CN117198002A

CN117198002A - GNSS ground disaster monitoring system and method

Info

Publication number: CN117198002A
Application number: CN202311167723.6A
Authority: CN
Inventors: 丁廉程; 张欢; 王帆; 李军焕
Original assignee: Cetc Xinghe Beidou Technology Xi'an Co ltd
Current assignee: Cetc Xinghe Beidou Technology Xi'an Co ltd
Priority date: 2023-09-11
Filing date: 2023-09-11
Publication date: 2023-12-08

Abstract

The invention provides a GNSS ground disaster monitoring system and a method, wherein the system comprises a plurality of monitoring subsystems, a monitoring main station and a ground disaster monitoring and early warning platform, and each monitoring subsystem is used for collecting and outputting sensor data; the monitoring master station comprises a Beidou RDSS all-in-one machine and a multi-system GNSS device, the multi-system GNSS device measures geology and outputs GNSS measurement data, the LoRa communication module transmits sensor data to the multi-system GNSS device, the multi-system GNSS device receives the sensor data, and the multi-system GNSS device uploads the GNSS measurement data and the sensor data to a ground disaster monitoring and early warning platform through the Beidou RDSS all-in-one machine. The ground disaster monitoring and early warning platform realizes trend early warning and abnormality early warning. The method is based on the system. The invention adopts LoRa communication and Beidou RDSS communication technology to solve the problem that GNSS equipment excessively depends on a base station.

Description

GNSS ground disaster monitoring system and method

Technical Field

The invention relates to the technical field of ground disaster monitoring, in particular to a GNSS ground disaster monitoring system and a GNSS ground disaster monitoring method.

Background

The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.

Global navigation satellite systems (Global Navigation Satellite System, GNSS), also known as global satellite navigation systems, are space-based radio navigation positioning systems that can provide all-weather 3-dimensional coordinates and velocity and time information to a user at any location on the earth's surface or near earth space.

The geological disaster monitoring is a work for measuring and monitoring the activity of the geological disaster and dynamic change of various inducing factors by using various technologies and methods, and is an important basis for predicting and forecasting the geological disaster. The GNSS ground disaster monitoring equipment monitors deformation and displacement of various geological disaster surfaces by using GNSS and communication technology, so as to achieve the purpose of real-time monitoring.

The conventional GNSS ground disaster monitoring equipment adopts a mobile communication technology, the communication is relatively simple, the data transmission rate meets the requirement of a monitoring system, but the communication is excessively dependent on a base station, and communication dead zones exist in some remote places (such as mountain areas and urban suburban areas) and cannot meet the monitoring requirement of the conventional GNSS ground disaster monitoring equipment.

In view of this, there is a need for an improvement in the ground fault monitoring in the prior art to solve the problem that the existing GNSS devices rely excessively on base stations.

Disclosure of Invention

The invention provides a GNSS ground disaster monitoring system and a GNSS ground disaster monitoring method, which solve the problem that GNSS equipment excessively depends on a base station by adopting LoRa communication and Beidou RDSS communication technologies.

The technical scheme for realizing the purpose of the invention is as follows:

in one aspect, the present invention provides a GNSS ground disaster monitoring system, including: the monitoring system comprises a plurality of monitoring subsystems for monitoring geological disasters in a base station communication blind area, a monitoring master station for monitoring the geological disasters and a ground disaster monitoring and early warning platform for early warning the trend of the ground disasters;

each monitoring subsystem collects and outputs sensor data;

the monitoring master station is communicated with each monitoring subsystem through a LoRa communication module and receives the sensor data; the monitoring master station measures geology to obtain GNSS measurement data, and uploads the GNSS measurement data and the sensor data to a ground disaster monitoring and early warning platform;

the ground disaster monitoring and early warning platform is communicated with the monitoring master station, and the ground disaster monitoring and early warning platform realizes trend early warning and abnormal early warning according to the GNSS measurement data and the sensor data.

The LoRa communication module receives sensor data of each monitoring subsystem and realizes communication between the multi-system GNSS equipment and the monitoring subsystem; the RDSS communication module is used for realizing communication between the multi-system GNSS equipment and the Beidou RDSS integrated machine, compressing and packing sensor data of each monitoring subsystem and received data such as GNSS original observed quantity, ephemeris and the like, and forwarding the data through the RDSS communication module; the GNSS processing module captures and tracks the original observed quantity and generates a navigation message. The invention adopts LoRa communication and Beidou RDSS communication technology to solve the problem that GNSS equipment excessively depends on a base station.

