Differential information forwarding method, forwarding device and unmanned aerial vehicle

Abstract

This invention discloses a differential information forwarding method, comprising the following steps: S1, setting parameters; S2, receiving differential information to be forwarded from a host computer; S3, encoding and transmitting the received differential information according to the set parameters; in step S1, the parameters include channel, transmit power, and modulation mode, wherein the modulation mode includes LoRa mode and GFSK mode; when the modulation mode is LoRa mode, two frequency points are set on each channel, with an interval of at least 55MHz between each frequency point, and a differential information signal is transmitted once at each frequency point, with the two frequency points alternately transmitting data frames; when the modulation mode is GFSK mode, three frequency points are set on each channel, with an interval of at least 55MHz between each frequency point, and a differential information signal is transmitted once at each frequency point; this invention employs a dual-frequency or triple-frequency retransmission mechanism, enabling the receiver to avoid interference points as much as possible in the time and frequency domains, greatly improving the data packet transmission success rate and adapting to complex electromagnetic environments.

Description

Technical Field

[0001] This invention belongs to the field of satellite positioning technology, specifically a differential information forwarding method, a forwarding device, and an unmanned aerial vehicle (UAV). Background Technology

[0002] For satellite positioning systems, conventional point positioning techniques suffer from pseudorange errors due to the refraction of satellite signals by the ionosphere and troposphere, resulting in positioning accuracy within the range of 5 to 10 meters. Clearly, such accuracy is insufficient for certain specific applications. Differential positioning technology can effectively improve positioning accuracy, achieving decimeter, centimeter, and millimeter-level precision.

[0003] For example, the principle behind BeiDou differential positioning is to compare the signals from two receivers to calculate the distance difference between them. To achieve accurate differential positioning, a reference station with high positioning accuracy is essential. Typically, a static station is used as a reference, which eliminates various errors caused by signal propagation, such as atmospheric errors and clock errors.

[0004] When using a static station for measurement, the satellite signals received by the two receivers come from the same satellite, and the reception time difference does not exceed 10 seconds. During this time period, the error between the pseudorange and the true distance of the two receivers is used for correction, and the differential pseudorange vector is calculated to obtain the distance difference between the two receivers and their relative positions.

[0005] Differential information dissemination base stations use differential positioning technology to send differential information to their surroundings. Users can use differential information to improve satellite positioning accuracy. However, existing differential information transmission has weak anti-interference capabilities and data is easily lost. Summary of the Invention

[0006] The purpose of this invention is to provide a differential information forwarding method, forwarding device, and UAV to solve at least one of the above-mentioned technical problems.

[0007] In a first aspect, embodiments of this application provide a differential information forwarding method, employing the following technical solution: A differential information forwarding method includes the following steps: S1. Set parameters; S2. Receive differential information to be forwarded from the host computer; S3. Encode the received differential information according to the set parameters and transmit it; In step S1, the parameters include channel, transmit power, and modulation mode, wherein the modulation mode includes LoRa mode and GFSK mode; When the modulation mode is LoRa mode, two frequency points are set on each channel, with a minimum interval of 55MHz between each frequency point. Each frequency point transmits a differential information signal once. The differential information signal includes multiple data frames, and the two frequency points transmit data frames alternately. When the modulation mode is GFSK mode, three frequency points are set on each channel, with each frequency point spaced at least 55MHz apart. Each frequency point transmits a differential information signal once. The differential information signal includes multiple data frames, and the three frequency points transmit data frames in turn.

[0008] In conjunction with the first aspect, in one implementation, when the modulation mode is LoRa mode, each data frame transmits 120 bytes, and each data frame transmission takes 67ms.

[0009] In conjunction with the first aspect, in one implementation, when the modulation mode is GFSK mode, each data frame transmits 59 bytes, and each data frame transmission takes 10ms.

[0010] In conjunction with the first aspect, in one implementation, when the modulation mode is GFSK mode, the channel frequency hopping pattern, radio frequency rate, channel bandwidth, modulation frequency offset, filter roll-off factor, channel convolutional coding, interleaving depth, and data frame format are all consistent with those of the differential information receiving device.

[0011] In conjunction with the first aspect, in one embodiment, setting parameters in step S1 includes: receiving a parameter configuration instruction from a host device and setting parameters according to the parameter configuration instruction.

[0012] In conjunction with the first aspect, in one implementation, encoding and transmitting the received differential information according to set parameters includes: S31. Filter the differential information; S32. Perform level conversion on the filtered differential information; S33. Encode the differential information after level conversion; S34. Modulate and output the encoded differential information via radio frequency. S35. The differential information output by radio frequency is pre-amplified and then amplified by the final power stage before being filtered and transmitted.

