Manned and airborne microwave radiation measurement and calibration system

Abstract

The invention belongs to the field of aviation microwave remote sensing detection and data inversion precision evaluation, and relates to a manned and airborne microwave radiation measurement and calibration system, which comprises a microwave radiometer antenna feeder and receiver module, has two working modes of a traditional channel and a fine spectrum channel, and is used for receiving and separating scientific data with different frequencies; the temperature measurement calibration module adopts a high and low temperature calibration source double-source design, and realizes on-orbit real-time periodic temperature control calibration and temperature measurement through a PID control algorithm; the data acquisition and system control module is used for acquiring antenna state information, receiving and processing scientific data and temperature data, performing data packet validity judgment according to the data acquired by the GPS receiving module, sending various processed data to a data management subsystem, and receiving and executing a remote control instruction of the data management subsystem; the GPS receiving module is used for acquiring the geographic position and the flight speed of the manned aerial vehicle; and the data preprocessing and display module is used for processing and displaying various data results in the man-machine.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation microwave remote sensing detection and data inversion accuracy assessment, and in particular relates to a manned aircraft-borne microwave radiation measurement and calibration system. Background Art

[0002] Microwave radiometers passively receive radiation energy and express it in terms of brightness temperature (brightness temperature). Their theoretical basis is atmospheric radiation transmission. Atmospheric microwave radiation transmission detection first clarifies the attenuation law and related physical quantities during transmission in the medium. When electromagnetic waves pass through a certain medium, on the one hand, the radiation energy will attenuate due to the absorption of the medium and the scattering of the electromagnetic waves by the medium. On the other hand, the radiation energy is enhanced due to the multiple scattering and self-emission of the medium itself. The fine spectrum microwave atmospheric detection payload can penetrate the Earth's atmosphere and certain cloud and rain layers to measure microwave radiation of specific frequencies on the Earth. Since ice, clouds, rain, snow and other particles in the atmosphere have a certain attenuation effect on the surface microwave radiation, different atmospheric information can be obtained from different channels. Through calibration and inversion, an accurate description of the Earth's atmosphere can be obtained.

[0003] Manned aircraft with high-resolution and high-frequency acquisition capabilities have gradually become a new type of remote sensing platform. Compared with drones, manned aircraft have lower restrictions on the size, weight, and power consumption of payloads, and aerial remote sensing detection missions have obvious advantages in terms of working area range, working field, and detection capabilities.

[0004] Manned aircraft microwave radiometer is a passive microwave remote sensing device, mainly used for long-range aviation remote sensing platforms, to achieve rapid acquisition of microwave brightness temperature information in complex environments, and output meteorological parameters in a specified area through a series of subsequent processing. There is an urgent need for a manned aircraft microwave radiation measurement and calibration system that can cope with complex flight environments and achieve all-weather microwave atmospheric detection and data analysis. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and propose a manned aircraft-borne microwave radiation measurement and calibration system to achieve all-weather microwave atmospheric detection and data analysis.

[0006] In view of this, the present invention proposes a manned aircraft microwave radiation measurement and calibration system, including: a microwave radiometer antenna feed and receiver module, a temperature measurement and calibration module, a data acquisition and system control module, a GPS receiving module and a data preprocessing and display module, wherein:

[0007] The microwave radiometer antenna feed and receiver module has two working modes: traditional channel and fine spectrum channel, and receives and separates scientific data of different frequencies;

[0008] The temperature measurement and calibration module adopts a dual-source design of high and low temperature calibration sources, and is used to realize on-orbit real-time periodic temperature control calibration and temperature measurement through a PID control algorithm;

[0009] The data acquisition and system control module is used to collect antenna status information, receive and process scientific data and temperature data, determine the validity of data packets based on the data acquired by the GPS receiving module, send the processed data to the data control subsystem, and receive and execute remote control instructions of the data control subsystem;

[0010] The GPS receiving module is used to obtain the geographical location and flight speed of the manned aircraft;

[0011] The data preprocessing and display module is used to process and display various data results in the manned machine.

[0012] Preferably, the microwave radiometer antenna feed and receiver module adopts a scanning flat antenna and a fixed parabolic antenna, 50-60GHz is set as a horizontal polarization channel, 183GHz and 229GHz are vertical polarization channels, including a 50-60GHz receiver, a 166 / 183GHz receiver and a 229GHz receiver, and the antenna feed is connected to each receiver.