Based on one aspect, in one possible implementation manner, the monitoring master station includes a multi-system GNSS device and a beidou RDSS integrated machine, the multi-system GNSS device receives satellite signals to obtain GNSS measurement data for measuring geology, and the GNSS measurement data is transmitted to the beidou RDSS integrated machine;

each monitoring subsystem is communicated with the multi-system GNSS equipment through the LoRa communication module, the multi-system GNSS equipment receives and processes the sensor data, and the sensor data are also transmitted to the Beidou RDSS integrated machine;

and the multisystem GNSS equipment sends the GNSS measurement data and the sensor data to the ground disaster monitoring and early warning platform through the RDSS/4G communication module.

Based on an aspect, in one possible implementation, a multi-system GNSS device includes a GNSS receiving module, a GNSS processing module, a LoRa communication module, and an RDSS communication module;

and the LoRa communication module is communicated with the monitoring subsystem, and the RDSS communication module is communicated with the Beidou RDSS integrated machine.

Based on one aspect, in one possible implementation, a LoRa communication module sends a query instruction to the monitoring subsystem, and the LoRa communication module receives the sensor data of the monitoring subsystem;

the GNSS receiving module receives satellite navigation signals, captures and tracks the satellite navigation signals through the GNSS processing module, and performs bit synchronization processing and frame synchronization processing on the satellite navigation signals to obtain original observables and navigation messages.

Based on an aspect, in one possible implementation, the GNSS processing module includes an acquisition processing sub-module that acquires satellite signals input by the RNSS/SBAS based on the PMF-FFT pseudo code acquisition module. The RNSS/SBAS is a regional navigation satellite system/satellite-based augmentation system, respectively.

The working principle of the PMF-FFT pseudo code capturing module of the invention is as follows: the digital intermediate frequency data coming from the ADC is mixed with a local carrier NCO, the digital intermediate frequency data is down-converted to a baseband, the baseband and a local reproduction code are sent into a matched filter correlator group, then partial correlation values output by the matched filter correlator group are sent into an FFT module for power spectrum analysis, and finally, the result output by the FFT is sent into a detection decision module for signal detection. The capture principle is that the pseudo code of local static is used as the tap coefficient of the matched filter correlator, so that the sampling data from ADC sequentially slides through the local sequence to generate a correlation value in each clock period, and when the two sequences are zero phase shifted, a correlation peak value is generated. The FFT conversion is to analyze the signal from the frequency domain, a fixed frequency sine and cosine signal is a single spectral line on the spectrogram, and Gaussian white noise contains all frequencies, and the FFT conversion is an infinitely wide frequency spectrum. When the phases of the local pseudo code and the receiving sequence pseudo code are aligned, the pseudo code is stripped; the signals after pseudo code is stripped in a short period are sine and cosine signals with approximately fixed frequency modulated by the baseband data symbol, and the fixed frequency is the carrier Doppler frequency. At this time, the signal is subjected to despreading processing, and the signal to noise ratio is high, so that the signal is a single spectral line on a spectrogram after spectral transformation; non-ideal is a narrow band of spectral lines. The amplitude of this line significantly exceeds the other noise lines due to the higher signal-to-noise ratio. And estimating the code phase and the carrier Doppler frequency according to the amplitude of the spectral line, and completing the pseudo code capturing.

The PMF-FFT capturing module comprises matched filter correlators and an FFT operation module, P matched filter correlators are vertically symmetrical, the length of each matched filter correlator is X, and M is the length of a pseudo-random code, so that M=XP. The 1 st matched filter correlator corresponds to the first X chips of the spread spectrum codes, the 2 nd matched filter correlator corresponds to the next X spread spectrum codes, and so on, and the upper and lower 2P matched filter correlators correspond to two paths of M pseudo random codes respectively. The method comprises the steps that a received signal is multiplied by a preset local carrier, and the carrier is stripped to obtain I, Q two paths of signals; the local pseudo-random code and the two paths of signals move relatively, and continuously perform correlation operation with the partial matched filter correlator. The PMF outputs corresponding to the upper path and the lower path are added and are transformed with N-point FFT; and then selecting the peak value with the largest output amplitude at N output ends of the FFT as the output of the correlator. The FFT is used to perform doppler shift estimation of the received signal.