[0013] In conjunction with the first aspect, in one embodiment, the transmit power is P_tx, and P_rx = P_tx + G_tx - L_path - L_other + G_rx, where P_rx is the signal strength received by the device for receiving differential information, in dBm; P_tx is the transmit power, in dBm; G_tx is the transmit antenna gain, in dBi; L_path is the transmission path loss, in dB; L_other is other losses, in dB; and G_rx is the receive antenna gain of the device for receiving differential information, in dBi. The receiving sensitivity of the device used to receive differential information is P_rx_sens, and P_rx ≥ P_rx_sens.

[0014] Secondly, embodiments of this application provide a forwarding device, which adopts the following technical solution: A forwarding device, based on the above-described differential information forwarding method, includes: The control module is used for data processing; A pre-filter component is used for data filtering, and the pre-filter component is electrically connected to the control module; The radio frequency unit includes a modulator and a radio frequency transmitter. The modulator is used for signal modulation, and the radio frequency transmitter is used for outputting the modulated signal. The radio frequency unit is electrically connected to the control module. An amplification module includes a preamplifier and a final power amplifier for signal preamplification and final power amplification, wherein both the preamplifier and the final power amplifier are electrically connected to the radio frequency transmitter. A post-filter is used to filter the amplified signal, and the post-filter is electrically connected to the final stage power amplifier component; An antenna feed line is used for signal transmission, and the antenna feed line is electrically connected to the post-filter. A blade antenna is used for signal transmission, and the blade antenna is electrically connected to the antenna feed line; A monitoring interface is used to receive parameter configuration instructions from a host computer, and the monitoring interface is electrically connected to the control module. A differential information input interface is used to receive differential information from a host computer, and the differential information input interface is electrically connected to the control module; A power interface is provided for power input and is electrically connected to the control module.

[0015] In conjunction with the second aspect, in one embodiment, the control module includes a controller, a baseband chip, and a level conversion circuit, wherein both the baseband chip and the level conversion circuit are electrically connected to the controller.

[0016] Thirdly, embodiments of this application provide a drone, employing the following technical solution: A drone includes the aforementioned relay device. By mounting the relay device on the drone, the drone can carry the relay device flexibly and maneuverably. The drone can also carry the relay device to high altitudes to improve the signal coverage of the relay device.

[0017] Compared with the prior art, the beneficial effects of the present invention are: (1) By adopting LoRa or GFSK modulation mode and in conjunction with multi-frequency retransmission mechanism, the system can achieve differential information broadcasting with a coverage radius of more than 100km when the UAV flies to a certain altitude, effectively expanding the service range.

[0018] (2) The present invention adopts a dual-frequency (LoRa mode) or three-frequency (GFSK mode) retransmission mechanism, which enables the receiver to avoid interference points as much as possible in the time and frequency domains, greatly improving the data packet transmission success rate and adapting to complex electromagnetic environments.

[0019] (3) The GFSK mode uses the existing equipment's communication parameters, ensuring interconnection with the existing receiving equipment; the LoRa mode provides stronger anti-interference and long-distance transmission capabilities, and the system can switch flexibly according to task requirements. Attached Figure Description

[0020] Figure 1 This is a block diagram of a forwarding device system in this embodiment; Figure 2 This is a flowchart of a differential information forwarding method in this embodiment; Figure 3 This is a flowchart illustrating how the received differential information is encoded and transmitted according to set parameters in this embodiment. Detailed Implementation

[0021] The technical solution of this application will now be clearly and completely described with reference to the accompanying drawings. The following embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. In the following description, the same reference numerals are used to denote the same or equivalent elements, and repeated descriptions are omitted.

[0022] In the description of this application, it should be understood that the terms "upper," "lower," "inner," "outer," "left," and "right," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the prepositions "first," "second," and "third," etc., are only used for the purpose of distinguishing the modified objects, and should not be construed as indicating or implying relative importance.

[0023] Furthermore, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0024] It should also be further understood that the term "and / or" as used in this application specification and the corresponding claims refers to any combination of one or more of the listed items and all possible combinations.

[0025] This embodiment provides a drone. The drone includes a fuselage and a differential information forwarding device mounted on the fuselage. By integrating the differential information forwarding device into the drone platform, the drone's high mobility and flexible deployment capabilities can be utilized to quickly deliver differential information broadcasting services to target areas. More importantly, the drone can climb to a certain altitude, significantly extending the line-of-sight transmission range of the signal, thereby enabling large-scale, highly reliable differential positioning enhancement services in areas with complex terrain or lack of infrastructure.

