Semi-airborne transient electromagnetic space-time synchronous real-time telemetry method and system

Abstract

The application belongs to the technical field of semi-airborne transient electromagnetic exploration, and provides a semi-airborne transient electromagnetic space-time synchronous real-time telemetry method and system. Positioning messages and second pulse signals output by a communication terminal are acquired, a hardware interrupt is triggered by using the second pulse signals to force calibration of a local timer, and absolute second alignment is performed in combination with the positioning messages to generate a nanosecond-level time reference. Based on the time reference, a direct memory access controller is controlled to perform asynchronous transfer and shunting of high-frequency electromagnetic data of a collection device between double buffer areas. After shunting, a data copy is intercepted to obtain a late channel signal time window, a background noise root mean square and a curve monotonicity distortion point are calculated, and a data quality evaluation index is generated. The index and analyzed positioning coordinates are packed into a hexadecimal telemetry instruction, which is sent to a cloud monitoring end via the communication terminal. The application effectively improves the space-time synchronization precision and remote real-time monitoring capability of semi-airborne transient electromagnetic exploration.

Description

Technical Field

[0001] This invention relates to the field of semi-airborne transient electromagnetic exploration technology, specifically to a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method and system. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Semi-airborne transient electromagnetic exploration technology achieves a combination of high efficiency and high precision through high-power ground transmission and airborne platform reception. In this technology system, to ensure the accuracy of subsequent data inversion, high-frequency electromagnetic signals must be precisely time-stamped, and this data must be strictly correlated with the spatial location of the receiver. Traditional acquisition systems typically rely on independent positioning modules to obtain location information and use local clocks to record sampling times. With the development of embedded technology, high-speed data transfer using direct memory access controllers has become a common method to ensure data continuity; furthermore, in areas without public network coverage, satellite-linked short message communication enables remote monitoring.

[0004] However, in actual operations of semi-airborne transient electromagnetic exploration, existing technologies still face challenges in achieving remote real-time quality monitoring. Because the systems typically employ independent positioning modules and communication terminals, or fail to fully utilize the physical signals of the communication terminals, there is a lack of tight physical coupling between the receiver's acquisition clock and the communication module's positioning clock. This heterogeneity of clock sources introduces unpredictable drift errors into the time reference. These minute deviations in the time reference directly affect the synchronization accuracy of high-frequency electromagnetic data and spatial location information, making it difficult to accurately map the calculated signal characteristics to corresponding geographic coordinates during remote data quality assessment. This, in turn, affects the ability to make real-time and accurate judgments on the validity of the acquired data. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method and system, which eliminates clock drift between heterogeneous communication modules and receivers, ensures that the original high-frequency electromagnetic data and spatial trajectory coordinates share the same satellite absolute time reference, and achieves high-precision spatial marking at the nanosecond to microsecond level.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method.

[0007] A semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method includes the following processes: The system acquires the location message and second pulse signal output by the communication terminal, uses the second pulse signal to trigger a hardware interrupt to force calibration of the local timer, and combines the location message to perform absolute second alignment to generate a nanosecond-level time reference. Based on a nanosecond-level time base, the direct memory access controller asynchronously transfers and splits the high-frequency electromagnetic data of the acquisition device between two buffers. The late channel signal time window is extracted from the data copy after diversion, the root mean square of the background noise and the monotonic distortion point of the curve are calculated, and a data quality evaluation index is generated. The data quality evaluation index and the parsed positioning coordinates are packaged into a telemetry command and sent to the cloud monitoring terminal via a communication terminal.

[0008] In one implementation of the first aspect of the present invention, acquiring the positioning message and second pulse signal output by the communication terminal includes: The receiver's original independent positioning module is removed, and the positioning unit integrated in the communication terminal is reused; The baud rate of the positioning message output by the communication terminal can be dynamically modified through the wireless configuration service. The second pulse signal output by the communication terminal is connected to the external interrupt pin and timer capture channel of the microcontroller.

[0009] In one implementation of the first aspect of the present invention, a hardware interrupt is triggered using a second pulse signal to force calibration of a local timer, and absolute second alignment is performed in conjunction with a positioning message to generate a nanosecond-level time base, including: When the rising edge of the second pulse signal is detected, the highest priority hardware interrupt of the microcontroller is triggered. Use an interrupt service routine to forcibly clear and calibrate the count value of the local sub-second timer; Extract the Coordinated Universal Time (UTC) absolute timestamp from the location message and concatenate it with the local zeroed count value to generate a continuous nanosecond-level time base.

