High-precision conduction integrated system based on Beidou No.3 + IOT

Abstract

The invention belongs to the technical field of satellite navigation and positioning, and particularly relates to a Beidou III + IOT-based high-precision conduction integrated system, which comprises a Beidou III high-precision positioning / attitude measurement terminal, a Beidou III short message communication terminal, a Beidou III positioning / communication all-in-one machine and a Beidou III communication separation service platform. The Beidou No.3 high-precision positioning / attitude measuring terminal has the advantages of low cost, low power consumption and high precision; the Beidou No.3 short message communication terminal overcomes the problems of limited single communication capacity, limited communication frequency and high packet loss rate in the Beidou short message transmission technology; the Beidou No.3 positioning / communication all-in-one machine overcomes the problem that the demodulation of LDPC (Low Density Parity Check) in the Beidou No.3 signal receiving and processing technology is very complicated through a full-frequency-point configurable broadband radio frequency technology and a layered fixed path minimum decoding technology; meanwhile, a Beidou No.3 communication separation service platform is built, and Beidou No.3 navigation communication integrated service demonstration application of the Internet, the sensor network and the Internet of Things is fused.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation and positioning technology, and specifically relates to a high-precision integrated communication and navigation system based on BeiDou-3+IOT. Background Art

[0002] Beidou is a satellite navigation system independently developed by my country. It has positioning, timing, and short message functions, and is low-cost and small in size, making it very suitable for wide-area IoT network layer solutions. Beidou short message technology provides a two-way channel for communication in the open sea and remote areas. However, due to the problems of packet loss, communication frequency and length limitations of Beidou short message civilian cards, there are still some problems in the actual application of Beidou short message transmission technology:

[0003] ① Due to the Beidou short message system and packet loss, Beidou short message communication cannot guarantee reliable transmission, and there is no verification mechanism. The sender cannot determine whether the information has accurately reached the destination;

[0004] ② The data length of Beidou short message transmission is limited. Even if a detection message is compressed, it needs to be divided into multiple times to complete the transmission. If the data is not fully received, the complete original message cannot be deciphered.

[0005] At the same time, in the arrangement of navigation messages, the Beidou system uses a multi-level LDPC code defined on GF (64). The classic decoding algorithm for multi-level LDPC codes is the multi-level sum-product algorithm (QSPA). The QSPA algorithm has approximately optimal decoding performance, and its decoding complexity is , is the degree of the check node. However, the high decoding complexity hinders the application of multivariate LDPC codes in practical systems. Although such coding method can greatly improve the demodulation capability of navigation messages under weak signal conditions, the side effect is that the demodulation algorithm is very complicated. How to implement LDPC decoding on navigation chips with very limited computing power and storage capacity is a task that requires a lot of research and long-term exploration.

[0006] Moreover, due to the limitation of pseudo-range observation quality, the ideal positioning accuracy of the positioning algorithm based on pseudo-range can only reach sub-meter level. In application scenarios such as municipal administration, GIS information collection, and drones, sub-meter level accuracy cannot meet the accuracy requirements. In addition, the existing high-precision positioning / attitude measurement terminals are mainly used in professional and high-end markets, and have the disadvantages of high cost, high power consumption, and lack of flexibility.

[0007] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0008] The purpose of the present invention is to provide a high-precision integrated navigation and communication system based on BeiDou-3 + IOT to solve the above problems. The system of the present invention proposes multiple technical solutions to solve the above problems, and develops corresponding equipment and platforms to implement the corresponding technical solutions. The system structure block diagram is shown in the attached figure. Figure 1 shown.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A high-precision integrated communication and navigation system based on BeiDou-3+IOT, including:

[0011] The BeiDou-3 high-precision positioning / attitude measurement terminal is composed of a data acquisition unit and a solution unit; the data acquisition unit is responsible for collecting satellite observation data and sending the data to the solution unit; the solution unit sends the solution result to the server via a 4G signal, and the host computer displays the solution result;

[0012] BeiDou-3 short message communication terminal, used to realize RDSS positioning function and short message communication function;

[0013] BeiDou-3 positioning / communication integrated device, used to realize BeiDou-3 civil RDSS positioning, BeiDou-3 RNSS BeiDou B1 and GPS_L1 single-mode or dual-mode hybrid positioning, short message communication and mobile network communication functions;

[0014] BeiDou-3 communication separation service platform is used to provide data infrastructure services, BeiDou communication services and operation and maintenance services.

[0015] Preferably, the data acquisition unit comprises: a receiver, a voltage stabilizing circuit, a charging circuit and a wireless module; the receiver is provided with two, serving as a main antenna and a slave antenna respectively; the voltage stabilizing circuit comprises a boost circuit and a buck circuit, using FP6276B as a boost chip and AMS1117-3.3 as a buck chip; the charging circuit uses TP4056 to charge the lithium battery; the wireless module is used to send the data collected by the receiver to the solution unit.

[0016] Preferably, the solving end of the solving unit is an ARM embedded solving platform, using Cortex-A8 as the processor, the OEM core board is connected to the wireless module via its own native serial port, and the MCU uses S5PV210.

[0017] Preferably, the BeiDou-3 short message communication terminal adopts TS-M1531, which integrates RDSS transceiver RF chip, baseband chip, PA circuit and LNA circuit, and an external SIM card and passive antenna to realize short message communication function and positioning navigation function.

[0018] Preferably, the Beidou-3 positioning / communication integrated device includes: a terminal signal receiving module, a terminal signal transmitting module and a data storage and supplementary transmission module; the terminal signal receiving module uses an internal RF module to complete analog down-conversion, filtering, and amplification processing, and realizes analog intermediate frequency signal sampling through an A / D module, and the baseband processing unit completes capture, tracking and demodulation processing to obtain observation quantities; the terminal signal transmitting module completes data stream formation according to the telegram information arrangement format, and sends it to the Beidou satellite via the antenna; the data storage and supplementary transmission module identifies each transmitted data frame and stores it in the transmission record memory list.

[0019] The system of the present invention also provides a novel BeiDou-3 signal receiving and processing method, which is used to solve the problem that the LDPC decoding complexity in the BeiDou-3 signal receiving and processing technology is too high and difficult to implement in navigation chips with very limited computing power and storage capacity. Specifically, it includes:

[0020] ① A full-frequency configurable broadband radio frequency method is proposed to achieve one broadband radio frequency supporting the reception and processing of multi-navigation frequency band signals;

[0021] ② Construct five types of paths such as the most reliable one, and propose a new fixed-path minimum decoding algorithm to reduce the complexity of LDPC decoding and improve the error correction function of LDPC decoding; reduce the storage requirement of LDPC decoding and accelerate the convergence speed of LDPC decoding.

[0022] As a preferred option, the baseband and RF integrated design adopts the civilian RNSS RF baseband integrated chip, which integrates a broadband RF unit and a high-performance, high-sampling-rate orthogonal 10-bit AD module, and can realize the reception and processing of four signals, GPSL1, B1I, Galileo E1, and GLONASS G1, through a single analog channel.

