CN114978852A

CN114978852A - GNSS data receiving and multi-channel parallel transmission method based on 4G network

Info

Publication number: CN114978852A
Application number: CN202210847411.9A
Authority: CN
Inventors: 杨永刚; 张良会; 吕菲; 韩平; 蒋龙; 张波; 余建乐
Original assignee: Sichuan Tibet Railway Technology Innovation Center Co ltd; Chengdu Orieange Temoray Co ltd
Current assignee: Sichuan Tibet Railway Technology Innovation Center Co ltd; Chengdu Orieange Temoray Co ltd
Priority date: 2022-07-19
Filing date: 2022-07-19
Publication date: 2022-08-30

Abstract

The invention discloses a GNSS data receiving and multi-channel parallel transmission method based on a 4G network, wherein a detection method receives GNSS observation data, normal PPPE dialing connection is kept by adopting MODEM _ SERVER and MODEM _ CLIENT double-thread processing technology, the analysis is carried out immediately after the original GNSS observation data is received, and then the analyzed data is respectively stored in a cache and a FLASH in an RTCM format; according to the method, multiple paths of GNSS data are transmitted in parallel, and the analyzed data are transmitted in parallel based on a data transmission protocol according to configured multilinks, so that the stability and reliability of the GNSS high-precision monitoring equipment are greatly optimized.

Description

GNSS data receiving and multi-channel parallel transmission method based on 4G network

Technical Field

The invention relates to the technical field of global navigation satellite system positioning, in particular to a GNSS data receiving and multi-path parallel transmission method based on a 4G network.

Background

With the continuous development of scientific technology, people have more demands on position information in many living and working environments, and with the rise of many satellite positioning and navigation systems, a global positioning and navigation system has a brand-new name GNSS, and the positioning of the GNSS global navigation satellite system utilizes the observed quantities of a group of satellites, such as pseudo range, ephemeris and satellite emission time, and the clock error of a user must be known. The global navigation satellite system is a space-based radio navigation positioning system that can provide users with all-weather 3-dimensional coordinates and velocity and time information at any location on the earth's surface or in near-earth space. At present, the core performance of the domestic GNSS high-precision monitoring equipment is not much different from that of foreign products, but certain gap exists in the aspects of stability and reliability, and particularly, the product performance needs to be further optimized under the conditions of complex environments such as high cold, high humidity and high shielding and strip-shaped areas. In addition, most GNSS devices perform single-path transmission or select one of multiple paths to perform transmission, and in places where network signals are interfered, observed data cannot be timely transmitted to multiple platforms for resolving processing, so that the positioning accuracy of the devices is affected, and therefore, the data processing and transmitting methods need to be continuously improved.

Disclosure of Invention

The technical problem solved by the invention is as follows: the defects that the core performance of conventional GNSS high-precision monitoring equipment is not greatly different from that of foreign products, but certain difference exists in stability and reliability, and particularly the product performance needs to be further optimized under complex environments such as severe cold, high humidity and high shielding and banded region conditions are overcome, and the GNSS data receiving and multi-path parallel transmission method based on the 4G network is provided.

The purpose of the invention is realized by the following technical scheme:

the GNSS data receiving and multi-path parallel transmission method based on the 4G network comprises the following steps:

receiving GNSS observation data, adopting MODEM _ SERVER and MODEM _ CLIENT double-thread processing technology to keep PPPE dialing normal connection, immediately analyzing after receiving original GNSS observation data, and respectively storing the analyzed data into a cache and a FLASH in an RTCM format;

and (4) carrying out parallel transmission on the multipath GNSS data, and carrying out parallel transmission on the analyzed data based on a data transmission protocol according to the configured multilink.

Specifically, the specific implementation of the MODEM _ SERVER responsible for the underlying command includes the following sub-steps:

step B1: starting a communication module;

step B2: initializing a serial port;

step B3: acquiring basic information of a module;

step B4: waiting for receiving a command sent by MODEM _ CLIENT;

step B5: analyzing the command, and acquiring a processing mode of the command through table lookup;

step B6: packaging the processing result and sending the packaged processing result to MODEM _ CLIENT;

step B7: judging whether exiting exists, if yes, performing step B8; if not, jumping back to the step B4;

step B8: and (6) exiting.

