A low-power freight tracking terminal based on multi-mode fusion

Abstract

This invention provides a low-power freight tracking terminal based on multi-mode fusion, including a main control board. The main control board is functionally divided into a main control core area, a main control communication area, a power management area, and a sensor area. The main control board also has a low-power wake-up module, which is electrically connected to the external interrupt pin of the STM32 main control circuit and the wake-up interface of the multi-mode fusion communication module. The low-power wake-up module is used to wake up the main control unit and the communication module when a preset event is detected. It adopts a single main control STM32 + BG95-S5 multi-module single-core hardware architecture, relies on a six-axis MEMS sensor as the hardware wake-up source, and achieves anti-interference and low power consumption through board physical partitioning, dual-link isolated power supply, metal shielding, and antenna clearance layout. It relies on the module's native PSM / eDRX sleep mode + hardware event triggered wake-up to achieve power saving. It focuses on hardware structure layout, circuit isolation, component selection, and board-level low-power optimization, and is biased towards physical terminal hardware structure and circuit design.

Description

Technical Field

[0001] This invention relates to the field of logistics tracking technology, specifically to a low-power freight tracking terminal based on multi-mode fusion. Background Technology

[0002] In cross-border logistics, ocean shipping, and livestock transportation, goods are often located in blind spots without terrestrial cellular network coverage, such as open ocean areas and desert regions. Traditional cargo tracking terminals are mainly divided into two categories: one is a pure cellular network tracking terminal, which is lower in cost but completely loses connection once it enters a signal blind spot, making it impossible to achieve full-process monitoring; the other is a traditional satellite tracking terminal, which can achieve global coverage, but it is expensive, usually over $100, and consumes a lot of power, requiring frequent charging or battery replacements, making it difficult to meet the core needs of small and medium-sized logistics enterprises for "low cost, long battery life, and global tracking without blind spots".

[0003] Furthermore, most existing devices have limited functionality, with some only providing positioning capabilities. Devices integrating multiple sensors suffer from unreasonable internal structural layouts. The lack of effective isolation between different functional modules causes high-frequency communication signals to interfere with the acquisition of weak sensor signals, affecting data accuracy. Additionally, replacing or upgrading different sensor configurations requires significant modifications to the entire device, a cumbersome process with high maintenance costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a low-power freight tracking terminal based on multi-mode fusion to solve the problems mentioned in the background. This invention features a novel structure that balances global coverage without blind spots with low cost and low power consumption. Because the main control communication area integrates a multi-mode fusion module supporting cellular and satellite communications, a single device can seamlessly switch between cellular and satellite networks, solving the problems of blind spots in traditional pure cellular terminals and high cost and power consumption in pure satellite terminals.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a low-power freight tracking terminal based on multi-mode fusion, comprising a main control board. The main control board is functionally divided into a main control core area, a main control communication area, a power management area, and a sensor area. The main control board also includes a low-power wake-up module, which is electrically connected to the external interrupt pin of the STM32 main control circuit and the wake-up interface of the multi-mode fusion communication module. The low-power wake-up module is used to wake up the main control unit and the communication module when a preset event is detected. The main control core area is equipped with an STM32 series single-chip microcontroller. The main control circuit serves as the core control unit of the terminal. The main control communication area is equipped with a multi-mode fusion communication module, which integrates cellular communication, satellite communication, and GNSS positioning capabilities. The multi-mode fusion communication module is electrically connected to the STM32 main control circuit. The power management area is physically separated from the main control core area, the main control communication area, and the sensor area. The power management area provides independent isolated power supply for each functional area and includes a main power supply link and an auxiliary power supply link. The sensor area is equipped with a sensor acquisition circuit, which is electrically connected to the STM32 main control circuit.

[0006] Furthermore, the multi-mode converged communication module is a BG95-S5 module, which supports the 3GPP R17 non-terrestrial network (NTN) standard and is compatible with the LTE Cat M1 / Cat NB2 cellular communication standard. The multi-mode converged communication module has a built-in GNSS positioning baseband to support multi-system satellite positioning.