[0010] In one implementation of the first aspect of the present invention, based on a nanosecond-level time base, the direct memory access controller is controlled to asynchronously transfer and split the high-frequency electromagnetic data of the acquisition device between two buffers, including: Create a first buffer and a second buffer in the memory; The direct memory access controller is used to automatically move the sampled data from the acquisition device to the current free buffer. When the current buffer is full, a half-full interrupt is triggered, which switches the pointer of the direct memory access controller to another buffer; While the direct memory access controller fills the switched buffer with data, it frees up the central processing unit to process the data in the full buffer.

[0011] As a further limitation of the first aspect of the invention, releasing the central processing unit from processing data in a full buffer includes: Prioritize the configuration of a secure digital input / output controller, and use the direct memory access channel to write the full transient electromagnetic waveform in the full-load buffer into the storage medium in the form of a binary raw stream, sector-aligned and lossless; Simultaneously, the idle computing power of the central processing unit is utilized to perform late-stage signal interception and feature extraction on the data copies in the full-load buffer.

[0012] As a further limitation of the first aspect of the invention, late-channel signal interception and feature extraction are performed on the data replicas within the full-load buffer, including: Using the instant the launcher shuts down as the time reference point, the quality evaluation observation window is opened after a preset delay time; Extract the set of voltage sequences within the quality assessment observation window; Calculate the local mean and root mean square error of the voltage sequence set as an indicator of the background noise energy; Perform first-order difference calculations on the voltage sequence set to count the total number of distortion points where abnormal voltage jumps occur between adjacent sampling points.

[0013] As a further limitation of the first aspect of the present invention, the calculation of the background noise energy and the monotonicity distortion point of the curve to generate a data quality evaluation index includes: Construct a comprehensive penalty function, which includes a root mean square error term, a total number of distortion points term, and a preset weighting coefficient. Calculate the value of the comprehensive penalty function; The function value is compared with a preset threshold boundary, and the data quality is mapped to a two-bit quantized status word based on the comparison result.

[0014] In one implementation of the first aspect of the present invention, the data quality evaluation index and the parsed positioning coordinates are packaged into a hexadecimal telemetry command, including: Remove redundant punctuation marks from the location message and convert the latitude and longitude coordinates to unsigned long integers by multiplying them by a preset scaling factor; Concatenate the unsigned long integer coordinate data with the two-bit quantized status word according to the preset protocol order; The concatenated data stream is converted into a compact fixed-length hexadecimal string and pushed into the serial port of the communication terminal.

[0015] Secondly, the present invention provides a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry system.

[0016] A semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry system includes: The time-space reference generation unit is used to acquire the second pulse signal and positioning message output by the communication terminal and generate a nanosecond-level time reference. The data acquisition and distribution unit is used to control the operation of the acquisition device based on a nanosecond-level time base, and to asynchronously transfer and distribute the acquired data between two buffers. The edge computing unit is used to extract late channel signal features from the offloaded data replicas and generate a data quality evaluation index. The telemetry communication unit is used to package the data quality evaluation index with the positioning coordinates and send them via the communication terminal.

[0017] In one implementation of the second aspect of the present invention, the spatiotemporal reference generation unit includes a microcontroller and a multiplexed communication terminal; The universal serial bus interface of the communication terminal is connected to the serial communication interface of the microcontroller for outputting positioning messages; The second pulse output terminal of the communication terminal is hardwired to the external interrupt pin and timer capture channel of the microcontroller; The microcontroller is configured to trigger a hardware interrupt when a rising edge of the second pulse signal is detected, force calibration of the local timer, and perform absolute second alignment in conjunction with the positioning message; The data acquisition and splitting unit includes an analog-to-digital converter, a direct memory access controller, and a double-buffered memory; The sampling output of the analog-to-digital converter is connected to the data source address of the direct memory access controller; The double-buffered memory includes a first storage area and a second storage area; The direct memory access controller is configured to trigger a half-full interrupt when the first memory area is full, and automatically switch the data flow to the second memory area; While the central processing unit processes data in the first memory area, the direct memory access controller continues to fill newly acquired data into the second memory area.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention reuses the positioning message and second pulse signal output by the communication terminal, uses the second pulse signal to trigger a hardware interrupt to force calibration of the local timer, and combines it with the positioning message for absolute second alignment to generate a nanosecond-level time reference. This effectively eliminates clock drift between heterogeneous communication modules and the receiver, ensuring that high-frequency electromagnetic data and spatial trajectory coordinates share the same satellite absolute time reference, thus improving the accuracy and stability of spatiotemporal synchronization. Based on the nanosecond-level time reference, the direct memory access controller asynchronously transfers and splits the high-frequency electromagnetic data from the acquisition device between two buffers, achieving efficient data processing and storage and ensuring continuous acquisition of massive amounts of high-frequency data. The late-channel signal time window is extracted from the split data copy, and the root mean square of the background noise and the monotonicity distortion point of the curve are calculated to generate a data quality evaluation index. This enables real-time quality control in areas lacking public networks and timely detection of data anomalies. The data quality evaluation index and the parsed positioning coordinates are packaged into hexadecimal telemetry commands and sent to the cloud monitoring terminal via a communication terminal. This enables the ground control center to monitor the three-dimensional spatial trajectory of the UAV and the validity of the observation data in real time, thereby improving the real-time performance and reliability of semi-airborne transient electromagnetic exploration.