Based on an aspect, in one possible implementation, the GNSS processing module includes a tracking processing sub-module;

the carrier tracking loop of the tracking processing sub-module is cascaded with a third-order PLL through a second-order FLL to realize carrier tracking of satellite navigation signals;

the carrier tracking loop of the tracking processing sub-module adopts a second-order FLL and a third-order PLL to respectively track the frequency difference and the residual phase difference.

The carrier tracking loop of the invention works as follows: as input digital intermediate frequency signal S _IF (n) first mix-multiply with the carrier replicated by the carrier ring, where the sine-responsible carrier is multiplied on the I branch and the cosine-replicated carrier is multiplied on the Q branch; then, the mixing results I and Q on the I branch and the Q branch are respectively related to the advanced, instant and lagging C/A codes copied by the code ring; then, correlation result i _E Correlation junctionFruit i _P Correlation result i _L Correlation result q _E Correlation result q _P Correlation result q _L After passing through the integrator-cleaner, respectively outputting coherent integration I _E Coherent integration I _P Coherent integration I _L Coherent integration Q _E Coherent integration Q _P Coherent integration Q _L The method comprises the steps of carrying out a first treatment on the surface of the Then, coherent integration on the real-time branch I _P And coherent integration Q _P The coherent integration value on the other two branches is used as the input of the code ring discriminator; finally, the carrier ring and the code ring respectively filter the output values of the discriminators, and the filtering results are used for adjusting the output phase, frequency and other states of the carrier numerical control oscillator and the C/A code numerical control oscillator, so that the carrier copied by the carrier ring is consistent with the receiving carrier, and meanwhile, the C/A instant code copied by the code ring is consistent with the receiving C/A code, and the carrier and the C/A code in the receiving signal at the next moment are thoroughly stripped in the tracking loop. During operation of the tracking loop, the carrier loop outputs Doppler frequency, integral Doppler and carrier phase measurements based on its replicated carrier signal state, while the code loop outputs code phase and pseudorange measurements based on its replicated C/A code signal state, and the carrier loop discriminator may additionally demodulate the navigation message data bits on the satellite signal.

Based on an aspect, in one possible implementation manner, the plurality of sensors of each monitoring subsystem are arranged in a geological monitoring area of a communication blind area of the monitoring base station.

Based on an aspect, in one possible implementation manner, the monitoring master station includes a Beidou RDSS integrated machine and a multi-system GNSS device;

the multi-system GNSS device measures geology and outputs GNSS measurement data;

the multi-system GNSS device is communicated with the monitoring subsystem through a LoRa communication module, and the LoRa communication module transmits the sensor data to the multi-system GNSS device;

the multi-system GNSS equipment is connected with the Beidou RDSS integrated machine, and uploads the GNSS measurement data and the sensor data to the ground disaster monitoring and early warning platform through the Beidou RDSS integrated machine;

the ground disaster monitoring and early warning platform is used for receiving the GNSS measurement data and the sensor data, realizing trend early warning and abnormal early warning and coping with the conditions of slow surface deformation and collapse.

Based on one aspect, in one possible implementation manner, the multi-system GNSS device amplifies, filters and analog-to-digital converts the received GNSS signals to obtain digital baseband signals, and the digital baseband signals acquire GNSS raw observables through capturing and tracking of a baseband loop and demodulate the digital baseband signals to obtain navigation messages;

the multi-system GNSS equipment acquires sensor data through the LoRa communication module, and the GNSS original observed quantity and the sensor data are compressed and packed through the multi-system GNSS equipment and are sent to the ground disaster monitoring and early warning platform through the Beidou RDSS integrated machine.

Based on an aspect, in one possible implementation manner, the multi-system GNSS device includes:

the radio frequency channel module is used for processing the GNSS electrical signals into digital intermediate frequency signals;

the baseband processing module is connected with the radio frequency channel module and is used for processing the digital intermediate frequency signals sent by the radio frequency channel module to obtain GNSS measurement data;

the RDSS communication module is connected with the baseband processing module and the Beidou RDSS integrated machine, and the Beidou RDSS integrated machine transmits GNSS measurement data to the ground disaster monitoring and early warning system through satellites;

the storage module is connected with the baseband processing module and is used for storing at least GNSS measurement data of the baseband processing module;

the ground disaster sensor of the monitoring subsystem collects sensor data, the ground disaster sensor transmits data through a LoRa communication module, the LoRa communication module is connected with the baseband processing module, and the storage module stores GNSS measurement data and ground disaster sensor data of the baseband processing module.