[0013] Preferably, the microwave radiometer antenna feed and receiver module use polarization wire grids and waveguide duplexers to achieve frequency separation of two frequency bands: 50-60 GHz and 166 / 183 GHz-229 GHz.

[0014] Preferably, the microwave radiometer antenna feed and receiver module includes a receiver unit, each frequency point receiver adopts a single sideband system, the local oscillator adopts a phase-locked technology, each frequency point receiver is added with a pre-LNA, and a filter is added near the frequency multiplier.

[0015] Preferably, the conventional channel is a filter bank channel, and the fine spectrum channel is a digital spectrometer channel with a bandwidth of 2 GHz.

[0016] Preferably, the temperature measurement and calibration module includes a calibration unit and a temperature control unit, wherein:

[0017] The calibration unit includes a high and low temperature calibration source, each of which includes a microwave absorber, a temperature measurement circuit and a shielding cover. The calibration body substrate is installed on the bottom plate of the receiver unit and is heat-insulated. The calibration body platinum resistors are respectively distributed at different positions of the center and edge of the black body, and the shielding cover adopts a composite material inner wall metallization. The calibration unit obtains the physical temperature of the black body by weighted calculation according to the actual measurement value of the temperature measurement circuit for the temperature measurement point and the temperature gradient distribution of the absorbing material.

[0018] The temperature control unit is used to achieve a temperature control accuracy better than ±0.1K through a PID control algorithm.

[0019] Preferably, the data acquisition and system control module is also used to adjust the receiver channel gain and control the related states of the microwave radiometer antenna feed and the receiver module according to the scientific data, the temperature data output by the temperature measurement and calibration module, and the collected angle coding signals and antenna status signals.

[0020] Preferably, the processing and display of the data preprocessing and display module includes: equipment status judgment, original voltage reading and display, GPS real-time demonstration, calibration result demonstration and route data statistics.

[0021] Preferably, the system further comprises a power supply module for converting a primary power supply into a secondary power supply to supply power to each module of the system.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] 1. This system operates in multiple frequency bands of 50-60GHz, 183GHz and 229GHz, adopts a dual-polarization design, including two working modes: traditional channel and fine spectrum channel. The two modes can work synchronously to achieve high-precision detection of atmospheric temperature and water vapor.

[0024] 2. This system adopts a calibration scheme with dual temperature-controlled calibration sources, which achieves precise calibration through high and low temperature blackbody sources. It has the characteristics of high stability and high reliability, can work stably in complex flight environments, and can be applied to fields such as aviation microwave remote sensing detection to achieve rapid collection of microwave brightness temperature information in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a general schematic diagram of the manned aircraft-borne microwave radiation measurement and calibration system of the present invention;

[0026] Figure 2 is the antenna unit block diagram;

[0027] Figure 3 is a temperature-controlled calibration source, wherein Figure 3(a) is a top view, Figure 3(b) is an internal side view, Figure 3(c) is an internal side view from another angle, and Figure 3(d) is a stereoscopic view of the temperature-controlled calibration source.

[0028] Reference numerals

[0029] 1. Calibration source base 2. Microwave window fixing frame 3. Microwave window

[0030] 4. Radiator 5. Auxiliary heating 6. Main heating

[0031] 7. Heat insulation board 8. Calibration source housing DETAILED DESCRIPTION

[0032] In order to achieve the above purpose, the present invention adopts the following technical scheme, and the entire radiometer system can be divided into several parts, such as antenna feed system, radiometer front end, data acquisition and system control unit, temperature control unit, power module, etc.

[0033] Antenna unit

[0034] The antenna unit includes a scanning flat-panel antenna and a fixed parabolic antenna, and the 50-60GHz, 166 / 183GHz and 229GHz multi-frequency dual-polarization antenna feed system is shared.

[0035] A quasi-optical polarization separator (polarization wire grid) is used to achieve polarization separation of the two frequency bands of 50-60 GHz and 166 / 183 GHz-229 GHz, of which 50-60 GHz is horizontal polarization and 166 / 183 GHz-229 GHz is vertical polarization.