[0019] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] Figure 1 This is a flowchart illustrating a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method provided as an exemplary embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] Semi-airborne transient electromagnetic exploration combines the advantages of high efficiency from airborne systems with high-power depth-penetrating ground-based systems. It is often deployed by unmanned aerial vehicles (UAVs) in remote mountainous areas without public network coverage. However, existing receiving systems face significant bottlenecks in engineering applications. Firstly, these systems generally employ an "offline blind acquisition" mode, lacking real-time quality control capabilities; the equipment only stores the raw waveforms on local media. If strong electromagnetic interference, severe aircraft attitude distortion, or hardware failures cause data loss, the issue can only be detected after the UAV lands and exports the data, resulting in extremely high wasted flight costs and project delays. Secondly, attaching an independent satellite short message terminal for location telemetry in areas without network coverage not only increases the load and power supply pressure but also triggers a serious heterogeneous clock drift problem. The positioning clock of the communication module and the acquisition clock of the receiver cannot be physically synchronized. In electromagnetic exploration, where extremely high time accuracy (nanosecond level) is required, even a slight break in the spatiotemporal reference can lead to misalignment between the telemetry trajectory and the underlying data, ultimately severely compromising the accuracy of subsequent 3D inversion.

[0025] In view of the problems existing in the existing solutions, this invention innovatively proposes a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method, such as... Figure 1 As shown, the process begins with initialization and configuration. On-site personnel connect to the short message module via Bluetooth and dynamically send configuration parameters such as baud rate and reporting frequency. This is followed by a time-space synchronization and high-speed acquisition phase. The system introduces a 1PPS pulse and NMEA message to trigger a hardware interrupt to calibrate the local timer and achieve absolute second alignment. Simultaneously, DMA is used to move data to a dual buffer for automatic A / B switching, and a time anchor point Tnow is inserted into the data stream. Next, in the asynchronous data splitting and processing phase, one data stream is written at high speed to the SD card in binary raw format via the SDIO / DMA channel, while the other stream undergoes late-stage window interception (from tstart to tend). The system then calculates Fpenalty (combining RMS and monotonicity detection) through feature extraction and penalty function, and maps it to a 2-bit quality evaluation index (Excellent / Good / Poor). Next, in the telemetry packaging and transmission stage, the system maps coordinates to fixed-length strings and the evaluation index to single characters, concatenates them into a fixed-length character instruction, and reports it via satellite link at preset intervals (e.g., every 2 minutes). Finally, in the ground receiving and visualization stage, the Python engine is used for MQTT subscription and stream parsing to restore latitude and longitude coordinates and quality scores. The trajectory is then redrawn in real time through the front-end GIS, and the quality index is mapped to primitive colors, while retaining 24-hour data.

[0026] This invention innovatively proposes a hardware integration architecture based on spatiotemporal multiplexing. In traditional semi-aerial acquisition systems, the positioning module and the telemetry communication module are usually independent physical units. This invention reconstructs the underlying hardware topology, directly eliminating the original independent GPS positioning module of the electromagnetic receiver and completely transferring and reusing its functions to the secondary-developed Beidou short message communication module. At the physical connection level, the short message module is connected to the main control board of the electromagnetic receiver through a dedicated aviation connector. The NMEA 0183 protocol messages (such as RMC, GGA, etc.) and the second pulse signal (1PPS) output by the GNSS positioning unit inside the module are directly introduced into the receiver's serial interface and external interrupt pin through hard wiring.

