Single Beidou positioning method and train remote monitoring and diagnosis system

Abstract

The invention discloses a single Beidou satellite positioning method and a diagnosis system. The method comprises the following steps: a non-Beidou satellite has a same-frequency signal with the same frequency as a specific frequency band signal of any frequency band of a Beidou satellite; the same-frequency signal and the specific-frequency-band signal are jointly input into a second filter to suppress the same-frequency signal so as to output a filtered baseband signal, the baseband signal is input into a baseband processor, and the baseband processor only demodulates the BPSK modulation signal to obtain first data; in the first data, only the data packet conforming to the Beidou navigation message format and the Beidou protocol is processed. Therefore, after the mixed signal comprising the specific frequency band signal and the same-frequency signal is received, the mixed signal comprising the specific frequency band signal and the same-frequency signal can be processed for multiple times and in multiple stages based on a mode that the filter filters and the baseband processor only processes the BPSK modulation signal and a mode that only Beidou data is processed in the first data; therefore, the signal of the non-Beidou navigation system is prevented from interfering with the single Beidou system in the embodiment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of radio orientation and radio navigation technology, in particular to a single Beidou positioning method and a train remote monitoring and diagnosis system. BACKGROUND

[0002] The application of the Beidou system in the field of rail transit is gradually deepening, and field technical personnel have proposed a single Beidou system, that is, only using the Beidou navigation system for navigation and positioning, which has significant advantages in terms of autonomy, safety, etc.

[0003] However, when using a single Beidou navigation system, the signals sent by other navigation system satellites may cause co-frequency interference to the signals sent by Beidou satellites, which causes the single Beidou satellite positioning system to be unable to completely shield the signals of non-Beidou satellites. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a single Beidou satellite positioning method and a train remote monitoring and diagnosis system, which can reduce or even avoid the co-frequency interference problem caused by non-Beidou satellites to the single Beidou system.

[0005] The purpose of the present application is achieved by the following technical solutions: In a first aspect, a single Beidou satellite positioning method receives signals sent by Beidou satellites and non-Beidou satellites through a Beidou navigation communication module, and shields the frequency band of the non-Beidou satellites; wherein the non-Beidou satellites have co-frequency signals with the same frequency as the specific frequency band signals of any one of the Beidou satellites; after receiving the specific frequency band signals and the co-frequency signals, the Beidou navigation communication module performs: the co-frequency signals and the specific frequency band signals are input to a second filter to suppress the co-frequency signals to output filtered baseband signals, and then the baseband signals are input to a baseband processor, and the baseband processor only demodulates BPSK modulated signals to obtain first data; in the first data, only data packets conforming to the Beidou navigation text format and the Beidou protocol are processed to isolate the co-frequency signals.

[0006] The present application has the following advantages: after receiving the mixed signals including the specific frequency band signals and the co-frequency signals, based on the filter filtering and the baseband processor processing only the BPSK modulated signals, and only processing the Beidou data in the first data, the mixed signals containing the specific frequency band signals and the co-frequency signals can be processed multiple times and multiple levels, thereby isolating the co-frequency signals to avoid interference from non-Beidou navigation system signals to the single Beidou system of the present application.

[0007] Preferably, the non-Beidou satellite is a GPS satellite, the specific frequency band signal is a Beidou B1C frequency band signal, and the same frequency signal is a GPS L1 frequency band signal.

[0008] Preferably, shielding the frequency band signal of the non-Beidou satellite comprises that the Beidou navigation communication module comprises a radio frequency front-end module, and the radio frequency front-end module shields the frequency band signal of the non-Beidou satellite through a combination of a band-pass filter (BPF) and a low-noise amplifier (LNA).

[0009] Preferably, the second filter is an adaptive filter, the adaptive filter generates a local reference signal as an expected signal template of the adaptive filter based on priori data of the Beidou satellite, and the adaptive filter iterates to suppress components of the GPS L1 frequency band signal.

