A GNSS data acquisition device

Abstract

This invention belongs to the field of satellite navigation and positioning technology, and discloses a GNSS data acquisition device. The device includes two sets of GNSS antenna terminals, dual independent radio frequency front-end modules, master-slave GNSS acquisition modules, a time synchronization unit, a signal processing and fusion unit, and a data output and storage unit. The dual radio frequency channels share a unified clock reference, and a filtering and amplification structure enhances anti-interference capabilities. The time synchronization unit achieves time alignment of observation data from the two acquisition modules. The signal processing and fusion unit runs a dual-antenna RTK calculation program, which can synchronously output positioning and heading information, and has a built-in power-off data protection structure. The output storage unit is equipped with multiple high-speed interfaces and a local storage architecture. This device can complete positioning and direction finding in an integrated manner without additional sensors, has outstanding anti-interference performance, preserves acquired data even in power-off situations, has strong interface adaptability, and high integration, and can be widely used in surveying, intelligent transportation, drones, autonomous driving, and other scenarios.

Description

Technical Field

[0001] This invention relates to the field of satellite navigation and positioning technology, and specifically to a GNSS data acquisition device. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) have been widely used in many fields, including surveying and mapping, intelligent transportation, precision agriculture, drone navigation, autonomous driving, and marine engineering. With the continuous expansion of application scenarios, the industry has placed higher demands on the accuracy of navigation and positioning equipment, its operational reliability, and the completeness of its functions.

[0003] Currently used GNSS data acquisition equipment still suffers from several technical limitations. Most commercial equipment employs a single-antenna architecture, only outputting the position and velocity information of the carrier, unable to directly acquire its heading and attitude data. To meet heading measurement requirements, additional inertial measurement units or electronic compasses must be configured, increasing system hardware costs and complexity, and introducing additional measurement deviations such as drift and magnetic interference errors. Some dual-antenna structures often use independent clock sources for their two acquisition modules, resulting in significant timestamp discrepancies in the observed data. This directly reduces the quality of baseline vector calculation, leading to large deviations in heading measurement results and making it difficult to adapt to high-precision application scenarios.

[0004] Meanwhile, with the rapid development of wireless communication technology, electromagnetic interference sources in the environment are increasing. Most existing devices lack effective out-of-band suppression methods in their radio frequency front-ends. In urban areas and industrial plants with complex electromagnetic environments, satellite signals are easily interfered with, leading to decreased positioning accuracy or even signal loss. In field operations or unattended applications, unexpected power outages are frequent, causing data being written to storage media to be lost, and in severe cases, damaging the storage file system and resulting in irreversible data loss. Furthermore, many devices have relatively simple interface types and data output formats, making it difficult to simultaneously meet the diverse needs of real-time data transmission, raw data storage, and remote configuration management.

[0005] Therefore, proposing a dual-antenna GNSS data acquisition device with high integration, excellent positioning and direction finding performance, strong anti-interference capability, reliable data operation and complete functions has important practical significance and application value. Summary of the Invention

[0006] The present invention aims to solve the problems mentioned in the background art by providing a GNSS data acquisition device.

[0007] The specific technical solution is as follows: A GNSS data acquisition device includes two GNSS antenna terminals, dual independent radio frequency front-end modules, a main GNSS acquisition module, a slave GNSS acquisition module, a time synchronization unit, a signal processing and fusion unit, and a data output and storage unit.

[0008] The two GNSS antenna terminals are used to receive multi-constellation, multi-frequency satellite radio frequency signals, and are independently installed at different locations on the carrier to form a measurement baseline.

[0009] The dual-channel independent RF front-end module includes two electrically isolated RF channels with identical parameters. The input terminals of the two RF channels are connected to two GNSS antenna terminals one by one. The dual-channel independent RF front-end module has a built-in unified clock reference source, which provides the same local oscillator clock signal to the two RF channels through a symmetrical clock distribution network. Each RF channel integrates an out-of-band interference suppression filter unit and a low-noise amplification unit.

[0010] The RF input terminals of the main GNSS acquisition module and the slave GNSS acquisition module are respectively connected to the two RF channel output terminals of the dual independent RF front-end module, which are used to perform baseband processing on the input RF signals and output the raw observation data.

[0011] The time synchronization unit is connected between the main GNSS acquisition module and the slave GNSS acquisition module. It is used to transmit the time synchronization signal output by the main GNSS acquisition module to the slave GNSS acquisition module, so that the observation timestamp of the slave GNSS acquisition module is synchronized with that of the main GNSS acquisition module.

[0012] The signal processing and fusion unit is connected to the data output terminals of the main GNSS acquisition module and the slave GNSS acquisition module, respectively. It is used to receive two channels of raw observation data and perform dual-antenna RTK calculations, and output the positioning results and heading angle information of the carrier. The signal processing and fusion unit integrates a power-off data protection mechanism consisting of a voltage detection unit, an energy storage unit and a control circuit.

[0013] The data output storage unit is connected to the signal processing and fusion unit to realize the real-time output and local storage of the calculated data and the original observation data.