[0023] As a preferred method, the method of constructing the most reliable five types of paths is specifically as follows:

[0024] ① The first category has only one path, which is the most reliable path and is recorded as Category I path.

[0025] ② The second category has There are paths, each of which has only one offset node and comes from the second row of the grid graph, which are denoted as type II paths.

[0026] ③ The third category has Paths, which are divided into two subcategories: the first subcategory includes The first offset node of each path is the node of the second row and first column of the grid graph, and the second offset node comes from the remaining columns of the second row of the grid graph, which is recorded as type III path; the second subcategory includes The first offset node of each path is the node in the second row and second column of the grid graph, and the second offset node is from the node in the second row and third column of the grid graph. Column, recorded as type IV path.

[0027] ④ The fourth category has There are paths, each path has only one offset node, and the offset nodes come from the 3rd to the 4th rows of the grid graph. The nodes of the row are recorded as type V paths.

[0028] ⑤ The fifth category has There are two paths, each with only one offset node. These paths are divided into two sub-categories: The offset nodes of the first sub-category come from , recorded as type VI path; the second small category of offset nodes comes from , recorded as Class VII path.

[0029] The system of the present invention also provides a new high-precision positioning solution method, which is used to solve the problem that the positioning accuracy of the positioning algorithm based on pseudo-range cannot meet the actual needs, and the traditional RTK technology consumes a lot of resources, and its cost and power consumption are relatively high. Specifically including:

[0030] ① Provide a low-cost new embedded single-frequency / multi-frequency RTK technology, using a new matrix operation engineering implementation method, an improved LAMBDA ambiguity search algorithm and an innovative ambiguity maintenance algorithm to achieve the minimum resource configuration of multi-frequency RTK technology;

[0031] ② A ionospheric delay correction technique is proposed under the condition of a limited number of available observations, and an ionospheric delay model of the BP neural network is established.

[0032] Preferably, establishing the ionospheric delay model of the BP neural network comprises the following steps:

[0033] Step 1: Assume the ionosphere as a thin film, and combine the known coordinates of the measuring station, the satellite altitude angle and the azimuth angle to calculate the coordinates of the puncture point of each satellite in the ionosphere single layer;

[0034] Step 2: Taking the puncture point distance and the difference between the puncture point distances as input, and the double difference ionospheric delay of the corresponding reference station as output to form a training sample, determine the BP neural network structure and parameters, and establish an ionospheric delay BP neural network model;

[0035] Step 3: Using the constructed model, the puncture point distance corresponding to the mobile station and the main reference station of the same satellite and the difference between the puncture point distances are used as input, and the double difference ionospheric delay of each satellite corresponding to the station can be estimated by interpolation.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The high-precision integrated communication and navigation system based on BeiDou-3+IOT of the present invention provides a low-cost, low-power, high-precision positioning / attitude measurement terminal, which comprehensively applies BeiDou-3 signal receiving and processing technology, low-cost inertial sensor combined navigation technology and high-precision positioning solution technology, and has information synchronization and single-frequency / multi-frequency RTK technology, and supports satellite navigation signals and inertial navigation signals of different frequencies.

[0038] (2) The high-precision integrated communication and navigation system based on BeiDou-3 + IOT of the present invention provides a BeiDou-3 short message communication terminal that applies BeiDou-3 short message data transmission technology, integrates RDSS and RNSS antennas, has low power consumption, RDSS positioning, short message communication functions, and can receive RNSS B1 / GPS L1 satellite navigation signals in real time.

[0039] (3) The high-precision integrated communication and navigation system based on BeiDou-3+IOT of the present invention provides a BeiDou-3 positioning / communication integrated machine that comprehensively applies BeiDou-3 short message data transmission technology, BeiDou-3 signal reception and processing technology, low-cost inertial sensor combined navigation technology and high-precision positioning solution technology. It has BeiDou-3 civil RDSS positioning, BeiDou-3 RNSS BeiDou B1 and GPS_L1 single-mode or dual-mode hybrid positioning, short message communication and mobile network communication functions, and RDSS is compatible with BeiDou-3 civil protocol, and RNSS supports NMEA-0183 protocol.

[0040] (4) The high-precision integrated communication and navigation system based on BeiDou-3+IOT of the present invention, combined with the application of BeiDou-3 short message data transmission technology, provides an open, compatible and extensible BeiDou-3 communication separation service platform, which can provide location monitoring, electronic fence, trajectory viewing, BeiDou short message and ground mobile communication conversion, picture, voice and super long text short message transmission and other services, and reserves sufficient data, communication and service interfaces to share information with government and enterprise management systems, provide data interface services for various related sub-platforms and application systems, support secondary development of sub-systems, and provide many conveniences in the fields of meteorological monitoring, geological disaster warning, intelligent transportation, smart cities and emergency rescue. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1This is a system block diagram of the high-precision communication and navigation integrated system based on BeiDou-3+IOT of the present invention;

[0042] Figure 2 It is a functional block diagram of broadband RF technology with full-frequency configurable broadband RF technology;

[0043] Figure 3 It is a check node grid diagram of hierarchical fixed path minimum and decoding technology;

[0044] Figure 4 It is a block diagram of the LDPC layered decoding algorithm of the layered fixed path minimum sum decoding technology;

[0045] Figure 5 This is the block diagram of ionospheric delay correction based on BP neural network;

[0046] Figure 6 This is the system block diagram of the BeiDou-3 high-precision positioning / attitude measurement terminal;

[0047] Figure 7 This is the overall logical architecture diagram of the BeiDou-3 communication separation service platform. DETAILED DESCRIPTION

[0048] The following is a clear and complete description of the technical solution of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Example 1

[0050] The present invention provides a high-precision communication and navigation integrated system based on BeiDou-3+IOT, comprising the following equipment and platforms: BeiDou-3 high-precision positioning / attitude measurement terminal, BeiDou-3 short message communication terminal, BeiDou-3 positioning / communication integrated machine and BeiDou-3 communication separation service platform.

[0051] Specifically, the following is a further description of the functions of each device and module:

[0052] (1) BeiDou-3 high-precision positioning / attitude measurement terminal

[0053] The overall hardware framework of the BeiDou-3 high-precision positioning / attitude measurement terminal system is shown in the attached figure. Figure 6 As shown, it includes two receivers responsible for collecting satellite observation data as the data collection unit of the main antenna and the slave antenna. The collection terminal is equipped with a wireless data transmission module, which sends data to the solution unit through the wireless module. This design takes into account that the antenna can be installed on the carrier more flexibly without being constrained by the signal cable, and the solution unit is an independent unit for easy maintenance.

[0054] When the system is working normally, the two receivers receive satellite signals through antennas, extract satellite information based on navigation messages, and give satellite observation values. The original data is then transmitted to the wireless module for packaging and sent to the solution unit. After solution, the results are sent to the server via 4G signals, and the solution results are displayed on the host computer.

[0055] The BeiDou-3 high-precision positioning / attitude measurement terminal includes: a data acquisition unit and a solution unit.

