Universal frequency shift keying signal test system for rail transit signal system

Abstract

The present invention relates to a universal frequency shift keying signal test system for a rail transit signal system, comprising a signal source, a frequency shift signal sending unit, a signal transmission path, a signal receiving unit, a receiving end and a host computer human-computer interaction unit, wherein the signal source, the frequency shift signal sending unit, the signal transmission path, the signal receiving unit, the receiving end and the host computer human-computer interaction unit are connected in sequence. Compared with the prior art, the present invention has the advantages of supporting multiple encoding modes and having corresponding decoding capabilities to cope with the testing of multiple frequency shift keying signals.

Description

Technical Field

[0001] The present invention relates to the technical field of signal testing, and in particular to a universal frequency shift keying signal testing system for a rail transit signal system. Background Art

[0002] In the field of rail transit signal systems, frequency shift keying technology (FSK) is mainly used in digital coded tracks, axle counters, beacon antennas and other systems. The frequency shift track circuit uses frequency parameters as control information and uses signal modulation to modulate the low-frequency signal to a higher frequency, but keeps its amplitude unchanged. The frequency changes with the amplitude of the low-frequency signal. While realizing automatic block blocking in sections, the frequency shift track circuit can also transmit driving information (such as driving speed, detailed line parameters, etc.) to provide the relevant information required for train operation control. In my country's circuits, the domestically produced 18-information frequency shift automatic block system and the UM-71 non-insulated track circuit both use phase-continuous frequency shift keying signals.

[0003] After searching, the Chinese patent publication number CN106124839A discloses a portable detector for track frequency shift signals and its detection method. The detector is composed of a magnetoresistive sensor, a temperature sensor, signal conditioning, analog-to-digital conversion, a DSP microprocessor, WIFI communication, an LCD display and a power supply unit; the detection method is composed of a magnetoresistive sensor unit detecting the effective value of the frequency shift current in the rail and the frequency of the frequency shift current, eliminating the inconvenience of frequency shift signal detection at the lead wire. However, the invention is used for on-site rapid detection, and its characteristics are small and portable, and it also needs to be coordinated with the distant code transmitting end when used.

[0004] After searching, the digital coding non-insulated track circuits currently used in my country's urban rail transit include AF-902 / 904 (Shanghai Line 2), FTGS audio track circuit, ZPW-2000A, UM71, etc. Various standards have differences in carrier frequency, frequency deviation, coding bit mode, etc. In the long run, the coexistence of multiple standards will continue, but there is no universal test platform available. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a universal frequency shift keying signal test system for rail transit signal systems. The system targets various existing frequency shift keying signals, the test system hardware can be reused, the modulation and demodulation algorithm software can be flexibly configured, and it supports multiple encoding methods and has corresponding decoding capabilities to cope with the testing of various frequency shift keying signals.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A universal frequency shift keying signal test system for a rail transit signal system comprises a signal source, a frequency shift signal sending unit, a signal transmission path, a signal receiving unit, a receiving end and a host computer human-computer interaction unit, wherein the signal source, the frequency shift signal sending unit, the signal transmission path, the signal receiving unit, the receiving end and the host computer human-computer interaction unit are connected in sequence.

[0008] Preferably, the signal source comprises a PXI chassis and an arbitrary waveform generator board installed on the PXI chassis;

[0009] The arbitrary waveform generator board generates a complex signal of a specific frequency to simulate the actual waveform of the track circuit when the train is running.

[0010] Preferably, the arbitrary waveform generator board adopts NI PXI-5422, Kunchi QT1237 or ADLINK PXI1117;

[0011] The signal source is also provided with a host computer interface for providing a waveform parameter setting input box, and the required baseband frequency, carrier frequency, modulation mode, coding information, and transmission path model parameters are selected within the applicable range according to the test items;

[0012] The signal source supports predefined high-frequency carrier frequencies of 1700Hz, 2KHz, 2300Hz, and 2600Hz, and also supports custom selection within the capabilities of the board;

[0013] The signal source pre-defines support for low-frequency baseband signal frequencies, from 10.3 Hz to 29.0 Hz in an arithmetic progression, with a tolerance of 1.1 Hz and a frequency deviation Δf of 11.0 Hz, and also supports custom selection within the capabilities of the board.