[0014] This solution employs a dual-antenna architecture, establishing a measurement baseline by deploying antennas at different locations on the carrier. This eliminates the need for additional sensors, allowing direct acquisition of the carrier's heading information, simplifying the application system's structure and reducing overall setup costs. The dual independent RF channels with consistent parameters, coupled with a unified clock reference source and a symmetrical clock distribution network, ensure consistent phase references for both RF signals, eliminating the impact of clock differences between the two channels and providing a stable signal foundation for subsequent high-precision calculations. Integrated filtering and amplification units in each channel preprocess the received satellite signals, improving signal quality. A time synchronization unit ensures strict alignment of observation data from both acquisition modules in the time dimension, preventing time deviations from interfering with baseline calculations and guaranteeing the accuracy of the direction finding results. An integrated power-loss data protection mechanism protects the data writing process from damage or loss during external power supply failures, enhancing equipment reliability. The integrated output and storage design simultaneously meets the needs of real-time data transmission and local storage, adapting to various application scenarios.

[0015] As a preferred embodiment of the present invention, the GNSS antenna terminal is a multi-frequency active antenna that supports the reception of satellite signals in multiple frequency bands; the antenna terminal has a built-in low-noise amplifier with a low noise figure; the antenna terminal integrates an antenna biaser that supports a certain range of DC power supply and has overcurrent protection and antenna open-circuit and short-circuit monitoring functions.

[0016] This solution features a multi-frequency antenna design that is compatible with multiple signal bands from different satellite navigation systems, supports signal access from more constellations, increases the number of available satellites in various environments, and enhances positioning stability and continuity. The built-in low-noise amplifier provides initial amplification of weak satellite signals received by the antenna while maintaining a low noise level, improving the device's signal reception sensitivity and ensuring normal satellite signal reception even in weak signal conditions. The integrated antenna biaser allows direct power supply to the antenna from the device itself, eliminating the need for a separate power supply line and simplifying wiring complexity during on-site installation. The accompanying protection and monitoring functions provide protection and status feedback in case of wiring abnormalities or overcurrent, improving antenna reliability and facilitating troubleshooting.

[0017] As a preferred embodiment of the present invention, the two radio frequency channels of the dual independent radio frequency front-end module have a high degree of isolation; the out-of-band interference suppression filtering unit adopts a surface acoustic wave filter, which has a strong out-of-band interference suppression capability and is used to suppress interference signals of mobile communication frequency band and wireless local area network frequency band; the input terminal of each independent radio frequency channel also integrates lightning protection and electrostatic protection circuits.

[0018] This solution features high isolation between the two RF channels, effectively preventing crosstalk between the two signals during transmission and ensuring the independence and purity of each signal, thus avoiding interference with the observation results. The use of a surface acoustic wave (SAW) filter for out-of-band interference suppression effectively filters out common interference signals from mobile communication and wireless LAN frequency bands, reducing the impact of the external electromagnetic environment on satellite signal reception. Even in complex electromagnetic environments such as urban areas and industrial zones, stable signal reception and positioning performance are maintained. Integrated surge and electrostatic discharge (ESD) protection circuitry at the input end protects against surges, static electricity, and other abnormal electrical impacts, enhancing the equipment's resilience in harsh environments such as outdoor settings and areas with large temperature differences, and extending the equipment's lifespan.

[0019] As a preferred embodiment of the present invention, the clock reference source is a temperature-compensated crystal oscillator, which has a high level of frequency stability and can cover a wide operating temperature range; the symmetrical clock distribution network adopts an equal-length wiring design to ensure that the phase deviation of the two local oscillator clock signals is within a very small range.

[0020] This solution employs a temperature-compensated crystal oscillator (TCC) as the clock reference source, maintaining a stable clock output over a wide temperature range. This reduces clock frequency drift caused by temperature variations, ensuring the stability of the RF front-end downconversion process and preventing signal phase deviation due to temperature drift. The symmetrical clock distribution network with equal-length wiring ensures that the local oscillator clock signals received by the two RF channels remain consistent along the transmission path, minimizing the phase difference between the two clocks and further guaranteeing the phase synchronization of the two RF signals. This provides a consistent clock reference for subsequent differential calculations, improving the accuracy of the calculation results.

[0021] As a preferred embodiment of the present invention, both the main GNSS acquisition module and the slave GNSS acquisition module adopt a full constellation, full frequency GNSS baseband chip, which supports signal reception from at least two global satellite navigation systems, supports an adjustable sampling rate within a certain range, and can output raw pseudorange, carrier phase, Doppler frequency shift observations and navigation messages; the main GNSS acquisition module has a real-time clock synchronization function and can output second pulse signals and serial time information.

[0022] This solution features a full-constellation, full-frequency baseband chip configuration, supporting access to more satellite navigation systems and signal frequencies. This enriches observation data sources, improves the redundancy and reliability of positioning calculations, and maintains normal positioning even in scenarios where some satellite signals are blocked. Adjustable sampling rate settings allow for adjustments to the data output frequency according to different application requirements, balancing the needs of high-precision dynamic scenarios with low-power static scenarios. The main acquisition module's real-time clock synchronization function outputs a stable time reference signal, providing a reliable time source for time synchronization between the two modules and a unified time reference for the entire device, ensuring consistency in the time base of all output data.

[0023] As a preferred embodiment of the present invention, the time synchronization unit uses a coaxial cable or an LVCMOS level pin header to connect the synchronization interface between the main GNSS acquisition module and the slave GNSS acquisition module, and the second pulse signal has a low transmission delay; the slave GNSS acquisition module calibrates its own clock and observation timestamp according to the received second pulse signal and time information, so as to achieve high-precision time synchronization with the main GNSS acquisition module.