[0056] The data acquisition unit consists of four modules: receiver, voltage regulator circuit, charging circuit and wireless module. Two receivers serve as data acquisition units for the main antenna and the slave antenna; the wireless module sends the data collected by the receiver to the solution end; the charging circuit uses TP4056 to charge the lithium battery. The voltage regulator circuit includes a boost circuit and a buck circuit. Considering that the data acquisition unit is powered by a 3.7v lithium battery and the commonly used sensor module operating voltage is generally 3.3V or 5V, FP6276B is selected as the boost chip (input voltage is 2.4~4.5V, output voltage is 5V, and can provide 2A current, which fully meets the system power consumption, and the conversion efficiency is as high as 91%); AMS1117-3.3 is used as the buck chip (input voltage 5V, output voltage 3.3V).

[0057] The data acquisition unit needs to work stably for a long time, so in order to make it more convenient to move, lithium batteries are considered to be used for power supply during the design.

[0058] The solving end of the solving unit is an ARM embedded solving platform, using Cortex-A8 as the processor. The design and production of the OEM core board are purchased online, and the MCU uses S5PV210. The power supply includes several parts: lithium battery charging circuit, lithium battery power display circuit, 3.7V boost circuit, 3.3V voltage regulator circuit, 1.8V\2.8V voltage regulator circuit. The core board comes with three native serial ports, one for debugging, and the other two for connecting wireless modules to achieve one-to-one communication. The MCU serial port resources are limited, and the USB2514B serial port expansion solution can be used to expand a USB HOST port into 4 serial ports. The interface expanded by this solution is USB, which can be converted into a serial port through a level conversion chip such as CH340. The remote communication module uses USR-LTE-7S4. The data transmission between the terminal monitoring carrier and the data processing center uses 4G network for real-time communication, and the observation data collected by the receiver is sent to the server for solving. The module packages the data internally, then establishes a TCP client socket interface, and transmits the data to the operator network through 4G / GPRS. The serial port AT command is used by the user to configure the working mode of the module and the IP address and port of the connection object. By connecting to the module via the serial port, the corresponding AT command can be sent to complete the module settings. The system also has a heartbeat packet function, and the server can know the online status of the module through the heartbeat packet. The communication between the terminal monitoring carrier and the server adopts the standard TCP / IP protocol. The length of TCP packaging can be set by the user. Since the serial port receiving buffer is 1000 bytes, the maximum packet size after the module is packaged is 1000 bytes.

[0059] (2) BeiDou-3 short message communication terminal

[0060] The multi-card communication terminal can fully realize the RDSS positioning function and short message communication function, and can support up to 16 Beidou user cards.

[0061] TS-M1531 integrates RDSS transceiver RF chip, baseband chip, PA circuit and LNA circuit. It can realize the short message communication function and positioning navigation function of Beidou-1 through an external SIM card and passive antenna. The low noise amplifier circuit can filter and amplify the RF signal input from the RX port. No external LNA and filter are required. The RDSS signal can be received directly through the RX port by connecting the passive antenna. The power amplifier circuit can provide 5W of transmission power. M1531 adopts a stamp hole surface mount package with a size of only 30mm×35mm. It has high integration and low power consumption, which is very suitable for applications with strict requirements on volume and power consumption.

[0062] The data storage chip is a NOR Flash chip W25Q128 with an SPI interface. The storage space of the chip is 128Mbit, which is equivalent to 16M bytes. The 16M capacity is divided into 256 blocks, each block is 64K, and each block is divided into 16 sectors, each sector is 4K bytes. The minimum erase unit of W25Q128 is one sector. The erase and write times of W25Q128 are up to 10W times, and the data content can be stored for 20 years. The supported voltage is 2.7-3.6V.

[0063] W25Q128 uses SPI interface to communicate with the outside. The maximum SPI clock can reach 80MHz. The standard SPI interface has 4 communication lines MISO, MOSI, SCLK, CS, which are connected to DO, DI, SCK, CS of W25Q128 respectively. MISO is the master device data input and slave device data output. MOSI is the master device data output and slave device data input. SCLK is the clock signal generated by the master device. CS is the slave device chip select signal, which is controlled by the master device.

[0064] The specific model of the microprocessor is STM32F103ZET6, which has 512KB Flash and 64K SRAM. The power supply voltage is 2.0V-3.6V, and the maximum frequency can reach 72MHz. STM32F103ZET6 has 5 serial ports, 3 SPI interfaces, 2 I2C interfaces, 11 timers, and 3 AD converters. The microprocessor module circuit is mainly composed of a microprocessor, a crystal oscillator circuit, a reset circuit, and some single-chip peripheral circuits.

[0065] (3) BeiDou-3 positioning / communication integrated device

[0066] It has the functions of BeiDou-3 civil RDSS positioning, BeiDou-3 RNSS BeiDou B1 and GPS_L1 single-mode or dual-mode hybrid positioning, short message communication and mobile network communication. RDSS is compatible with BeiDou-3 civil protocol, and RNSS supports NMEA-0183 protocol. Specifically including:

[0067] ① Terminal signal reception

[0068] The BeiDou-3 positioning / communication integrated device uses the internal RF module to complete analog down-conversion, filtering, amplification and other processing, and then uses the A / D module to implement analog intermediate frequency signal sampling. The baseband processing unit then completes the capture, tracking and demodulation processing to obtain pseudorange, carrier phase, carrier-to-noise ratio, Doppler and other observation quantities, and demodulates the telegram information at the same time. The IC card management unit implements the encryption and decryption processing of the RDSS service, and the RNSS realizes positioning and solution based on the observation quantities and telegram information.

[0069] ② Terminal signal transmission

[0070] The RDSS baseband processing unit completes data stream formation, coding processing, spread spectrum modulation, carrier modulation, etc. according to the strongest received power and the telegram information arrangement format to form the inbound digital intermediate frequency signal of the corresponding beam. The inbound digital intermediate frequency signal passes through the D / A chip in the module to generate an analog intermediate frequency signal, which is up-converted by the RF unit to form an inbound RF signal, which is sent to the power amplifier for amplification and then sent to the Beidou satellite via the antenna.

[0071] ③ Data storage retransmission

[0072] The data format sent by the Beidou communication terminal includes frame identification, frame sequence number, frame type, data content and data check, etc. The frame sequence number is used to identify the record of data packet transmission and the identity ID of the data packet. Each transmitted data frame is uniquely identified and stored in the transmission record memory list.

[0073] (4) BeiDou-3 communication separation service platform

[0074] The BeiDou-3 communication separation service platform adopts a hierarchical and modular structure design. With the help of mature cloud computing architecture and middleware as the basic support, it provides basic technical services and open interfaces. The platform is divided into six logical layers: application layer, interface layer, service layer, data layer, communication layer, and terminal layer. The specific logical architecture is as follows: Figure 7 shown.