[0026] The unmanned aerial vehicle (UAV) can be a fixed-wing UAV, a rotary-wing UAV (such as a multi-rotor UAV), or a vertical takeoff and landing (VTOL) compound UAV, selected based on mission endurance, payload capacity, and takeoff and landing conditions. The differential information relay device is typically installed in the UAV's belly or fuselage, with its blade-shaped antenna mounted externally to ensure omnidirectional radiation characteristics and reduce airframe obstruction. The UAV platform provides the necessary power supply, mounting structure, and possible data and control interfaces for the relay device (e.g., via an onboard flight control computer or data link).

[0027] When a drone performs a differential information relay mission, its workflow typically includes takeoff, climb, cruise broadcasting, maneuvering adjustments, and return. During the cruise broadcasting phase, the drone maintains a certain altitude (e.g., hundreds to thousands of meters) and flies around or hovers at a fixed point. The differential information relay device continuously receives differential information from ground stations or BeiDou regional augmentation and monitoring equipment (which can be transmitted back via data link) and converts it into radio frequency signals for broadcast according to the set modulation mode and parameters.

[0028] A key advantage of drones lies in their high degree of adjustability. Combined with the adjustable transmit power of the relay device, dynamic optimization of coverage can be achieved. Specifically, the system can dynamically calculate and set the minimum required transmit power (P_tx_min) of the relay device based on real-time mission requirements (required coverage radius R_desired), the current drone flight altitude (H), and environmental electromagnetic conditions. This principle is based on the link budget equation of wireless communication: P_rx = P_tx + G_tx - L_path - L_other + G_rx Where P_rx is the signal strength (in dBm) received by the ground receiving equipment (the equipment used to receive differential information, i.e., the differential information receiving device), P_tx is the transmit power (in dBm) of the repeater, G_tx is the transmit antenna gain (in dBi), L_path is the transmission path loss (in dB), L_other is other losses (in dB), including feeder loss, atmospheric attenuation, penetration loss, fading margin, etc., and G_rx is the receive antenna gain of the ground receiving equipment (in dBi). To ensure successful communication, P_rx ≥ P_rx_sens, where P_rx_sens is the receive sensitivity (in dBm) of the ground receiving equipment (the equipment used to receive differential information). Therefore, the minimum transmit power to meet the current coverage requirements is: P_tx_min = P_rx_sens - G_tx + L_path + L_other - G_rx The transmission path loss L_path is a key variable, depending on the signal frequency (f) and the straight-line distance (d) from the UAV to the ground user. The distance d is not simply the desired ground coverage radius (R_desired), but rather a slant range closely related to the UAV's flight altitude H. In a simplified model that does not consider the Earth's curvature: d = sqrt(R_desired^2 + H^2) The Free Space Path Loss (FSPL) model is used as the basis, with an additional environmental margin L_excess (e.g., 10-30 dB, selected based on suburban or urban environments) to estimate the actual loss. L_path ≈ 32.44 + 20*log10(f_MHz) + 20*log10(d_km) + L_excess In practice, the host computer (ground command center) or the UAV's onboard computing unit can calculate P_tx_min in real time based on the preset R_desired, the current or planned H, the known operating frequency f, antenna gain, typical receiver sensitivity, and other loss budgets (other losses can be preset through testing or experience). This calculation is then used to send commands to the repeater via the monitoring interface, adjusting its transmit power to near this minimum value. This dynamic power control strategy minimizes the power consumption of the repeater while ensuring reliable reception for ground users, thereby extending the UAV's endurance. Simultaneously, while maintaining coverage, appropriately lowering the flight altitude H can significantly reduce the slant range d, thereby reducing path loss L_path and allowing for lower transmit power, further saving energy.

[0029] In addition, the drone platform can switch between LoRa and GFSK modes based on interference monitoring or communication quality feedback to adapt to different communication distances, anti-interference requirements, and compatibility requirements with existing equipment.

[0030] Based on the above UAV embodiment, this embodiment describes in detail the specific structure of the differential information forwarding device. This forwarding device is an independent functional module that can be installed on a UAV or applied to other mobile or fixed platforms.

[0031] like Figure 1 As shown in the schematic block diagram (not showing all connections), a transponder mainly includes a control module, a signal processing link, a radio frequency transmission link, an antenna unit, and an external interface.