[0007] Furthermore, the low-power wake-up module is a six-axis MEMS inertial sensor. The low-power wake-up module has a built-in three-axis accelerometer and a three-axis gyroscope. The low-power wake-up module integrates a hardware motion detection logic unit. The hardware interrupt output pin of the low-power wake-up module is connected to the external interrupt pin of the STM32 main control circuit and the external wake-up pin of the multi-mode fusion communication module, respectively.

[0008] Furthermore, the main power supply link is a DC-DC converter based on the SCT2231TVBR chip, and the output of the main power supply link is electrically connected to the power supply pin of the multi-mode fusion communication module to provide core power to the communication module.

[0009] Furthermore, the auxiliary power supply link is an LDO low dropout linear regulator. The input of the auxiliary power supply link is electrically connected to the battery, and the output of the auxiliary power supply link is electrically connected to the STM32 main control circuit in the main control core area, the sensor acquisition circuit in the sensor area, and the RF front-end circuit in the main control communication area. The auxiliary power supply link is used to isolate the switching noise generated by the DC-DC converter and provide low-noise and clean power to the sensitive circuit.

[0010] Furthermore, the main control communication area is also equipped with a radio frequency front-end circuit, which includes an antenna impedance matching network, ESD protection devices and radio frequency switches. The main control board has an antenna clearance area in the radio frequency front-end circuit area for deploying the cellular main antenna, GNSS positioning antenna and satellite communication antenna. The antenna clearance area on the main control board is surrounded by a complete plane to achieve electromagnetic isolation.

[0011] Furthermore, the sensor area is equipped with multiple sensor interfaces and acquisition circuits. The sensor area includes a temperature and humidity sensor acquisition circuit based on the SHT30 chip and a six-axis MEMS inertial sensor acquisition circuit. Each sensor circuit in the sensor area is electrically connected to the STM32 main control circuit through the I²C bus.

[0012] Furthermore, metal shielding covers are provided between the main control communication area, the main control core area, and the sensor area to reduce electromagnetic interference of radio frequency communication signals to the main control circuit and the sensor acquisition circuit.

[0013] Furthermore, the multi-mode fusion communication module supports PSM power-saving mode and eDRX extended discontinuous reception mode, the STM32 main control circuit in the main control core area supports STOP deep sleep mode, and the low-power wake-up module is constantly powered by the auxiliary power supply link.

[0014] Furthermore, the main control board is also equipped with multiple level conversion circuits, which are 1.8V to 3.3V bidirectional level converters. The level conversion circuits are electrically connected between the STM32 main control circuit and the multi-mode fusion communication module. The level conversion circuits realize signal level matching and bidirectional communication between two types of devices with different voltage domains.

[0015] The beneficial effects of this invention are:

[0016] 1. This invention is a dedicated hardware terminal for freight tracking. It adopts an STM32 main control + BG95-S5 multi-mode integrated communication module architecture. In terms of hardware, it features functional partitioning of the main control board, dual-link isolated power supply, electromagnetic shielding and antenna clearance layout. It relies on the hardware interrupt of a six-axis MEMS sensor to achieve event-triggered wake-up. In terms of communication, it is compatible with 3GPPR17NTN and LTECatM1 / NB2. It focuses on hardware structure isolation, anti-interference design and flexible expansion of sensors in freight scenarios.

[0017] 2. This invention is aimed at cross-border ocean freight and logistics cargo tracking, while the prior art is specifically used for fishery supervision of fishing vessels entering and leaving fishing ports. In terms of communication and positioning, this invention adopts the BG95-S5 multi-mode fusion module, which supports 3GPPR17NTN satellite network + LTE cellular full network access + GNSS multi-system positioning. It can automatically switch between dual modes without blind spots, and is powered by a single battery with dual-link isolation. It relies on a six-axis MEMS sensor to realize hardware wake-up of motion events. It collects parameters such as cargo temperature and humidity, attitude and vibration through the sensor area and metal shielding cover, and resists electromagnetic interference, adapting to the complex ocean electromagnetic environment.

