter 1 performs a spread spectrum modulation on the transmitter 1, and a receiver 2 The phase of the PN code string subjected to spread spectrum modulation is surely matched, the ID data signal sent from the transmitter 1 is reliably detected by the receiver 2, and the time required for synchronization acquisition is shortened to increase the transmission efficiency.
[Selection] Figure 1

Description

  The present invention relates to a train detection device that detects the presence or absence of a train using a spread spectrum communication system, and more particularly to improvement in the stability of train detection.

  The track circuit in a railway divides the rail into a predetermined length to form an electric circuit, transmits a train detection signal from the boundary of the track circuit on the train entry side, and trains of a predetermined level at the boundary of the track circuit on the train entry side When the detection signal is received, it is determined that the train is not on the track circuit, the train enters the track circuit, the rail is short-circuited by the axle, and the train detection signal received is below a certain level. It is determined that the train is on the track circuit.

  When the train detection signal is transmitted to this track circuit, the harmonics of the operating current are extremely strong in the case of the AC electrification section. In order to detect a train without being affected by harmonic noise or the like of this operating current, a train detection device using a spread spectrum communication method is disclosed in Patent Document 1, Patent Document 2, Patent Document 3, and the like. ing. The train detection device using this spread spectrum communication system, the train detection signal from the transmission unit is spread spectrum modulated with a pseudo noise code (hereinafter referred to as PN code), spread to a wide frequency band and transmitted to the rail, the reception unit Receives a spectrum-spread signal sent to the rail, and spread-modulates the received signal using the same PN code as the transmitter. When spread modulation is performed using this PN code, the noise signal mixed in the received signal is spread in spectrum, and the train detection signals are collected in the original frequency band and returned to the original train detection signal generated in the transmitter. It is. By removing the noise component from the spread-modulated signal through a narrow bandpass filter, a transmitted train detection signal is obtained.

In order to obtain a train detection signal by performing spread modulation in this receiving unit, it is necessary to match the phase of the PN code to be spread modulated with the phase of the received PN code. A received signal spread-modulated using a PN code has a very small S / N ratio, and the synchronization timing cannot be extracted from the received signal by a normal method. Therefore, the PN code of the receiving unit is changed to the time series of the PN code of the received signal. The synchronization acquisition to convert the signal into a pulse signal in accordance with the above and the synchronization holding to operate so that the synchronization is not lost even after a lapse of time after the completion of the synchronization acquisition is required.
Japanese Patent No. 3291607 JP-A-9-99836 JP 2004-276761 A

  In order to make the phase of the PN code subjected to spread modulation in the receiving unit coincide with the phase of the received PN code as described above, if the receiving unit is provided with synchronization acquisition means and synchronization holding means, the configuration of the receiving unit becomes very complicated. As a result, synchronization acquisition takes time. Further, in the case of a non-insulated track circuit, at the time of detecting a train in which the track circuit is short-circuited at the train axle, the reception level is lowered, so that synchronization detection by the received signal becomes unstable. In addition, there is a disadvantage that the train detection performance is deteriorated due to the malfunction due to the malfunction due to the interference with the train detection signal transmitted to the adjacent track circuit.

  The present invention improves such disadvantages, and makes it easy to match the phase of the spread signal generated in the transmission unit and the spread signal generated in the reception unit without the need for synchronization acquisition means or synchronization holding means in the reception unit. An object of the present invention is to obtain a train detection device that can reliably detect a transmitted train detection signal.