[0024] This scheme employs a low-latency transmission medium to connect the synchronization interfaces of the master and slave modules, minimizing latency loss during synchronization signal transmission and ensuring that the accuracy of the synchronization signal is not significantly affected by the transmission path. The slave module calibrates its own clock and timestamp based on the second pulse and time information output by the master module. This ensures high consistency in the timestamps of the observation data from both acquisition modules, eliminating time deviations caused by independent clocks in the two modules, avoiding baseline calculation errors due to time asynchrony, and effectively improving the calculation accuracy of dual-antenna direction finding.

[0025] As a preferred embodiment of the present invention, the signal processing fusion unit adopts an ARM architecture processor and has a built-in dual-antenna RTK calculation engine based on carrier phase double difference technology, which is used to calculate the baseline vector between the two antennas and the carrier heading angle; the signal processing fusion unit has reserved an inertial navigation fusion interface to support external inertial measurement units to realize integrated navigation.

[0026] This solution employs a dedicated processor to run a dual-antenna RTK calculation engine. It processes the raw observation data from two synchronized time streams, eliminates various common errors through differential calculations, calculates the baseline vector between the two antennas, and thus obtains the vehicle's heading information, achieving integrated output of positioning and direction finding functions. A reserved inertial navigation fusion interface supports subsequent external inertial measurement devices, enabling combined operation of satellite navigation and inertial navigation. Even in scenarios with brief satellite signal obstruction or interruption, it can still continuously output navigation information, improving the equipment's continuous operation capability and scenario adaptability under complex conditions.

[0027] As a preferred embodiment of the present invention, the power-down data protection mechanism includes a voltage detection unit, an energy storage unit, and a control circuit. The voltage detection unit is used to monitor the external power supply voltage in real time. When the detected voltage is lower than a preset threshold, it sends an interrupt signal to the processor. After responding to the interrupt, the processor stops unnecessary tasks, writes the observed data in the cache to the storage medium, and performs file system synchronization operations. The energy storage unit is in a charging state when the external power supply is normal. When the external power supply is interrupted, it provides power to the processor and storage medium through an anti-backflow circuit, providing continuous power for a certain period of time.

[0028] This solution utilizes a voltage detection unit to monitor the external power supply status in real time, triggering protection actions the moment an abnormal power drop occurs, ensuring timely response of the protection mechanism. Upon receiving an interrupt signal, the processor halts unnecessary tasks and concentrates computing power to complete data writing and file system synchronization. This allows for the preservation of critical data within the limited backup power supply time, enhancing the effectiveness of the protection mechanism. The energy storage unit's charging and discharging design stores energy during normal device operation and automatically switches to power supply mode during external power outages. This eliminates the need for an additional backup power supply, simplifying power supply design and preventing data corruption and file system anomalies caused by interrupted data writing during power outages. This significantly improves data storage reliability, making it particularly suitable for unattended operations, fieldwork, and other scenarios where timely response after a power outage is difficult.

[0029] As a preferred embodiment of the present invention, the energy storage unit is a supercapacitor with a capacity within a reasonable range; the preset voltage threshold is within a reasonable voltage range.

[0030] This solution utilizes supercapacitors as energy storage components, featuring rapid charging and discharging, long cycle life, and excellent low-temperature performance. It is suitable for applications with frequent start-stop cycles and large temperature variations, and its capacity is not prone to decay over long-term use, ensuring the long-term stability and effectiveness of the power-off protection function. A reasonably set voltage threshold ensures timely triggering of protection before the power supply voltage drops to a level that affects normal equipment operation, while also preventing false triggering due to small voltage fluctuations, thus improving the stability and accuracy of the protection mechanism.

[0031] As a preferred embodiment of the present invention, the data output storage unit supports at least two standard satellite navigation data formats and is equipped with a USB high-speed interface and an Ethernet interface; the storage part adopts an architecture of a ring buffer plus a removable storage card, and the storage card adopts a general file system, which supports the automatic generation of observation data files and navigation data files according to time.

[0032] This solution supports multiple standard data format outputs, adapting to various host computer software and control systems. It can directly interface with various application platforms without additional format conversion, enhancing device compatibility. It is equipped with multiple high-speed physical interfaces, enabling high-speed data transmission and file reading via local interfaces, as well as remote data access and device configuration via network interfaces, meeting the needs of different scenarios. The storage architecture, featuring a ring buffer and memory card, caches real-time data, preventing data loss due to delayed writes and improving data storage continuity. The removable memory card, combined with a universal file system, facilitates data export and retrieval. The design of automatically generating files based on time allows for orderly management of collected data, facilitating subsequent data retrieval and post-processing.

[0033] As a preferred embodiment of the present invention, the device adopts a metal shell structure, including an upper cover, a PCBA functional module and a lower shell; the upper cover is provided with a heat dissipation structure, and the two sides of the lower shell are respectively provided with an antenna interface, a power switch, a status indicator light group, a data interface and a network port; the dual independent radio frequency front-end module, the main GNSS acquisition module, the slave GNSS acquisition module, the time synchronization unit, the signal processing and fusion unit and the data output and storage unit are all integrated on the PCBA functional module, and the PCBA functional module adopts a layout design that separates the radio frequency area and the digital area.