Based on one aspect, in one possible implementation manner, the digital intermediate frequency signals enter an FPGA chip of the baseband processing unit after being sampled, the FPGA chip captures corresponding satellites according to satellite numbers sent by a DSP chip of the baseband processing unit, and rough signal code phases and carrier frequencies of all satellites are obtained, so that successfully captured satellites are obtained;

the DSP chip performs tracking synchronization, tracks and obtains accurate original observables such as code phase and carrier frequency, and completes decoding after bit synchronization, frame synchronization and the like, and meanwhile, the DSP chip extracts the observed measurement value and original telegraph text generation from the channel processing module.

On the other hand, the invention provides a GNSS ground disaster monitoring method, which is based on the GNSS ground disaster monitoring system, and comprises the following steps:

the monitoring master station receives sensor data sent in real time by a plurality of monitoring subsystems positioned in a communication blind area of the monitoring base station in real time through the LoRa communication module;

the method comprises the steps of monitoring geology of a main station to obtain GNSS measurement data;

and uploading the GNSS measurement data and the sensor data to a ground disaster monitoring and early warning platform by the monitoring master station.

Based on another aspect, in one possible implementation manner, the method further includes:

and the ground disaster monitoring and early warning platform realizes trend early warning and abnormality early warning according to the GNSS measurement data and the sensor data.

the monitoring subsystem sends the sensor data to the multi-system GNSS equipment through the LoRa communication module;

the multi-system GNSS equipment receives satellite signals to obtain GNSS measurement data for measuring geology, and the GNSS measurement data are also transmitted to the Beidou RDSS all-in-one machine;

Compared with the prior art, the invention has the beneficial effects that:

Drawings

FIG. 1 is a schematic block diagram of a GNSS ground disaster monitoring system provided by the present invention;

FIG. 2 is a flow chart of a multi-system GNSS device according to the present invention;

FIG. 3 is a block diagram of a PMF-FFT acquisition module provided by the present invention;

FIG. 4 is a schematic diagram of a trace processing submodule according to the present invention; the method comprises the steps of carrying out a first treatment on the surface of the

FIG. 5 is a flowchart of a GNSS ground disaster monitoring method according to the present invention.

Detailed Description

The present invention will be described in detail below with reference to the embodiments shown in the drawings, but it should be understood that the embodiments are not limited to the present invention, and functional, method, or structural equivalents and alternatives according to the embodiments are within the scope of protection of the present invention by those skilled in the art.

Referring to fig. 1, the present invention provides a GNSS ground disaster monitoring system, including: the monitoring system comprises a plurality of monitoring subsystems for monitoring geological disasters in a base station communication blind area, a monitoring master station for monitoring the geological disasters and a ground disaster monitoring and early warning platform for early warning the trend of the ground disasters; each monitoring subsystem collects and outputs sensor data; the monitoring master station is communicated with each monitoring subsystem through the LoRa communication module and receives sensor data; the monitoring master station measures geology to obtain GNSS measurement data, and uploads the GNSS measurement data and sensor data to the ground disaster monitoring and early warning platform; the ground disaster monitoring and early warning platform is communicated with the monitoring master station, and the ground disaster monitoring and early warning platform realizes trend early warning and abnormal early warning according to GNSS measurement data and sensor data.

Referring to fig. 2, the monitoring master station according to the embodiment of the present invention includes a multi-system GNSS device and a beidou RDSS all-in-one machine, where the multi-system GNSS device receives satellite signals to obtain GNSS measurement data for measuring geology, and the GNSS measurement data is transmitted to the beidou RDSS all-in-one machine; each monitoring subsystem is communicated with the multi-system GNSS equipment through the LoRa communication module, the multi-system GNSS equipment receives and processes sensor data, and the sensor data can be also transmitted to the Beidou RDSS integrated machine; the multisystem GNSS device sends GNSS measurement data and sensor data to the ground disaster monitoring and early warning platform through the RDSS/4G communication module, and in practical application, the sensor data is not excluded from being conveyed in other modes.

