A high-speed rail GSM-R signal detection method and system based on handheld terminal

Abstract

The present invention discloses a high-speed rail GSM-R signal detection method and system based on a handheld terminal, the method comprising: converting and processing the GSM-R signal to obtain baseband data and inputting it into a terminal decoding system; based on the terminal decoding system, decoding the baseband data by a Viterbi algorithm, and outputting GSM-R decoded data; performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data; based on a terminal device, displaying the GSM-R decoded data and GSM-R spectrum data through a graphical interface. By using the present invention, interference with signal data can be discovered in a timely manner and located and checked, thereby reducing the time for troubleshooting external wireless interference. As a high-speed rail GSM-R signal detection method and system based on a handheld terminal, the present invention can be widely used in the field of wireless signal detection technology.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless signal detection, and in particular to a high-speed rail GSM-R signal detection method and system based on a handheld terminal. Background Art

[0002] The GSM-R mobile communication system is a digital wireless communication system dedicated to railways, which is used to provide functions such as wireless train control information transmission, emergency communication and group call communication to ensure the safe operation of trains. The operating frequency band of the GSM-R mobile communication system is 885MHz~889MHz for uplink and 930MHz~934MHz for downlink. The available bandwidth is narrow, the frequency reuse is high, and it is easily affected by external interference, which can cause GSM-R mobile communication system failures. It is necessary to monitor the interference of the GSM-R wireless environment. However, the existing high-speed rail GSM-R mobile communication system maintenance mainly uses spectrum analyzers for detection, which can only measure the spectrum waveform of the wireless environment and cannot effectively monitor and identify interference. Summary of the invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide a high-speed rail GSM-R signal detection method and system based on a handheld terminal, which can timely detect interference in signal data and locate and troubleshoot it, thereby reducing the time for troubleshooting external wireless interference.

[0004] The first technical solution adopted by the present invention is: a high-speed rail GSM-R signal detection method based on a handheld terminal, comprising the following steps:

[0005] Convert and process the GSM-R signal to obtain baseband data and input it into the terminal decoding system;

[0006] Based on the terminal decoding system, the baseband data is decoded by the Viterbi algorithm and the GSM-R decoded data is output;

[0007] Perform Fourier transform and automatic gain control on the baseband data to obtain GSM-R spectrum data;

[0008] Based on the terminal equipment, GSM-R decoding data and GSM-R spectrum data are displayed through a graphical interface.

[0009] Furthermore, the step of converting the GSM-R signal to obtain baseband data and inputting the baseband data into the terminal decoding system specifically includes:

[0010] Get GSM-R signal;

[0011] Performing bandwidth radio frequency sampling processing on the GSM-R signal to obtain a sampled GSM-R signal;

[0012] The sampled GSM-R signal is filtered by a low-pass filter to obtain a filtered GSM-R signal;

[0013] The filtered GSM-R signal is sampled and judged, and the baseband data is output and input to the terminal decoding system.

[0014] Furthermore, the step of decoding the baseband data by using the Viterbi algorithm based on the terminal decoding system and outputting the GSM-R decoded data specifically includes:

[0015] Obtaining a wireless frame standard bit sequence;

[0016] According to the wireless frame standard bit sequence, the baseband data is searched and matched by a matched filtering method to obtain synchronized baseband data;

[0017] Based on the synchronized baseband data, the training sequence in the regular time slot is extracted and channel estimation processing is performed on it to obtain a channel estimation value;

[0018] Based on the synchronized baseband data, the data sequence in the regular time slot is extracted and equalized and subjected to standard Viterbi decoding to obtain GSM-R decoded data.

[0019] Furthermore, the specific calculation process of the matched filtering method is as follows:

[0020]

[0021] In the above formula, k * represents the best matching timing point, X represents the baseband data, k represents the timing offset, i represents the sampling point index, L * (i) represents the conjugation of the local synchronization sequence generated according to the standard.

[0022] Further, the calculation formula of the channel estimation value is as follows:

[0023]

[0024] In the above formula, Y(n) represents the training sequence in the regular time slot, L * represents the locally generated training sequence, h represents the channel estimation value, and n represents the index of the data.

[0025] Furthermore, the calculation formula for the synchronized baseband data equalization processing is as follows:

[0026] F(n)=D(n)h *

[0027] In the above formula, D(n) represents the data sequence in the regular time slot, F(n) represents the equalized baseband data, and h *represents the conjugate of the channel estimate.