[0014] Preferably, the test system further comprises a noise source connected to the frequency-shifted signal sending unit, and the noise source comprises power frequency interference, white noise or Gaussian noise.

[0015] Preferably, the frequency-shift signal sending unit includes a signal modulation and analog signal generation circuit, which supports a variety of frequency shift keying modulations, including BFSK (Binary Frequency Shift Key) and MSK (Minimal Shift Key).

[0016] The frequency-shift signal transmission unit supports a variety of information coding protocols, including an 8-bit header, 37-bit data information and a 16-bit cyclic check bit, and supports different coding lengths;

[0017] The carrier frequency of the frequency-shift signal sending unit covers the carrier frequency used in the field of rail transit signals, supports 18 types of defined track circuit low-frequency information, and supports customized low-frequency information.

[0018] Preferably, the signal transmission path includes a plurality of tuning zones, each tuning zone including a transmitting tuning unit of the track segment, an air-core coil, and a receiving tuning unit of the next adjacent track segment.

[0019] Preferably, the signal transmission path selects an actual transmission medium or a transmission path simulation model.

[0020] Preferably, the signal receiving unit comprises an analog signal isolation and conditioning unit, an analog signal sampling transmission and storage unit which are connected in sequence.

[0021] Preferably, the receiving end collects the original data signal and converts it into a binary data stream for storage, and uses the stored original data as a data source, selects different algorithms for demodulation and decoding, and then determines the baseband recovery index and bit error rate index under each algorithm.

[0022] Preferably, the host computer human-computer interaction unit is used to provide waveform observation, eigenvalue calculation, demodulation algorithm selection, decoding information flow, and bit error rate calculation.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1) Reuse one set of hardware equipment to save costs;

[0025] 2) Different demodulation algorithms use the same data set, and the performance indicators are credible for comparison, which can be used to judge the accuracy and consistency of message data and the judgment of interval occupancy security information.

[0026] 3) For transmission links with the same characteristics, study the advantages and disadvantages of different modulation methods and the feasibility of sending more detailed line information.

[0027] 4) Applicable to the tests required for new method verification and function improvement, and can be used to develop new functions of insulated tracks. For example, in the Shanghai Line 2 reconstruction project, this system provides a simulation test device for testing the AF-904 track circuit, as well as a simulation test device for the next generation of urban signal systems.

[0028] 5) Suitable for parameter performance testing of transponders, frequency-shift track circuits, etc., such as energy threshold requirements, parameter adjustment of carrier modulation methods, comparison of effects of different modulation methods, signal-to-noise ratio, frequency offset and bit error rate comparison. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the hardware structure of the present invention;

[0030] Figure 2 It is a schematic diagram of module functions of a specific embodiment of the present invention;

[0031] Figure 3 It is the work flow chart of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0033] like Figure 1 As shown, a universal frequency shift keying signal test system for a rail transit signal system includes a signal source 1, a frequency shift signal sending unit 2, a signal transmission path, a signal receiving unit 3, a receiving end 4 and a host computer human-computer interaction unit 5, wherein the signal source 1, the frequency shift signal sending unit 2, the signal transmission path, the signal receiving unit 3, the receiving end 4 and the host computer human-computer interaction unit 5 are connected in sequence.

[0034] The test system is built on the PXI bus to complete the generation and acquisition of analog signals. The signal source includes a PXI chassis and an arbitrary waveform generator board installed on the PXI chassis; the arbitrary waveform generator board generates a complex signal of a specific frequency to simulate the actual waveform of the track circuit when the train is running.