[0032] The control module is the core processing unit of the relay device, responsible for overall system control, data processing, parameter configuration, and status monitoring. In a specific implementation, the control module includes an external microcontroller unit (MCU) as the main controller, a baseband chip integrating an ARM core and RF front-end, and necessary level conversion circuitry. Both the baseband chip and the level conversion circuitry are electrically connected to the MCU. The MCU interacts with the ARM core of the baseband chip and transmits control commands via interfaces such as a Universal Asynchronous Receiver / Transmitter (UART). The level conversion circuitry converts signal levels input from external interfaces (such as RS422 and CAN bus levels) into TTL / CMOS levels that can be processed by the controller and the baseband chip, and vice versa. The main functions performed by the control module include: parsing parameter configuration instructions from the host computer through the monitoring interface, and configuring parameters such as the baseband chip's operating mode (LoRa / GFSK), channel, and transmit power accordingly; receiving differential information data streams transmitted through the differential information input interface and forwarding them to the baseband chip for encoding processing; controlling the timing of the entire signal transmission, especially frequency switching and data frame scheduling in multi-frequency hopping retransmission mode; monitoring the status of the radio frequency unit (such as power, temperature, etc.) and reporting status and alarm information through the monitoring interface.

[0033] The signal processing link and the radio frequency transmission link are responsible for converting digital differential information into high-frequency radio signals that can be radiated through an antenna. This link specifically includes the following components, which are connected sequentially or in parallel according to the signal flow direction: Pre-filter component: Directly connected to the differential information input interface and / or monitoring interface, it is used to perform preliminary filtering on the input differential information data stream or parameter configuration command signal, filtering out out-of-band noise and interference, and improving signal integrity. It is usually implemented using a low-pass or band-pass filter circuit.

[0034] The radio frequency (RF) unit, at its core, consists of the modulator and RF transmitter within the baseband chip. The modulator, based on the modulation mode (LoRa or GFSK) and related parameters (such as spreading factor, bandwidth, frequency offset, etc.) set by the control module, modulates the encoded baseband digital signal onto an intermediate frequency (IF) or directly onto an RF carrier. The RF transmitter performs preliminary frequency synthesis, frequency conversion, and amplification on the modulated signal, outputting a low-power modulated RF signal.

[0035] Amplification Module: Used to amplify the weak signal output from the RF unit to the required transmit power level. It includes a preamplifier and a final power amplifier. The preamplifier primarily provides a certain gain to drive the final power amplifier and may have linear amplification capabilities. The final power amplifier is crucial for achieving the final output power; its gain and saturation output power determine the device's maximum transmit capability. Both amplifiers are electrically connected to the output of the RF transmitter, amplifying the signal sequentially. The transmit power P_tx is typically adjusted by the control module changing the bias voltage or gain control signal of the final power amplifier.

[0036] Post-filter: Connected to the output of the final stage power amplifier, it is used to filter out harmonic components and spurious emissions generated during power amplification, ensuring the purity of the output signal spectrum and compliance with radio management regulations. LC bandpass filters or cavity filters are typically used.

[0037] Antenna feeder: A low-loss coaxial cable used to transmit filtered RF signals from inside the device housing to an externally mounted blade antenna. Its characteristic impedance (typically 50 ohms) must be matched with the front-end and rear-end components.

[0038] Blade antenna: As the final radiating element, it converts the high-frequency current energy transmitted from the feed line into electromagnetic waves and radiates them into space. Blade antennas typically have an omnidirectional or near-omnidirectional radiation pattern (in the horizontal plane), making them suitable for applications requiring wide-area coverage. Their compact structure makes them suitable for installation on space-constrained platforms such as drones. The antenna connects to the antenna feed line via its connector (such as a TNC type).

[0039] External interfaces serve as a bridge connecting the relay device to external systems (such as UAV platforms, BeiDou regional augmentation and monitoring equipment, and ground stations), and mainly include: Monitoring interface: For example, a CAN bus interface, used to receive parameter configuration commands from a host computer (via UAV data link or direct cable). These commands include, but are not limited to: setting the modulation mode (LoRa / GFSK), selecting the working channel, adjusting the transmit power level, initiating a reset and restart, etc. This interface is also used for the repeater to report its own RF status, operating parameters, and fault alarm information to the outside world.

[0040] Differential information input interface: For example, an RS422 serial interface, specifically designed to receive real-time differential information data streams from BeiDou regional augmentation monitoring equipment. This interface continuously receives raw differential information data or pre-encapsulated data packets.

[0041] Power interface: Used to connect to the DC power supply provided by the drone platform or an external power source to power all circuit modules within the transponder. Considering power consumption, the power supply typically needs to have a certain power output capability (e.g., supporting a maximum input of 20W or more).