[0034] This solution features a metal casing design that enhances the structural strength and protection of the equipment while also providing electromagnetic shielding to reduce the impact of external electromagnetic interference on the internal circuitry. The top cover incorporates a heat dissipation structure, improving heat dissipation and ensuring that internal components operate within a suitable temperature range even during prolonged operation or in high-temperature environments, thus enhancing operational stability. Integrating all functional circuits onto a single PCBA module increases the equipment's integration level, reduces its overall size, and facilitates installation and deployment on various platforms. The separate layout of the RF and digital areas reduces noise interference from digital circuits on the RF receiving circuitry, further improving signal reception quality and operational stability. Interfaces are strategically located on both sides of the lower casing for easy wiring during on-site installation, and status indicator lights allow operators to easily monitor the equipment's operating status.

[0035] The present invention has the following beneficial effects: 1. Integrated positioning and direction finding, reducing system cost and complexity: Utilizing a dual-antenna architecture with high-precision time synchronization, it achieves high-precision positioning and heading angle measurement simultaneously without the need for additional inertial measurement or magnetic heading devices, directly outputting the vehicle's position, velocity, and heading information. This design simplifies the hardware composition of the application system, reduces overall setup costs and wiring complexity, and avoids drift errors and magnetic interference errors introduced by additional sensors, thus improving the reliability of direction finding results.

[0036] 2. Excellent anti-interference capability and stable operation in complex environments: The dual-channel independent RF front-end module 2 adopts a high-isolation dual-channel design, coupled with the built-in out-of-band filter unit in each channel, which can effectively suppress common electromagnetic interference from mobile communication and wireless LAN, reducing the impact of the external electromagnetic environment on satellite signal reception. A unified clock reference and symmetrical allocation design ensure phase consistency between the two signals, avoiding calculation errors introduced by channel differences. Combined with the electromagnetic shielding effect of the metal casing and the PCB's separate digital-analog layout, the device can maintain stable signal reception and calculation performance even in complex electromagnetic environments such as urban canyons and industrial plants.

[0037] 3. Secure and reliable data, suitable for unattended and field scenarios: The integrated power-loss data protection mechanism, through real-time voltage monitoring and backup power supply via energy storage, can trigger protection the instantaneously upon unexpected external power interruption, ensuring the safe writing of current data and the normal shutdown of the file system. This fundamentally solves the problems of data loss and file system corruption caused by sudden power outages. This design significantly improves the reliability of data storage, especially suitable for application scenarios such as field surveying and unattended monitoring where timely handling after a power outage is difficult, avoiding the loss of critical data.

[0038] 4. Abundant Interfaces and Formats, Strong Scene Adaptability: The data output storage unit 7 provides multiple high-speed physical interfaces, supporting various standard navigation data formats for direct connection to various host computer software, control systems, and data platforms without additional format conversion. The device also supports real-time data transmission, local storage of raw data, and remote parameter configuration, meeting diverse usage needs and flexibly adapting to various application scenarios such as surveying, autonomous driving, drones, and precision agriculture.

[0039] 5. High integration and stability, convenient installation and deployment: All functional circuits are integrated into a single PCBA functional module 9, combined with a compact metal housing structure, resulting in a small overall size, light weight, and high structural strength, facilitating integration and installation on various carriers and equipment. The heat dissipation design of the top cover 8 ensures the temperature stability of the equipment during long-term operation, while lightning protection and electrostatic discharge protection circuits enhance the equipment's tolerance to harsh environments, improving the overall environmental adaptability and service life of the machine.

[0040] 6. Flexible expansion and easy function upgrades: The signal processing fusion unit 6 has a reserved inertial navigation fusion interface, which can be connected to an external inertial measurement unit according to usage requirements to realize the combined operation of satellite navigation and inertial navigation. Even in scenarios where satellite signals are briefly blocked or interrupted, navigation information can still be continuously output, further improving the continuous working capability of the equipment. At the software level, it supports flexible configuration of multiple parameters, and the operating mode can be adjusted according to different scenarios, which also facilitates subsequent function upgrades and algorithm iterations. Attached Figure Description

[0041] Figure 1 A schematic diagram of the structure of the GNSS data acquisition device provided in the embodiments of the present invention. Figure 1 ; Figure 2 A schematic diagram of the structure of the GNSS data acquisition device provided in the embodiments of the present invention. Figure 2 ; Figure 3 A schematic diagram of the structure of the GNSS data acquisition device provided in the embodiments of the present invention. Figure 3 ; Figure 4This is an exploded structural diagram of the GNSS data acquisition device provided in an embodiment of the present invention; Figure 5 This is a partial structural diagram of the GNSS data acquisition device provided in an embodiment of the present invention; Figure 6 The radio frequency front-end circuit diagram of the GNSS data acquisition device provided in the embodiments of the present invention; Figure 7 The circuit diagram of the dual GNSS acquisition module of the GNSS data acquisition device provided in the embodiment of the present invention.

[0042] In the attached image: 1. GNSS antenna terminal; 2. Dual-channel independent RF front-end module; 3. Main GNSS acquisition module; 4. Slave GNSS acquisition module; 5. Time synchronization unit; 6. Signal processing and fusion unit; 7. Data output and storage unit; 8. Top cover; 9. PCBA functional module; 10. Bottom shell; 11. Antenna interface; 12. Power switch; 13. Status indicator light group; 14. Data interface; 15. Network port. Detailed Implementation

[0043] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0045] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0046] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] Example 1 like Figures 1-7 As shown, the GNSS data acquisition device provided in this embodiment mainly consists of seven functional parts, namely two GNSS antenna terminals 1, dual-channel independent radio frequency front-end modules 2, main GNSS acquisition module 3, slave GNSS acquisition module 4, time synchronization unit 5, signal processing and fusion unit 6, and data output and storage unit 7.