[0010] Preferably, the baseband processor only demodulates a BPSK modulated signal to obtain first data, comprising: in the baseband signal processing process, the frequency spectrum characteristics of the baseband signal are obtained by fast Fourier transform (FFT) operation, and the signal type is analyzed according to the frequency spectrum form to determine whether the BPSK modulated signal is concentrated in a single main lobe region, whether the spectrum presents a double main lobe feature, and only the BPSK modulated signal is processed to obtain the first data.

[0011] Preferably, the baseband processor only demodulates a BPSK modulated signal to obtain first data further comprises: suppressing the BOC modulated signal in the baseband signal: the baseband signal is down-converted and quantized into a digital intermediate frequency signal by frequency reduction and analog-to-digital conversion (ADC) sampling, and then the baseband I / Q components are demodulated by digital quadrature down-conversion processing to suppress the BOC modulated signal in the baseband signal.

[0012] Preferably, in the first data, only data packets conforming to the Beidou navigation message format and the Beidou protocol are processed, comprising: after being parsed according to the Beidou navigation message format, the synchronization header and CRC of the first data are checked; the specific bit position of the message is extracted with the fixed synchronization code at the start of each subframe, and the table is verified whether it conforms to the Beidou protocol range; if it does not conform to the Beidou navigation message format or the protocol, the corresponding data packet is discarded.

[0013] The second aspect is a train remote monitoring and diagnosis system, comprising: the Beidou navigation communication module, and the Beidou navigation communication module is arranged on the locomotive; a host computer, the host computer is in communication connection with the Beidou navigation communication module.

[0014] Preferably, the Beidou navigation communication module comprises a Beidou third-generation SIM card.

[0015] Preferably, the host is equipped with a subsystem for monitoring and diagnosing the state of the locomotive BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 A flowchart of a single-Beidou positioning method according to an embodiment of the present application; Figure 2 A structure diagram of a Beidou navigation communication module according to an embodiment of the present application; Figure 3 A test result diagram according to some embodiments of the present application; Figure 4 A test result diagram according to some embodiments of the present application; Figure 5 A test result diagram according to some embodiments of the present application. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be described in detail below with reference to the embodiments. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0019] Referring to Figures 1-5 The embodiments of the present application disclose a single-Beidou positioning method and a train remote monitoring and diagnosis system.

[0020] The single-Beidou positioning method according to an embodiment of the present application refers to Figure 1 It is understood that the Beidou navigation communication module receives signals sent by Beidou satellites and non-Beidou satellites, and shields the frequency bands of the non-Beidou satellites.

[0021] Here, the Beidou navigation communication module can be any hardware device equipped with any generation of Beidou SIM card, such as Figure 2 The Beidou navigation communication module shown in FIG. 1 can be installed on a Beidou board, and then connected to a power supply and other devices.

[0022] In some cases, the non-Beidou satellites have co-frequency signals with the same frequency as the specific frequency signals of any frequency band of the Beidou satellites, for example, the center frequencies of Beidou B1C frequency band (1575.42 MHz) and GPS L1 frequency band (1575.42 MHz) are completely overlapped, and the hardware filter cannot completely isolate the co-frequency signals, and the GPS L1 frequency band will cause co-frequency interference to the single-Beidou system.

[0023] Therefore, continuing with the example of the BeiDou B1C band (1575.42 MHz) and the GPS L1 band (1575.42 MHz), the BeiDou navigation communication module receives the specific frequency band signal (B1C band) and the same frequency signal (GPS L1 band) and then performs the following: The co-frequency signal and the specific frequency band signal are input together to the second filter to suppress the co-frequency signal and output the filtered baseband signal; specifically, the second filter can be an adaptive filter, which preliminarily processes the mixed signal of the co-frequency signal and the specific frequency band signal through filtering, or it can be other filters that can achieve the corresponding function.

[0024] Considering that filters may not completely isolate signals at the same frequency, and that BeiDou B1C band signals often use BPSK (Binary Phase Shift Keying) modulation while GPS L1 band signals use BOC (Binary Offset Carrier) modulation, the baseband signal can be input to a baseband processor, which only demodulates the BPSK modulated signal to obtain the first data. In this way, isolation of GPS L1 band signals is achieved by distinguishing the types of modulated signals.