[0036] The frequency separation of 166 / 183 GHz and 229 GHz adopts microwave waveguide duplexer solution.

[0037] To prevent the influence of stray electromagnetic radiation from the surface, the antenna is designed with a radome.

[0038] Receiver Unit

[0039] The receiver unit includes 50-60GHz receiver, 166 / 183GHz receiver and 229GHz receiver.

[0040] · Each frequency receiver adopts a single sideband system. In selecting the sideband, it is necessary to take into account the image suppression and the working range of the broadband spectrometer, and also the engineering feasibility of the ultra-wideband intermediate frequency circuit. The high spectrum detection channel has a high spectral resolution and needs to adopt phase-locked loop technology.

[0041] To solve the problem of local oscillator harmonic leakage, a pre-LNA is added to each frequency receiver, and a filter is added near the frequency multiplier, and then the relevant modules are treated with a metal shielding cavity.

[0042] The receiver unit also includes multi-stage amplifiers, filters, mixers, detectors and other circuits, which are used to amplify, filter, down-convert and detect the received microwave signals.

[0043] The circuit is equipped with a gain control module, and the attenuation is ≥20dB voltage control.

[0044] The last amplifier before detection P-1dB-OUT≥+6dBm

[0045] Calibration unit

[0046] The calibration unit includes high and low temperature calibration sources, which are respectively a high temperature controlled microwave absorbing black body and a low temperature controlled microwave absorbing black body.

[0047] The calibration optical path passes through the antenna reflection surface. The high and low temperature radiation sources and the microwave radiation signals of the ground objects use the same optical path to enter the receiver, so the calibration accuracy is high.

[0048] The calibration source consists of three parts, namely, microwave absorber, temperature control circuit and shielding cover.

[0049] Calibration is performed once per rotation.

[0050] Temperature control unit

[0051] The temperature control unit is used to control the temperature of the calibration source to stabilize it within the set temperature range to ensure calibration accuracy.

[0052] The temperature control unit adopts PID control algorithm. The temperature control accuracy is better than ±0.1K.

[0053] Data acquisition and system control unit

[0054] The data acquisition and system control unit is mainly responsible for collecting and quantifying the scientific data and temperature data of the receiver unit. According to the data processing results, the receiver channel gain is adjusted to make the channel work in the best state.

[0055] The unit is also responsible for collecting angle coding signals and antenna status signals, and controlling the scanning drive and angle coding circuits.

[0056] ·Control the power on and off of each channel of the receiver through data injection.

[0057] Receive remote control commands from the digital control subsystem, execute the commands after decoding, and control the working status of the fine spectrum.

[0058] ·Format the data and send it to the data management system.

[0059] Encode the engineering telemetry parameters and send them to the digital management subsystem after encoding.

[0060] Power supply unit

[0061] The power supply unit is responsible for converting the primary power supply into secondary power supply to supply power to each unit of the radiometer system.

[0062] +28V main power input, +12V, -12V, +5.6V secondary power outputs.

[0063] With over-voltage and over-current protection functions.

[0064] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0065] Example

[0066] An embodiment of the present invention provides a manned aircraft-borne microwave radiation measurement and calibration system.

[0067] Figure 1 This is the overall schematic diagram of the fine spectrum microwave detector. It has many detection frequency points and a wide frequency band span, so a reasonable frequency division scheme is required. 50-60GHz, 166GHz, 183GHz, and 229GHz share a scanning flat antenna and a fixed parabolic antenna. The polarized wire grid divides the input signal frequency into two frequency bands: 50-60GHz and 166 / 183GHz-229GHz. The microwave waveguide duplexer scheme is used for the frequency separation of 166 / 183GHz and 229GHz.

[0068] Polarization wire grid and waveguide duplexer are used to achieve frequency separation of each frequency band. The disadvantages of using polarization wire grid and frequency selective surface (FSS) to achieve frequency separation, such as complex optical path and large structure, are avoided, making the system easy to install, small in size and light in weight.