The multi-system GNSS device comprises a GNSS receiving module, a GNSS processing module, a LoRa communication module and an RDSS communication module; the LoRa communication module is communicated with the monitoring subsystem, and the RDSS communication module is communicated with the Beidou RDSS all-in-one machine.

The LoRa communication module sends a query instruction to the monitoring subsystem, and receives sensor data of the monitoring subsystem; the GNSS receiving module receives satellite navigation signals, captures and tracks the satellite navigation signals through the GNSS processing module, and performs bit synchronization processing and frame synchronization processing on the satellite navigation signals to obtain original observables and navigation messages.

The GNSS processing module comprises a capturing processing sub-module which captures satellite signals input by RNSS/SBAS based on a PMF-FFT pseudo code capturing module. In practical application, the working principle of the PMF-FFT pseudo code capturing module of the embodiment of the invention is as follows: the digital intermediate frequency data coming from the ADC is mixed with a local carrier NCO, the digital intermediate frequency data is down-converted to a baseband, the baseband and a local reproduction code are sent into a matched filter correlator group, then partial correlation values output by the matched filter correlator group are sent into an FFT module for power spectrum analysis, and finally, the result output by the FFT is sent into a detection decision module for signal detection. The capture principle is that the pseudo code of local static is used as the tap coefficient of the matched filter correlator, so that the sampling data from ADC sequentially slides through the local sequence to generate a correlation value in each clock period, and when the two sequences are zero phase shifted, a correlation peak value is generated. The FFT conversion is to analyze the signal from the frequency domain, a fixed frequency sine and cosine signal is a single spectral line on the spectrogram, and Gaussian white noise contains all frequencies, and the FFT conversion is an infinitely wide frequency spectrum. When the phases of the local pseudo code and the receiving sequence pseudo code are aligned, the pseudo code is stripped; the signals after pseudo code is stripped in a short period are sine and cosine signals with approximately fixed frequency modulated by the baseband data symbol, and the fixed frequency is the carrier Doppler frequency. At this time, the signal is subjected to despreading processing, and the signal to noise ratio is high, so that the signal is a single spectral line on a spectrogram after spectral transformation; non-ideal is a narrow band of spectral lines. The amplitude of this line significantly exceeds the other noise lines due to the higher signal-to-noise ratio. And estimating the code phase and the carrier Doppler frequency according to the amplitude of the spectral line, and completing the pseudo code capturing.

Referring to fig. 3, a PMF-FFT capturing module according to an embodiment of the present invention includes a matched filter correlator and an FFT operation module, P matched filter correlators are symmetric up and down, and each matched filter correlator has a length of X, and if M is a pseudo-random code length, then m=xp. The 1 st matched filter correlator corresponds to the first X chips of the spread spectrum codes, the 2 nd matched filter correlator corresponds to the next X spread spectrum codes, and so on, and the upper and lower 2P matched filter correlators correspond to two paths of M pseudo random codes respectively. The method comprises the steps that a received signal is multiplied by a preset local carrier, and the carrier is stripped to obtain I, Q two paths of signals; the local pseudo-random code and the two paths of signals move relatively, and continuously perform correlation operation with the partial matched filter correlator. The PMF outputs corresponding to the upper path and the lower path are added and are transformed with N-point FFT; and then selecting the peak value with the largest output amplitude at N output ends of the FFT as the output of the correlator. The FFT is used to perform doppler shift estimation of the received signal.

The GNSS processing module comprises a tracking processing sub-module; the carrier tracking loop of the tracking processing sub-module is cascaded with a third-order PLL through a second-order FLL to realize carrier tracking of satellite navigation signals; the carrier tracking loop of the tracking processing sub-module adopts a second-order FLL and a third-order PLL to respectively track the frequency difference and the residual phase difference.