[0025] Therefore, in the first data, only data packets that conform to the BeiDou navigation message format and BeiDou protocol can be processed, thereby further isolating the co-frequency signals.

[0026] It is understood that, after receiving the mixed signal including signals of a specific frequency band and signals of the same frequency, this application embodiment can process the mixed signal including signals of a specific frequency band and signals of the same frequency multiple times and in multiple levels based on the filtering of the filter and the method of the baseband processor only processing the BPSK modulated signal and the method of only processing BeiDou data in the first data, thereby isolating the signals of the same frequency and avoiding interference from signals of non-BeiDou navigation system to the single BeiDou system of this embodiment.

[0027] Next, refer to Figures 1-2 The methods of the embodiments of this application will be described in conjunction with some specific examples.

[0028] like Figure 2As shown, the BeiDou navigation and communication module includes at least a radio frequency module, a reference clock, an RDSS low-noise amplifier, a 10W power amplifier, a baseband chip, a BeiDou SIM card, an RNSS low-noise amplifier, and an RNSS positioning module. It integrates BeiDou-3 and BeiDou-2 RDSS short message communication, positioning, and single BeiDou RNSS positioning functions. The module supports three-port passive antenna operating modes (such as TX, RX, and RNSS), and internally integrates an RDSS radio frequency transceiver chip, a power amplifier chip, a baseband chip, a low-noise amplifier circuit, an IC card, and an RNSS low-noise amplifier and positioning module to achieve short message communication, positioning, navigation, and timing functions. The module has dual independent serial port outputs for RDSS / RNSS functions, allowing the host computer to upgrade the RDSS / RNSS functions via the corresponding serial ports.

[0029] Among them, the baseband chip supports the BeiDou-2 4.0 protocol and the BeiDou-3 protocol and has strong software compatibility, enabling RDSS short message communication function; and the RNSS positioning module supports BDS (BeiDou Navigation System) single-mode operation and has obtained a single BeiDou certification certificate, achieving a positioning accuracy of <2.5m (CEP50).

[0030] Based on the above, in the embodiments of this application, reference is made to Figure 1 As shown, the single BeiDou positioning method includes the following steps: S1. Receive mixed signals transmitted by BeiDou satellites and non-BeiDou satellites through the BeiDou navigation and communication module, and shield the frequency bands of the non-BeiDou satellites, specifically including: based on Figure 2 The radio frequency front-end module of the Beidou navigation and communication module shields the frequency band signals of non-Beidou satellites through its combination of bandpass filter (BPF) and low noise amplifier (LNA).

[0031] In detail, the BeiDou navigation and communication module has two built-in LNAs (Low Noise Amplifiers). One LNA operates on the S-band, filtering and amplifying the RDSS satellite signals with low noise, eliminating the need for an external LNA; it can be directly connected to a passive antenna. The other LNA operates on the BD2 B1 band and uses a passive antenna. Therefore, the mixed signal received by the RF front-end module—a mixture of BeiDou B1C and GPS L1 band signals—is initially filtered for out-of-band noise by the BPF and then converted into a digital signal by the ADC. Furthermore, the built-in BD2 B1 module, operating in single BD2 B1 mode, can simultaneously process multiple frequency signals from the BeiDou system (e.g., B1, B2, B3), thereby improving positioning accuracy using multi-band information, especially in complex environments such as ionospheric delay.

[0032] However, even if the hardware layer limits specific frequency bands through bandpass filters (BPF), GPS L1 signals may still exist as in-band noise, interfering with the demodulation of BeiDou signals. Therefore, the following steps are performed: High-performance filters are used to filter out interference signals from non-BeiDou frequency bands, improving the signal-to-noise ratio.

[0033] S2. For the Beidou navigation and communication module receiving a specific frequency band signal and the same frequency signal, input the same frequency signal and the specific frequency band signal together into a second filter to suppress the same frequency signal and output a filtered baseband signal.