[0028] Further, the step of performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data specifically includes:

[0029] The port of the decoding terminal system is monitored by polling receiving mode to obtain the GSM-R signal;

[0030] The GSM-R signal is converted and processed by Fourier transform to obtain a GSM-R frequency domain signal;

[0031] The GSM-R frequency domain signal is subjected to gain amplification processing through automatic gain control processing to obtain GSM-R spectrum data.

[0032] Furthermore, the display of GSM-R decoding data and GSM-R spectrum data through a graphical interface based on the terminal device also includes:

[0033] Based on the terminal device, it is sent to the APP interface program through the callback function, and the GSM-R decoding data and GSM-R spectrum data are displayed through the APP interface.

[0034] The second technical solution adopted by the present invention is: a high-speed rail GSM-R signal detection system based on a handheld terminal, comprising:

[0035] The acquisition module is used to convert the GSM-R signal to obtain the baseband data and input it into the terminal decoding system;

[0036] The decoding module, based on the terminal decoding system, decodes the baseband data through the Viterbi algorithm and outputs GSM-R decoded data;

[0037] A processing module, used for performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data;

[0038] The display module displays GSM-R decoding data and GSM-R spectrum data through a graphical interface based on the terminal device.

[0039] The beneficial effects of the method and system of the present invention are as follows: the present invention converts and processes the GSM-R signal according to its characteristics, converts it into a corresponding baseband data signal and sends it to a terminal decoding system, decodes the baseband data through the Viterbi algorithm, and can not only realize the spectrum scanning function of the spectrum analyzer, but also realize signal decoding and interference positioning, timely troubleshoot interference and discover problems, and finally, by performing Fourier transform and automatic gain control processing on the GSM-R decoded data, the GSM-R spectrum data and decoded data are displayed through a graphical interface, effectively improving the GSM-R signal monitoring capability and shortening the external wireless interference troubleshooting time. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of the steps of a high-speed rail GSM-R signal detection method based on a handheld terminal of the present invention;

[0041] Figure 2 This is a structural block diagram of a high-speed rail GSM-R signal detection system based on a handheld terminal of the present invention;

[0042] Figure 3 It is a schematic diagram of the process of decoding and locating the GSM-R signal according to the present invention. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0044] Reference Figure 1 and Figure 3 The present invention provides a high-speed rail GSM-R signal detection method based on a handheld terminal, the method comprising the following steps:

[0045] S1, convert the GSM-R signal to obtain baseband data and input it into the terminal decoding system;

[0046] Specifically, the RF acquisition module collects GSM-R signals and converts them into baseband data according to the GSM-R signal characteristics, the specific center frequency and sampling rate. The GSM-R signal is in duplex mode, the uplink frequency band is 885-889MHz, the downlink frequency band is 930-934MHz, and the bandwidth of each GSM-R frequency point is 200kHz. The process of converting it into baseband data is to perform broadband RF sampling on the GSM-R RF signal transmitted from the base station, receive it through the channelization separation method, filter out channel noise and interference through low-pass filtering of the sampled signal, equalize the channel characteristics, sample and judge the output waveform of the receiving filter, convert and restore it into a baseband signal, i.e., baseband data, and transmit it to the Android handheld terminal through the USB interface. A C language terminal simulator is deployed on the Android handheld terminal to build a C language environment.

[0047] S2, based on the terminal decoding system, decodes the baseband data through the Viterbi algorithm and outputs GSM-R decoded data;

[0048] Specifically, the baseband decoding module uses C language, deploys a C language simulator in the terminal decoding system, builds a C language environment, decodes the baseband data through the Viterbi algorithm, and outputs GSM-R decoded data.

[0049] S21, obtaining a wireless frame standard bit sequence;

[0050] S22, performing search and matching processing on the baseband data by a matched filtering method according to the wireless frame standard bit sequence to obtain synchronized baseband data;

[0051] Specifically, firstly, the synchronization sequence search is performed on the GSM baseband data to complete the synchronization of the wireless frame. According to the protocol, the synchronization sequence length is 64 bits. It is assumed that its standard sequence is as follows:

[0052] L(n),n=1,2,…,64

[0053] The matched filtering method is used to search for the position point where the baseband data matches the standard sequence at the maximum value. The specific calculation process of the matched filtering method is as follows:

[0054]

[0055] In the above formula, k * represents the best matching timing point, X represents the baseband data, k represents the timing offset, i represents the sampling point index, L * (i) represents the conjugation of the local synchronization sequence generated according to the standard.