Specifically, the MODEM _ CLIENT is used for processing logic transactions, network on-off detection, network signal quality detection and 4G module exception, and includes the following sub-steps:

step C1: acquiring network information;

step C2: acquiring equipment information;

step C3: if the dialing is performed, if yes, go to step C4; if not, jumping back to the step C1;

step C4: dialing;

step C5: if the IP is acquired and the network can be connected, performing step C6; if not, performing an exception handling program and returning to the step C1;

step C6: updating network information and equipment information;

step C7: if the program exits, if so, ending the program; if not, go back to step C5.

Specifically, the data transmission protocol comprises communication protocols based on TCP, MQTT, NTRIP1.0, NTRIP2.0, and RTK.

Specifically, the data transmission is based on MQTT, and the data transmission method further comprises a server connection sub-step and a data analysis sub-step.

Specifically, the server connection substep further comprises:

step E1: initializing, and acquiring the configuration of a message queue telemetry transmission protocol;

step E2: checking whether the network status is available, if yes, proceeding to step E3; if not, continuing to check;

step E3: setting message queue telemetry transmission protocol parameters and a callback function;

step E4: connecting a server;

step E5: checking whether the connection is successful, if so, performing step E6; if not, jumping back to the step E2;

step E6: subscribing to a topic;

step E7: it is checked whether an exit is required.

Specifically, the data parsing substep further comprises:

step F1: checking whether data exists;

step F2: analyzing the data/command;

step F3: data are specifically processed;

step F4: checking whether to quit, if so, quitting; if not, go back to step F1.

Specifically, the method further comprises a link configuration step, wherein the link configuration step comprises the following substeps:

step D1: initializing serial port parameters;

step D2: receiving serial port data;

step D3: analyzing data according to a serial port protocol;

step D4: judging whether the first two bytes are synchronous codes or not, if so, performing step D5; if not, returning the error state of the synchronous code and jumping back to the step D2;

step D5: judging whether the third byte is a supported CMD, if so, performing the step D6; if not, returning to the CMD error state and jumping back to the step D2;

step D6: judging whether the fourth byte and the fifth byte are the supported MSG _ ID, if so, performing step D7; if not, returning to MSG _ ID error state and jumping back to step D2;

step D7: judging whether the 6 th byte to the 9 th byte are legal data lengths or not, if so, performing the step D8; if not, returning a data _ len error state and jumping back to the step D2;

step D8: storing the data, the data length and the check codes of the last two bytes into a cache;

step D9: checking the protocol data, generating a check code, comparing whether the check code is consistent, and if so, performing step D10; if not, returning the error state of the check code and jumping back to the step D2;

step D10: returning the state code, CMD, MSG _ ID and data _ len needed data;

step D11: calling interface functions in other modules for processing;

step D12: and the serial port sends the processing result and the state.

Specifically, the method further comprises an initialization step, wherein the initialization step comprises the following sub-steps:

after the step is started, fork operation is carried out to divide the process into a parent process sub-step and a child process sub-step, wherein the parent process sub-step further comprises the following steps:

step S1: initializing and applying for resources;

step S2: creating a task;

step S3: starting a task;

step S4: blocking the wait for exit signal;

step S5: releasing resources;

step S6: exiting all the sub-processes;

step S7: finishing;

the sub-process sub-step further comprises:

step A1: initializing a log system;

step A2: starting a log system and starting to record logs;

step A3: blocking the wait for exit signal;

step A4: releasing resources;

step A5: and (6) ending.

Specifically, the original GNSS observation data is received and output by a high-precision GNSS board card module; the static precision of the GNSS observation data is that the plane reaches 2.5mm +1ppm and the height reaches 5mm +1ppm, and the dynamic precision is that the plane reaches 8mm +1ppm and the height reaches 15mm +1 ppm.

The invention has the beneficial effects that:

1. the method adopts the combination of a high-end processor and a Linux operating system, enhances the stability of the system, and prevents the system from crashing and not working normally in a severe environment, thereby ensuring the stable operation in a complex field environment.

2. The method changes the original single-path transmission into multi-path parallel transmission, enhances the data processing capacity and improves the data transmission efficiency.

3. The method adopts a multi-frequency RTK high-precision navigation positioning module, the static precision is that the plane can reach 2.5mm +1ppm and the elevation can reach 5mm +1ppm, the dynamic precision is that the plane can reach 8mm +1ppm and the elevation can reach 15mm +1ppm, and effective transmission of multi-path data is realized, so that the positioning precision is greatly improved

4. The method adopts a built-in EMMC storage scheme, the capacity reaches 32G, observation data in a continuous 7-day RTCM format can be stored, hardware detection and capacity check are performed before a module is started, and simple exception handling can be performed. The method has the advantages of ensuring data loss under abnormal conditions, supporting storage interval setting, supporting deletion of the overdue files and saving power-off data.