[0034] Specifically, taking the second filter as an adaptive filter as an example, the adaptive filter generates a local reference signal based on the prior data of the Beidou satellite to serve as the desired signal template of the adaptive filter, and the adaptive filter iterates to suppress the components of the GPS L1 band signal.

[0035] In some examples, the adaptive filter employs the Least Mean Square Error (LMS) algorithm, iteratively updating the filter weights based on the error signal (the difference between the target signal and the output signal), including: S21, Input mixed signal x ( n and reference signals that conform to the ideal waveform of BeiDou signals d ( n ).

[0036] S22, Calculate the filter output y ( n )= w^T ( n ) x ( n ),in, w It is a weight vector.

[0037] S23, Calculation Error e(n) = d(n) - y(n).

[0038] S24, Updated weight vector w(n + 1) = w(n) + μe(n) x(n) ,in, μ This is the step size factor.

[0039] Explanation: x(n) is the sampled value of the input mixed signal at time n (the actual received signal); d(n) is the sampled value of the ideal Beidou reference signal at time n (the signal generated inside the receiver); n is the sampling point 0 ≤ n ≤ N-1. y(n) Let n be the output signal (estimated value) at time n.

[0040] In this way, by iterating to minimize the error, the output of the adaptive filter gradually approaches the pure BeiDou signal, thereby suppressing the components of the GPS L1 band signal.

[0041] S3. The baseband signal is input to the baseband processor, which demodulates only the BPSK modulated signal to obtain the first data, specifically including: S31. During the baseband signal processing, the spectral characteristics of the baseband signal are obtained by using Fast Fourier Transform (FFT) operation, and the signal type is determined by analyzing the spectral morphology. In the baseband signal: if the signal energy is significantly concentrated in a single main lobe region, it is determined to be the BPSK modulation signal; if the spectrum shows double main lobe characteristics, it is determined to be the BOC modulation signal. The baseband chip only processes the BPSK modulation signal to obtain the first data.

[0042] Furthermore, if the baseband processor only detects the BPSK signal, it may lead to misjudgment; therefore, S3 also includes: S31. Suppressing the BOC modulation signal in the baseband signal, specifically including: The baseband signal is down-converted and quantized into a digital intermediate frequency signal by down-conversion and analog-to-digital conversion (ADC) sampling, and then demodulated to extract the baseband I / Q components by digital quadrature down-conversion processing, so as to suppress the BOC modulation signal in the baseband signal.

[0043] In some examples, the BeiDou B1I signal operates at 1561.098 MHz, very close to GPS L1. The modulation scheme is BPSK, and the possible GPS L1 band signal is at 1575.42 MHz, modulated using BOC(1,1), and down-converted to an intermediate frequency (e.g., 4 MHz). Then, a sampling rate is selected. Based on the BeiDou B1I bandwidth of 2.046 MHz, the ADC sampling rate needs to be ≥4.092 MHz (satisfying the Nyquist criterion) to avoid spectral aliasing.

[0044] Then, the intermediate frequency signal is shifted to the baseband via a digital mixer to generate in-phase (I-path) and quadrature (Q-path) components: I(n) = x(n) · cos(2πfIFnTs), Q(n) = x(n) · sin(2πfIFnTs) ; in, fIFfIF This is the intermediate frequency; fIFnTs is the phase accumulation in discrete time; S4. In the first data, only data packets conforming to the BeiDou navigation message format and the BeiDou protocol are processed, specifically including: After parsing the BeiDou navigation message format, the synchronization header and CRC of the first data are verified; with the synchronization code at the beginning of each subframe as a fixed value, bits at specific positions in the message are extracted, and the table is looked up to verify whether it conforms to the BeiDou protocol range; if it does not conform to the BeiDou navigation message format or the protocol, the corresponding data packet is discarded.