[0075] The design of the BeiDou-3 communication separation service platform provides data infrastructure services, BeiDou communication services, and operation and maintenance services. The specific implementation methods and technical routes are as follows:

[0076] ① Platform data service solution

[0077] The data infrastructure service provides standardized data collection, data storage, processing and analysis services for multi-type and multi-protocol terminals, and provides basic data services for various business applications through standardized and open interface services, including four major functional modules: data access, data storage, data analysis, and data access.

[0078] ② Platform communication technology solution

[0079] The platform communication service provides basic information services such as message broadcasting, short message link management, and command control, supplementing the communication capabilities of the application system and achieving global coverage of all business systems without blind spots. It mainly includes communication access module, communication maintenance module, and communication service module.

[0080] ③ Platform operation and maintenance service plan

[0081] The operation and maintenance service provides monitoring and guarantee services for the operation and maintenance of the platform, and realizes terminal management, operation and maintenance process management, operation and maintenance monitoring and other services.

[0082] Example 2

[0083] The present invention provides a novel BeiDou-3 short message data transmission method, which is used to solve the problems of limited single communication capacity, limited communication frequency and high packet loss rate of BeiDou short message transmission technology, and realize stable and reliable data communication. Specifically, it includes the following steps:

[0084] ① Design a packet loss feedback mechanism to ensure reliable data transmission;

[0085] To implement the packet loss feedback mechanism, the Beidou terminal needs to maintain three variables: the send feedback flag, the confirmation flag, and the receive feedback flag;

[0086] Send feedback flag: the correct data is received and the feedback flag is waiting to be sent;

[0087] Confirmation flag: the feedback flag waiting for reception after sending data;

[0088] Receive feedback flag: received feedback flag;

[0089] After the short message terminal sends a message, it writes the message flag into the confirmation flag. The message flag is set as follows: if the data unit in the sent message is not the last segment of the subpacket data, its flag is recorded; if the data in the sent message is processed by small data sticking, the flag of the last merged data unit is recorded. Then it enters the waiting state.

[0090] Each time the Beidou terminal at the sending end receives a message, it checks whether the first byte of the message content is a feedback flag; if it is a feedback flag, set its third bit to 0 and write the receiving feedback flag. Compare the confirmation flag of the shared memory with the receiving feedback flag; if they are the same, it proves that this data is sent successfully, and delete the successfully sent data unit in the sending buffer; if they are different, compare the receiving feedback flag with the flag of each data unit in the sending array one by one; if it is the same as one of them, it proves that part of the data is sent successfully, and one of the units has a bit error, delete the successfully sent data unit in the sending buffer, and point the sending buffer read pointer to the data unit with a bit error; if the receiving feedback flag is different from the flag of each unit or no feedback is received within one minute, it proves that the data transmission fails, and continue to send until it is sent 3 times; if all 3 times fail, modify the user status table and delete the corresponding data unit in the sending buffer.

[0091] After receiving the correct data, the receiver sends feedback to the Beidou terminal of the sender. The specific operations are as follows: after receiving the data, the Beidou terminal of the receiver extracts the data unit; determines whether the data of the unit is correct; if correct, sets the third bit of its flag to 1, writes the send feedback flag, and then reads the next unit; if wrong, the subsequent data is not processed and is directly discarded. The send feedback flag records the flag of the last unit of correct data received.

[0092] Deadlock may occur during the communication process, that is, both Beidou send data to each other and wait for each other's feedback information, resulting in an infinite dead loop. To avoid the above situation, set the priority of the send feedback flag to be higher than the priority of sending data, that is, whether it is the first time to send or resend data, it is necessary to check the send feedback flag before sending data. If the send feedback flag is not empty (the default setting of the send feedback flag is 0xff, 0xff is empty), it will be written to the first byte of the message content, and the data of the send array will be written after the feedback flag; if the data in the send array has filled the satellite's message content, the feedback flag will be sent first, and the data in the original send array will be sent 1 minute later.

[0093] ② Through error checking strategy, the BeiDou-3 short message communication is realized without distortion;

[0094] After receiving the data from the user terminal, the Beidou terminal processes it according to the terminal protocol. If it is communication data, the long message is segmented and the small data is not processed. Then, the CRC-CCITT cyclic check code is used to calculate the payload of each segment of data to obtain two check bits, which are written into the two bytes after the payload of each segment of data.

[0095] After receiving the data, the Beidou terminal at the receiving end extracts the data unit, performs CRC-CCITT check calculation on the data payload in the unit, obtains a two-bit check code, and compares the check bit after the data payload for error checking. Error checking is the judgment of message distortion. After processing the user data according to the terminal protocol, the Beidou terminal segments the long message, does not process the small data, and then adds a flag bit, a length bit, and a check bit to each segment of data to form a data unit. The Beidou communication mechanism is based on the data unit as the smallest unit.

[0096] ③ Design a packet sticking mechanism to improve the efficiency of small data transmission;

[0097] When the Beidou terminal sends data, it starts from the send buffer pointer and reads the second byte (i.e., length bit) of the unit pointed by the pointer; if the length of the unit data (the data unit consists of a flag bit, a length bit, a data payload, and a check bit) is less than 1995 bytes, it is written into the send array; then read the next unit in the send buffer, and if the sum of the data length (the sum of the length of the unit data and the length of the data unit written into the send array) is less than 1995 bytes, it is written into the send array; repeat the previous step until the sum of the data length is greater than 1995 bytes or the send buffer is empty, and stop reading. Regardless of whether the send array is full or not, once the timer expires, the data in the send array is packaged and sent by satellite. If it is a message composed of merged data units, each unit of data in the message content is the last segment of data (if it is not the last segment of the split data, the data length must be 1995 bytes, so it will not be written into the send array).

[0098] When the receiving Beidou terminal receives the data, it will remove the Beidou protocol packet header and tail, write the data in the content into the receiving buffer, and then read the data of the corresponding length according to the length bit, extract the data unit, and determine whether it is distorted; if there is no distortion, it will be parsed and sent to the corresponding user terminal, and the above steps will be repeated until the data unit is distorted or the receiving buffer is empty.

[0099] ④ Through the subpacketization strategy, the long message can be correctly transmitted;

[0100] The specific operation process of long message in the sending Beidou terminal is as follows: after receiving the user terminal data, the Beidou terminal assigns a data sequence number to the user terminal data. The data sequence number occupies 3 bits, that is, the cycle interval is 8; if the length of the user terminal data is too long (the data payload length is greater than 1911 bytes, it is considered a long message), it is segmented with 1911 bytes as the upper limit; then a segment sequence number is assigned to each segment of data in sequence, and the segment sequence number identifies the position of the segment of data in the user terminal data; each segment of data after segmentation is subjected to the following operations:

[0101] Step 1: Write its segment sequence number into bits 0-2 of the message content flag;

[0102] Step 2: Write 0 to the third bit of the flag, indicating that this segment of data is sent data, not a feedback flag;

[0103] Step 3: Write 0 to the 4th bit of the flag bit of the non-last data segment, and write 1 to the 4th bit of the flag bit of the last data segment;

[0104] Step 4: Write the data sequence number into bits 5-7 of the flag bit;

[0105] Step 5: Write the length of the data segment into the length bit;

[0106] Step 6: Calculate the check code of the data segment using the CRC-CCITT generated polynomial and write it into the two bytes after the data payload.