[0027] To enhance the flexibility of field operations, this architecture embeds a Bluetooth wireless configuration service into the short message module. Field personnel do not need to open the receiver chassis or carry a dedicated host computer; they can directly connect to the module via Bluetooth using a mobile terminal (phone) to issue configuration commands in real time in the field environment, dynamically modify the output baud rate of RMC and GGA messages and the reporting frequency of BeiDou short messages, thus achieving lightweight adaptive configuration of the module's working mode.

[0028] The core innovation of this architecture lies in eliminating clock drift between the receiver and the communication link through the physical-level introduction of a single external reference source. In semi-airborne electromagnetic exploration, late-channel data of weak secondary fields require rigorous nanosecond to microsecond spatial marking. This system does not rely on expensive independent timing hardware, but instead utilizes an introduced short message module (1PPS) signal to precisely "tame" the receiver's local master clock. Specifically, the "1PPS" signal is connected to the microcontroller's advanced timer input capture channel or external interrupt pin. Without external PPS constraints, the cumulative time error model of the receiver's local ordinary passive / active crystal oscillator is as follows: (1); In the formula, This represents the cumulative drift error of the local clock. This is the local clock frequency of the microcontroller. For standard frequency, This is due to hardware jitter.

[0029] In this invention, whenever the receiver detects a 1PPS rising edge, the microcontroller immediately triggers a high-priority hardware interrupt, forcibly clearing and calibrating the local sub-second timer. Simultaneously, it extracts the NMEA time message synchronously sent by the short message module for absolute second alignment. Through this combined mechanism of "second-level hard reset and sub-second-level local interpolation," it ensures that the high-frequency electromagnetic raw data stored on the SD card and the spatial trajectory coordinates reported by the short message module completely share the same satellite absolute time reference at the underlying level.

[0030] After achieving spatiotemporal unification at the underlying level, this invention further establishes a data flow link between the aerial acquisition nodes and the ground monitoring terminal. The reused short message module, while receiving NMEA messages, compresses and packages the current operational location (longitude, latitude, and altitude) and system status at a preset 2-minute interval, and sends it to the remote server via satellite link. On the ground, this system employs an automated stream parsing terminal based on the MQTT (Message Queuing Telemetry Transport) protocol.

[0031] Specifically, the Python engine deployed in the control center acts as a client, accessing a designated MQTT topic and listening for messages pushed by satellite equipment in real time. Once data is received, the Python program automatically performs message unpacking and latitude / longitude coordinate conversion, and immediately drives the front-end two-dimensional geographic information map to update the UAV's latest real-time location. This link can automatically cache spatial vector data from the last 24 hours, enabling operators to achieve real-time monitoring of receiver tracking and flight path deviation even in areas without public network signals.

[0032] In semi-airborne transient electromagnetic exploration, due to the extremely high frequency and exponentially decreasing signal strength of the secondary field attenuation signal, the receiver must maintain a synchronous sampling rate of tens of thousands of hertz. To simultaneously satisfy the conflicting tasks of full raw data storage and real-time quality edge evaluation within limited embedded resources, this invention proposes a high-speed asynchronous data splitting mechanism based on DMA transfer and dual buffers.

[0033] This system utilizes a multi-bus matrix within a microcontroller (MCU) to achieve efficient data distribution. After acquiring signals from the front-end sensor, the analog-to-digital converter (ADC) does not directly read the data via CPU addressing, but instead uses a direct memory access (DMA) controller. In the microcontroller's static random access memory (SRAM), this invention allocates two logically symmetrical storage areas: buffer A and buffer B. After the ADC completes a sampling conversion of a preset length, the DMA automatically moves the data to buffer A. When buffer A is full, the system does not stop sampling but automatically redirects the DMA pointer to buffer B via a hardware interrupt. During the DMA filling of buffer B, the CPU is freed up to process the data already filled in buffer A. This architecture avoids prolonged CPU blocking during storage, ensuring the continuity and integrity of the original electromagnetic data.

[0034] To achieve absolute time alignment between the acquired electromagnetic response and the spatial location provided by the BeiDou short message module, this invention designs a precise marking mechanism based on external pulse triggering. Utilizing the 1PPS pulse signal introduced in the first part, the microcontroller, upon detecting the rising edge of the pulse, not only calibrates the local clock but also immediately inserts a time synchronization flag bit into the current data stream buffer. Let the sampling frequency be... f s The time interval between two adjacent sampling points is t=1 / f s If the first i If the sampling point exactly corresponds to the 1PPS signal trigger point, then the ... i + k Each sampling point relative to UTC absolute time T utc precise time T now It can be represented as: (2); In the formula, k This is the count value of the current sampling point relative to the start point of the second pulse. δ jitter This provides nanosecond-level instruction latency error compensation. By embedding time anchors in the raw data stream in real time, the system achieves physical alignment of the acquired data with the short message location trajectory on the time axis, resolving the data timing disorder problem caused by heterogeneous modules.