[0018] 3. This invention balances global coverage without blind spots with low cost and low power consumption. Because the main control communication area integrates a multi-mode fusion module that supports cellular and satellite communications, a single device can seamlessly switch between cellular and satellite networks, solving the problems of blind spots in traditional pure cellular terminals and high cost and power consumption in pure satellite terminals.

[0019] 4. This invention significantly improves battery life through a unique low-power wake-up mechanism. By setting up an independent three-axis accelerometer as a low-power wake-up module, its hardware interrupt output can directly wake up the multi-mode fusion communication module in deep sleep. During the entire static storage or smooth transportation process, the high-power main communication module can be completely dormant, with only the low-power accelerometer on duty. Wake-up and operation are triggered only at the moment a transportation event occurs, avoiding unnecessary operation, achieving extremely low power consumption, and extending the usage time without charging.

[0020] 5. This invention adopts a single-main-controller STM32+BG95-S5 multi-module single-core hardware architecture, relies on a six-axis MEMS sensor as the hardware wake-up source, and achieves anti-interference and low power consumption through physical partitioning of the board, dual-link isolated power supply, metal shielding, and antenna clearance layout. It also relies on the module's native PSM / eDRX sleep mode + hardware event-triggered wake-up to achieve power saving. It focuses on hardware structure layout, circuit isolation, component selection and board-level low power consumption optimization, and is biased towards physical terminal hardware structure and circuit design. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the overall principle of a low-power freight tracking terminal based on multi-mode fusion according to the present invention.

[0022] Figure 2 This is a schematic diagram of the motherboard circuit of a low-power freight tracking terminal based on multi-mode fusion according to the present invention.

[0023] Figure 3 This is a schematic diagram of the power supply circuit of a low-power freight tracking terminal based on multi-mode fusion according to the present invention.

[0024] Figure 4This is a schematic diagram of level conversion for a low-power freight tracking terminal based on multi-mode fusion according to the present invention.

[0025] Figure 5 This is a schematic diagram of the temperature and humidity sensor control circuit of a low-power freight tracking terminal based on multi-mode fusion according to the present invention. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0027] Please see Figure 1-5 This invention provides a technical solution: a low-power freight tracking terminal based on multi-mode fusion, comprising a main control board. The main control board is functionally divided into a main control core area, a main control communication area, a power management area, and a sensor area. The main control board also includes a low-power wake-up module, which is electrically connected to the external interrupt pin of the STM32 main control circuit and the wake-up interface of the multi-mode fusion communication module. The low-power wake-up module is used to wake up the main control unit and the communication module when a preset event is detected. The main control core area contains an STM32 series microcontroller main control circuit, serving as the core of the terminal. The system comprises a core control unit; the main control communication area is equipped with a multi-mode fusion communication module, which integrates cellular communication, satellite communication, and GNSS positioning capabilities, and is electrically connected to the STM32 main control circuit; the power management area is physically separated from the main control core area, the main control communication area, and the sensor area, and provides independent isolated power supply for each functional area, including a main power supply link and an auxiliary power supply link; the sensor area is equipped with sensor acquisition circuitry, which is electrically connected to the STM32 main control circuit, and the core hardware architecture is STM32. The dual-core control architecture of the main control MCU + BG95-S5 multi-mode fusion communication module is physically partitioned and completely isolated from the plane, divided into four functional areas: main control core area, main control communication area, power management area, and sensor area. Each functional area is isolated from the ground plane, and metal shielding covers are set between the main control communication area and the main control core area and sensor area to further suppress electromagnetic interference of radio frequency signals. The BG95-S5 module has integrated the cellular communication baseband and satellite communication baseband into the same package, which is no longer the three-chip architecture of "main control unit + independent signal processing unit + radio frequency transceiver" interconnected by an external bus. Therefore, it reduces the number of board-level chips, bus trace length and signal attenuation risk introduced by interconnection interfaces.