[0107] In this way, data units can be formed, and the processed data units are written into the sending buffer in sequence and wait for sending. If the received data is the first data unit of the split data, its segment sequence number and data sequence number are recorded, and the data payload in the data unit is written into the terminal buffer; continue to receive the next data unit, compare the data sequence number, if the same, then compare the segment sequence number; if it is confirmed to be the next data unit to be received, the data payload is written into the terminal buffer. Repeat the above steps until the last data unit is received and the reorganization is completed, and then parse the terminal buffer data and send it to the corresponding user terminal.

[0108] Example 3

[0109] In order to implement LDPC decoding on a navigation chip with very limited computing power and storage capacity, the present invention provides a new BeiDou-3 signal receiving and processing method to overcome the problem that LDPC decoding is too complicated. Specifically, the following steps are included:

[0110] ① A full-frequency configurable broadband radio frequency method is proposed to achieve one broadband radio frequency supporting the reception and processing of multi-navigation frequency band signals;

[0111] The BeiDou-3 positioning system can be divided into a baseband part and a radio frequency part. The baseband part completes the processing function of low-frequency digital signals, and the radio frequency part completes the processing of high-frequency analog signals with a high dynamic range, including low-noise amplification, power amplification, frequency conversion, modulation and demodulation. This solution uses a civilian RNSS radio frequency baseband integrated chip to achieve baseband and radio frequency integrated design, and the radio frequency circuit supports broadband radio frequency signal processing. A single intermediate frequency baseband digital signal can support multi-system satellite navigation signals, providing a one-stop solution.

[0112] The broadband RF circuit used in this chip is based on silicon RF integrated circuit technology. It down-converts satellite navigation RF signals of multiple modes and frequencies to an intermediate frequency signal, and quantizes it into a digital signal through an analog-to-digital converter and sends it to the baseband processor, thereby realizing multi-mode (or multi-system) positioning function with a single Die chip, greatly reducing the chip or circuit board area. By integrating a broadband RF unit and a high-performance, high-sampling-rate orthogonal 10-bit AD module, a single analog channel can complete the reception of four signals: GPSL1, B1I, Galileo E1, and GLONASS G1, effectively saving power consumption and reducing area; high SFDR (spurious-free dynamic range) orthogonal 10-bit sampling gives the receiver the potential to work reliably under complex and strong interference.

[0113] The functional block diagram of broadband RF technology is as follows: Figure 2 As shown. Among them, the RF front-end analog processing has made breakthroughs in key RF integrated circuit technologies such as multi-mode and multi-channel system architecture design, channel isolation, digital-analog mixed signal design, low power design, consistency design, low noise design, image suppression design, and active filter design through broadband zero intermediate frequency design, high-speed high-bit sampling, open-loop automatic gain control, and wide-range adjustable local oscillator design technology.

[0114] The BDS / GPS / GLONASS multi-mode satellite navigation RF baseband integrated chip developed based on broadband RF circuit technology is compatible with the mainstream domestic BDS / GPS / GLONASS baseband processors and the mainstream foreign GPS baseband processors. It has the advantages of low power consumption and high performance, and can be widely used in portable GNSS multi-mode navigation equipment (such as mobile phones, PDAs, car navigation equipment, etc.) and professional navigation equipment, and has a strong overall market competitive advantage. The chip return test has verified that the use of broadband RF technology saves 60% of the area, thereby reducing costs and reducing power consumption by 30%.

[0115] Another advantage of broadband RF technology is that it can support BDS / GPS / GLONASS frequencies through software configuration. Conventional RF chips have a fixed operating frequency band range, or require peripheral hardware settings to work in a certain frequency band range. However, the chip RF front end supports software configuration of the operating frequency band, that is, different chips use exactly the same hardware peripheral circuits, and through different software configurations, the chip can support different frequency band ranges, greatly enhancing the flexibility of design and use and reducing hardware expansion costs.

[0116] ② A new fixed-path minimum decoding algorithm is proposed to construct five types of paths, such as the most reliable one, to reduce the complexity of LDPC decoding, improve the error correction function of LDPC decoding, reduce the storage requirement of LDPC decoding, and accelerate the convergence speed of LDPC decoding.

[0117] In the factor graph of a multivariate LDPC code, there is a permutation node between the variable node and the check node. The permutation node converts the finite field elements of the variable node message and Multiply the corresponding non-zero elements in (permutation process) to sum the finite field elements of the check node message Divide the corresponding non-zero elements in (inverse permutation process). For a certain degree The check node is and ( ) represent the input reliability vector after permutation and the output reliability vector before inverse permutation respectively, and the corresponding finite field element vector is recorded as and .Will Rearrange the vectors in ascending order according to the second LLR value.

[0118] Will attach Figure 3 Each column of nodes in the grid diagram shown is divided into two sets. The first set contains the nodes, which represent the nodes with the highest reliability in the column, and the remaining nodes in the column are divided into the second set. Indicates The second set of columns, using express The reliability of the set. Decoding is performed by constructing paths on the grid graph. Each path has two attributes: one is the check value, which is equal to the sum of the finite field elements of each node in the path; the other is the reliability, which is equal to the sum of the LLRs of each node in the path. The path composed of the nodes in the first row of the grid graph has the highest reliability and is called the most reliable path; the nodes in the most reliable path are called zero nodes because the LLR of these nodes is 0; the nodes in other paths that are different from the most reliable path are called offset nodes. All paths are divided into the following five categories, and the specific construction method is as follows:

[0119] ① The first category has only one path, which is the most reliable path and is recorded as Category I path.

[0120] ② The second category has There are paths, each of which has only one offset node and comes from the second row of the grid graph, which are denoted as type II paths.

[0121] ③ The third category has Paths, which are divided into two subcategories: the first subcategory includes The first offset node of each path is the node of the second row and first column of the grid graph, and the second offset node comes from the remaining columns of the second row of the grid graph, which is recorded as type III path; the second subcategory includes The first offset node of each path is the node in the second row and second column of the grid graph, and the second offset node is from the node in the second row and third column of the grid graph. Column, recorded as type IV path.

[0122] ④ The fourth category has There are paths, each path has only one offset node, and the offset nodes come from the 3rd to the 4th rows of the grid graph. The nodes of the row are recorded as type V paths.

[0123] ⑤ The fifth category has There are two paths, each with only one offset node. These paths are divided into two sub-categories: The offset nodes of the first sub-category come from , recorded as type VI path; the second small category of offset nodes comes from , recorded as Class VII path.

[0124] Taking a single check node as a layer, the number of layers is .definition For the In the iteration, the variable node Passed to the check node news; For the In the iteration, check node Pass to variable node news; For the In the iteration, Variable nodes after layer update A posteriori message of For the check node A collection of connected variable nodes, For variable nodes The set of connected check nodes, is the maximum number of iterations. See the attached LDPC layered decoding algorithm block diagram Figure 4 .