The train detection device of the present invention is connected to one boundary of each track circuit and transmits a signal wave to the rail, and is connected to the other boundary of the track circuit and receives the signal wave transmitted to the rail. A receiver,
The transmitter includes a transmission signal generation unit, a transformer, a synchronization signal generation unit, a spread code generation unit, and a spread modulation unit, and the transmission signal generation unit is modulated with predetermined ID data assigned to a connected track circuit. A modulation signal is generated, and the transformer converts a commercial voltage output from a commercial power source into a low-voltage AC signal, and the synchronization signal generator synchronizes the AC signal converted by the transformer according to the frequency of the commercial power source. Generating a signal, the spreading code generating section generates a predetermined wide band PN code sequence based on the synchronizing signal generated by the synchronizing signal generating section, and the spreading modulation section generates a modulated signal generated by the transmission signal generating section. To generate a signal wave by performing spread spectrum modulation using the PN code sequence generated by the spread code generator,
The receiver includes a transformer, a synchronization signal generator, a spread code generator, a spread demodulator, a bandpass filter, and a train detector, and the transformer reduces the commercial voltage output from the same commercial power source as the transmitter. The voltage is converted into an AC signal, and the synchronization signal generation unit generates a synchronization signal corresponding to the frequency of a commercial power source from the AC signal converted by the transformer, and the spreading code generation unit is generated by the synchronization signal generation unit The wideband PN code string determined in advance is generated by the synchronized signal, and the spread demodulation unit generates a signal wave demodulated by performing spread spectrum modulation on the received signal wave with the PN code sequence generated by the spread code generation unit. The band-pass filter removes a noise component from the signal wave spread by the spread demodulation unit and extracts a modulation signal, and the train detection unit extracts the modulation signal extracted by the band-pass filter. The level of the signal, and detecting a rail presence of a train in the track circuit.

  Either one of the synchronization signals generated by the transmitter and the receiver unit is corrected according to the propagation time caused by the line length between the transmitter and the receiver.

  In the present invention, a PN code string is generated by a synchronization signal corresponding to the frequency of the same commercial power source at the transmitter and the receiver, and a PN code string that is subjected to spread spectrum modulation by the transmitter, and the spread spectrum modulation is performed by the receiver. The phase of the PN code string can be reliably matched, the ID data signal sent from the transmitter can be reliably detected by the receiver, and the transmission efficiency can be improved by reducing the time required for synchronization acquisition. Can do.

  FIG. 1 is a block diagram showing the configuration of the train detection apparatus of the present invention. As shown in the figure, the train detection apparatus has a transmitter 1 connected to one boundary of each track circuit 1T to 3T and a receiver 2 connected to the other boundary.

  The transmitter 1 includes a transmission signal generator 3, a transformer 4, a synchronization signal generator 5, a spread code generator 6, a frequency multiplication circuit 7, a QPSK modulator 8, a spread modulator 9, a D / A converter 10, and an amplifier 11. Have

  The transmission signal generator 3 creates an ID data signal including an identifier assigned to the track circuit 2T and outputs the ID data signal to the QPSK modulator 8. The transformer 4 converts the commercial voltage output from the commercial power supply 12 into a low-voltage AC signal and outputs it to the synchronization signal generator 5. As shown in the block diagram of FIG. 2, the synchronization signal generation unit 5 includes a band pass filter (BPF) 13 and a waveform shaping circuit 14. The BPF 13 receives the AC signal converted by the transformer 4 and removes the noise component, and the waveform shaping circuit 14 generates a synchronization signal corresponding to the frequency of the commercial power supply 12 from the AC signal from which the noise component is removed to generate a spread code. To the unit 6 and the frequency multiplier 6. The spread code generator 6 generates a wide-band PN code sequence determined in advance by the input synchronization signal and outputs it to the spread modulator 9. The frequency multiplication circuit 7 multiplies the frequency of the input synchronization signal by an integer to generate a clock signal corresponding to the number of chips of the spread code and outputs it to the D / A converter 10. The QPSK modulator 8 performs quadrature phase modulation on the ID data signal sent from the transmission signal generator 3 to increase the transmission bit rate and outputs the result to the spread modulator 9. The spread modulation unit 9 performs spread spectrum modulation on the input ID data signal with the PN code sequence input from the spread code generation unit 6 and spreads the spread signal in a frequency band far wider than the frequency band of the ID data signal. Output to the A converter 10. The D / A converter 10 converts the input spread signal into a DC signal wave by the clock signal sent from the frequency multiplication circuit 7 and outputs it to the amplifier 11. The amplifier 11 amplifies the transmitted signal wave and sends it out to the rail 16 via the matching transformer 15.