Referring to fig. 4, the carrier tracking loop according to the embodiment of the present invention works as follows: as input digital intermediate frequency signal S _IF (n) first mix-multiply with the carrier replicated by the carrier ring, where the sine-responsible carrier is multiplied on the I branch and the cosine-replicated carrier is multiplied on the Q branch; then, the mixing results I and Q on the I branch and the Q branch are respectively related to the advanced, instant and lagging C/A codes copied by the code ring; then, correlation result i _E Correlation result i _P Correlation result i _L Correlation result q _E Correlation result q _P Correlation result q _L After passing through the integrator-cleaner, respectively outputting coherent integration I _E Coherent integration I _P Coherent integration I _L Coherent integration Q _E Coherent integration Q _P Coherent integration Q _L The method comprises the steps of carrying out a first treatment on the surface of the Then, coherent integration on the real-time branch I _P And coherent integration Q _P The coherent integration value on the other two branches is used as the input of the code ring discriminator; finally, the carrier ring and the code ring respectively filter the output values of the discriminators, and the filtering result is used for adjusting the output phase and frequency of the carrier numerical control oscillator and the C/A code numerical control oscillator so as to make the carrier ring duplicateThe carrier wave of the code ring keeps consistent with the receiving carrier wave, and meanwhile, the C/A instant code copied by the code ring keeps consistent with the receiving C/A code, so that the carrier wave and the C/A code in the receiving signal at the next moment are thoroughly stripped in the tracking loop. During operation of the tracking loop, the carrier loop outputs Doppler frequency, integral Doppler and carrier phase measurements based on its replicated carrier signal state, while the code loop outputs code phase and pseudorange measurements based on its replicated C/A code signal state, and the carrier loop discriminator may additionally demodulate the navigation message data bits on the satellite signal.

The plurality of sensors of each monitoring subsystem are arranged in a geological monitoring area of a communication blind area of a monitoring base station.

The monitoring master station comprises a Beidou RDSS integrated machine and a multi-system GNSS device, wherein the multi-system GNSS device measures geology and outputs GNSS measurement data; the multi-system GNSS device is communicated with the monitoring subsystem through a LoRa communication module, the LoRa communication module transmits sensor data to the multi-system GNSS device, the multi-system GNSS device receives the sensor data, the multi-system GNSS device is connected with the Beidou RDSS integrated machine, and the multi-system GNSS device uploads GNSS measurement data and the sensor data to the ground disaster monitoring and early warning platform through the Beidou RDSS integrated machine; the ground disaster monitoring and early warning platform is used for receiving GNSS measurement data and sensor data, realizing trend early warning and abnormal early warning and coping with the conditions of slow surface deformation and collapse.

The multi-system GNSS device of the embodiment of the invention amplifies, filters and analog-to-digital converts the received GNSS signals to obtain digital baseband signals, and the digital baseband signals acquire GNSS original observables through capturing and tracking of a baseband loop and demodulate the GNSS original observables to obtain navigation messages; sensor data is acquired by the multisystem GNSS equipment through the LoRa communication module, and the GNSS original observed quantity and the sensor data are compressed and packed through the multisystem GNSS equipment and are sent to the ground disaster monitoring and early warning platform through the Beidou RDSS integrated machine.

The multi-system GNSS device according to the embodiment of the invention comprises:

the ground disaster sensor of the monitoring subsystem collects sensor data, the ground disaster sensor transmits data through the LoRa communication module, the LoRa communication module is connected with the baseband processing module, and the storage module stores GNSS measurement data and ground disaster sensor data of the baseband processing module.

According to the embodiment of the invention, the digital intermediate frequency signals enter the FPGA chip of the baseband processing unit after being sampled, the FPGA chip captures corresponding satellites according to the satellites sent by the DSP chip of the baseband processing unit, and rough signal code phases and carrier frequencies of all satellites are obtained, so that successfully captured satellites are obtained; the DSP chip performs tracking synchronization, tracks and obtains accurate original observables such as code phase and carrier frequency, and completes decoding after bit synchronization, frame synchronization and the like, and meanwhile, the DSP chip extracts the observed measurement value and original telegraph text generation from the channel processing module.

Referring to fig. 5, an embodiment of the present invention further provides a GNSS ground disaster monitoring method, based on the foregoing GNSS ground disaster monitoring system, the method includes:

and uploading GNSS measurement data and sensor data to a ground disaster monitoring and early warning platform by the monitoring master station.

The GNSS ground disaster monitoring method of the embodiment of the invention comprises the following steps in addition to the above steps:

and the ground disaster monitoring and early warning platform realizes trend early warning and abnormal early warning according to the GNSS measurement data and the sensor data.