[0028] Main control core area circuit: The main control core area is the core control unit of the terminal. The core device is an STM32 series microcontroller. It is equipped with an 8MHz passive crystal clock circuit, a reset circuit, an SWD program download and debugging circuit, and a serial port debugging interface circuit. The STM32 microcontroller is connected to various acquisition circuits in the sensor area through the I²C bus, and is connected to the multi-mode fusion communication module through the UART serial port via a level conversion circuit. It realizes the working logic control, data acquisition and processing, communication command transmission and reception, and low power mode management of the entire terminal. The microcontroller supports STOP deep sleep mode, and the static sleep current can be reduced to the microamp level to meet the low power standby requirements of the terminal.

[0029] In this embodiment, the main control communication area also includes a radio frequency (RF) front-end circuit, which includes an antenna impedance matching network, ESD protection devices, and an RF switch. The main control board has an antenna clearance area in the RF front-end circuit region for deploying the cellular main antenna, GNSS positioning antenna, and satellite communication antenna. A complete plane is laid around the antenna clearance area on the main control board to achieve electromagnetic isolation. The multi-mode fusion communication module is a BG95-S5 module, which supports the 3GPP R17 Non-Terrestrial Network (NTN) standard and is compatible with LTE Cat M1 / Cat. The NB2 cellular communication standard is used. The multi-mode fusion communication module has a built-in GNSS positioning baseband to support multi-system satellite positioning. The multi-mode fusion communication module supports PSM power-saving mode and eDRX extended discontinuous reception mode. The STM32 main control circuit in the main control core area supports STOP deep sleep mode. The low-power wake-up module is constantly powered by the auxiliary power supply link. The main control board is also equipped with multiple sets of level conversion circuits. The level conversion circuit is a 1.8V to 3.3V bidirectional level converter. The level conversion circuit is electrically connected between the STM32 main control circuit and the multi-mode fusion communication module. The level conversion circuit realizes signal level matching and bidirectional communication between two types of devices with different voltage domains.

[0030] Main control communication area circuit: The main control communication area is the core of the terminal's communication and positioning. The core component is the BG95-S5 multi-mode converged communication module. This module supports the 3GPP R17 non-terrestrial network (NTN) standard, is compatible with the LTE Cat M1 / CatNB2 cellular communication standard, and has a built-in GNSS multi-system positioning baseband. It can simultaneously realize cellular network communication, satellite network communication and global satellite positioning, truly achieving global coverage without blind spots. The module is equipped with radio frequency front-end circuit, SIM card circuit and level conversion circuit.

[0031] RF front-end circuitry: includes impedance matching networks for the cellular main antenna and GNSS positioning antenna, ESD protection devices and RF traces. The main control board has a reserved antenna clearance area in the corresponding area, and a complete plane is laid around the antenna clearance area to ensure that the antenna radiation efficiency is not interfered with. SIM card circuitry: is equipped with ESD protection and filtering circuitry, supports industrial-grade Nano SIM card access, and provides authentication support for cellular and satellite communications.

[0032] Level conversion circuit: Multiple 1.8V to 3.3V bidirectional level converters are provided, which are electrically connected between the STM32 main control circuit (3.3V voltage domain) and the BG95-S5 module (1.8V voltage domain) to achieve level matching of signals such as serial communication and SIM card interface, and ensure the stability of bidirectional communication.