[0056] S23, based on the synchronized baseband data, extracting the training sequence in the regular time slot and performing channel estimation processing on it to obtain a channel estimation value;

[0057] Specifically, the training sequence in the regular time slot is channel estimated. In the GSM protocol specification, it is defined that each carrier frequency contains 8 consecutive regular time slots (TS0-TS7). According to the protocol, the regular time slot is extracted from the wireless frame, and the training sequence part Y(n), n=1,2,…,26 is extracted from the regular time slot. Assume that the training sequence is Y(n), n=1,2,…,26. The channel estimate is obtained through the correlation value, and the calculation formula of the channel estimate value is as follows:

[0058]

[0059] In the above formula, Y(n) represents the training sequence in the regular time slot, L * represents the locally generated training sequence, h represents the channel estimation value, and n represents the index of the data.

[0060] S24. Based on the synchronized baseband data, extract the data sequence in the regular time slot and perform equalization and standard Viterbi decoding on it to obtain GSM-R decoded data.

[0061] Specifically, the data part in the regular time slot is demodulated and Viterbi decoded. Assuming that the data part in the regular time slot is D(n), the original signal is equalized by the channel estimation value. The calculation steps of the equalization are as follows:

[0062] F(n)=D(n)h *

[0063] In the above formula, D(n) represents the data sequence in the regular time slot, F(n) represents the equalized baseband data, and h * represents the conjugate of the channel estimate;

[0064] Then the equalized data is subjected to standard Viterbi decoding, and the calculation formula is as follows:

[0065] A(n)=phase[D(n)]

[0066] In the above formula, phase[·] represents the phase function, and A(n) represents the signal phase data;

[0067] According to the protocol, the standard constellation phase that is most receptive to A(n) is found. The three bits corresponding to this phase are the constellation demodulation bits. All constellation demodulation bits are input into the standard Viterbi decoding module to output the original information bit stream. The constellation is mainly used for mapping during modulation and for correctly demodulating data during reception. Therefore, signal demodulation is required through the constellation.

[0068] S25, in summary, construct GSM-R decoding data;

[0069] Specifically, the GSM-R decoding data includes the main frequency of the current cell, the cell ID number, the base station identification code, the current cell signal-to-noise ratio, the location area code, the mobile country code, the mobile network code, the signal strength, the networking structure, the frequency points included in the current cell and the neighboring cell information of the current cell.

[0070] S3. Perform Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data and display the GSM-R decoding data and GSM-R spectrum data through a graphical interface based on the terminal device.

[0071] Specifically, the APP program of the Android handheld terminal uses the Java language to complete GSM-R signal processing, including fast Fourier transform (FFT) and automatic gain control (AGC), and displays GSM-R spectrum data and decoding data through a graphical interface.

[0072] S31, monitoring the port of the decoding terminal system by polling reception mode to obtain the GSM-R signal;

[0073] Specifically, after the APP program of the Android handheld terminal is started, the GSM-R signal detection setting parameters are obtained, including the main frequency point and initial signal gain of the current cell, and the relevant threads are started. The thread starts the socket connection data acquisition service (ZeroMQ protocol) and listens to the port through the polling reception method to obtain GSM-R decoding data.

[0074] S32, converting the GSM-R signal through Fourier transform to obtain a GSM-R frequency domain signal;

[0075] S33, performing gain amplification processing on the GSM-R frequency domain signal through automatic gain control processing to obtain GSM-R spectrum data;

[0076] Specifically, the collected decoded data is sent to the message queue through the thread callback function. After the message queue handler captures the decoded data, it performs FFT and AGC processing on the decoded data. The FFT processing is to convert the signal of the GSM-R decoded data into the corresponding frequency domain signal, that is, B = FFT (Y[real], Y(imag)). Assuming that the input signal is Y, Y[real] is the real signal, and Y(imag) is the imaginary signal. After Fourier transform (FFT), the spectrum data of the input signal is obtained. The AGC processing is to use different gains to amplify signals of different strengths so that the final output amplitude of the signal is maintained at a unified standard, that is, OUT[i] = B[i]-AGC+OFFSET, AGC is the dynamic gain of data sampling, OFFSET is the signal offset, and the B[i] signal is corrected to output the final OUT[i] signal.

[0077] S34. Call back the amplified GSM-R decoded data to the terminal display device through the callback function.

[0078] Specifically, the processed data is sent to the APP interface program through the callback function, and the spectrum data and decoded data are displayed through the APP interface.