[0035] The arbitrary waveform generator board adopts NI PXI-5422, Kunchi QT1237 or ADLINK PXI1117; the signal source is also provided with a host computer interface 7 for providing a waveform parameter setting input box, and the required baseband frequency, carrier frequency, modulation mode, coding information, and transmission path model parameters are selected within the applicable range according to the test items;

[0036] The signal source supports predefined high-frequency carrier frequencies of 1700Hz, 2KHz, 2300Hz, and 2600Hz, and also supports custom selection within the capabilities of the board;

[0037] The signal source pre-defines support for low-frequency baseband signal frequencies, from 10.3 Hz to 29.0 Hz in an arithmetic progression, with a tolerance of 1.1 Hz and a frequency deviation Δf of 11.0 Hz, and also supports custom selection within the capabilities of the board.

[0038] When a simulated transmission path is used instead of a real transmission path, the transmitting end may be loaded with noise. The test system further comprises a noise source 6 connected to the frequency-shifted signal transmitting unit. The noise source comprises power frequency interference, white noise or Gaussian noise.

[0039] The frequency shift signal sending unit includes a signal modulation and analog signal generation circuit, which supports multiple frequency shift keying modulations, including BFSK (Binary Frequency Shift Key) and MSK (Minimal Shift Key).

[0040] The frequency-shift signal transmission unit supports a variety of information coding protocols, including an 8-bit header, 37-bit data information and a 16-bit cyclic check bit, and supports different coding lengths;

[0041] The carrier frequency of the frequency-shift signal sending unit covers the carrier frequency used in the field of rail transit signals, supports 18 types of defined track circuit low-frequency information, and supports customized low-frequency information.

[0042] The signal transmission path includes several tuning areas, each tuning area includes a transmitting tuning unit of the track section, an air-core coil, and a receiving tuning unit of the next adjacent track section.

[0043] The signal transmission path selects the actual transmission medium or the transmission path simulation model. The selected track frequency shift transmission model assumes that the track transmission network is a circuit with uniformly distributed parameters, and uses the uniform transmission theory to model and analyze it.

[0044] The signal receiving unit comprises an analog signal isolation and conditioning unit, an analog signal sampling transmission and storage unit which are connected in sequence.

[0045] The receiving end collects the original data signal and converts it into a binary data stream for storage, and uses the stored original data as a data source, selects different algorithms for demodulation and decoding, and then determines the baseband recovery index and bit error rate index under each algorithm.

[0046] The upper computer human-computer interaction unit is used to provide waveform observation, characteristic value calculation, demodulation algorithm selection, decoding information flow, and bit error rate calculation.

[0047] The receiving end is connected to the signal source or to the simulated transmission path unit; the response waveform of the frequency-shifted track circuit receiving end is monitored in real time, and filtered and analyzed. The analog signal is collected by undersampling data, bandpass filtered, and then stored in binary digital form; since the FSK frequency-shifted signal has typical narrowband signal characteristics, the Zoom-FFT algorithm is used for demodulation. Specific embodiments

[0049] Taking the ZPW-2000 track circuit as an example, the differences between the indicators under Zoom-FFT and ordinary FFT demodulation methods are studied:

[0050] Assume that the carrier frequency f0 of a certain section is 2600Hz, and the frequency of the low-frequency signal to be modulated is 13.6Hz, then the frequency of the frequency-shifted signal in the track is 2589Hz and 2611Hz. The frequency-shifted signal has 8 carrier frequencies and 14 low frequencies, with a total of 144 possible combinations. These combinations are all in the test sequence and can be selected through the first host computer 11. In addition, the first host computer 11 can also choose whether to load noise, select the noise type, set the noise attribute, etc. When using the simulated transmission path, the transmission path model parameters can also be selected on the first host computer 11. On the second host computer 21, you can choose to load Zoom-FFT and ordinary FFT algorithms to demodulate the collected signals in real time at the same time, and the advantages and disadvantages of the two algorithms can be compared by observing the waveform on the virtual oscilloscope. In addition, you can load the stored waveform data, choose to load Zoom-FFT and ordinary FFT algorithms to demodulate this data set offline at the same time, and the advantages and disadvantages of the two algorithms can be compared by observing the waveform on the virtual oscilloscope.