[0033] In this embodiment, the main power supply link is a DC-DC converter based on the SCT2231TVBR chip. The output of the main power supply link is electrically connected to the power pin of the multi-mode fusion communication module to provide core power to the communication module. The auxiliary power supply link is an LDO low-dropout linear regulator. The input of the auxiliary power supply link is electrically connected to the battery. The output of the auxiliary power supply link is electrically connected to the STM32 main control circuit in the main control core area, the sensor acquisition circuit in the sensor area, and the RF front-end circuit in the main control communication area. The auxiliary power supply link is used to isolate the switching noise generated by the DC-DC converter and provide low-noise clean power to the sensitive circuit. A dual-link isolated power supply scheme is adopted—the main power supply link is powered by a DC-DC synchronous buck converter to power the main control chip and the communication module to balance high current requirements and conversion efficiency; the auxiliary power supply link is powered by a low-noise LDO low-dropout linear regulator to power the six-axis MEMS sensor and the RF front-end separately, isolating the coupling of DC-DC switching noise to the sensitive circuit from the source, which is different from the single-channel power supply method in the prior art that does not make targeted power supply partitioning.

[0034] Power management area circuitry: The power management area adopts a dual-link isolated power supply architecture, physically separated from other functional areas, to avoid power supply noise interference to sensitive circuits. This includes the main power supply link and the auxiliary power supply link.

[0035] Main power supply link: The core is the SCT2231TVBR type DC-DC synchronous buck converter, whose input is connected to the battery power supply, and whose output provides 3.8V core power supply for the BG95-S5 multi-mode fusion communication module, meeting the power supply requirements of the communication module when transmitting at high power;

[0036] Auxiliary power supply link: The core is a low-dropout linear regulator (LDO), whose input is directly connected to the battery power supply, and whose output provides a clean 3.3V power supply to the STM32 main control circuit, sensor area acquisition circuit, RF front-end precision circuit, and low-power wake-up module. The LDO output power supply has no switching noise of DC-DC converter, which can effectively ensure the accuracy of weak sensor signal acquisition and RF signal processing, while providing uninterrupted power supply to the low-power wake-up module.

[0037] In this embodiment, the low-power wake-up module is a six-axis MEMS inertial sensor. The low-power wake-up module integrates a three-axis accelerometer and a three-axis gyroscope. The low-power wake-up module integrates a hardware motion detection logic unit. The hardware interrupt output pin of the low-power wake-up module is connected to the external interrupt pin of the STM32 main control circuit and the external wake-up pin of the multi-mode fusion communication module, respectively. The sensor area is provided with multiple sensor interfaces and acquisition circuits. The sensor area includes a temperature and humidity sensor acquisition circuit based on the SHT30 chip and a six-axis MEMS inertial sensor acquisition circuit. Each sensor circuit in the sensor area is electrically connected to the STM32 main control circuit through an I²C bus.

[0038] Sensor area and low-power wake-up circuit: The sensor area is equipped with multiple standardized sensor acquisition circuits, all of which are electrically connected to the STM32 main control circuit via the I²C bus;

[0039] Temperature and humidity acquisition circuit: The core is the SHT30 digital temperature and humidity sensor, which is equipped with filtering and reset circuits to achieve high-precision acquisition of temperature and humidity parameters in freight environments.

[0040] Six-axis MEMS inertial sensor circuit: The core is a 6-axis MEMS chip, which integrates a three-axis accelerometer and a three-axis gyroscope, and integrates a hardware motion detection logic unit. It also serves as a low-power wake-up module for the terminal.