[0125] Example 4

[0126] The present invention also adopts a low-cost inertial sensor combined navigation method. The BDS / INS combined navigation combines the information of Beidou navigation and inertial navigation, and can provide the carrier with full-attitude navigation information including attitude, speed and position, etc. The output navigation data frequency is relatively high, and the accuracy of the navigation information is higher than that of a single navigation system. The data of various navigation systems are integrated to achieve complementary advantages. When the various navigation systems are shallowly combined, the systems do not affect each other, which solves the problem that the positioning accuracy diverges rapidly over time when inertial navigation is used alone, and the problem that satellite navigation is easily interfered when used alone is solved. Specifically, the following steps are included:

[0127] ① The inertial navigation mechanical arrangement algorithm is used to solve the problem of uneven motion switching. The constant zero bias of the accelerometer and gyroscope calculated by the Beidou navigation system is used to correct the original output of the inertial sensor, thereby realizing real-time correction of the inertial navigation system.

[0128] The simplified strapdown attitude update algorithm is

[0129] (1)

[0130] (2)

[0131] For medium and low speed vehicles, such as ground speed , in the inertial force equation, the second term on the right side is The maximum magnitude is about , so the influence of the earth's rotation and the earth's curvature can be ignored, and the velocity update equation is simplified to:

[0132] (3)

[0133] (4)

[0134] in, for The inertial velocity at time, For quaternion The corresponding posture array, is the accelerometer in the time period The specific force increment of the internal output.

[0135] Low-cost MEMS systems usually move within a small range, such as hundreds of meters. In this case, the local rectangular coordinate system can be selected as the navigation reference coordinate system ( The navigation starting point is used as the coordinate origin ( ), three coordinate axes ( , and ) point to the east, north and sky respectively. In the rectangular coordinate system, the navigation positioning differential equation becomes very simple, which is , discretize it to get the position update equation:

[0136] (5)

[0137] It is not difficult to obtain the low-precision inertial navigation system error equation corresponding to the above simplified navigation algorithm, as follows

[0138] (6)

[0139] (7)

[0140] (8)

[0141] and are the first-order Markov process random errors of the gyroscope and accelerometer respectively, and the calculation formula is as follows:

[0142] (9)

[0143] (10)

[0144] It is practical to assume that the time-dependent error model is a first-order Markov process:

[0145] First, compared with the random constant model, the first-order Markov model can avoid the over-convergence of the filter after a long period of combined filtering, which will lead to the deterioration of the filter's anti-interference performance;

[0146] Second, if there is indeed a large random constant component in the inertial device error, the influence of the random constant error can be eliminated by correcting the inertial device error feedback through the filter;

[0147] Third, compared with establishing both random constant and first-order Markov process models at the same time, using only the latter is beneficial to reducing the modeling dimension and filtering calculation amount.

[0148] ② Adopt a time synchronization algorithm based on filtering online estimation and compensation.

[0149] The time synchronization error of the integrated navigation is random, and the existence of the time synchronization error hinders the improvement of the positioning performance of the integrated system. In the low-precision inertial navigation / satellite / geomagnetic integrated navigation system, the attitude misalignment angle of the inertial navigation system is selected. , speed error , positioning error , gyro-related drift , accelerometer related bias , Installation deviation angle , and magnetic inclination and magnetic declination As a state (20 dimensions in total),

[0150] (11)

[0151] The state space model of the system is

[0152] (12)

[0153] ③ Use the installation angle error estimation algorithm to reduce the installation and use conditions of the inertial navigation.

[0154] When the low-precision inertial navigation system is initialized during navigation, the horizontal attitude angle can be calculated by the accelerometer output in a stationary state. However, due to the low gyro accuracy, the azimuth autonomous alignment cannot be completed, and it can only be achieved by geomagnetic measurement, or by relying on satellite navigation information measurement under motion conditions. The installation angle error estimation algorithm specifically includes the following steps:

[0155] Step 1: Use the accelerometer to perform horizontal attitude alignment;

[0156] In a static environment, the linear motion of the carrier and its derivative are both 0, which can be simplified to:

[0157] (13)

[0158] In practical applications, in order to reduce the influence of accelerometer measurement noise and external shaking interference acceleration, the average specific force over a short period of time is often used for calculation. ,have to:

[0159] (14)

[0160] The above formula is expanded into component form, that is:

[0161] (15)

[0162] It can be solved as follows:

[0163] (16)

[0164] The above formula shows the posture array The third row vector is the projection of the vertical line to the ground under the load system. From the above formula, we can only get the attitude matrix The last row of elements in , and ,and All elements in the first two rows of are uncertain and can take any value as long as the right-hand gesture matrix is ​​satisfied. The three row vectors are , and , that is, ,structure A simple method is as follows:

[0165] a) Take The third row vector of ;

[0166] b) In Find the element with the largest absolute value in (For example, the first element ), swap with any non-j-th column element and Take the opposite number, set the remaining element to 0, and construct a temporary vector (For example, ), obviously is a non-zero vector and Orthogonal, then Normalization is The second row vector of ;

[0167] c) The first row vector of is constructed as .

[0168] In step b) above, select the element with the largest absolute value , you can choose any absolute value greater than (even slightly greater than 0) is also feasible.

[0169] It is worth pointing out that the attitude matrix given after the above processing is If we calculate the three Euler angles, only the horizontal attitude angle (pitch angle and roll angle) reflects the true attitude of the carrier, while the azimuth angle has no actual physical meaning and can be recorded as , The system is called the local horizontal coordinate system, and its implicit azimuth is invalid or uncertain.

[0170] Step 2: Geomagnetic measurement azimuth alignment;

[0171] During the initial alignment process, if the geomagnetic measurement information is available, the small magnetic declination effect can usually be ignored, and the magnetic azimuth can be directly used to approximate the geographic azimuth for azimuth alignment. Of course, if the local magnetic declination parameters are known, appropriate compensation can be made to improve the azimuth accuracy.

[0172] Assuming that the accelerometer is aligned horizontally, the attitude matrix is ​​obtained The true pose matrix is , which can be decomposed into:

[0173] (17)

[0174] in, is a matrix related to orientation and can be expanded as:

[0175] (18)

[0176] According to the measurement relationship of the Earth's magnetic field

[0177] Right now (19)

[0178] Where, the normalized geomagnetic vector , Substituting equation (18) into , expand and take only and Quantity, get:

[0179] (20)

[0180] From the above formula, we can get:

[0181] (twenty one)

[0182] or

[0183] (twenty two)

[0184] in, is the four-quadrant inverse tangent function. So far, the orientation correction matrix is ​​obtained , and then use equation (18) to complete the azimuth alignment. Rearrange it as follows

[0185] (twenty three)

[0186] Step 3: Use satellite navigation to align the position;

[0187] After completing the horizontal alignment, if the satellite navigation signal is available, for fixed-wing aircraft, the flight speed direction is generally along the longitudinal axis of the carrier (directly forward). According to the track angle of the running trajectory or the satellite measurement velocity vector, it is easy to obtain the azimuth of the longitudinal axis of the carrier relative to the geographic north. Using this azimuth, By calculating the pitch angle and roll angle, the initial attitude matrix can be obtained to complete the attitude initialization.