  The receiver 2 includes a preamplifier 18, a transformer 19, a synchronization signal generator 20, a phase corrector 21, a spread code generator 22, a frequency multiplier 23, an A / D converter 24, a spread demodulator 25, and a narrow band. A band pass filter (BPF) 26, a QPSK demodulator 27, a received signal check unit 28, a squaring circuit 29, a low pass filter (LPF) 30, a level determination unit 31, and a train detection determination unit 32 are provided.

  The preamplifier 18 inputs the signal wave sent from the transmitter 1 to the rail 16 from the matching transformer 17, amplifies the input signal wave, and outputs the amplified signal wave to the A / D converter 24. The transformer 19 converts the AC voltage output from the commercial power supply 12 into a low-voltage AC signal and outputs it to the synchronization signal generator 20. The synchronization signal generation unit 20 has the same configuration as the synchronization signal generation unit 5 of the transmitter 1, receives an AC signal converted by the transformer 19, removes noise components, and corresponds to the frequency of the commercial power supply 12. Is output to the phase correction unit 21. The phase correction unit 21 shifts the input synchronization signal in accordance with the phase difference of the AC voltage generated by the line length between the transmitter 1 and the receiver 2 of the cable carrying the power from the commercial power supply 12 to transmit the transmitter 1. And the phase shift of the receiver 2 are corrected, and the corrected synchronization signal is output to the spread code generator 22 and the frequency multiplier 23. The spread code generator 22 generates the same PN code string as that of the spread code generator 6 of the transmitter 1 based on the input synchronization signal, and outputs it to the spread demodulator 25. The frequency multiplying circuit 23 multiplies the frequency of the input synchronization signal by an integer to generate a clock signal corresponding to the number of chips of the spread code and outputs it to the A / D converter 24. The A / D converter 24 converts the signal wave amplified by the preamplifier 18 into a digital received signal by the clock signal sent from the frequency multiplier 23 and outputs the digital received signal to the spread demodulator 25. The spread demodulator 25 performs spread spectrum modulation on the input received signal using the PN code sequence input from the spread code generator 22, spreads the noise signal mixed in the received signal over a wide frequency band, and includes an ID data signal included in the received signal. Are generated in the original frequency band and output to the BPF 26. The BPF 26 removes a noise component from the input spread signal, extracts a received signal including an ID data signal, and outputs the received signal to the QPSK demodulator 27 and the squaring circuit 29. The QPSK demodulator 27 outputs the received signal obtained by performing quadrature phase modulation on the input received signal to the received signal checking unit 28. The reception signal checking unit 28 confirms whether or not the input reception signal matches the ID data signal corresponding to the track circuit 2T, and outputs the confirmation result to the train detection determination unit 32. The square circuit 29 generates a square signal of the input received signal and outputs it to the LPF 30. The LPF 30 removes the double frequency component appearing in the input square signal and outputs it to the level determination unit 31. The level determination unit 31 determines the reception level of the input signal and outputs it to the train detection determination unit 32. When the train detection determination unit 32 is input from the reception signal checking unit 28 that the ID data signal corresponding to the track circuit 2T is received, the train detection determination unit 32 trains the track circuit 2T according to the reception level determination result by the level determination unit 31. It is determined whether or not 33 is present.

  The operation of the train detection apparatus configured as described above will be described with reference to the waveform diagrams of FIGS.

  The transmitter 1 provided in the track circuit 2T converts the commercial voltage output from the commercial power supply 12 into a low-voltage AC signal by the transformer 4 and outputs it to the synchronous signal generator 5. The synchronous signal generator 5 is input. A synchronization signal is generated by the AC signal thus generated and output to the spread code generator 6 and the frequency multiplication circuit 7. When the synchronization signal generator 5 generates a synchronization signal, the BPF 13 of the synchronization signal generator 5 removes the noise component of the AC signal input from the transformer 4 and, as shown in FIG. The AC signal is output to the waveform shaping circuit 14. The waveform shaping circuit 14 is shaped into a pulse signal as shown in FIG. 3 (b) using, for example, zero volts of the input AC signal as a threshold, and from the shaped pulse signal, as shown in FIG. A synchronization signal corresponding to the frequency of the power supply 12 is generated. As shown in FIG. 3D, the spread code generator 6 generates a wideband PN code string specific to the track circuit 2T and outputs it to the spread modulator 9 as shown in FIG. The frequency multiplication circuit 7 multiplies the frequency of the input synchronization signal by an integer to generate a clock signal corresponding to the number of chips of the spread code and outputs it to the D / A converter 10.