[0041] The low-power wake-up module is continuously powered by the LDO in the auxiliary power supply link. Its hardware interrupt output pin is connected to the external interrupt pin of the STM32 main control circuit and the external wake-up pin of the BG95-S5 module, respectively. The terminal adopts a low-power operation mechanism of "sleep monitoring - event wake-up - on-demand operation": when the goods are in a static storage state, the STM32 main control enters the STOP deep sleep mode, and the BG95-S5 module enters the PSM deep sleep mode. The entire machine is only monitored by the low-power six-axis MEMS sensor, and the static current is reduced to the microamplitude level. When the goods are moved or transportation is started, the six-axis MEMS sensor detects continuous motion events and immediately outputs a level signal through the hardware interrupt pin, synchronously waking up the STM32 main control and the BG95-S5 module. In the communication module, once the terminal enters working mode, the low-power wake-up mechanism relies on the motion detection logic unit built into the six-axis MEMS sensor to generate a hardware interrupt: when the goods are in a stationary state in the warehouse, both the STM32 main controller and the BG95-S5 module enter deep PSM sleep mode, with only the six-axis MEMS sensor being constantly powered by the auxiliary power supply link and maintaining a low power consumption level; once a real freight event such as loading / unloading, transportation vibration, or abnormal collision occurs, the sensor completes the motion judgment locally and sends a level signal directly to the STM32's external wake-up pin through the hardware interrupt output pin, waking up the terminal and reporting data in a purely hardware manner within a microsecond delay, and then going back to sleep after the task is completed. This is fundamentally different from the "satellite orbit transit time prediction + RTC timed wake-up" software timing low-power strategy used in the comparative document.

[0042] Upon waking, the STM32 controller reads cargo environment and status data collected by temperature and humidity sensors and inertial sensors via the I²C bus, while simultaneously controlling the BG95-S5 module to acquire GNSS positioning information. The module prioritizes reporting data via cellular networks according to preset logic. If it is in a blind area with no cellular signal, such as in the open ocean or desert, it automatically switches to satellite communication, sending data packets including location, temperature, humidity, and vibration status to the cloud management platform. After data reporting is complete, the terminal automatically re-enters deep sleep mode, achieving low-power operation throughout its entire lifecycle.

[0043] Meanwhile, the sensor area has a reserved standardized expansion interface, which can be flexibly expanded to connect other types of sensors, such as light sensors, gas sensors, vibration sensors, etc., according to different freight scenarios. Customized monitoring needs for different scenarios can be achieved without modifying the main control circuit hardware, which greatly reduces the equipment maintenance and upgrade costs.

[0044] In this embodiment, metal shielding covers are provided between the main control communication area, the main control core area, and the sensor area to reduce electromagnetic interference of radio frequency communication signals to the main control circuit and the sensor acquisition circuit. The sensor area and the metal shielding covers are used to collect parameters such as cargo temperature and humidity, attitude and vibration, and to resist electromagnetic interference, adapting to the complex ocean electromagnetic environment.

[0045] This invention uses the actual occurrence of a freight event as the wake-up condition, avoiding the ineffective cycle performance consumption caused by RTC timed wake-up during long periods of cargo stillness. The power consumption model is directly synchronized with the actual freight rhythm. In terms of communication capabilities, the module is compatible with 3GPP R17 NTN, LTE Cat M1, and LTE Cat NB2 standards. When cellular networks are available, it prioritizes low-cost cellular communication for data transmission, and automatically switches to satellite networks when entering blind areas such as oceans, achieving global coverage without blind spots. Regarding sensors, the sensor area reserves multiple standardized expansion interfaces, supporting pluggable selection of temperature and humidity sensors or acceleration sensors according to different freight scenarios such as cold chain, fragile goods, and general cargo. The main control communication area hardware can be adapted without modification. Unlike the comparison documents that focus on the multi-type data access capabilities at the software protocol level, this invention is a dedicated hardware design for the specific working conditions of the freight vertical scenario, such as vibration and shock, electromagnetic interference, high salt and humidity, and multiple monitoring requirements.