[0188] For multi-rotor aircraft, such as quad-rotor drones, the flight speed and direction are arbitrary (i.e., they can fly in any direction along the carrier), and the orientation determination method similar to that of fixed-wing aircraft can no longer be used. However, it can be achieved by performing linear acceleration maneuvers in the horizontal direction. The basic principle is described as follows:

[0189] The contrast force equation is approximated and transformed as follows:

[0190] (twenty four)

[0191] Acceleration maneuvers mean is not zero, it can be obtained by the difference of satellite navigation speed at two times, and the approximate calculation is

[0192] (25)

[0193] Expand (24), and only take and The amount is:

[0194] (26)

[0195] From the above formula, we can get:

[0196]

[0197] ④ Based on I2C, SPI, GPIO and other data interfaces, realize the functions of parameter configuration, data reading, interrupt triggering and so on of the same inertial navigation.

[0198] Example 5

[0199] The present invention also provides a high-precision positioning solution method, which specifically includes the following steps:

[0200] ① Provide a new embedded single-frequency / multi-frequency RTK technology;

[0201] Traditional RTK technology consumes a lot of resources, and its cost and power consumption limit its promotion and application in the civilian consumer market. The present invention develops innovative single-frequency / multi-frequency RTK technology, so that the algorithm can run on consumer-grade microprocessors together with existing common navigation software. This technology achieves the minimum resource configuration of multi-frequency RTK technology by adopting a new matrix operation engineering implementation method, an improved LAMBDA ambiguity search algorithm and an innovative ambiguity maintenance algorithm.

[0202] RTK technology requires that the base station be built at a known point. The base station receives satellite signals and sends them to the user in real time through the network. The user will jointly solve the received satellite signals and the received base station signals in real time to obtain the coordinate increment (baseline vector) between the base station and the rover. When the distance between the base station and the rover is 30 kilometers or less, the plane position accuracy of 1-2 cm can be achieved.

[0203] The biggest problem encountered in traditional RTK applications is the effective range of reference station correction data. The spatial correlation of satellite errors gradually loses linearity as the distance between stations increases. When the distance is far, the user data after differential processing still contains large observation errors, resulting in a reduction in accuracy and the inability to resolve the integer ambiguity of the carrier phase.

[0204] In order to overcome the defects of traditional RTK technology, in the current network RTK technology, the linear attenuation error model is replaced by a regional network error model, that is, a network composed of multiple reference stations is used to estimate the error model of a region, which can provide more effective correction data for users in the network coverage area and provide a technical basis for the practical application of RTK modules.

[0205] In RTK positioning technology, the correct solution of ambiguity has always been a difficult problem. Among the current ambiguity search methods, the LAMBDA algorithm is the most effective, but it requires a large number of matrix operations and thousands of search data processing. Especially in low-cost and low-power embedded environments, it is necessary to effectively improve the consumption of memory resources and MIPS computing resources during the ambiguity fixation process, while improving the correctness of ambiguity fixation and the reliability of baseline calculation.

[0206] In the observation preprocessing, the observation reliability estimation process is introduced, and the observations with higher reliability are processed first in the satellite selection, and the DOP distribution of the current constellation is taken into consideration. Some satellites only use the dual-bandwidth lane combination method. This can effectively reduce the matrix dimension and minimize the impact on the correctness of the ambiguity search.

[0207] In the matrix calculation process, by decomposing the relevant matrix operation process, the memory acquisition, calculation, and release process in the matrix operation is planned in advance to maximize the reuse of the ambiguity variance covariance matrix. Preprocess the data in advance to reduce the demand for calculation accuracy in the calculation process, simplify the 8-byte floating point calculation process to 4-byte floating point calculation, thereby improving the consumption of memory resources and MIPS computing resources.

[0208] The simplification of the ambiguity search process will have a certain impact on the ambiguity fixation. Therefore, after the ambiguity search process, it is necessary to use prior information to perform a secondary check on the reliability of the ambiguity. The estimation of the ambiguity search results in the position space can be adjusted by the calculation results of the prior floating point solution. The consistency of the ambiguity can be judged by other satellites that are not involved in the search for a secondary test. The position results of the previous and subsequent ambiguity searches can also be statistically analyzed multiple times to improve the correctness and reliability of the ambiguity fixation.

[0209] ② Propose an ionospheric delay correction technique under the condition of limited number of available observations;

[0210] The ionospheric delay variation is a complex nonlinear system. It is difficult to interpolate and fit the nonlinear mapping law of ionospheric delay variation through conventional interpolation models. The BP neural network has nonlinear fitting properties and can well express the law of ionospheric delay variation. It has a large amount of sample data, which fully makes up for the shortcomings of conventional interpolation model calculations.

[0211] To establish the ionospheric delay model of the BP neural network, first, according to the thin ionosphere hypothesis, the ionosphere is assumed to be a thin film. Combined with the known coordinates of the measuring station, the satellite altitude angle and the azimuth angle, the coordinates of the puncture point of each satellite in the ionosphere single layer are solved. Then, the puncture point distance and the difference between the puncture point distances are used as input, and the double difference ionospheric delay of the corresponding reference station is used as the output to form the training sample, determine the BP neural network structure and parameters, and establish the ionospheric delay BP neural network model; for any station receiver in the network RTK service area, using the constructed model, the puncture point distance and the difference between the puncture point distances corresponding to the mobile station and the main reference station of the same satellite are used as input, and the double difference ionospheric delay of each satellite corresponding to the station can be interpolated and estimated. The ionospheric delay correction framework is attached. Figure 5 .

[0212] The high-precision integrated navigation and communication system based on Beidou-3+IOT provided by the present invention supports working in different environments through high-precision navigation+IOT and combining Beidou short message and mobile network communication. For example:

[0213] Within the city, services are provided in areas such as smart transportation, smart bracelets, and smart cities.

[0214] Intelligent transportation: Beidou navigation can provide real-time information on the current lane occupancy status. Combined with the Internet of Things, it can intelligently plan navigation routes and adjust traffic light durations.

[0215] Smart bracelet: Provides real-time health management for users through the Internet of Things. At the same time, through high-precision positioning, it can understand the user's location in real time and prevent children and the elderly from getting lost.

[0216] Smart city: Through Beidou navigation + Internet of Things, many urban infrastructures are improved and upgraded, such as smart manhole covers, smart street lights, etc., thereby promoting the construction of smart cities.