[0048] Both GNSS antenna terminals 1 employ the same technical specifications, being multi-frequency active GNSS antennas capable of receiving signals from multiple commonly used satellite navigation frequency bands. The antennas integrate low-noise amplifiers to initially amplify weak received satellite signals while maintaining a low noise level. They also integrate antenna biasers, allowing DC power supply from the device, and feature overcurrent protection and open / short circuit monitoring. The antenna physical interfaces can utilize common RF connector types for easy connection to RF cables. During use, the two antenna terminals 1 are mounted at different locations on the top of the carrier, forming a measurement baseline of a certain length.

[0049] The dual-channel independent RF front-end module 2 is a key component of the device's RF signal processing. It contains two completely independent RF channels with high isolation to prevent crosstalk. Each channel is equipped with an electrostatic discharge (ESD) protection device, a surface acoustic wave (SAW) filter, and a low-noise amplifier along the signal transmission direction. The SAW filter's passband covers commonly used GNSS frequencies, effectively suppressing interference signals from mobile communications, wireless LANs, and other sources outside the passband. The module incorporates a high-stability temperature-compensated crystal oscillator (TCO), and a clock distribution circuit with symmetrical, equal-length wiring provides a unified local oscillator clock signal to the down-conversion circuits of both RF channels, ensuring phase consistency between the two signals. Each channel's input is also equipped with a surge protector, working in conjunction with the ESD protection device to enhance the channel's electrical protection capabilities.

[0050] Both the main GNSS acquisition module 3 and the slave GNSS acquisition module 4 utilize full-constellation, full-frequency GNSS baseband chips, enabling simultaneous tracking of satellite signals from multiple navigation systems. Both modules support multiple adjustable sampling rates and can output raw pseudorange, carrier phase, Doppler shift, and other observations, as well as navigation message data. The main GNSS acquisition module 3 also features real-time clock synchronization, outputting high-precision second pulse signals and standard-format time information. The main acquisition module 3 is also equipped with multiple status indicator lights, corresponding to power supply, satellite acquisition status, and calculation status, allowing users to intuitively assess the device's operating status. The module's power supply end is equipped with a filtering circuit to ensure low power supply ripple; the module also includes a reset circuit and a backup power circuit to ensure stable module operation and continued clock operation after power failure.

[0051] The time synchronization unit 5 uses a low-latency transmission medium to connect the synchronization interface and serial communication interface of the main GNSS acquisition module 3 and the slave GNSS acquisition module 4. The main GNSS acquisition module 3 outputs a second pulse signal every second, and simultaneously outputs the corresponding time information through the serial interface. When the slave GNSS acquisition module 4 receives the signal edge of the second pulse, it latches its own timing counter and combines it with the received time information to calibrate its own system time with the timestamp of the observation data, achieving high-precision time synchronization with the main GNSS acquisition module 3 and ensuring strict alignment of the time bases of the two observation data.

[0052] The signal processing and fusion unit 6 employs a dual-core ARM processor, equipped with corresponding RAM and solid-state storage, running an embedded operating system and incorporating a dual-antenna RTK algorithm. The processor first preprocesses the raw observation data output from the main GNSS acquisition module 3 and the secondary GNSS acquisition module 4. Then, it performs differential calculations on the synchronized observation data using the algorithm to eliminate common errors and calculate the baseline vector between the two antennas, thereby converting it into the vehicle's heading angle information. The unit has multiple reserved communication interfaces, allowing for the connection of an external inertial measurement unit to achieve combined operation of satellite navigation and inertial navigation. The unit also integrates a power-down data protection mechanism, consisting of a voltage detection chip, energy storage components, and control circuitry, ensuring safe data writing even when external power is interrupted.

[0053] The power-down data protection mechanism operates as follows: The voltage detection chip monitors the external input supply voltage in real time. When the voltage drops below a preset threshold, it immediately sends an interrupt signal to the processor. Upon receiving the interrupt signal, the processor immediately stops unnecessary tasks, writes the observed data in the buffer to the storage medium, and calls the file system synchronization function to ensure that all data is completely written to the physical storage medium. The energy storage element is in a charging state when the device is powered normally, and automatically switches to a power supply state when the external power is lost, providing backup power to the processor and storage medium for a period of time to ensure that the data writing and file system shutdown operations can be completed completely.

[0054] The data output storage unit 7 is equipped with multiple high-speed physical interfaces, including a USB high-speed interface and an Ethernet interface. The USB interface supports multiple operating modes: it can be used as a virtual serial port to output real-time navigation data, or it can switch to a large-capacity storage mode, allowing users to directly read files stored on the memory card. The Ethernet interface supports network service mode, allowing users to remotely connect to the device via the network to obtain real-time data or modify device configuration parameters. The storage section adopts an architecture of a circular buffer combined with a removable memory card. The buffer is used to cache real-time observation data, avoiding data loss due to write latency; the memory card uses a general file system, supports large-capacity storage, and the device can automatically create directories and data files according to time, facilitating data management and retrieval.

[0055] Example 2 like Figures 1-7 As shown, this embodiment provides a detailed description of the mechanical structure of the device. The device is constructed entirely of an aluminum alloy shell and consists of three parts: an upper cover 8, a PCBA functional module 9, and a lower shell 10.

[0056] The surface of the top cover 8 is equipped with a dense heat dissipation grid structure to increase the heat dissipation area of ​​the device, enhance the device's natural heat dissipation capacity, and ensure the temperature stability of the internal circuits during long-term operation.