[0035] The core technological advancement of this invention lies in the fact that, when the buffer is full and data processing is triggered, the microprocessor does not employ the traditional blocking serial processing method, but instead implements an asymmetric asynchronous parallel data processing strategy. Specifically, the system logically divides the raw data stream into a full storage link and an edge evaluation link. On the main storage link, the system prioritizes the configuration of an SDIO controller, utilizing the peripheral direct memory access (DMA) channel to write the full transient electromagnetic waveforms in the buffer into a high-speed binary raw stream to the physical storage medium (SD card). This process does not involve any data tampering or lossy compression, ensuring the absolute integrity of the raw data required for subsequent deep inversion. Simultaneously, on the edge evaluation branch link, the microprocessor utilizes the system's remaining idle computing power to perform real-time feature extraction on data copies in the same buffer. Given the extremely low bandwidth characteristics of satellite communication links, this branch link actively discards redundant waveform data, extracting only the key statistical features of the late channels of each attenuation curve through a preset truncation window downsampling strategy. Furthermore, to eliminate potential risks posed by complex calculations to high-speed concurrent writes, the system incorporates a dynamic load balancing mechanism: once the SD card bus write latency approaches the threshold or memory stack consumption is too rapid, the system adaptively reduces the sampling evaluation frequency of the edge evaluation link, forcibly relinquishing computing resources to prioritize the continuity of the main storage task. This clear prioritization design ensures that core feature vectors characterizing the current spatial point observation quality are successfully extracted without missing any original high-frequency sampling data, thus providing a reliable data source for short-message adaptive telemetry.

[0036] Semi-airborne transient electromagnetic systems generate massive amounts of raw waveform data during flight data acquisition. Due to the extremely narrow downlink bandwidth of the BeiDou short message communication system (typically only tens of bytes per message), direct transmission of the raw waveforms is impossible. Therefore, this invention proposes a lightweight feature extraction algorithm executed within a microcontroller. By focusing on late-stage channel data that is most sensitive to noise, it achieves dynamic evaluation of the current operation quality. Specifically, it includes: (1) Precise definition of the time window for late-stage trait.

[0037] In the physical mechanism of transient electromagnetic methods, the electromagnetic response of the subsurface medium exhibits an exponential decay process of the secondary field after the transmitting current is turned off. Early trace data signals have large amplitudes, primarily reflecting shallow geoelectric characteristics; while late trace data signals are extremely weak, reflecting deep geological information but also highly susceptible to interference from external electromagnetic fields or sudden changes in aircraft attitude. Therefore, the purity of late trace signals is the best indicator of the validity of electromagnetic data across all time periods.

[0038] This system incorporates synchronous interception logic within the microcontroller, using the instant the transmitter shuts down as the time reference point. t=0, the microcontroller uses an internal high-frequency timer to perform a preset delay. t start Then open the quality evaluation observation window, and in t end The window is closed here. This observation window avoids the early strong signal phase and specifically captures the tail sequence where pure background noise overlaps with a weak secondary field. Assume that within this window, the ADC acquires a total of [number missing] samples at a fixed frequency. N A discrete voltage sequence of points, denoted as set. V ={ V 1, V 2,..., V N}

[0039] (2) A joint evaluation model based on residual statistics and morphological discrimination.

[0040] To quickly arrive at quality conclusions under limited microcontroller computing power, this invention employs a joint mathematical model based on root mean square residuals (RMS) and curve monotonicity detection. Thanks to the hardware floating-point unit (FPU) built into the main control chip, this algorithm can be completed in real-time during the asynchronous intervals of data writing to the SD card.

[0041] First, to address the random broadband noise caused by electromagnetic interference, the system calculates the local mean of the voltage sequence within the late observation window. With root mean square error (RMS): (3); (4); The RMS value directly reflects the energy level of the background noise. If there are low-frequency distortions caused by drastic changes in aircraft attitude, coil wind noise caused by complex airflow, or high-frequency noise introduced due to poor connection of the receiving coil caused by vibration during the current semi-aerial operation, the RMS value will increase by an order of magnitude.