[0042] The mechanical and environmentally adaptable design of the transponder is crucial for reliable operation in harsh environments such as those of drones. Structure and Sealing: The main unit housing is milled from a single piece of aluminum alloy to ensure structural strength and electromagnetic shielding. Waterproof conductive rubber strips and gaskets are used to seal areas such as the cover plate and connector mounting holes, and conductive adhesive is used at joints to achieve overall airtightness and prevent moisture and salt spray intrusion. Sealing screw holes can be provided on the housing for airtightness testing.

[0043] Triple-proof treatment: All fasteners are made of stainless steel for corrosion resistance. The outer surface of the housing is treated with a multi-layer baking paint: first, an epoxy zinc yellow anti-rust primer (thickness ≥80μm) is applied, followed by an epoxy micaceous iron oxide intermediate coat, and finally an acrylic polyurethane topcoat, with the total coating thickness controlled at 200-300μm, providing excellent resistance to salt spray and moisture. The external connector housing is nickel-plated.

[0044] Vibration and shock resistance: The circuit board and shielding cover are secured with combination screws featuring flat washers and spring washers. Wire thread inserts are installed in the screw holes at critical locations to enhance thread strength and prevent loosening. All onboard connectors are equipped with mechanical locking devices to prevent loosening during vibration.

[0045] Thermal Management: For devices that generate a lot of heat, such as power modules and power amplifiers, a window is made on the back of the soldering area of ​​the printed circuit board (the side in contact with the housing) to remove the solder mask layer, and thermal grease with a high thermal conductivity is filled between the device and the housing to establish an efficient heat conduction path. The metal housing is used as a heat sink to achieve passive and efficient heat dissipation.

[0046] Antenna and Feeder: The blade antenna's outer casing is made of integrally molded fiberglass. Sealant is applied between the antenna socket and the casing, and a rubber gasket is installed between the antenna and the mounting surface of the antenna to achieve a waterproof seal. The antenna material itself is corrosion-resistant. The antenna feeder is waterproofed by using a heat-shrinkable sheath with hot melt adhesive at the connector-to-cable junction. The cable insulation and sheath materials (such as foamed polyethylene and polyurethane) are selected to withstand temperatures down to -65°C, ensuring that it maintains its flexibility and electrical properties even at extreme low temperatures of -50°C, without cracking or performance degradation.

[0047] Through the aforementioned sophisticated electronic design, rigorous mechanical structure design, and comprehensive environmental adaptability design, this transponder achieves miniaturization (e.g., dimensions ≤225mm×145mm×50mm, weight ≤1.4kg), low power consumption (maximum average power consumption ≤20W), high reliability, and powerful wireless broadcasting capabilities, making it an ideal payload to support UAVs in achieving beyond-line-of-sight, anti-interference differential information broadcasting.

[0048] The forwarding device is used to receive differential information transmitted from the host computer (a device that can transmit differential information, such as a differential information publishing base station), and forward the received differential information to a more distant location so that it can be received and utilized by differential information receiving devices at a more distant location.

[0049] like Figure 2 As shown, this embodiment also provides a differential information forwarding method executed by the aforementioned forwarding device. The core of this method lies in achieving long-distance, high-reliability differential information broadcasting through configurable parameters, particularly supporting both LoRa and GFSK modulation modes and their respective multi-frequency retransmission mechanisms. The method mainly includes three steps: parameter setting (S1), receiving the differential information to be forwarded from the host computer (S2), and encoding and transmitting the received differential information according to the set parameters (S3). A detailed description follows.

[0050] S1. Set the parameters of the forwarding device.

[0051] This step is the initialization or reconfiguration phase of the method operation. Parameters mainly include channel, transmit power, and modulation mode. Two modulation modes are available: LoRa and GFSK. These parameters are typically not set via physical switches on the device itself, but rather remotely controlled by software. Specifically, the repeater's monitoring interface receives parameter configuration commands from a host device (such as the control computer in the ground command center). The control module (MCU) parses these commands, extracts the parameter values ​​to be set, and then configures the baseband chip and other related hardware (such as the power amplifier bias circuit) through internal communication interfaces (such as SPI, I2C, or register configuration), thereby completing channel selection, transmit power adjustment, and modulation mode switching.