5. The method adopts an SQLite database, wherein the SQLite is a lightweight embedded database in a process, the database is a file, and a self-sufficient, serverless, zero-configuration and transactional SQL database engine is realized. It is a zero configuration database, which represents the greatest difference between SQLite and other databases: the SQLite is not required to be configured in the system and can be directly used. And the SQLite is not an independent process and can be statically or dynamically connected according to the requirements of the application program. The SQLite has direct access to its stored files.

6. The visual configuration module of the method is designed to interact with the PC end serial port software upper computer, receive and respond to various operations of the upper computer, perform various data interaction, and realize the functions of configuring equipment parameters, displaying various equipment information of equipment to the upper computer, upgrading equipment firmware and the like.

7. The method adopts the independent design of network management and network application, adopts MODEM _ SERVER and MODEM _ CLIENT double-thread technology to process, saves the stability of the network, improves the connection reliability, and can automatically recover when a fault occurs.

8. On the basis that the original equipment supports one protocol, the method instead supports TCP CLIENT, TCP SERVER, MQTT, NTRIP1.0, NTRIP2.0, RTK and other communication transmission protocols.

9. The method has the advantages of low power consumption design of the system, reduction of the main frequency, closing of unused peripherals, great reduction of the working power consumption of the whole equipment and achievement of longer running time.

10. The method adopts the MQTT protocol and platform communication, provides a remote control function, realizes remote inquiry and configuration management, realizes OTA file remote upgrade, and solves the problem of low byte stream upgrade speed.

11. The method writes the data cached in the memory into the file in time and closes the file in time. Logic is reasonably designed, resources are distributed, and processing speed is guaranteed.

12. When the method is used for performing read-write access operation on the file, a management mechanism of system locking is adopted, and the problem of data integrity damage is solved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

FIG. 1 is a main program software flow diagram;

FIG. 2 is a MODEM _ SERVER software flow chart;

FIG. 3 is a flowchart of MODEM _ CLIENT software;

FIG. 4 is a visualization configuration module software flow diagram;

fig. 5 is MQTT software flow chart.

Detailed Description

It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The following detailed description will be selected to more clearly understand the technical features, objects and advantages of the present invention. It should be understood that the embodiments described are illustrative of some, but not all embodiments of the invention, and are not to be construed as limiting the scope of the invention. All other embodiments that can be obtained by a person skilled in the art based on the embodiments of the present invention without any inventive step are within the scope of the present invention.

The first embodiment is as follows:

in this embodiment, the GNSS data receiving and multi-path parallel transmission method based on the 4G network includes the following steps:

As shown in fig. 2, specifically, the MODEM _ SERVER is responsible for the specific implementation of the underlying command, and includes the following sub-steps:

step B1: starting a communication module;

step B2: initializing a serial port;

step B3: acquiring basic information of a module;

step B4: waiting for receiving a command sent by MODEM _ CLIENT;

step B7: if yes, go to step B8; if not, jumping back to the step B4;

step B8: and (6) exiting.

As shown in fig. 3, specifically, the MODEM _ CLIENT is responsible for processing some logic transactions, network on-off detection, network signal quality detection, and 4G module exception handling, and includes the following sub-steps:

step C1: acquiring network information;

step C2: acquiring equipment information;

step C4: dialing;

step C6: updating network information and equipment information;

As shown in fig. 5, in particular, the MQTT-based data transmission further includes a connection server sub-step and a data parsing sub-step.

Specifically, the server connection substep further comprises:

step E4: connecting a server;

step E6: subscribing to a topic;

step E7: it is checked whether an exit is required.

Specifically, the data parsing substep further comprises:

step F1: checking whether data exists;

step F2: analyzing the data/command;

step F3: data are specifically processed;

step F4: checking whether to quit, if so, quitting; if not, go back to step F1.

As shown in fig. 4, specifically, the method further includes a link configuration step, where the link configuration step includes the following sub-steps:

step D1: initializing serial port parameters;

step D2: receiving serial port data;

step D3: analyzing data according to a serial port protocol;

step D6: judging whether the fourth byte and the fifth byte are the supported MSG _ ID, if so, performing step D7; if not, returning the MSG _ ID error state and jumping back to the step D2;

step D10: returning the state code, CMD, MSG _ ID and data _ len needed data;

step D11: calling interface functions in other modules for processing;

step D12: and the serial port sends the processing result and the state.