[0042] Secondly, to address the low-frequency attitude noise caused by severe aircraft turbulence, the system introduces a morphological monotonicity penalty mechanism. Ideally, the late-stage TEM decay curve should remain monotonically decreasing in a logarithmic coordinate system. The system performs first-order difference calculations on adjacent sampling points within the window: (5); If it appears D i A non-monotonic anomalous jump with a voltage <0 (i.e., the voltage at the later time step is abnormally higher than that at the previous time step) is considered a distortion point. The system counts the total number of distortion points within the observation window, denoted as . C err Ultimately, the system constructs a comprehensive penalty function that reflects the degree of degradation of the current frame data.F penalty : (6); In the formula, α , β , γ All are weighting coefficients calibrated based on actual sensor sensitivity and flight conditions. (Through the exponential term) The introduction of this algorithm gives it extremely high sensitivity to structural distortions that disrupt the monotonicity of data.

[0043] (3) Dimension reduction and quantification mapping of quality evaluation index.

[0044] Calculate Then, the system must reduce the status word from a continuous floating-point number to a very small number of bytes to meet the requirements for sending short messages.

[0045] The microcontroller internally presets a set of threshold boundaries based on historical statistics. and ), and generate a 2-bit final quality evaluation index through discretization mapping logic: like This indicates that the late signal is smooth and has extremely low noise, which the system judges as a good state, and the quantization mapping is 0x00 (which is subsequently presented as a green trajectory point on the monitoring end). like This indicates the presence of a slight, controllable disturbance. The system determines the condition to be good and the quantization mapping is 0x01 (yellow trajectory point). like This indicates that the data has been severely contaminated or has experienced a loose connection failure. The system determines this as "poor status / invalid" and assigns a quantization mapping of 0x02 (red warning point).

[0046] Through the aforementioned edge computing mechanism, this invention successfully compresses the bulky and untransmittable original waveform data into a high-density quality feature status word that occupies only a few bits, realizing the core telemetry concept of transmitting only conclusions and not data in semi-aerial exploration.

[0047] Given that commercial BeiDou short message terminals, in their reporting mode, require the payload to be input via serial port in plaintext format (hexadecimal characters), and cannot directly transmit native floating-point numbers, this system establishes a dedicated dimensionality reduction and transcoding mechanism within the receiver's microcontroller.

[0048] When the preset 2-minute reporting cycle arrives, the microcontroller immediately performs transcoding and packaging actions: First, it removes redundant NMEA protocol punctuation, multiplies the parsed high-precision latitude and longitude coordinates by a fixed scaling factor to convert them into unsigned long integers, and then maps them into compact fixed-length hexadecimal strings through an algorithm; Second, it directly maps the electromagnetic data quality evaluation index calculated in the third part into a single-feature-bit hexadecimal character.

[0049] Finally, the system concatenates a hexadecimal string representing absolute spatial coordinates with a hexadecimal character representing the current data acquisition quality, according to a preset protocol, to generate a fixed-length pure character instruction, which is then pushed into the short message module's serial port. This standardized packetization method perfectly meets the underlying transmission requirements of commercial communication terminals, achieving synchronous reporting of spatial location and underlying electromagnetic signal quality within extremely narrow bandwidths.

[0050] After the telemetry character stream is transmitted downlink via satellite and pushed to the cloud, this system deploys a stream parsing network based on the MQTT subscription mechanism at the remote monitoring end. At the monitoring end, the Python data processing engine, acting as an MQTT client, connects to the specified topic and continuously listens for the message stream pushed by the satellite equipment. Once data arrival is detected, the Python program immediately performs reverse parsing and unpacking, restoring it to physical latitude, longitude, and status scores, and drives the front-end Geographic Information System (GIS) components in real time to perform trajectory visualization and redrawing.

[0051] The front-end drawing logic is strongly tied to the parsed quality index: the program automatically maps the latest acquired coordinates to different primitives based on the QCScore (e.g., good quality points are rendered as green markers, while data distortion or significant interference is rendered as red highlighted markers), and automatically constructs the aircraft's motion vector using blue lines. Furthermore, the program internally builds an automatic circular queue that continuously retains and refreshes spatial trajectory data from the past 24 hours.

[0052] Through this satellite-MQTT-Python front-end collaborative link, ground operators can monitor the three-dimensional position, anti-loss status, and validity of electromagnetic exploration data of the semi-aerial system in areas without public network coverage in real time, simply by looking at a remote screen. This completely changes the traditional semi-aerial blind mining working mode.