[0052] The specific details of the parameter settings have a profound impact on subsequent launch behavior: The modulation mode is LoRa mode: In this mode, the system employs linear spread spectrum modulation technology. To combat interference, the system activates two transmission frequencies (denoted as F1 and F2) on each designated operating channel. The interval between these two frequencies is at least 55MHz. This larger interval helps to disperse the signal in the frequency domain, preventing narrowband interference from affecting both frequencies simultaneously. Each frequency transmits the differential information to be forwarded completely once. The differential information is organized into multiple consecutive data frames. During transmission, an "alternating transmission" strategy is adopted: frequency F1 transmits the first frame, then frequency F2 transmits the first frame; then frequency F1 transmits the second frame, then frequency F2 transmits the second frame; this process alternates until all data frames have been transmitted on both frequencies. This dual diversity in the time and frequency domains greatly improves the probability that the receiver will successfully receive at least one complete copy of the data. In one specific embodiment, each data frame in LoRa mode is 120 bytes long, and the transmission duration of each frame is approximately 67ms.

[0053] The modulation mode is GFSK: This mode prioritizes compatibility with existing equipment (differential information receiving devices, such as geodesic BeiDou differential user terminals). The system uses or strictly matches the entire set of physical layer communication parameters of existing equipment (differential information receiving devices). These physical layer communication parameters include: channel frequency hopping pattern, radio frequency rate, channel bandwidth, modulation frequency offset, filter roll-off factor, channel convolutional coding method, interleaving depth, and data frame format. That is, when the modulation mode is GFSK, the channel frequency hopping pattern, radio frequency rate, channel bandwidth, modulation frequency offset, filter roll-off factor, channel convolutional coding, interleaving depth, and data frame format used by the repeater are all consistent with those of the differential information receiving device. Similarly, to resist interference, three frequency points (denoted as F1, F2, and F3) are set on each channel, with a frequency interval of at least 55MHz. The transmission strategy is "alternating transmission": frequency point F1 transmits the first frame, then frequency point F2 transmits the first frame, followed by frequency point F3; after completing the first round of transmitting the first frame for all frequencies, the second round begins: frequency point F1 transmits the second frame, frequency point F2 transmits the second frame, frequency point F3 transmits the second frame, and so on, forming a sequence of alternating transmission for the three frequencies. In a specific embodiment, each data frame in GFSK mode is 59 bytes long, and each frame transmission takes approximately 10ms, resulting in a higher data throughput.

[0054] The setting of the transmit power P_tx not only affects coverage area but also directly impacts device power consumption and battery life. Its setting principle is based on link budget, ensuring that the signal strength P_rx received by the ground receiver in the outermost coverage area is not lower than its receiver sensitivity P_rx_sens. The link budget formula is: P_rx = P_tx + G_tx - L_path - L_other + G_rx Where G_tx is the transmit antenna gain, L_path is the transmission path loss, L_other is other losses (feeder loss, atmospheric attenuation, penetration loss, fading margin, etc.), and G_rx is the receive antenna gain. By estimating or calculating L_path in real time (which depends on the flight altitude H, coverage radius R, and operating frequency f), and combining it with other known or set loss and gain values, the minimum transmit power P_tx_min that meets communication requirements can be derived, and the transmit power can be set near this value to achieve optimized power usage.

[0055] S2. Receive differential information to be forwarded from the host computer.

[0056] This step is the data input phase. The forwarding device continuously or on demand receives differential information data streams from a host computer (a device capable of transmitting differential information, such as a differential information dissemination base station) through its dedicated differential information input interface (such as an RS422 interface). This data stream contains information such as differential correction values ​​used to improve the positioning accuracy of the user terminal. The received differential information data is temporarily stored in the buffer of the control module, awaiting subsequent processing.

[0057] S3. Encode the received differential information according to the set parameters and transmit it.

[0058] This step is the core signal processing and radiation stage, converting digital differential information into radio waves for transmission. For example... Figure 3 As shown, this process can be further subdivided into the following sub-steps: S31. Filter the differential information. The raw differential digital signal received from the input interface is filtered to eliminate high-frequency noise, glitches, and potential out-of-band interference, improving signal purity and stability, and providing a high-quality digital baseband signal for subsequent level conversion and encoding. This filtering is performed by the aforementioned pre-filtering component.

[0059] S32. Perform level conversion on the filtered differential information. Since the level standard of the external interface (such as RS422) differs from the level standard of the internal controller and baseband chip (usually TTL or CMOS level), level conversion is required. This step is performed by the level conversion circuit (such as an RS422 / TTL converter chip) in the control module to ensure correct identification of the logic signals.