[0079] Reference Figure 2 , a high-speed rail GSM-R signal detection system based on a handheld terminal, comprising:

[0080] The acquisition module is used to convert the GSM-R signal to obtain the baseband data and input it into the terminal decoding system;

[0081] The decoding module, based on the terminal decoding system, decodes the baseband data through the Viterbi algorithm and outputs GSM-R decoded data;

[0082] A processing module, used for performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data;

[0083] The display module displays GSM-R decoding data and GSM-R spectrum data through a graphical interface based on the terminal device.

[0084] The contents of the above method embodiments are all applicable to the present system embodiments. The functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0085] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A high-speed rail GSM-R signal detection method based on a handheld terminal, characterized in that: The following steps are involved: Convert and process the GSM-R signal to obtain baseband data and input it into the terminal decoding system; Based on the terminal decoding system, the baseband data is decoded by the Viterbi algorithm and the GSM-R decoded data is output; Perform Fourier transform and automatic gain control on the baseband data to obtain GSM-R spectrum data; Based on the terminal equipment, GSM-R decoding data and GSM-R spectrum data are displayed through a graphical interface; The step of converting the GSM-R signal to obtain baseband data and inputting the baseband data into the terminal decoding system specifically includes: Get GSM-R signal; Performing bandwidth radio frequency sampling processing on the GSM-R signal to obtain a sampled GSM-R signal; The sampled GSM-R signal is filtered by a low-pass filter to obtain a filtered GSM-R signal; Perform sampling and decision processing on the filtered GSM-R signal, output baseband data and input it into the terminal decoding system; The step of decoding the baseband data by using the Viterbi algorithm based on the terminal decoding system and outputting the GSM-R decoded data specifically includes: Obtaining a wireless frame standard bit sequence; According to the wireless frame standard bit sequence, the baseband data is searched and matched by a matched filtering method to obtain synchronized baseband data; Based on the synchronized baseband data, the training sequence in the regular time slot is extracted and channel estimation processing is performed on it to obtain a channel estimation value; Based on the synchronized baseband data, the data sequence in the regular time slot is extracted and equalized and subjected to standard Viterbi decoding to obtain GSM-R decoded data; The step of performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data specifically includes: The port of the decoding terminal system is monitored by polling receiving mode to obtain the GSM-R signal; The GSM-R signal is converted and processed by Fourier transform to obtain a GSM-R frequency domain signal; The GSM-R frequency domain signal is subjected to gain amplification processing through automatic gain control processing to obtain GSM-R spectrum data.

2. According to claim 1, a high-speed rail GSM-R signal detection method based on a handheld terminal is characterized in that: The specific calculation process of the matched filtering method is as follows: In the above formula, k * represents the best matching timing point, X represents the baseband data, k represents the timing offset, i represents the sampling point index, L * (i) represents the conjugation of the local synchronization sequence generated according to the standard.

3. According to claim 2, a high-speed rail GSM-R signal detection method based on a handheld terminal is characterized in that: The calculation formula of the channel estimation value is as follows: In the above formula, Y(n) represents the training sequence in the regular time slot, L * represents the locally generated training sequence, h represents the channel estimation value, and n represents the index of the data.

4. According to claim 3, a high-speed rail GSM-R signal detection method based on a handheld terminal is characterized in that: The calculation formula for the synchronized baseband data equalization processing is as follows: F(n)=D(n)h * In the above formula, D(n) represents the data sequence in the regular time slot, F(n) represents the equalized baseband data, and h * represents the conjugate of the channel estimate.

5. According to claim 4, a high-speed rail GSM-R signal detection method based on a handheld terminal is characterized in that: The method of displaying GSM-R decoding data and GSM-R spectrum data through a graphical interface based on a terminal device also includes: Based on the terminal device, it is sent to the APP interface program through the callback function, and the GSM-R decoding data and GSM-R spectrum data are displayed through the APP interface.

6. A high-speed rail GSM-R signal detection system based on a handheld terminal, characterized in that: The method for detecting a high-speed rail GSM-R signal based on a handheld terminal according to claim 1 comprises the following modules: The acquisition module is used to convert the GSM-R signal to obtain the baseband data and input it into the terminal decoding system; The decoding module, based on the terminal decoding system, decodes the baseband data through the Viterbi algorithm and outputs GSM-R decoded data; A processing module, used for performing Fourier transform and automatic gain control processing on the baseband data to obtain GSM-R spectrum data; The display module displays GSM-R decoding data and GSM-R spectrum data through a graphical interface based on the terminal device.

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