[0057] PCBA functional module 9 integrates all the electronic functional circuits of the device, including components related to the dual independent RF front-end module 2, the main GNSS acquisition module 3, the slave GNSS acquisition module 4, the signal processing and fusion unit 6, and the data output and storage unit 7. The PCB board adopts a layout design that separates the RF area and the digital area, and the two types of areas are grounded and isolated to reduce the interference of digital circuit noise on the RF receiving circuit.

[0058] Two radio frequency antenna interfaces are provided on one side of the lower housing 10 for connecting two external GNSS antenna terminals 1; the other side of the lower housing 10 is provided with a power switch 11, a status indicator light group 12, a USB data interface 13, and an Ethernet interface 14. The bottom of the lower housing 10 is provided with multiple mounting holes for easy fixing of the device on a carrier or mounting base.

[0059] The complete workflow of this equipment is as follows: S1. Two GNSS antenna terminals 1 receive multi-frequency radio frequency signals from various satellite navigation systems; S2. The two radio frequency signals enter the corresponding channels of the dual independent radio frequency front-end module 2 respectively. After electrostatic protection, filtering and amplification, they are down-converted into intermediate frequency signals. S3. Two intermediate frequency signals are input to the main GNSS acquisition module 3 and the slave GNSS acquisition module 4 respectively for baseband signal processing to generate raw observation data and navigation messages. S4. The main GNSS acquisition module 3 outputs a second pulse signal and time information to the slave GNSS acquisition module 4. The slave GNSS acquisition module 4 calibrates its own clock and data timestamp to achieve time synchronization between the two modules. S5, the main GNSS acquisition module 3 transmits the raw observation data from the GNSS acquisition module 4 to the signal processing and fusion unit 6. After data preprocessing, dual-antenna RTK calculation is performed to obtain the position, velocity and heading angle information of the carrier. S6. The calculated result data and the original observation data are output to the outside world and stored locally in real time through the data output storage unit 7. S7. When the voltage detection circuit detects an external power interruption, it immediately triggers a power-down protection interrupt. The processor uses the power of the energy storage element to complete the writing of the last frame of data and safely closes the file system to avoid data corruption.

[0060] In summary, the working principle of the GNSS data acquisition device provided in this embodiment is as follows: This equipment consists of seven main functional modules: a GNSS antenna terminal (1), a dual-channel independent RF front-end module (2), a main GNSS acquisition module (3), a slave GNSS acquisition module (4), a time synchronization unit (5), a signal processing and fusion unit (6), and a data output and storage unit (7). All functional circuits are integrated into a PCBA functional module (9), which is encapsulated within a metal housing formed by the upper cover (8) and the lower shell (10). The complete working principle of the equipment can be divided into four parts: signal reception and RF processing, baseband acquisition and time synchronization, computation and data output, and power-off protection mechanism.

[0061] 1. Signal reception and radio frequency processing Two GNSS antenna terminals 1 are independently installed at different locations on the carrier, forming a measurement baseline of a set length, and synchronously receiving satellite radio frequency signals from multiple constellations and frequencies. The GNSS antenna terminal 1 has a built-in low-noise amplifier unit, which can initially amplify weak satellite signals and improve receiving sensitivity; the integrated antenna biaser can be powered by the equipment, and at the same time realizes overcurrent protection and line status monitoring.

[0062] The two satellite signals are transmitted to two independent RF channels of the dual-channel independent RF front-end module 2, maintaining high isolation between the channels to avoid crosstalk. Within each channel, the signal undergoes electrostatic discharge (ESD) protection, out-of-band filtering, and low-noise amplification to filter out external interference signals from mobile communication and wireless LAN frequency bands, while further amplifying the effective satellite signal. The module incorporates a unified clock reference source, providing a completely consistent local oscillator clock signal to both RF channels through a symmetrical, equal-length wiring clock distribution network, ensuring a unified phase reference for both signals and eliminating clock phase differences between the two channels. Lightning protection devices are also installed at the channel inputs to enhance the electrical withstand capability of the equipment in harsh environments.

[0063] 2. Baseband acquisition and time synchronization The two signals, after being processed by the radio frequency front end, are input to the main GNSS acquisition module 3 and the slave GNSS acquisition module 4, respectively. The two acquisition modules complete the baseband signal processing, acquire, track and demodulate the satellite signals, and output the raw pseudorange, carrier phase, Doppler shift observations and navigation message data.

[0064] The main GNSS acquisition module 3 serves as the time reference source for the entire system, outputting a second pulse signal and serial time information. The time synchronization unit 5 uses a low-latency transmission medium to connect the main and slave acquisition modules, accurately transmitting the synchronization signal output from the main GNSS acquisition module 3 to the slave GNSS acquisition module 4. Triggered by the synchronization signal, the slave GNSS acquisition module 4 calibrates its own clock with the observation data timestamp, ensuring strict alignment of the time references of the two observation data streams. This eliminates the time deviation caused by the independent clocks of the two modules, providing a foundation for subsequent high-precision calculations.

[0065] 3. Calculation and Data Output The two raw observation data streams, after time synchronization, are transmitted to the signal processing and fusion unit 6. The signal processing and fusion unit 6 is equipped with a processor that runs the RTK algorithm. Through carrier phase differential processing, it eliminates common errors such as satellite clock error, receiver clock error, and atmospheric delay, calculates the baseline vector between the two antennas, further converts it into the heading angle information of the carrier, and outputs high-precision positioning and velocity results.