[0060] S33. The differential information after level conversion is encoded. The converted digital signal is sent to the control module. The MCU transmits it to the processing unit (such as the ARM core) within the baseband chip via serial port or other means. The baseband chip performs a series of baseband encoding processes on the data according to the currently set modulation mode and related parameters. For GFSK mode, this may include convolutional coding, interleaving, etc., to enhance the ability to resist burst errors; for LoRa mode, unique spread spectrum coding is performed to generate a baseband signal with noise immunity. The encoded data is organized into data frames that conform to the frame format requirements.

[0061] S34. The encoded differential information is modulated and output via radio frequency. The modulator in the baseband chip modulates the baseband data frame onto the radio frequency carrier according to the configured mode (LoRa or GFSK) and parameters (such as carrier frequency, bandwidth, spreading factor, etc.). Then, the radio frequency transmitter performs necessary up-conversion, filtering, and preliminary drive amplification on the modulated signal to generate a low-power radio frequency modulated signal, which is then output to the subsequent amplification module.

[0062] S35. The differential information output by the RF unit is pre-amplified and then filtered before transmission after final stage power amplification. The signal output by the RF unit first enters the pre-amplifier for preliminary amplification to obtain sufficient power to drive the final stage power amplifier. The final stage power amplifier is crucial for power enhancement, amplifying the signal to the level corresponding to the final set transmit power P_tx. The amplified signal contains spurious components such as harmonics, which need to be filtered by a post-filter (such as an LC bandpass filter) to suppress unwanted spectral radiation and ensure that the output signal meets the spectrum specifications. Finally, the clean, high-power RF signal is transmitted to the blade antenna through the antenna feed line, where it is converted into electromagnetic waves and radiated omnidirectionally or directionally into space.

[0063] Throughout the transmission process, the control module strictly manages the timing, especially controlling the switching of the radio frequency unit between different frequency points and scheduling the transmission order of data frames to achieve the aforementioned anti-interference retransmission mechanism of "alternating transmission at dual frequency points" (LoRa mode) or "rotating transmission at three frequency points" (GFSK mode).

[0064] Detailed description of working modes and examples of data flow To more clearly illustrate the specific workflow of the two modulation modes, we will explain it in conjunction with specific data volumes: Example of LoRa mode workflow: Assume the maximum amount of differential information that needs to be forwarded per second is 350 bytes. In LoRa mode, each frame can transmit 120 bytes, taking 67ms. Therefore, it takes 3 frames to transmit all 350 bytes (3 frames total 360 bytes, with slight redundancy).

[0065] The launch process strictly follows the dual-frequency alternation strategy: Transmit the first frame of data (120 bytes, 67ms) on frequency F1.

[0066] Switch to frequency F2 and transmit the first frame of data (120 bytes, 67ms). (At this point, the first frame of data has been transmitted once on each of the two frequencies.) Switch back to frequency F1 and transmit the second frame of data (120 bytes, 67ms).

[0067] Switch to frequency F2 and transmit the second frame of data (120 bytes, 67ms).

[0068] Switch back to frequency F1 and transmit the third frame of data (120 bytes, 67ms).

[0069] Switch to frequency F2 and transmit the third frame of data (120 bytes, 67ms).

[0070] Thus, the 350 bytes of differential information were repeatedly broadcast using two frequency points, with three frames transmitted at each frequency point. Throughout the cycle, even if either frequency point was temporarily interrupted due to interference, the receiver could still successfully receive all data frames from the other frequency point, thereby ensuring a data packet transmission success rate of no less than 95% in complex electromagnetic environments.

[0071] Example of GFSK mode workflow: Assume the maximum amount of differential information that needs to be forwarded per second is 600 bytes. In GFSK mode, each frame can transmit 59 bytes, taking 10ms. Therefore, it takes 11 frames to transmit all 600 bytes (11 frames totaling 649 bytes).

[0072] The launch process strictly follows the three-frequency rotation strategy: Transmit the first frame of data (59 bytes, 10ms) on frequency F1.

[0073] Switch to frequency F2 and transmit the first frame of data (59 bytes, 10ms).

[0074] Switch to frequency F3 and transmit the first frame of data (59 bytes, 10ms). (First round complete; the first frame of data is transmitted once on each of the three frequencies.) Switch back to frequency F1 and transmit the second frame of data (59 bytes, 10ms).

[0075] Switch to frequency F2 and transmit the second frame of data (59 bytes, 10ms).

[0076] Switch to frequency F3 and transmit the second frame of data (59 bytes, 10ms).

[0077] ... Repeat this process until completion: Switch back to frequency F1 and transmit the 11th frame of data (59 bytes, 10ms).