[0051] The simulation transmission path model selects different frequency-shift track circuit transfer functions and parameters, which is more conducive to research and testing.

[0052] The carrier frequency, modulation frequency, frequency shift index, frequency deviation, upper and lower sidebands of the frequency shift signal are analyzed and calculated, and the error is calculated. The peak value and energy spectrum are analyzed using the FFT-RMS measurement method; the spectrum leakage is prevented by adding a Hanning window.

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A universal frequency shift keying signal test system for rail transit signal system, characterized in that: It includes a signal source, a frequency-shift signal sending unit, a signal transmission path, a signal receiving unit, a receiving end and a host computer human-computer interaction unit, wherein the signal source, the frequency-shift signal sending unit, the signal transmission path, the signal receiving unit, the receiving end and the host computer human-computer interaction unit are connected in sequence; The signal source comprises a PXI chassis and an arbitrary waveform generator board installed on the PXI chassis; The arbitrary waveform generator board generates a complex signal of a specific frequency to simulate the actual waveform of the track circuit when the train is running; The arbitrary waveform generator board adopts NIPXI-5422, Kunchi QT1237 or ADLINK PXI1117; The signal source is also provided with a host computer interface for providing a waveform parameter setting input box, and the required baseband frequency, carrier frequency, modulation mode, coding information, and transmission path model parameters are selected within the applicable range according to the test items; The signal source supports predefined high-frequency carrier frequencies of 1700Hz, 2KHz, 2300Hz, and 2600Hz, and also supports custom selection within the capabilities of the board; The signal source pre-defines the low-frequency baseband signal frequency, which ranges from 10.3 Hz to 29.0 Hz in an arithmetic progression, with a tolerance of 1.1 Hz and a frequency deviation Δf of 11.0 Hz. It also supports custom selection within the capacity of the board. The frequency shift signal sending unit includes a signal modulation and analog signal generation circuit, which supports a variety of frequency shift keying modulations, including BFSK and MSK, where BFSK is binary frequency shift keying and MSK is minimum frequency shift keying; The frequency-shift signal transmission unit supports a variety of information coding protocols, including an 8-bit header, 37-bit data information and a 16-bit cyclic check bit, and supports different coding lengths; The carrier frequency of the frequency-shift signal sending unit covers the carrier frequency used in the field of rail transit signals, supports 18 types of defined track circuit low-frequency information, and supports customized low-frequency information.

2. A universal frequency shift keying signal test system for rail transit signal system according to claim 1, characterized in that: The test system further comprises a noise source connected to the frequency-shift signal sending unit, and the noise source comprises power frequency interference, white noise or Gaussian noise.

3. The universal frequency shift keying signal test system for rail transit signal system according to claim 1, characterized in that: The signal transmission path includes several tuning areas, each tuning area includes a transmitting tuning unit of the track section, an air-core coil, and a receiving tuning unit of the next adjacent track section.

4. A universal frequency shift keying signal test system for rail transit signal system according to claim 1 or 3, characterized in that: The signal transmission path selects an actual transmission medium or a transmission path simulation model.

5. The universal frequency shift keying signal test system for rail transit signal system according to claim 1, characterized in that: The signal receiving unit comprises an analog signal isolation and conditioning unit, an analog signal sampling transmission and storage unit which are connected in sequence.

6. The universal frequency shift keying signal test system for rail transit signal system according to claim 1, characterized in that: The receiving end collects the original data signal and converts it into a binary data stream for storage, and uses the stored original data as a data source, selects different algorithms for demodulation and decoding, and then determines the baseband recovery index and bit error rate index under each algorithm.

7. The universal frequency shift keying signal test system for rail transit signal system according to claim 1, characterized in that: The upper computer human-computer interaction unit is used to provide waveform observation, characteristic value calculation, demodulation algorithm selection, decoding information flow, and bit error rate calculation.

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