As shown in fig. 1, specifically, the method further includes an initialization step, where the initialization step includes the following sub-steps:

step S1: initializing and applying for resources;

step S2: creating a task;

step S3: starting a task;

step S4: blocking the wait for exit signal;

step S5: releasing resources;

step S6: exiting all the sub-processes;

step S7: finishing;

the sub-process sub-step further comprises:

step A1: initializing a log system;

step A2: starting a log system and starting to record logs;

step A3: blocking the wait for exit signal;

step A4: releasing resources;

step A5: and (6) ending.

The foregoing shows and describes the general principles, principal features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

It should be noted that, for simplicity of description, the above-mentioned embodiments of the method are described as a series of acts or combinations, but those skilled in the art should understand that the present application is not limited by the order of acts described, as some steps may be performed in other orders or simultaneously according to the present application. Further, those skilled in the art should also appreciate that the embodiments described in the specification are preferred embodiments and that the acts and elements referred to are not necessarily required in this application.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a ROM, a RAM, etc.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.

Claims

1. The GNSS data receiving and multi-path parallel transmission method based on the 4G network is characterized by comprising the following steps:

2. The GNSS data receiving and multi-path parallel transmission method based on 4G network according to claim 1, wherein the MODEM _ SERVER is responsible for implementation of the underlying command, and comprises the following sub-steps:

step B1: starting a communication module;

step B2: initializing a serial port;

step B3: acquiring basic information of a module;

step B4: waiting for receiving a command sent by MODEM _ CLIENT;

step B8: and (6) exiting.

3. The method for GNSS data reception and multi-path parallel transmission based on 4G network as claimed in claim 1, wherein the MODEM _ CLIENT is responsible for handling logic transactions, network on-off detection, network signal quality detection and 4G module exception, and comprises the following sub-steps:

step C1: acquiring network information;

step C2: acquiring equipment information;

step C3: if yes, go to step C4; if not, jumping back to the step C1;

step C4: dialing;

step C6: updating network information and equipment information;

4. The method for GNSS data reception and multi-path parallel transmission based on 4G network as claimed in claim 1, wherein the data transmission protocol comprises communication protocols based on TCP, MQTT, NTRIP1.0, NTRIP2.0 and RTK.

5. The method for GNSS data reception and multi-path parallel transmission based on 4G network as claimed in claim 4, wherein the data transmission protocol is based on MQTT, further comprising a connection server sub-step and a data parsing sub-step.

6. The method for GNSS data reception and multi-path parallel transmission based on 4G network according to claim 5, wherein the connection server sub-step further comprises:

step E3: setting message queue telemetering transmission protocol parameters and callback functions;

step E4: connecting a server;

step E6: subscribing to a topic;

step E7: it is checked whether an exit is required.

7. The method of claim 5, wherein the data parsing sub-step further comprises:

step F1: checking whether data exists;

step F2: analyzing the data/command;

step F3: data are specifically processed;

step F4: checking whether to quit, if so, quitting; if not, go back to step F1.

8. The GNSS data reception and multi-path parallel transmission method based on 4G network according to claim 1, further comprising a link configuration step, the link configuration step comprising the substeps of:

step D1: initializing serial port parameters;

step D2: receiving serial port data;

step D3: analyzing data according to a serial port protocol;

step D10: returning the data required by the state code, CMD, MSG _ ID and data _ len;

step D11: calling interface functions in other modules for processing;

step D12: and the serial port sends the processing result and the state.

9. The method for GNSS data reception and multi-path parallel transmission based on 4G network according to claim 1, further comprising an initialization step, wherein the initialization step comprises the following sub-steps:

step S1: initializing and applying for resources;

step S2: creating a task;

step S3: starting a task;

step S4: blocking the wait for exit signal;

step S5: releasing resources;

step S6: exiting all the sub-processes;

step S7: finishing;

the sub-process sub-step further comprises:

step A1: initializing a log system;

step A2: starting a log system and starting to record logs;

step A3: blocking the wait for exit signal;

step A4: releasing resources;

step A5: and (6) ending.

10. The GNSS data receiving and multi-path parallel transmission method based on the 4G network according to claim 1, wherein the original GNSS observation data is received and outputted by a high precision GNSS board card module; the static precision of the GNSS observation data is that the plane reaches 2.5mm +1ppm and the height reaches 5mm +1ppm, and the dynamic precision is that the plane reaches 8mm +1ppm and the height reaches 15mm +1 ppm.