[0066] The calculated results and the original observation data are sent together to the data output storage unit 7. The data output storage unit 7 supports multiple standard navigation data formats and can output data in real time through different physical interfaces. Simultaneously, through a ring buffer and memory card architecture, data is written to local storage media according to time rules, achieving local data retention. The unit also supports host computer configuration functions, allowing adjustment of the device's operating parameters via an interface.

[0067] 4. Power failure protection mechanism The power-down protection mechanism integrated in the signal processing fusion unit 6 is jointly implemented by the voltage detection unit, the energy storage unit, and the control circuit. During normal operation, the energy storage unit is in a charging and energy storage state; the voltage detection unit monitors the external power supply voltage in real time, and when it detects that the voltage drops below a set threshold, it immediately sends an interrupt trigger signal to the processor.

[0068] Upon receiving an interrupt signal, the processor immediately halts all non-essential tasks, concentrates its computing power to write the observation data from the cache to the storage medium, and invokes the file system for synchronization to ensure all data is completely written to the physical medium. The energy storage unit automatically switches to power mode after an external power outage, providing backup power to the processor and storage medium for a period of time. This ensures the complete completion of data writing and the safe shutdown of the file system, preventing data loss and file system corruption.

[0069] Furthermore, in terms of mechanical structure, the heat dissipation structure of the upper cover 8 can accelerate the dissipation of internal heat, ensuring stable temperature during long-term operation; the metal casing can act as electromagnetic shielding, reducing the impact of external electromagnetic interference on the internal circuitry; the PCBA functional module 9 adopts a layout that separates the RF area and the digital area, reducing interference from internal digital circuitry to RF reception, further improving the stability of equipment operation. Various interfaces and status indicators distributed on the sides of the lower shell 10 enable connection and interaction between the equipment and external systems, as well as status visualization.

[0070] How to use: The use of this equipment can be carried out according to the process of installation and deployment, wiring connection, parameter configuration, operation and data acquisition, data export and daily maintenance.

[0071] 1. Installation and Deployment: First, fix the main body of the equipment to the preset installation position on the carrier through the mounting holes at the bottom of the lower shell 10, ensuring that the equipment is firmly installed and in a stable position. Install the two GNSS antenna terminals 1 at the designated positions on the top of the carrier, and adjust the antenna positions to ensure that there are no obvious obstructions above, ensuring smooth satellite signal reception; maintain a suitable baseline distance between the two GNSS antenna terminals 1 to meet the requirements for direction finding accuracy.

[0072] 2. Wiring Connection: Using matching RF cables, connect the two GNSS antenna terminals 1 to the antenna interfaces 11 on the side of the lower housing 10, tightening the connectors to ensure a reliable connection. Connect the appropriate power supply line to the device's power port. Depending on actual usage requirements, select either the USB data interface 14 or the network port 15 to connect the device to the host computer, control system, or transmission network.

[0073] 3. Parameter Configuration: Connect the device to the host computer via USB or network to access the device configuration interface. Set the sampling rate, enabled satellite constellation type, data output format, output baud rate, and other operating parameters according to the application scenario. Confirm the storage mode and file generation rules. Save the configuration after setting the parameters; the device can automatically remember the parameters and run directly according to the configuration on the next startup.

[0074] 4. Data Acquisition Operation: Close power switch 12 to start the device. Observe the device's operating status through the status indicator light group 13. After the device starts, it automatically enters satellite acquisition mode. Once the satellite signal acquisition is stable and the calculation status is normal, the device enters continuous working mode, outputting navigation data in real time. At the same time, it writes the raw data and calculation results to the local storage medium according to the set rules. During operation, the power supply, satellite acquisition, and calculation status of the device can be judged in real time through the indicator lights.

[0075] 5. Data Export and Routine Maintenance: When data stored locally needs to be retrieved, the device can be remotely accessed via the network interface to read the stored files. Alternatively, the device can be switched to mass storage mode, and data files on the memory card can be read directly via the USB interface. During daily use, regularly check the antenna cable connection status, power supply stability, and device heat dissipation. Clean dust from the device surface promptly to ensure long-term stable operation.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A GNSS data acquisition device, characterized in that, It includes two GNSS antenna terminals (1), dual independent radio frequency front-end modules (2), a main GNSS acquisition module (3), a slave GNSS acquisition module (4), a time synchronization unit (5), a signal processing and fusion unit (6), and a data output and storage unit (7); The two GNSS antenna terminals (1) are used to receive multi-constellation multi-frequency satellite radio frequency signals, and the two GNSS antenna terminals (1) are used to be independently installed at different positions on the carrier to form a measurement baseline; The dual-channel independent RF front-end module (2) includes two electrically isolated RF channels with identical RF channel parameters. The input terminals of the two RF channels are respectively connected to two GNSS antenna terminals (1). The dual-channel independent RF front-end module (2) has a built-in unified clock reference source. The clock reference source provides the same local oscillator clock signal to the two RF channels through a symmetrical clock distribution network. Each RF channel integrates an out-of-band interference suppression filter unit and a low-noise amplification unit. The radio frequency input terminals of the main GNSS acquisition module (3) and the slave GNSS acquisition module (4) are respectively connected to the two radio frequency channel output terminals of the dual independent radio frequency front-end module (2) to perform baseband processing on the input radio frequency signals and output the raw observation data. The time synchronization unit (5) is connected between the main GNSS acquisition module (3) and the slave GNSS acquisition module (4) and is used to transmit the time synchronization signal output by the main GNSS acquisition module (3) to the slave GNSS acquisition module (4) so ​​that the observation timestamp of the slave GNSS acquisition module (4) is synchronized with the main GNSS acquisition module (3). The signal processing and fusion unit (6) is connected to the data output terminals of the main GNSS acquisition module (3) and the slave GNSS acquisition module (4) respectively. It is used to receive two channels of raw observation data and perform dual-antenna RTK calculation, and output the positioning result and heading angle information of the carrier. The signal processing and fusion unit (6) integrates a power-off data protection mechanism consisting of a voltage detection unit, an energy storage unit and a control circuit. The data output storage unit (7) is connected to the signal processing fusion unit (6) to realize the real-time output and local storage of the calculated data and the original observation data.