[0078] Switch to frequency F2 and transmit the 11th frame of data (59 bytes, 10ms).

[0079] Switch to frequency F3 and transmit the 11th frame of data (59 bytes, 10ms).

[0080] Thus, the 600 bytes of differential information were repeatedly broadcast using three frequency points, with 11 frames transmitted at each frequency. This mode, while maintaining full compatibility with existing military receiving equipment, significantly improves anti-jamming performance through three-frequency diversity.

[0081] It should be noted that although the present invention has been disclosed above with specific embodiments, the above embodiments are not intended to limit the present invention. Those skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims.

Claims

1. A differential information forwarding method, characterized in that, Includes the following steps: S1. Set parameters; S2. Receive differential information to be forwarded from the host computer; S3. Encode the received differential information according to the set parameters and transmit it; In step S1, the parameters include channel, transmit power, and modulation mode, wherein the modulation mode includes LoRa mode and GFSK mode; When the modulation mode is LoRa mode, two frequency points are set on each channel, with a minimum interval of 55MHz between each frequency point. Each frequency point transmits a differential information signal once. The differential information signal includes multiple data frames, and the two frequency points transmit data frames alternately. When the modulation mode is GFSK mode, three frequency points are set on each channel, with each frequency point spaced at least 55MHz apart. Each frequency point transmits a differential information signal once. The differential information signal includes multiple data frames, and the three frequency points transmit data frames in turn.

2. The forwarding method according to claim 1, characterized in that, When the modulation mode is LoRa, each data frame transmits 120 bytes, and each data frame takes 67ms to transmit.

3. The forwarding method according to claim 1, characterized in that, When the modulation mode is GFSK, each data frame is 59 bytes transmitted, and each data frame takes 10ms to transmit.

4. The forwarding method according to claim 1, characterized in that, When the modulation mode is GFSK, the channel frequency hopping pattern, radio frequency rate, channel bandwidth, modulation frequency offset, filter roll-off factor, channel convolutional coding, interleaving depth, and data frame format are all consistent with those of the differential information receiving device.

5. The forwarding method according to claim 1, characterized in that, In step S1, setting parameters includes: receiving parameter configuration instructions from the host device and setting parameters according to the parameter configuration instructions.

6. The forwarding method according to claim 1, characterized in that, The received differential information is encoded and transmitted according to the set parameters, including: S31. Filter the differential information; S32. Perform level conversion on the filtered differential information; S33. Encode the differential information after level conversion; S34. Modulate and output the encoded differential information via radio frequency. S35. The differential information output by radio frequency is pre-amplified and then amplified by the final power stage before being filtered and transmitted.

7. The forwarding method according to claim 1, characterized in that, The transmit power is P_tx, and P_rx = P_tx + G_tx - L_path - L_other + G_rx, where P_rx is the signal strength received by the device receiving differential information, in dBm; P_tx is the transmit power, in dBm; G_tx is the transmit antenna gain, in dBi; L_path is the transmission path loss, in dB; L_other is other losses, in dB; and G_rx is the receive antenna gain of the device receiving differential information, in dBi. The receiving sensitivity of the device used to receive differential information is P_rx_sens, and P_rx ≥ P_rx_sens.

8. A forwarding device, based on the differential information forwarding method according to any one of claims 1-7, characterized in that, include: The control module is used for data processing; A pre-filter component is used for data filtering, and the pre-filter component is electrically connected to the control module; The radio frequency unit includes a modulator and a radio frequency transmitter. The modulator is used for signal modulation, and the radio frequency transmitter is used for outputting the modulated signal. The radio frequency unit is electrically connected to the control module. An amplification module includes a preamplifier and a final power amplifier for signal preamplification and final power amplification, wherein both the preamplifier and the final power amplifier are electrically connected to the radio frequency transmitter. A post-filter is used to filter the amplified signal, and the post-filter is electrically connected to the final stage power amplifier component; An antenna feed line is used for signal transmission, and the antenna feed line is electrically connected to the post-filter. A blade antenna is used for signal transmission, and the blade antenna is electrically connected to the antenna feed line; A monitoring interface is used to receive parameter configuration instructions from a host computer, and the monitoring interface is electrically connected to the control module. A differential information input interface is used to receive differential information from a host computer, and the differential information input interface is electrically connected to the control module; A power interface is provided for power input and is electrically connected to the control module.

9. The relay device according to claim 8, characterized in that, The control module includes a controller, a baseband chip, and a level conversion circuit, both of which are electrically connected to the controller.

10. A drone, characterized in that, Includes the forwarding device described in any one of claims 8-9.

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