[0046] The foregoing has shown and described the basic principles and main features of the present invention and its advantages. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0047] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-power freight tracking terminal based on multi-mode fusion, comprising a main control board, characterized in that: The main control board is functionally divided into a main control core area, a main control communication area, a power management area, and a sensor area. The main control board is also equipped with a low-power wake-up module. The low-power wake-up module is electrically connected to the external interrupt pin of the STM32 main control circuit and the wake-up interface of the multi-mode fusion communication module. The low-power wake-up module is used to wake up the main control unit and the communication module when a preset event is detected. The main control core area is equipped with an STM32 series microcontroller main control circuit, which serves as the core control unit of the terminal. The main control communication area is equipped with a multi-mode fusion communication module, which integrates cellular communication, satellite communication and GNSS positioning capabilities, and is electrically connected to the STM32 main control circuit. The power management area is physically separated from the main control core area, the main control communication area, and the sensor area. The power management area provides independent isolated power supply for each functional area. The power management area includes the main power supply link and the auxiliary power supply link. The sensor area is equipped with a sensor acquisition circuit, which is electrically connected to the STM32 main control circuit.

2. The low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The multi-mode converged communication module is a BG95-S5 module. The multi-mode converged communication module supports the 3GPP R17 non-terrestrial network (NTN) standard and is compatible with the LTE Cat M1 / Cat NB2 cellular communication standard. The multi-mode converged communication module has a built-in GNSS positioning baseband to support multi-system satellite positioning.

3. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The low-power wake-up module is a six-axis MEMS inertial sensor. The low-power wake-up module has a built-in three-axis accelerometer and a three-axis gyroscope. The low-power wake-up module integrates a hardware motion detection logic unit. The hardware interrupt output pin of the low-power wake-up module is connected to the external interrupt pin of the STM32 main control circuit and the external wake-up pin of the multi-mode fusion communication module, respectively.

4. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The main power supply link is a DC-DC converter based on the SCT2231TVBR chip. The output of the main power supply link is electrically connected to the power supply pin of the multi-mode fusion communication module to provide core power to the communication module.

5. A low-power freight tracking terminal based on multi-mode fusion according to claim 4, characterized in that: The auxiliary power supply link is an LDO low dropout linear regulator. The input of the auxiliary power supply link is electrically connected to the battery. The output of the auxiliary power supply link is electrically connected to the STM32 main control circuit in the main control core area, the sensor acquisition circuit in the sensor area, and the RF front-end circuit in the main control communication area. The auxiliary power supply link is used to isolate the switching noise generated by the DC-DC converter and provide low-noise and clean power to the sensitive circuit.

6. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The main control communication area is also equipped with a radio frequency front-end circuit, which includes an antenna impedance matching network, ESD protection devices and radio frequency switches. The main control board has an antenna clearance area in the radio frequency front-end circuit area for deploying the cellular main antenna, GNSS positioning antenna and satellite communication antenna. The antenna clearance area on the main control board is surrounded by a complete plane to achieve electromagnetic isolation.

7. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The sensor area is equipped with multiple sensor interfaces and acquisition circuits. The sensor area includes a temperature and humidity sensor acquisition circuit based on the SHT30 chip and a six-axis MEMS inertial sensor acquisition circuit. Each sensor circuit in the sensor area is electrically connected to the STM32 main control circuit through the I²C bus.

8. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: Metal shielding covers are installed between the main control communication area, the main control core area, and the sensor area to reduce electromagnetic interference of radio frequency communication signals to the main control circuit and the sensor acquisition circuit.

9. A low-power freight tracking terminal based on multi-mode fusion according to claim 5, characterized in that: The multi-mode fusion communication module supports PSM power-saving mode and eDRX extended discontinuous reception mode. The STM32 main control circuit in the main control core area supports STOP deep sleep mode. The low-power wake-up module is constantly powered by the auxiliary power supply link.

10. A low-power freight tracking terminal based on multi-mode fusion according to claim 1, characterized in that: The main control board is also equipped with multiple level conversion circuits. The level conversion circuit is a 1.8V to 3.3V bidirectional level converter. The level conversion circuit is electrically connected between the STM32 main control circuit and the multi-mode fusion communication module. The level conversion circuit realizes signal level matching and bidirectional communication between two types of devices with different voltage domains.

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