The GNSS ground disaster monitoring method of the embodiment of the invention comprises the following steps:

the monitoring subsystem sends the sensor data to the multi-system GNSS equipment through the LoRa communication module, the multi-system GNSS equipment receives the sensor data, the sensor data is transmitted to the Beidou RDSS integrated machine, and in practical application, the sensor data is not excluded from being transmitted in other modes;

and the multisystem GNSS equipment transmits the GNSS measurement data and the sensor data to the ground disaster monitoring and early warning platform through the RDSS/4G communication module.

Referring to fig. 3, the tracking processing sub-module of the embodiment of the invention processes satellite signals as follows: as input digital intermediate frequency signal S _IF (n) first mix-multiply with the carrier replicated by the carrier ring, where the sine-responsible carrier is multiplied on the I branch and the cosine-replicated carrier is multiplied on the Q branch; then, the mixing results I and Q on the I branch and the Q branch are respectively related to the advanced, instant and lagging C/A codes copied by the code ring; then, correlation result i _E ，i _P ，i _L ，q _E ，q _P ，q _L After passing through the integrator-cleaner, respectively outputting coherent integration I _E ，I _P ，I _L ，Q _E ，Q _P ，Q _L The method comprises the steps of carrying out a first treatment on the surface of the Then, the integral value I on the instant branch _P And Q _P The coherent integration value on the other two branches is used as the input of the code ring discriminator; finally, the carrier ring and the code ring respectively filter the output values of the discriminators, and the filtering result is used for adjusting the output phase and frequency states of the carrier numerical control oscillator and the C/A code numerical control oscillator so as to keep the carrier copied by the carrier ring and the receiving carrier oneSo that the C/A instant code copied by the code ring is consistent with the received C/A code, and the carrier wave and the C/A code in the received signal at the next moment are thoroughly stripped in the tracking loop. During operation of the tracking loop, the carrier loop outputs Doppler frequency, integral Doppler and carrier phase measurements based on its replicated carrier signal state, while the code loop outputs code phase and pseudorange measurements based on its replicated C/A code signal state, and the carrier loop discriminator may additionally demodulate the navigation message data bits on the satellite signal.

The carrier tracking loop is cascaded with a third-order PLL through a second-order FLL to realize carrier tracking of satellite navigation signals, and the tracking of frequency difference and residual phase difference is respectively completed by adopting the second-order FLL and the third-order PLL.

Referring to fig. 3, the PMF-FFT pseudo code acquisition structure according to the embodiment of the present invention operates according to the following principle: the digital intermediate frequency data coming from the ADC is mixed with a local carrier NCO, the digital intermediate frequency data is down-converted to a baseband, the baseband and a local reproduction code are sent into a matched filter bank, then partial correlation values output by the matched filter bank are sent into an FFT module for power spectrum analysis, and finally, the result output by the FFT is sent into a detection decision module for signal detection. The capture principle is that the pseudo code of local rest is used as the tap coefficient of the matched filter, so that the sampling data from ADC sequentially slides through local sequence to generate a correlation value in each clock period, and when the two sequences are zero phase shifted, a correlation peak value is generated. The FFT conversion is to analyze the signal from the frequency domain, a fixed frequency sine and cosine signal is a single spectral line on the spectrogram, and Gaussian white noise contains all frequencies, and the FFT conversion is an infinitely wide frequency spectrum. When the local pseudocode and the received sequence pseudocode are phase aligned. Peeling the pseudo code; the signals after pseudo code is stripped in a short period are sine and cosine signals with approximately fixed frequency modulated by the baseband data symbol, and the fixed frequency is the carrier Doppler frequency. At this time, the signal is subjected to despreading processing, and the signal to noise ratio is high, so that the signal is a single spectral line on a spectrogram after spectral transformation; in the non-ideal case, a narrow band spectrum is used, and the amplitude of the spectrum is obviously higher than that of other noise spectrum due to higher signal-to-noise ratio. The estimation of code phase and carrier Doppler frequency can be carried out according to the amplitude and the amplitude of spectral lines, and the capture of pseudo codes is completed.