[0053] This implementation proposes a semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry system, comprising: a spatiotemporal reference generation unit, used to acquire the second pulse signal and positioning message output by the communication terminal to generate a nanosecond-level time reference; a data acquisition and splitting unit, used to control the operation of the acquisition equipment based on the nanosecond-level time reference and asynchronously transfer and split the acquired data between two buffers; an edge computing unit, used to extract late-channel signal features from the split data copy and generate a data quality evaluation index; and a telemetry communication unit, used to package the data quality evaluation index and positioning coordinates and send them via the communication terminal.

[0054] In this implementation, the spatiotemporal reference generation unit includes a microcontroller and a multiplexed communication terminal; the general-purpose serial bus interface of the communication terminal is connected to the serial communication interface of the microcontroller for outputting positioning messages; the second pulse output terminal of the communication terminal is hardwired to the external interrupt pin and timer capture channel of the microcontroller; the microcontroller is configured to trigger a hardware interrupt when the rising edge of the second pulse signal is detected, force calibration of the local timer, and perform absolute second alignment in conjunction with the positioning message; The data acquisition and splitting unit includes an analog-to-digital converter, a direct memory access controller, and a double-buffered memory. The sampling output of the analog-to-digital converter is connected to the data source address of the direct memory access controller. The double-buffered memory includes a first storage area and a second storage area. The direct memory access controller is configured to trigger a half-full interrupt when the first storage area is full, and automatically switch the data flow to the second storage area. While the central processing unit processes the data in the first storage area, the direct memory access controller continues to fill the second storage area with newly acquired data.

[0055] In summary, this system reconstructs the underlying hardware topology, reuses the positioning function of the BeiDou short message module, and directly introduces its output 1PPS pulse signal and NMEA message into the electromagnetic receiver. When the receiver detects the 1PPS rising edge, it immediately triggers a microcontroller hardware interrupt, forcibly calibrating the local timer and performing absolute second alignment. This combination of second-level hard reset and sub-second-level local interpolation eliminates clock drift between heterogeneous communication modules and the receiver at the physical level, ensuring that the original high-frequency electromagnetic data and spatial trajectory coordinates share the same satellite absolute time reference, achieving high-precision spatial marking at the nanosecond to microsecond level.

[0056] To address the conflict between the high-frequency sampling rate of tens of thousands of hertz and the computing power of the microcontroller, the system is designed with a high-speed asynchronous data distribution mechanism based on direct memory access (DMA) and symmetric dual buffers (A and B). The system decouples the data flow: the main backbone uses SDIO / DMA channels to prioritize writing the full original binary stream to the SD card without loss to ensure deep inversion requirements; the edge computing branch utilizes the microprocessor's idle computing power to perform feature extraction on data copies. The system also incorporates a dynamic load balancing mechanism, proactively relinquishing computing resources when storage resources are scarce, ensuring that the continuous acquisition and processing of massive amounts of high-frequency data do not block each other.

[0057] To achieve real-time quality control in areas lacking public networks, the system constructs a joint evaluation model at the microcontroller front end, combining residual root mean square (RMS) and curve monotonicity detection for the time window of late-stage channel signals susceptible to noise. This model quantizes the degradation level of the original waveform into a 2-bit quality evaluation index (Excellent, Good, Poor). Subsequently, the system compresses and packages the processed spatial coordinates and signal quality status words into a fixed-length hexadecimal character stream, which is transmitted back via a short message link. The ground control center can then use the MQTT protocol and Python engine to analyze and visualize the UAV's 3D spatial trajectory and the validity of the current observation data in real time.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method, characterized in that, Includes the following processes: The system acquires the location message and second pulse signal output by the communication terminal, uses the second pulse signal to trigger a hardware interrupt to force calibration of the local timer, and combines the location message to perform absolute second alignment to generate a nanosecond-level time reference. Based on a nanosecond-level time base, the direct memory access controller asynchronously transfers and splits the high-frequency electromagnetic data of the acquisition device between two buffers. The late channel signal time window is extracted from the data copy after diversion, the root mean square of the background noise and the monotonic distortion point of the curve are calculated, and a data quality evaluation index is generated. The data quality evaluation index and the parsed positioning coordinates are packaged into a telemetry command and sent to the cloud monitoring terminal via a communication terminal.

2. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 1, characterized in that, Acquire the location message and second pulse signal output by the communication terminal, including: The receiver's original independent positioning module is removed, and the positioning unit integrated in the communication terminal is reused; The baud rate of the positioning message output by the communication terminal can be dynamically modified through the wireless configuration service. The second pulse signal output by the communication terminal is connected to the external interrupt pin and timer capture channel of the microcontroller.

3. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 1, characterized in that, A hardware interrupt is triggered using a second pulse signal to force calibration of the local timer, and absolute second alignment is performed in conjunction with the location message to generate a nanosecond-level time base, including: When the rising edge of the second pulse signal is detected, the highest priority hardware interrupt of the microcontroller is triggered. Use an interrupt service routine to forcibly clear and calibrate the count value of the local sub-second timer; Extract the Coordinated Universal Time (UTC) absolute timestamp from the location message and concatenate it with the local zeroed count value to generate a continuous nanosecond-level time base.

4. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 1, characterized in that, Based on a nanosecond-level time base, the direct memory access controller asynchronously transfers and distributes the high-frequency electromagnetic data from the acquisition device between two buffers, including: Create a first buffer and a second buffer in the memory; The direct memory access controller is used to automatically move the sampled data from the acquisition device to the current free buffer. When the current buffer is full, a half-full interrupt is triggered, which switches the pointer of the direct memory access controller to another buffer; While the direct memory access controller fills the switched buffer with data, it frees up the central processing unit to process the data in the full buffer.

5. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 4, characterized in that, Release the CPU from processing data in the full buffer, including: Prioritize the configuration of a secure digital input / output controller, and use the direct memory access channel to write the full transient electromagnetic waveform in the full-load buffer into the storage medium in the form of a binary raw stream without loss. Simultaneously, the idle computing power of the central processing unit is utilized to perform late-stage signal interception and feature extraction on the data copies in the full-load buffer.

6. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 5, characterized in that, Perform late-channel signal truncation and feature extraction on the data copies within the full buffer, including: Using the instant the launcher shuts down as the time reference point, the quality evaluation observation window is opened after a preset delay time; Extract the set of voltage sequences within the quality assessment observation window; Calculate the local mean and root mean square error of the voltage sequence set as an indicator of the background noise energy; Perform first-order difference calculations on the voltage sequence set to count the total number of distortion points where abnormal voltage jumps occur between adjacent sampling points.

7. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 6, characterized in that, Calculate the background noise energy and the monotonicity distortion point of the curve to generate a data quality evaluation index, including: Construct a comprehensive penalty function, which includes a root mean square error term, a total number of distortion points term, and a preset weighting coefficient. Calculate the value of the comprehensive penalty function; The function value is compared with a preset threshold boundary, and the data quality is mapped to a two-bit quantized status word based on the comparison result.

8. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry method as described in claim 1, characterized in that, The data quality evaluation index and the parsed positioning coordinates are packaged into hexadecimal telemetry commands, including: Remove redundant punctuation marks from the location message and convert the latitude and longitude coordinates to unsigned long integers by multiplying them by a preset scaling factor; Concatenate the unsigned long integer coordinate data with the two-bit quantized status word according to the preset protocol order; The concatenated data stream is converted into a compact fixed-length hexadecimal string and pushed into the serial port of the communication terminal.

9. A semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry system, characterized in that, include: The time-space reference generation unit is used to acquire the second pulse signal and positioning message output by the communication terminal and generate a nanosecond-level time reference. The data acquisition and distribution unit is used to control the operation of the acquisition device based on a nanosecond-level time base, and to asynchronously transfer and distribute the acquired data between two buffers. The edge computing unit is used to extract late channel signal features from the offloaded data replicas and generate a data quality evaluation index. The telemetry communication unit is used to package the data quality evaluation index with the positioning coordinates and send them via the communication terminal.

10. The semi-airborne transient electromagnetic spatiotemporal synchronous real-time telemetry system as described in claim 9, characterized in that, The spatiotemporal reference generation unit includes a microcontroller and a multiplexed communication terminal; The universal serial bus interface of the communication terminal is connected to the serial communication interface of the microcontroller for outputting positioning messages; The second pulse output terminal of the communication terminal is hardwired to the external interrupt pin and timer capture channel of the microcontroller; The microcontroller is configured to trigger a hardware interrupt when a rising edge of the second pulse signal is detected, force calibration of the local timer, and perform absolute second alignment in conjunction with the positioning message; The data acquisition and splitting unit includes an analog-to-digital converter, a direct memory access controller, and a double-buffered memory; The sampling output of the analog-to-digital converter is connected to the data source address of the direct memory access controller; The double-buffered memory includes a first storage area and a second storage area; The direct memory access controller is configured to trigger a half-full interrupt when the first memory area is full, and automatically switch the data flow to the second memory area; While the central processing unit processes data in the first memory area, the direct memory access controller continues to fill newly acquired data into the second memory area.

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