[0045] In detail, this can be achieved through the following layered technical means: S41. Fast matching of protocol features for first-level filtering: Perform synchronization header verification to verify the BeiDou D1 / D2 messages: start each subframe with a fixed synchronization code (e.g., 0xEB90 for D1 messages and 0x5555 for D2 messages). Perform sliding window matching on the demodulated bitstream (window width = synchronization code length). If three consecutive matching attempts fail, discard the data packet.

[0046] In some examples, hardware acceleration can be used, such as parallel comparison of the FPGA's built-in shift registers, to reduce latency.

[0047] Protocol identifier detection, based on dedicated fields for the BeiDou B1I or BeiDou B1C frequency bands: B1I messages: Navigation Message Type Identifier (e.g., bits 3-8 represent the satellite PRN number, ranging from 1 to 63); and B1C messages: B-CNAV1 identifier in the pilot channel (a specific combination of bits). For example, bits at specific locations in the messages can be extracted and a table can be looked up to verify compliance with the BeiDou protocol.

[0048] S42. Message structure verification for second-level filtering: Perform frame length and CRC check. BeiDou D1 message: 600 bits per subframe (including CRC-24Q check code).

[0049] For example, to check if the frame length matches, the CRC is calculated and compared with the checksum at the end of the message; if it fails, the message is discarded. In some examples, the BeiDou CRC polynomial (such as 0x1864CFB) can be pre-stored, and a hardware CRC module can be used to accelerate the process.

[0050] Furthermore, the timestamp and satellite health status are assessed. A BeiDou-specific field is included in the message: it contains the BeiDou system time (BDT) and a satellite health flag. For example, the timestamp is checked to ensure it is in a valid BDT format (e.g., week count ≤ 8191). If the health flag is "unavailable," the message is discarded.

[0051] S43. Dynamic protocol switching, such as B1I / B1C adaptive switching.

[0052] Understandably, the method achieves highly reliable single BeiDou signal parsing through a three-stage process: modulation feature recognition, interference suppression, and BeiDou signal extraction, combined with frequency / time domain joint processing.

[0053] The train remote detection and diagnosis system according to the embodiments of this application includes the Beidou navigation and communication module in the foregoing embodiments, and the Beidou navigation and communication module is installed on the locomotive; a host computer, which is communicatively connected to the Beidou navigation and communication module.

[0054] As the application of the BeiDou system in the field of rail transit is gradually deepening, BeiDou-2 has problems such as insufficient positioning accuracy (>5m CEP50) in complex railway scenarios (tunnels, mountainous areas, etc.), limited short message communication capacity, poor real-time performance and high cost of data backhaul under no-fire backhaul conditions.

[0055] In contrast, the completion of the global network of the BeiDou-3 system has broadened its coverage, enabling it to meet the positioning needs of cross-border transport locomotives. Furthermore, BeiDou-3's short message communication function has seen significant improvements in both byte count and reliability, which is crucial for emergency communication and off-line data transmission for trains.

[0056] Therefore, in some embodiments, the BeiDou navigation and communication module includes a BeiDou-3 SIM card, and the host is equipped with a subsystem for monitoring and diagnosing the locomotive status.

[0057] Understandably, the research and design of BeiDou-3 technology fully considered system functionality, ease of use, security, openness, scalability, compatibility, advanced technology, and stability, and carried out targeted design. Given that locomotive operation safety is paramount in railway transportation safety, the safety and independence of the system equipment must be guaranteed, without increasing potential locomotive malfunctions. The device incorporates a self-diagnostic fault design. The system's functions and operations are intelligently designed without altering the locomotive's existing operating modes. The system boasts strong reliability and redundancy; when the device malfunctions, it does not affect the locomotive's original functions, thus ensuring the reliability of the entire locomotive control system. Simultaneously, the module interface compatibility design is strengthened, with hardware interfaces consistent with the existing BeiDou-2 communication modules, ensuring the system can complete the hardware upgrade to BeiDou positioning and BeiDou-3 communication functions with minimal modifications. Furthermore, the train remote monitoring and diagnostic system based on a single BeiDou system fully utilizes existing locomotive-mounted integrated information monitoring devices and multi-band combined antenna resources. By integrating a single BeiDou-3 hardware module into the corresponding position on the BeiDou board, it achieves dynamic navigation, positioning, speed measurement, and timing using a single BeiDou-3 system. Simultaneously, it uses the short message communication function of the BeiDou-3 satellite system to achieve locomotive operation data transmission, emergency communication, and no-fire data feedback functions. These functions provide railway bureaus with a more convenient, efficient, and secure way to acquire data, and also provide strong support for the timely detection and handling of train malfunctions.