2. The GNSS data acquisition device according to claim 1, characterized in that, The GNSS antenna terminal (1) is a multi-frequency active antenna that supports satellite signal reception in L1, L2, L5 and L-band frequencies. The antenna terminal (1) has a built-in low-noise amplifier with a gain of 20dB to 30dB and a noise figure of no more than 2dB. The antenna terminal (1) integrates an antenna biaser that supports 3V to 5V DC power supply and has overcurrent protection and antenna open / short circuit monitoring functions.

3. The GNSS data acquisition device according to claim 1, characterized in that, The isolation between the two radio frequency channels of the dual independent radio frequency front-end module (2) is not less than 50dB; the out-of-band interference suppression filter unit is a surface acoustic wave filter with an out-of-band suppression capability of not less than 50dB, used to suppress interference signals between the mobile communication frequency band and the wireless local area network frequency band; the input terminal of each independent radio frequency channel is also integrated with lightning protection and ESD electrostatic protection circuit.

4. The GNSS data acquisition device according to claim 1, characterized in that, The clock reference source is a temperature-compensated crystal oscillator with a frequency stability within ±1ppm and an operating temperature range of -40℃ to +85℃. The symmetrical clock distribution network adopts an equal-length wiring design to ensure that the phase deviation between the two local oscillator clock signals is no greater than 1 nanosecond.

5. The GNSS data acquisition device according to claim 1, characterized in that, Both the main GNSS acquisition module (3) and the slave GNSS acquisition module (4) adopt a full constellation full-frequency GNSS baseband chip, which supports the reception of signals from at least two global satellite navigation systems, supports an adjustable sampling rate in the range of 1Hz to 20Hz, and can output raw pseudorange, carrier phase, Doppler frequency shift observations and navigation messages; the main GNSS acquisition module (3) has a real-time clock synchronization function and can output second pulse signals and serial time information.

6. The GNSS data acquisition device according to claim 1 or 5, characterized in that, The time synchronization unit (5) is connected to the synchronization interface of the main GNSS acquisition module (3) and the slave GNSS acquisition module (4) by a coaxial cable or LVCMOS level pin header, and the transmission delay of the second pulse signal is no more than 200 nanoseconds. The GNSS acquisition module (4) calibrates its own clock and observation timestamp based on the received second pulse signal and time information, thereby achieving microsecond-level time synchronization with the main GNSS acquisition module (3).

7. The GNSS data acquisition device according to claim 1, characterized in that, The signal processing fusion unit (6) adopts an ARM architecture processor and has a built-in dual-antenna RTK calculation engine based on carrier phase double difference technology, which is used to calculate the baseline vector between the two antennas and the heading angle of the carrier; the signal processing fusion unit (6) has a reserved inertial navigation fusion interface to support external inertial measurement units to realize GNSS / INS integrated navigation.

8. The GNSS data acquisition device according to claim 1 or 7, characterized in that, The power-down data protection mechanism includes a voltage detection unit, an energy storage unit, and a control circuit. The voltage detection unit monitors the external power supply voltage in real time and sends an interrupt signal to the processor when the detected voltage is lower than a preset threshold. After responding to the interrupt, the processor stops unnecessary tasks, writes the observed data in the cache to the storage medium, and performs file system synchronization operations. The energy storage unit is in a charging state when the external power supply is normal, and provides power to the processor and storage medium through an anti-backflow circuit when the external power supply is interrupted, providing a continuous power supply duration of not less than 300 milliseconds.

9. The GNSS data acquisition device according to claim 1, characterized in that, The data output storage unit (7) supports at least two standard satellite navigation data formats and is equipped with a USB high-speed interface and an Ethernet interface. The storage part adopts a ring buffer plus a removable storage card architecture. The storage card adopts the FAT32 file system and supports automatic generation of observation data files and navigation data files according to time.

10. The GNSS data acquisition device according to any one of claims 1-9, characterized in that, The device adopts a metal shell structure, including an upper cover (8), a PCBA functional module (9), and a lower shell (10). The upper cover (8) is equipped with a heat dissipation structure, and the lower shell (10) is equipped with an antenna interface (11), a power switch (12), a status indicator group (13), a data interface (14), and a network port (15) on both sides. The dual-channel independent radio frequency front-end module (2), the main GNSS acquisition module (3), the slave GNSS acquisition module (4), the time synchronization unit (5), the signal processing fusion unit (6), and the data output storage unit (7) are all integrated on the PCBA functional module (9). The PCBA functional module (9) adopts a layout design that separates the radio frequency area and the digital area.

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