  On the other hand, an ID data signal including an identifier assigned to the track circuit 2T generated by the transmission signal generator 3 is quadrature-phase modulated by the QPSK modulator 8 and output to the spread modulator 9. The spread modulation unit 9 performs spread spectrum modulation on the ID data signal modulated by the QPSK modulation unit 8 using the PN code sequence input from the spread code generation unit 6 and spreads it to a frequency band far wider than the frequency band of the ID data signal. The spread signal is output to the D / A converter 10. The D / A converter 10 converts the input spread signal into a DC signal wave by the clock signal sent from the frequency multiplication circuit 7 and outputs it to the amplifier 11. The amplifier 11 amplifies the sent signal wave and performs matching transformation. It is sent to the rail 16 through the container 15.

  The receiver 2 converts the commercial voltage output from the commercial power source 12 into a low-voltage AC signal by the transformer 19 and sends it to the synchronization signal generator 20, and generates a synchronization signal from the AC signal input by the synchronization signal generator 20. The generated synchronization signal is corrected by the phase correction unit 21 for the phase shift between the transmitter 1 and the receiver 2 and output to the spread code generation unit 6 and the frequency multiplication circuit 7. In this state, when a signal wave transmitted to the rail 16 is received via the matching transformer 7, the received signal wave is amplified by the preamplifier 18, and the amplified received wave is frequency multiplied by the A / D converter 24. The clock signal sent from the circuit 23 is converted into a digital reception signal and output to the spread demodulation unit 25. As shown in FIG. 4A, a noise signal is added to the received signal sent to the spread demodulator 25 when propagating on the rail 13. Therefore, the spread demodulation unit 25 performs spread spectrum modulation on the transmitted signal wave using the PN code string sent from the spread code generation unit 22 and mixes it with the received signal wave as shown in FIG. A noise signal is spread over a wide frequency band to generate a spread signal in which ID data signals included in the received signal are collected in the original frequency band, and output to the BPF 26. As shown in FIG. 4C, the BPF 26 removes a noise component from the input spread signal, extracts a received signal including an ID data signal, and outputs the received signal to the QPSK demodulator 27 and the squaring circuit 29. The PN code string subjected to spread spectrum modulation by the spread spectrum demodulator 25 is generated by the synchronization signal corresponding to the frequency of the commercial power source 12 same as that of the transmitter 1 and is generated by the cable length between the transmitter 1 and the receiver 2. Since phase shift correction is performed according to the phase difference of the commercial voltage, the phase can be matched with the PN code string generated in the transmitter 1. Since the generated PN code string is unique to the same orbital circuit 2T as the PN code string generated in the transmitter 1, the received signal that has been spread-modulated by the spread demodulator 25 and passed through the BPF 26 is, for example, orbital. It does not include a signal generated by a PN code string different from that of the track circuit 2T transmitted to the circuit 3T, and is not affected by a signal transmitted to another track circuit.

  The QPSK demodulator 27 performs quadrature phase modulation on the input received signal and demodulates it. The received signal check unit 28 checks whether the demodulated received signal matches the ID data signal corresponding to the track circuit 2T. The result is output to the train detection determination unit 32. The squaring circuit 29 generates a square signal of the input received signal, and the LPF 30 removes a double frequency component appearing in the square signal and outputs it to the level determination unit 31. The level determination unit 31 determines the reception level of the input signal and outputs it to the train detection determination unit 32. When the train detection determination unit 32 is input from the reception signal checking unit 28 that the ID data corresponding to the track circuit 2T is received, the train 33 is added to the track circuit 2T by the determination result of the reception level by the level determination unit 31. It is determined whether or not there is a line.