[0058] Compared to the limited short message capacity of 78 bytes in existing locomotive / power car remote monitoring and diagnostic systems using BeiDou-2, this embodiment increases the short message capacity to 210 bytes by using a BeiDou-3 SIM card with a single BeiDou communication and positioning module. This short message communication function allows the locomotive / power car to send and receive information even when network connectivity is unavailable, which is crucial for communication in emergency situations. Furthermore, using a BeiDou-3 SIM card with a single BeiDou communication and positioning module significantly improves positioning accuracy. For the locomotive, this means it can more accurately determine its own location, thereby improving driving safety and reliability. For example, in automatic driving systems, high-precision positioning is fundamental to achieving autonomous driving.

[0059] The above content will be explained in detail below with reference to some specific embodiments.

[0060] In subsequent embodiments, the module's dynamic navigation positioning, speed measurement, and time synchronization functions are realized through software and hardware simulation. Combined with the vehicle-mounted subsystem of the China Locomotive Remote Monitoring and Diagnosis System, the locomotive operation data transmission, emergency communication, and no-fire data feedback functions are realized using the BeiDou-3 satellite system short message communication.

[0061] In some embodiments, the technical parameters, key characteristics, external dimensions, and docking interfaces of the BeiDou-3 module are studied in depth, while the GPS positioning function is removed, and the overall design and system block diagram of the system are completed.

[0062] In some embodiments, the module's dynamic navigation positioning, speed measurement, and time synchronization functions are realized through software and hardware simulation. Combined with the vehicle-mounted subsystem of the China Locomotive Remote Monitoring and Diagnosis System, the system uses BeiDou-3 satellite system short message communication to realize locomotive operation data transmission, emergency communication, and no-fire data feedback functions.

[0063] In some embodiments, the design, production, and debugging of a prototype train remote monitoring and diagnostic system based on a single BeiDou system are described. After sending a command to the BeiDou module to modify the positioning to single-mode BeiDou, the starting field of the latitude and longitude information returned by the BeiDou module's serial port can be used to determine whether only BeiDou positioning information is output. The positioning information output by the single BeiDou system on the left starts with $BDGGA, while the positioning information output by GPS+BeiDou on the right starts with $GNGGA. Verification results are as follows... Figure 3 As shown.

[0064] In some embodiments, the system was tested and operational on locomotive HXD3C-8264 of the Xiju New Section. Currently, its operational status is good, with normal BeiDou online rate and locomotive positioning function. The onboard test plan verifies the system's technical status by checking the main processor board of the onboard subsystem, the BeiDou board indicator light status, and querying the corresponding locomotive's real-time BeiDou data in the China Locomotive Remote Monitoring and Diagnostic System Ground Integrated Management System. The specific test plan is as follows: Verification Method 1: Remotely access the main processor board system to check the BeiDou status and GPS visible satellite status of the internal program of the main processor board. Check the main control program - LDP status - BeiDou board status, and verify if the BeiDou board software version is a single-BeiDou version. Simultaneously check if only the number of BeiDou satellites has a value, while the number of GPS satellites is empty. Verification Method 2: Verify the single-BeiDou mode indicator light of the onboard subsystem's main BeiDou board. Observe the status of the BeiDou board indicator light to determine if the modification was successful. The results are referenced... Figure 5 As shown. Verification Method 3: Query the real-time BeiDou data of the corresponding locomotive in the Ground Integrated Management System of the China Locomotive Remote Monitoring and Diagnostic System. Check whether the locomotive's BeiDou data in the Ground Integrated Management System of the China Locomotive Remote Monitoring and Diagnostic System shows that the locomotive is in single BeiDou positioning mode. Figure 5 As shown.