[0217] Outside the city, due to the poor network environment, remote working environment and long-term operation, this system with low power consumption, low cost and high precision and combining Beidou short message and mobile network communication is very suitable for providing services in the fields of geological disaster monitoring, meteorological monitoring, precision agriculture and emergency rescue. The base station conducts deformation monitoring and early warning of landslides, subsidence and other geological disasters. The monitoring data is uploaded to the cloud data platform through mobile network communication or Beidou short message communication for system solution and early warning output.

[0218] Meteorological monitoring: Through the meteorological monitoring station combined with low-power Beidou short message communication, meteorological monitoring of wind direction, wind speed, rainfall, humidity and temperature, air pressure and temperature can be achieved. The equipment is deployed in the field and needs to work for a long time, so it is particularly suitable to use this system with low power consumption and short message communication. At the same time, long-term operation can be achieved by combining solar or wind power generation.

[0219] Precision agriculture: Precision agriculture technology is supported by high-precision satellite navigation technology, which infiltrates relevant technologies into all aspects of agricultural production to improve agricultural output and benefits. For example, the BDS / / INS combined navigation + Internet of Things of this system can realize automatic driving of agricultural machinery.

[0220] Emergency rescue: command and dispatch of rescue vehicles through Beidou navigation, search for disaster victims through Beidou high-precision positioning, and emergency communication through Beidou short messages.

[0221] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A high-precision integrated communication and navigation system based on BeiDou-3+IOT, characterized in that: include: The BeiDou-3 high-precision positioning / attitude measurement terminal is composed of a data acquisition unit and a solution unit; the data acquisition unit is responsible for collecting satellite observation data and sending the data to the solution unit; the solution unit sends the solution result to the server via a 4G signal, and the host computer displays the solution result; BeiDou-3 short message communication terminal, used to realize RDSS positioning function and short message communication function; BeiDou-3 positioning / communication integrated device, used to realize BeiDou-3 civil RDSS positioning, BeiDou-3 RNSS BeiDou B1 and GPS_L1 single-mode or dual-mode hybrid positioning, short message communication and mobile network communication functions; BeiDou-3 communication separation service platform is used to provide data infrastructure services, BeiDou communication services and operation and maintenance services.

2. The high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 1 is characterized in that: The data acquisition unit includes: a receiver, a voltage stabilization circuit, a charging circuit and a wireless module; the receiver is provided with two, serving as a main antenna and a slave antenna respectively; the voltage stabilization circuit includes a boost circuit and a buck circuit, using FP6276B as a boost chip and AMS1117-3.3 as a buck chip; the charging circuit uses TP4056 to charge the lithium battery; the wireless module is used to send the data collected by the receiver to the solution unit.

3. The high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 2 is characterized in that: The solving end of the solving unit is an ARM embedded solving platform, using Cortex-A8 as a processor, the OEM core board is connected to the wireless module through its own native serial port, and the MCU uses S5PV210.

4. The high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 1 is characterized in that: The BeiDou-3 short message communication terminal adopts TS-M1531, which integrates RDSS transceiver RF chip, baseband chip, PA circuit and LNA circuit, and an external SIM card and passive antenna to realize short message communication function and positioning navigation function.

5. The high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 1 is characterized in that: The Beidou-3 positioning / communication integrated machine includes: a terminal signal receiving module, a terminal signal transmitting module and a data storage and supplementary transmission module; the terminal signal receiving module uses an internal radio frequency module to complete analog down-conversion, filtering, and amplification processing, and realizes analog intermediate frequency signal sampling through an A / D module. The baseband processing unit completes capture, tracking and demodulation processing to obtain observation quantities; the terminal signal transmitting module completes data stream formation according to the telegram information arrangement format, and sends it to the Beidou satellite via the antenna; the data storage and supplementary transmission module identifies each transmitted data frame and stores it in the transmission record storage list.

6. A new BeiDou-3 signal receiving and processing method for the high-precision communication and navigation integrated system based on BeiDou-3+IOT as described in claim 1, characterized in that: The following steps are involved: S61. Propose a full-frequency configurable broadband RF method to achieve baseband and RF integrated design; S62. A new fixed-path minimum decoding algorithm is proposed to construct five types of paths, including the most reliable ones.

7. The novel BeiDou-3 signal receiving and processing method for the high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 1 according to claim 6 is characterized in that: The baseband and RF integrated design adopts the civilian RNSS RF baseband integrated chip, which integrates the broadband RF unit and the high-performance high-sampling rate orthogonal 10-bit AD module, and can realize the reception and processing of GPS L1, B1I, Galileo E1 and GLONASS G1 signals through a single analog channel.

8. The novel BeiDou-3 signal receiving and processing method for the high-precision integrated communication and navigation system based on BeiDou-3+IOT according to claim 1 according to claim 6 is characterized in that: The specific method for constructing the most reliable five types of paths is: S81. There is only one path in the first category, which is the most reliable path and is recorded as Category I path. S82, the second category has There are paths, each of which has only one offset node and comes from the second row of the grid graph, which are denoted as type II paths. S83, the third category has Paths, which are divided into two subcategories: the first subcategory includes The first offset node of each path is the node of the second row and first column of the grid graph, and the second offset node comes from the remaining columns of the second row of the grid graph, which is recorded as type III path; the second subcategory includes The first offset node of each path is the node in the second row and second column of the grid graph, and the second offset node is from the node in the second row and third column of the grid graph. Column, recorded as type IV path. S84, the fourth category has There are paths, each path has only one offset node, and the offset nodes come from the 3rd to the 4th rows of the grid graph. The nodes of the row are recorded as type V paths. S85, the fifth category has There are two paths, each with only one offset node. These paths are divided into two sub-categories: The offset nodes of the first sub-category come from , recorded as type VI path; the second small category of offset nodes comes from , recorded as Class VII path.

9. A high-precision positioning solution method for the high-precision communication and navigation integrated system based on Beidou-3+IOT as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Provide a new embedded single-frequency / multi-frequency RTK technology, using a new matrix operation engineering implementation method, an improved LAMBDA ambiguity search algorithm, and an innovative ambiguity maintenance algorithm to achieve the minimum resource configuration of multi-frequency RTK technology; Step 2: Propose an ionospheric delay correction technology under the condition of a limited number of available observations and establish an ionospheric delay model of the BP neural network.

10. The high-precision positioning solution method for the high-precision communication and navigation integrated system based on Beidou-3+IOT according to claim 1 according to claim 9, characterized in that: The establishment of the ionospheric delay model of the BP neural network includes the following steps: S101, assuming that the ionosphere is a thin film, and combining the known coordinates of the measuring station, the satellite altitude angle and the azimuth angle, the coordinates of the puncture point of each satellite in the ionosphere single layer film are calculated; S102, using the puncture point distance and the difference between the puncture point distances as input quantities, and the double difference ionospheric delay of the corresponding reference station as output quantities to form training samples, determine the BP neural network structure and parameters, and establish an ionospheric delay BP neural network model; S103, using the constructed model, taking the puncture point distance corresponding to the mobile station and the main reference station of the same satellite and the difference in the puncture point distance as input, the double difference ionospheric delay of each satellite corresponding to the station can be estimated by interpolation.

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