The PMF-FFT capturing module is composed of matched filter correlators and an FFT operation module, P matched filter correlators are symmetrical up and down in fig. 3, the length of each correlator is X, and if M is the pseudo-random code length, then m=xp. The 1 st correlator corresponds to the first X chips of the spreading codes, the 2 nd correlator corresponds to the next X spreading codes, and so on, and the upper and lower 2P matched filter correlators correspond to two paths of M pseudo random codes respectively. The method comprises the steps that a received signal is multiplied by a preset local carrier, and the carrier is stripped to obtain I, Q two paths of signals; the local pseudo-random code and the two paths of signals move relatively, and continuously perform correlation operation with the partial matched filter. The PMF outputs corresponding to the upper path and the lower path are added and are transformed with N-point FFT; and then selecting the peak value with the largest output amplitude at N output ends of the FFT as the output of the correlator. The FFT is used to perform doppler shift estimation of the received signal.

It should be noted that, in the embodiment of the present invention, after the GNSS device captures and tracks the received signal, the signal is then subjected to bit synchronization and frame synchronization, so as to obtain the original observed quantity and navigation message from the received signal, and finally realize the positioning function.

Bit synchronization (bit synchronization): in order to obtain the original observations, the transmission time of the received signal must be determined, and a part of the transmission time of the signal is implicit in the received navigation message, and another part of the transmission time is related to the position of the message subframe, so that after the signal enters the tracking phase, bit synchronization is also required to be completed, i.e. the edge of the data bit is found from the received signal, and then frame synchronization is realized, i.e. the starting edge of the subframe is found from the received signal. The most common histogram method is currently used for OEM board bit synchronization.

Frame synchronization: after bit synchronization (bit synchronization) is achieved, in order to determine the edges of the subframes in the satellite signal, the synchronization code of the subframes needs to be searched from the bit stream, so that the subframe synchronization is also abbreviated as frame synchronization. The frame synchronization flow of SBAS signals is different from other signals.

After the subframe synchronization is completed, decoding can be performed and a navigation message can be extracted; according to the bit edge signal obtained by bit synchronization and the subframe edge information obtained by frame synchronization, and the value of the code NCO in the tracking link, the pseudo-range observed quantity can be assembled, the observed quantity of the carrier phase can be determined according to the value of the carrier NCO in the tracking link, the Doppler frequency can be obtained by integrating the observed quantity of the carrier phase, and the generation of the observed quantity is completed.

The above list of detailed descriptions is only specific to practical embodiments of the present invention, and they are not intended to limit the scope of the present invention, and all equivalent embodiments or modifications that do not depart from the spirit of the present invention should be included in the scope of the present invention.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.

Claims

1. A GNSS ground disaster monitoring system, comprising: the monitoring system comprises a plurality of monitoring subsystems for monitoring geological disasters in a base station communication blind area, a monitoring master station for monitoring the geological disasters and a ground disaster monitoring and early warning platform for early warning the trend of the ground disasters;

each monitoring subsystem collects and outputs sensor data;

2. The GNSS ground disaster monitoring system of claim 1, wherein the monitoring master station includes a multi-system GNSS device and a beidou RDSS all-in-one machine, the multi-system GNSS device receives satellite signals to obtain GNSS measurement data for measuring geology, and the GNSS measurement data is transmitted to the beidou RDSS all-in-one machine;

each monitoring subsystem is communicated with a multi-system GNSS device through a LoRa communication module, and the multi-system GNSS device receives and processes the sensor data;

3. The GNSS ground disaster monitoring system of claim 2 wherein the multi-system GNSS device includes a GNSS receiving module, a GNSS processing module, a LoRa communication module and an RDSS communication module;

4. A GNSS ground disaster monitoring system according to claim 3 wherein a LoRa communication module sends a query command to said monitoring subsystem, the LoRa communication module receiving said sensor data of said monitoring subsystem;

5. The GNSS ground disaster monitoring system of claim 3 wherein the GNSS processing module includes an acquisition processing sub-module that acquires satellite signals input by the RNSS/SBAS based on the PMF-FFT pseudo code acquisition module.

6. A GNSS ground disaster monitoring system according to claim 3 wherein the GNSS processing module includes a tracking processing sub-module;

7. The GNSS ground disaster monitoring system of claim 1 wherein the plurality of sensors of each of the monitoring subsystems are disposed in a geological monitoring area of a monitoring base station communication blind area.

8. A method for monitoring a GNSS ground disaster, based on the GNSS ground disaster monitoring system according to any of the claims 1 to 7, characterized in that the method comprises:

9. The GNSS ground disaster monitoring method of claim 8, further comprising:

10. The GNSS ground disaster monitoring method of claim 8, further comprising: