A fast storage method for passive microwave radiation measurement of unmanned aerial vehicles

Abstract

The invention discloses a fast storage method for passive microwave radiation measurement of unmanned aerial vehicle, comprising the following steps: step one, building a hardware system; step two, data acquisition; step three, data preprocessing and encoding; step four, data storage; the invention adopts an SD dual polling writing method based on timer triggering under a multi-task framework, and realizes stable, reliable and high-speed SD storage under the uninterrupted acquisition requirements of an unmanned aerial vehicle-borne microwave radiometer by adopting time-sharing processing technology and a polling structure, solves the data storage problem during the continuous acquisition of unmanned aerial vehicle passive microwave radiation measurement, can greatly reduce the time occupied by storage without affecting the normal sampling task of the unmanned aerial vehicle-borne radiometer, ensures the spatial continuity of ground data, and is beneficial to subsequent data processing and image stitching, and the method has good portability. In addition to the unmanned aerial vehicle radiometer, it can also be used to improve the data storage efficiency under the multi-task framework.

Description

Technical Field

[0001] The invention relates to the technical field of information storage, and in particular to a fast storage method for passive microwave radiation measurement of an unmanned aerial vehicle. Background Art

[0002] Microwave radiometer is a high-sensitivity broadband noise receiver working in the microwave band. It can extract the change of weak microwave radiation signal in the strong background noise. It mainly processes Gaussian white noise radiated by ground objects. UAV-borne microwave radiometer has the advantages of high spatial resolution, convenient operation, strong real-time performance and low cost. It can observe brightness temperature at the scale of plots, provide data support for soil moisture monitoring and snow observation model inversion and satellite ground verification, fill the gap that the low resolution (~25km) of satellite-borne radiometer cannot meet the small and medium-scale applications, and solve the defects of ground-based radiometer with small observation range, poor mobility and easy to be restricted by terrain.

[0003] The detection sensitivity of a microwave radiometer is related to the receiver bandwidth and integration time. The larger the product of bandwidth and integration time, the higher the sensitivity. However, there are various limitations in the actual design. For example, the International Telecommunication Union's regulations on the use of various frequency bands result in the bandwidth of the microwave radiometer not being too large, especially for the L and S frequency bands with more uses. One of the most important advantages of drone-borne data is its high temporal and spatial resolution, which also means that the integration time will not be too long. High-speed acquisition can enable drone-borne microwave radiometers to obtain microwave remote sensing data with higher temporal and spatial resolution, and help detect and suppress radio frequency interference. For rapidly changing ground targets, in order to ensure data quality and achieve interference detection and suppression, it is necessary to reduce the integration time and increase the sampling frequency, but the resulting large amount of data also makes online transmission impossible. Summary of the invention

[0004] The purpose of the present invention is to provide a fast storage method for passive microwave radiation measurement of unmanned aerial vehicles, so as to solve the problem that the high sampling rate proposed in the above background technology makes it impossible to allocate a large amount of continuous time for data storage, and the traditional storage method cannot meet the problem of fast data storage under a multi-task framework.

[0005] To achieve the above object, the present invention provides the following technical solution: a fast storage method for passive microwave radiation measurement of unmanned aerial vehicle, comprising the following steps: step 1, building a hardware system; step 2, data collection; step 3, data preprocessing and encoding; step 4, data storage;

[0006] In the above step one, the hardware system of the passive microwave radiation measurement device of the unmanned aerial vehicle is first built. The hardware system specifically includes an antenna, a matching load, a radio frequency switch, a first low-noise amplifier, a bandpass filter, a second low-noise amplifier, a mixing circuit, an intermediate frequency amplifier, a variable gain amplifier, a square-law detector, a video amplifier, an AD sampling unit, a microcontroller unit MCU, a temperature measurement unit, an SD memory, a DA control circuit and a GPS module.

[0007] In the above step 2, the following steps are specifically included:

[0008] 2.1 Measure the brightness temperature of the target object through the antenna to obtain the brightness temperature signal of the target object;

[0009] 2.2 Measure the temperature of the matching load and each internal device through the temperature measurement unit to obtain the temperature signal of the matching load and each internal device;

[0010] 2.3 Obtain the flight attitude information of the drone through the GPS module and obtain the GPS signal, where the flight attitude information includes time, longitude and latitude, altitude, heading angle and speed;

[0011] In the above step 3, the following steps are specifically included:

[0012] 3.1 The brightness temperature signal of the target object obtained in step 2.1 is mixed, amplified, detected and AD sampled, and then transmitted to the microcontroller unit MCU through the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding;

[0013] 3.2 The temperature signals of the matching load and each internal device obtained in step 2.2 are transmitted to the microcontroller unit MCU via the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding;

[0014] 3.3 After the GPS signal obtained in step 2.3 is converted into RS232 standard level, the TTL level is converted into RS232 standard level, and the serial port of the microcontroller unit MCU is connected for communication. The data format adopts NMEA0183 protocol, and the microcontroller unit MCU performs preprocessing and encoding;

[0015] In the above step 4, the microcontroller unit MCU adopts a timer-triggered SD dual polling storage method (DPSM) to write the pre-processed and encoded data in step 3 into the SD memory to achieve data storage.

[0016] Preferably, in step one, the microcontroller unit MCU is electrically connected to an AD sampling unit, a DA control circuit, a temperature measurement unit, an SD memory, a GPS module and a radio frequency switch, the radio frequency switch is electrically connected to an antenna, a matching load and a first low noise amplifier, the first low noise amplifier is electrically connected to a bandpass filter, the bandpass filter is electrically connected to a second low noise amplifier, the second low noise amplifier is electrically connected to a mixing circuit, the mixing circuit is electrically connected to a local oscillator and an intermediate frequency amplifier, the intermediate frequency amplifier is electrically connected to a variable gain amplifier, and the variable gain amplifier is electrically connected to the DA control circuit, the variable gain amplifier is electrically connected to a square-law detector, the square-law detector is electrically connected to a video amplifier, and the video amplifier is electrically connected to the AD sampling unit.

[0017] Preferably, the SD memory is connected to the MCU via a secure digital input and output (SDIO) interface, and the SD memory adopts a direct memory access (DMA) mode.

[0018] Preferably, the microcontroller unit MCU adopts an STM32F103ZET6 chip, the AD sampling unit adopts an AD7866 chip, the DA control circuit adopts a MAX532 chip, the GPS module adopts a NEO-M8N module, and the temperature measurement unit adopts a DS18B20 temperature sensor.

[0019] Preferably, in step 4, the data storage step includes setting the block size, obtaining the SD memory state, setting the write address, selecting and enabling the device mode, and waiting for the card programming to be completed. The first four steps are defined as process 1, and waiting for the card programming to be completed is defined as process 2. A write status flag (WSF) and a write completion flag (WFF) are defined. I and J in the structure (I, J) are defined to represent the values ​​of WSF and WFF respectively. Here, the state (4, 4) represents that the write status flag is 4 and the write completion flag is 4. Then, the data storage process of the microcontroller unit MCU based on the SD double polling write method triggered by the timer is as follows:

[0020] 4.1 The main program polls the write status flag to determine whether the last write operation is completed. If not, it means that the write has timed out, and returns "storage failed" and initializes, and the flag is cleared; if completed, it is initialized directly and the flag is cleared;

[0021] 4.2 Wait for data collection to be ready, complete encoding, set WSF to 1, and start storage;

[0022] 4.3 When the main program is running in an infinite loop, the program will continuously enter the timer interrupt, that is, when the timer runs to a certain number of times, the timer interrupt update flag will be set to 1, and then enter the timer interrupt; each time the interrupt is entered, it will poll whether the write status flag is set. If it is set, the state is (1, 0) at this time, and 4.4 is performed; if it is not set, wait for the next timer interrupt, and the timer interrupt threshold is set to the frequency of the AD acquisition unit;

[0023] 4.4 The write status flag is incremented immediately, and the data block 1 process 1 operation is performed; when the process is completed, the write completion flag is incremented and the next operation is entered. At this time, the state is (2, 1);

[0024] 4.5 When the flag bit is judged to be (2, 1), data block 1 process 2 is written and the write completion flag bit is polled to determine whether the block writing is completed. If completed, the write completion flag bit is incremented and enter 4.6. At this time, the state is (2, 2); otherwise, the interrupt is directly jumped out and wait for the next polling;

[0025] 4.6 For the data block 2 writing process, repeat the above process 1 and process 2 operations, and the writing flag status is completed to (3, 4);

[0026] 4.7 polls the flag bit and waits for the above process to be completed. The write status flag bit is incremented. At this time, the state is (4, 4). At this point, the entire write process is completed and returns to 4.1.

[0027] Preferably, the underlying logic of waiting for the completion of card programming adopts a polling query flag structure, specifically: in the first polling, the main function acts as a server, and sends a request for querying the flag after a time interval of the entire sampling cycle to determine whether the writing process is completed; in the second polling, the timer interrupt is used as a server, and it sends a request for querying the flag after a time interval of the sampling cycle to determine the progress of the storage process, and checks the card status to determine whether the card programming step is completed.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts an SD dual polling writing method based on timer triggering under a multi-task framework, and by adopting time-sharing processing technology and polling structure, it realizes stable, reliable and high-speed SD storage under the uninterrupted acquisition requirements of the drone-borne microwave radiometer, solves the data storage problem during the continuous acquisition of drone passive microwave radiation measurement, and can greatly reduce the time occupied by storage without affecting the normal sampling task of the drone-borne radiometer, ensuring the spatial continuity of ground data, which is beneficial to subsequent data processing and image stitching. The method has good portability and can be used to improve the data storage efficiency under the multi-task framework in addition to the drone radiometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a flow chart of the method of the present invention;

[0030] Figure 2 It is a hardware system block diagram of the present invention;

[0031] Figure 3 This is a schematic diagram of the SDIO interface of the present invention;

[0032] Figure 4 It is the GPS module analysis flow chart of the present invention;

[0033] Figure 5 It is the timing diagram of three storage modes under the fast acquisition task;

[0034] Figure 6 It is a storage logic flow chart of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] See also Figure 1-6 , an embodiment provided by the present invention: a fast storage method for passive microwave radiation measurement of unmanned aerial vehicles, comprising the following steps: step 1, building a hardware system; step 2, data collection; step 3, data preprocessing and encoding; step 4, data storage;

[0037] In the above step one, the hardware system of the passive microwave radiation measuring device of the unmanned aerial vehicle is firstly built, and the hardware system specifically includes an antenna, a matching load, a radio frequency switch, a first low noise amplifier, a band pass filter, a second low noise amplifier, a mixing circuit, an intermediate frequency amplifier, a variable gain amplifier, a square law detector, a video amplifier, an AD sampling unit, a micro control unit MCU, a temperature measurement unit, an SD memory, a DA control circuit and a GPS module. The micro control unit MCU is electrically connected to the AD sampling unit, the DA control circuit, the temperature measurement unit, the SD memory, the GPS module and the radio frequency switch. The radio frequency switch is electrically connected to the antenna, the matching load and the first low noise amplifier. The first low noise amplifier is electrically connected to the band pass filter. The band pass filter is electrically connected to the second low noise amplifier. The device is electrically connected to a mixing circuit, the mixing circuit is electrically connected to a local oscillator and an intermediate frequency amplifier, the intermediate frequency amplifier is electrically connected to a variable gain amplifier, and the variable gain amplifier is electrically connected to a DA control circuit, the variable gain amplifier is electrically connected to a square law detector, the square law detector is electrically connected to a video amplifier, and the video amplifier is electrically connected to an AD sampling unit; wherein the SD memory is connected to the MCU via a secure digital input and output (SDIO) interface, and the SD memory adopts a direct memory access (DMA) mode; the microcontroller unit MCU adopts an STM32F103ZET6 chip, the AD sampling unit adopts an AD7866 chip, the DA control circuit adopts a MAX532 chip, the GPS module adopts a NEO-M8N module, and the temperature measurement unit adopts a DS18B20 temperature sensor;

[0038] In the above step 2, the following steps are specifically included:

[0039] 2.1 Measure the brightness temperature of the target object through the antenna to obtain the brightness temperature signal of the target object;

[0040] 2.2 Measure the temperature of the matching load and each internal device through the temperature measurement unit to obtain the temperature signal of the matching load and each internal device;

[0041] 2.3 Obtain the flight attitude information of the drone through the GPS module and obtain the GPS signal, where the flight attitude information includes time, longitude and latitude, altitude, heading angle and speed;

[0042] In the above step 3, the following steps are specifically included:

[0043] 3.1 The brightness temperature signal of the target object obtained in step 2.1 is mixed, amplified, detected and AD sampled, and then transmitted to the microcontroller unit MCU through the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding;

[0044] 3.2 The temperature signals of the matching load and each internal device obtained in step 2.2 are transmitted to the microcontroller unit MCU via the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding;

[0045] 3.3 After the GPS signal obtained in step 2.3 is converted into RS232 standard level, the TTL level is converted into RS232 standard level, and the serial port of the microcontroller unit MCU is connected for communication. The data format adopts NMEA0183 protocol, and the microcontroller unit MCU performs preprocessing and encoding;

[0046] In the above step 4, the microcontroller unit MCU adopts the SD dual polling writing method based on timer triggering. Method, DPSM), write the data preprocessed and encoded in step 3 into the SD memory to realize data storage. The steps of data storage include setting block size, obtaining SD memory status, setting write address, selecting and enabling device mode and waiting for card programming to be completed. The underlying logic of waiting for card programming to be completed adopts a polling query flag structure, specifically: in the first polling, the main function acts as a server, and sends a request for querying the flag after a time interval of the entire sampling cycle to determine whether the writing process is completed; in the second polling, the timer interrupt is used as a server, and it sends a request for querying the flag after a time interval of the sampling cycle to determine the progress of the storage process, and checks the card status to determine whether the card programming step is completed; define the first four steps as process 1, define waiting for card programming to be completed as process 2, define a write status flag (WSF) and a write completion flag (WFF), define I and J in the structure (I, J) to represent the values ​​of WSF and WFF respectively, here the state (4, 4) represents that the write status flag is 4 and the write completion flag is 4, then the data storage process of the microcontroller unit MCU based on the SD double polling write method triggered by the timer is:

[0047] 4.1 The main program polls the write status flag to determine whether the last write operation is completed. If not, it means that the write has timed out, and returns "storage failed" and initializes, and the flag is cleared; if completed, it is initialized directly and the flag is cleared;

[0048] 4.2 Wait for data collection to be ready, complete encoding, set WSF to 1, and start storage;

[0049] 4.3 When the main program is running in an infinite loop, the program will continuously enter the timer interrupt, that is, when the timer runs to a certain number of times, the timer interrupt update flag will be set to 1, and then enter the timer interrupt; each time the interrupt is entered, it will poll whether the write status flag is set. If it is set, the state is (1, 0) at this time, and 4.4 is performed; if it is not set, wait for the next timer interrupt, and the timer interrupt threshold is set to the frequency of the AD acquisition unit;

[0050] 4.4 The write status flag is incremented immediately, and the data block 1 process 1 operation is performed; when the process is completed, the write completion flag is incremented and the next operation is entered. At this time, the state is (2, 1);

[0051] 4.5 When the flag bit is judged to be (2, 1), data block 1 process 2 is written and the write completion flag bit is polled to determine whether the block writing is completed. If completed, the write completion flag bit is incremented and enter 4.6. At this time, the state is (2, 2); otherwise, the interrupt is directly jumped out and wait for the next polling;

[0052] 4.6 For the data block 2 writing process, repeat the above process 1 and process 2, and the writing flag status is completed to (3, 4);

[0053] 4.7 polls the flag bit and waits for the above process to be completed. The write status flag bit is incremented. At this time, the state is (4, 4). At this point, the entire write process is completed and returns to 4.1.

[0054] The method provided in the above embodiment is used to perform an experimental comparison with storage in the main program (using Main Function Storage Method, MFSM) and storage in an interrupt with a higher priority (using Interrupt Triggered Storage Method, ITSM). The results are shown in the following table:

[0055]

[0056]

[0057] Based on the above, the advantages of the present invention are that the SD dual polling writing mode (DPSM) based on timer triggering proposed in the present invention adopts time-sharing processing technology, divides the running time of the processor into short time periods, reasonably arranges the time of sampling tasks, data processing tasks, data encoding tasks and data storage tasks, makes full use of resources, and improves resource utilization; at the same time, the idea of ​​the web solution polling structure is applied to the program, and the single-core single-threaded MCU is simulated as a multi-threaded MCU with the help of the DMA device mode. Compared with storing in the main program and storing in a higher priority interrupt, the storage process will not delay the entire sampling cycle, the total time consumption is reduced by 90-95%, and the time consumption of the card programming step is reduced by 93-99%, which greatly saves the timing of storage occupancy; applying this method to the drone microwave radiometer can ensure that the radiometer performs high-frequency sampling at equal intervals in time as much as possible, and stores it in real time, ensuring the spatial continuity of the ground data, which is beneficial to subsequent data processing and image stitching; and the storage method has good portability. In addition to the drone radiometer, it can also be used to improve the data storage efficiency under the multi-task framework.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A rapid storage method for passive microwave radiation measurement of an unmanned aerial vehicle, comprising the following steps: Step 1: build the hardware system; Step 2: data collection; Step 3: data preprocessing and encoding; Step 4: data storage; It is characterized by: In the above step 1, the hardware system of the passive microwave radiation measurement device of the unmanned aerial vehicle is firstly built, and the hardware system specifically includes an antenna, a matching load, a radio frequency switch, a first low noise amplifier, a bandpass filter, a second low noise amplifier, a mixing circuit, an intermediate frequency amplifier, a variable gain amplifier, a square law detector, a video amplifier, an AD sampling unit, a micro control unit MCU, a temperature measurement unit, an SD memory, a DA control circuit and a GPS module; In the above step 2, the following steps are specifically included: 2.1 Measure the brightness temperature of the target object through the antenna to obtain the brightness temperature signal of the target object; 2.2 Measure the temperature of the matching load and each internal component through the temperature measurement unit to obtain the temperature signal of the matching load and each internal component; 2.3 Obtain the flight attitude information of the drone through the GPS module and obtain the GPS signal, where the flight attitude information includes time, longitude and latitude, altitude, heading angle and speed; In the above step 3, the following steps are specifically included: 3.1 The brightness temperature signal of the target object obtained in step 2.1 is mixed, amplified, detected and AD sampled, and then transmitted to the microcontroller unit MCU through the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding; 3.2 The temperature signals of the matching load and each internal device obtained in step 2.2 are transmitted to the microcontroller unit MCU via the SPI interface, and the microcontroller unit MCU performs preprocessing and encoding; 3.3 After the GPS signal obtained in step 2.3 is converted into RS232 standard level, the TTL level is converted into RS232 standard level, and the serial port of the microcontroller unit MCU is connected for communication. The data format adopts NMEA0183 protocol, and the microcontroller unit MCU performs preprocessing and encoding; In the above step 4, the microcontroller unit MCU adopts a timer-triggered SD dual polling storage method (DPSM) to write the pre-processed and encoded data in step 3 into the SD memory to achieve data storage; In the step 4, the data storage steps include setting the block size, obtaining the SD memory status, setting the write address, selecting and enabling the device mode, and waiting for the card programming to be completed. The first four steps are defined as process 1, and waiting for the card programming to be completed is defined as process 2. The write status flag (WSF) and the write completion flag (WFF) are defined. I and J in the definition structure (I, J) represent the values ​​of WSF and WFF respectively. Here, the state (4, 4) represents that the write status flag bit is 4 and the write completion flag bit is 4. The data storage process of the microcontroller unit MCU based on the SD double polling write method triggered by the timer is: 4.1 The main program polls the write status flag to determine whether the last write operation is completed. If not, it means that the write has timed out, and returns "storage failure" and initializes, and the flag is cleared; if completed, it is initialized directly and the flag is cleared; 4.2 Wait for data collection to be ready, complete encoding, set WSF to 1, and start storage; 4.3 When the main program runs in an infinite loop, the program will continuously enter the timer interrupt, that is, when the timer runs to a certain number of times, the timer interrupt update flag will be set to 1, and then enter the timer interrupt; each time the interrupt is entered, it will poll whether the write status flag is set. If it is set, the state is (1, 0) at this time, and 4.4 is performed; if it is not set, wait for the next time to enter the timer interrupt, and the timer interrupt threshold is set to the frequency of the AD acquisition unit; 4.4 The write status flag is incremented immediately, and the data block 1 process 1 operation is performed; when the process is completed, the write completion flag is incremented and the next operation is entered. At this time, the status is (2, 1); 4.5 When the flag bit is judged as (2, 1), data block 1 process 2 is written and the write completion flag is polled to determine whether the block writing is completed. If completed, the write completion flag is incremented and enter 4.

6. At this time, the state is (2, 2); otherwise, the interrupt is directly jumped out and wait for the next polling; 4.6 For the data block 2 writing process, repeat the above process 1 and process 2 operations, and the writing flag status is completed to (3, 4); 4.7 polls the flag bit and waits for the above process to be completed. The write status flag bit is incremented. At this time, the state is (4, 4). At this point, the entire write process is completed and returns to 4.

1.

2. The rapid storage method for passive microwave radiation measurement of an unmanned aerial vehicle according to claim 1 is characterized by: In the step one, the microcontroller unit MCU is electrically connected to an AD sampling unit, a DA control circuit, a temperature measurement unit, an SD memory, a GPS module and a radio frequency switch, the radio frequency switch is electrically connected to an antenna, a matching load and a first low noise amplifier, the first low noise amplifier is electrically connected to a band pass filter, the band pass filter is electrically connected to a second low noise amplifier, the second low noise amplifier is electrically connected to a mixing circuit, the mixing circuit is electrically connected to a local oscillator and an intermediate frequency amplifier, the intermediate frequency amplifier is electrically connected to a variable gain amplifier, and the variable gain amplifier is electrically connected to the DA control circuit, the variable gain amplifier is electrically connected to a square law detector, the square law detector is electrically connected to a video amplifier, and the video amplifier is electrically connected to the AD sampling unit.

3. The rapid storage method for passive microwave radiation measurement of an unmanned aerial vehicle according to claim 2 is characterized by: The SD memory is connected to the MCU via a secure digital input and output (SDIO) interface, and the SD memory adopts a direct memory access (DMA) mode.

4. The rapid storage method for passive microwave radiation measurement of an unmanned aerial vehicle according to claim 2 is characterized by: The microcontroller unit MCU adopts STM32F103ZET6 chip, the AD sampling unit adopts AD7866 chip, the DA control circuit adopts MAX532 chip, the GPS module adopts NEO-M8N module, and the temperature measurement unit adopts DS18B20 temperature sensor.

5. The rapid storage method for passive microwave radiation measurement of an unmanned aerial vehicle according to claim 1 is characterized by: The underlying logic of waiting for the completion of card programming adopts a polling query flag structure, specifically: in the first polling, the main function acts as a server, and sends a request for querying the flag after a time interval of the entire sampling cycle to determine whether the writing process is completed; in the second polling, the timer interrupt is used as a server, and it sends a request for querying the flag after a time interval of the sampling cycle to determine the progress of the storage process, and checks the card status to determine whether the card programming step is completed.

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