  Thus, since the transmitter 1 and the receiver 2 generate the PN code string by the synchronization signal corresponding to the frequency of the commercial power supply 12, the transmitter 1 and the receiver 2 The phase of the PN code string subjected to spread spectrum modulation can be made to coincide with each other, the ID data signal sent from the transmitter 1 can be reliably detected by the receiver 2, and the time required for acquisition is shortened. Thus, transmission efficiency can be increased.

  In the above description, the transmitter 1 and the receiver 2 generate the PN code string by using the synchronization signal corresponding to the frequency of the commercial power supply 12, but instead of the transformers 4 and 19 of the transmitter 1 and the receiver 2. A GPS receiver may be provided to generate a synchronization signal from a GPS time pulse.

It is a block diagram which shows the structure of the train control apparatus of this invention. It is a block diagram which shows the structure of a synchronizing signal generation part. It is a waveform diagram of an output waveform and a PN code string in a synchronization signal generation unit of a transmission unit. It is a spectrum distribution diagram of a signal from which a received signal, a signal subjected to spread demodulation and a noise component are removed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Transmitter, 2; Receiver, 3; Transmission signal generation part, 4; Transformer, 5; Synchronization signal generation part,
6; spread code generator, 7; frequency multiplier, 8; QPSK modulator, 9; spread modulator,
10; D / A converter, 11; amplifier, 12; commercial power supply, 13; BPF,
14; waveform shaping circuit, 15; matching transformer, 16; rail, 17; matching transformer,
18; Preamplifier, 19; Transformer, 20; Synchronization signal generation unit, 21; Phase correction unit,
22; spread code generator, 23; frequency multiplier, 24; A / D converter,
25; spread demodulation unit, 26; BPF, 27; QPSK demodulation unit, 28; received signal checking unit,
29; square circuit, 30; LPF, 31; level determination unit, 32; train detection determination unit,
33; Train.

Claims (2)

A transmitter connected to one boundary of each track circuit and transmitting a signal wave to the rail; and a receiver connected to the other boundary of the track circuit and receiving a signal wave transmitted to the rail;
The transmitter has a transmission signal generation unit, a transformer, a synchronization signal generation unit, a spread code generation unit, and a spread modulation unit,
The transmission signal generator generates a modulation signal modulated with predetermined ID data assigned to a connected track circuit, the transformer converts a commercial voltage output from a commercial power source into a low-voltage AC signal, and the synchronization The signal generation unit generates a synchronization signal corresponding to the frequency of the commercial power supply from the AC signal converted by the transformer, and the spreading code generation unit is a broadband PN determined in advance by the synchronization signal generated by the synchronization signal generation unit. A code string is generated, and the spread modulation unit generates a signal wave by performing spread spectrum modulation on the modulation signal generated by the transmission signal generation unit using the PN code sequence generated by the spread code generation unit,
The receiver includes a transformer, a synchronization signal generator, a spread code generator, a spread demodulator, a bandpass filter, and a train detector.
The transformer converts a commercial voltage output from the same commercial power source as the transmitter into a low-voltage AC signal, and the synchronization signal generator synchronizes the AC signal converted by the transformer according to the frequency of the commercial power source. Generating a signal, the spreading code generating unit generates a wide-band PN code sequence determined in advance by the synchronizing signal generated by the synchronizing signal generating unit, and the spreading demodulating unit generates the received signal wave as the spreading code generating unit. A signal wave demodulated by spread spectrum modulation using the PN code sequence generated in step (b), the bandpass filter removes a noise component from the signal wave spread by the spread demodulation unit, and extracts a modulated signal; The train detector according to claim 1, wherein the detector detects the presence or absence of a train in the track circuit based on the level of the modulation signal extracted by the bandpass filter.   The train detection apparatus according to claim 1, wherein either one of the synchronization signals generated by the transmitter and the receiver unit is corrected according to a propagation time caused by a line length between the transmitter and the receiver.

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