[0065] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A single BeiDou satellite positioning method, characterized in that, The BeiDou navigation and communication module receives signals transmitted by BeiDou satellites and non-BeiDou satellites, and blocks the frequency bands of the non-BeiDou satellites; wherein, the non-BeiDou satellites have co-frequency signals with the same frequency as the signals of any specific frequency band of the BeiDou satellites. The BeiDou navigation and communication module receives a specific frequency band signal and the same frequency signal, and then executes the following: The co-frequency signal and the specific frequency band signal are input together to the second filter to suppress the co-frequency signal and output the filtered baseband signal. Then the baseband signal is input to the baseband processor, which demodulates only the BPSK modulated signal to obtain the first data. In the first data, only data packets that conform to the BeiDou navigation message format and BeiDou protocol are processed to isolate the co-frequency signal.

2. The single BeiDou satellite positioning method according to claim 1, characterized in that, The non-BeiDou satellites are GPS satellites, the specific frequency band signal is the BeiDou B1C frequency band signal, and the same frequency signal is the GPS L1 frequency band signal.

3. The single BeiDou satellite positioning method according to claim 2, characterized in that, The frequency bands that shield the signals from non-BeiDou satellites include: The BeiDou navigation and communication module includes a radio frequency front-end module, which uses its bandpass filter (BPF) and low-noise amplifier (LNA) combination to shield the frequency band signals of non-BeiDou satellites.

4. The single BeiDou satellite positioning method according to claim 2, characterized in that, The second filter is an adaptive filter. Based on the prior data of the BeiDou satellite, the adaptive filter generates a local reference signal as the desired signal template of the adaptive filter. The adaptive filter iterates to suppress the components of the GPS L1 band signal.

5. The single BeiDou satellite positioning method according to claim 2, characterized in that, The baseband processor obtains first data by demodulating only the BPSK modulated signal, including: In the baseband signal processing, the spectral characteristics of the baseband signal are obtained using Fast Fourier Transform (FFT) operations. The spectral morphology is analyzed to determine the signal type. In the baseband signal: If the signal energy is significantly concentrated in a single main lobe region, it is determined to be the BPSK modulated signal; if the spectrum exhibits dual main lobe characteristics, it is determined to be the BOC modulated signal. The first data is obtained by processing only the BPSK modulated signal.

6. The single BeiDou satellite positioning method according to claim 5, characterized in that, The baseband processor, which obtains first data by demodulating the BPSK modulated signal, also includes: suppressing the BOC modulated signal in the baseband signal. The baseband signal is down-converted and quantized into a digital intermediate frequency signal by down-conversion and analog-to-digital converter (ADC) sampling. Then, the baseband I / Q components are demodulated by digital quadrature down-conversion processing to suppress the BOC modulation signal in the baseband signal.

7. The single BeiDou satellite positioning method according to claim 2, characterized in that, In the first data, only data packets conforming to the BeiDou navigation message format and the BeiDou protocol are processed, including: After parsing the BeiDou navigation message format, the synchronization header and CRC of the first data are verified; with the synchronization code at the beginning of each subframe as a fixed value, bits at specific positions in the message are extracted, and the table is looked up to verify whether it conforms to the BeiDou protocol range. If the data packet does not conform to the BeiDou navigation message format or the protocol, the corresponding data packet is discarded.

8. A remote monitoring and diagnostic system for trains, characterized in that, include: The Beidou navigation and communication module according to any one of claims 1-7, wherein the Beidou navigation and communication module is mounted on the locomotive; The host computer is communicatively connected to the BeiDou navigation and communication module.

9. The train remote monitoring and diagnostic system according to claim 8, characterized in that, The BeiDou navigation and communication module includes a BeiDou-3 SIM card.

10. The train remote monitoring and diagnostic system according to claim 8, characterized in that, The host computer is equipped with a subsystem that is used to monitor and diagnose the condition of the locomotive.

Images