[0069] After the microwave radiation signal passes through the quasi-optical path, the incident unpolarized wave will be polarized according to the angle. It should be noted that in this case, the polarization direction is defined in the scattering plane on the earth's surface rather than in the reflector scanning plane: the vertical polarization direction refers to the electric field direction of the E vector parallel to the scattering plane (that is, the E vector is parallel to the scanning plane), and the horizontal polarization direction refers to the electric field direction of the E vector perpendicular to the scattering plane (that is, the E vector is perpendicular to the scanning plane).

[0070] According to the channel configuration, it can be seen that the 50-60 GHz receiver receives horizontal polarization information; the 166 / 183 / 229 GHz receiver receives vertical polarization information.

[0071] The device includes: microwave radiometer antenna feed and receiver module, temperature measurement and calibration module, data acquisition and system control module, GPS receiving module and data preprocessing and display module, among which,

[0072] The microwave radiometer antenna and receiver module has two working modes: traditional channel and fine spectrum channel, which can receive and separate scientific data of different frequencies;

[0073] The temperature measurement and calibration module adopts a dual-source design of high and low temperature calibration sources, which is used to achieve on-orbit real-time periodic temperature control calibration and temperature measurement through PID control algorithm;

[0074] Data acquisition and system control module, used to collect antenna status information, receive and process scientific data and temperature data, determine the validity of data packets based on data acquired by the GPS receiving module, send processed data to the data control subsystem, and receive and execute remote control commands of the data control subsystem;

[0075] GPS receiving module, used to obtain the geographical location and flight speed of the manned aircraft;

[0076] The data preprocessing and display module is used to process and display various data results in the manned machine.

[0077] The following details:

[0078] Antenna unit

[0079] Antenna unit block diagram see Figure 2 . A scanning flat-panel antenna and a fixed parabolic antenna are combined, and the feed source uses a 90° offset parabolic reflector and a conical corrugated horn. The antenna system operates in three frequency bands: 50-60GHz, 183GHz and 229GHz. The 50-60GHz band signal is horizontally polarized, and the 183GHz and 229GHz band signals are vertically polarized. A polarization wire grid is used to preliminarily divide the input signal frequency into two frequency bands: 50-60GHz and 166 / 183GHz-229GHz. A microwave waveguide duplexer is then used to separate the 166 / 183GHz and 229GHz band signals. The antenna body material and support mechanism are made of metal forged aluminum, and the reflective surface is precisely polished, ground and gold-plated.

[0080] Receiver Unit

[0081] All frequency receivers use a single sideband system. When selecting the sideband, it is necessary to consider image suppression, the working range of the broadband spectrometer, and the engineering feasibility of the ultra-wideband intermediate frequency circuit. In order to improve the receiver sensitivity, a low noise amplifier (LNA) is set in front of each frequency receiver, and a filter is set near the frequency multiplier to suppress the leakage of the local oscillator harmonics. At the same time, the relevant modules are treated with metal shielding cavities to further reduce the leakage of local oscillator harmonics.

[0082] Calibration unit

[0083] The temperature-controlled calibration source is shown in Figure 3. Figure 3(a) is a top view, Figure 3(b) is an internal side view, Figure 3(c) is an internal side view from another angle, and Figure 3(d) is a stereogram of the temperature-controlled calibration source.

[0084] In the figure, 1 is the calibration source base, 2 is the microwave window fixing frame, 3 is the microwave window, 4 is the radiator, 5 is the auxiliary heating, 6 is the main heating, 7 is the heat insulation board, and 8 is the calibration source housing.

[0085] The calibration unit uses high and low temperature calibration sources for two-point calibration. The low temperature calibration source is a microwave absorbing black body controlled at low temperature, and the high temperature calibration source is a microwave absorbing black body controlled at high temperature. During calibration, the high and low temperature calibration source and the observed microwave radiation signal pass through the same optical path and enter the receiver through the antenna reflection surface, thereby achieving a higher calibration accuracy. The real-time periodic calibration method during flight is adopted.

[0086] Temperature control unit

[0087] Platinum resistance temperature sensors are distributed at different locations such as the center and edge of the microwave blackbody to monitor the system temperature in real time and use a PID control algorithm. The temperature control accuracy is better than ±0.1K. Ensure that the system reaches a stable state before flight. According to the actual measurement values ​​of each temperature measurement point and the temperature gradient distribution of the absorbing material, the physical temperature of the blackbody is obtained by weighted calculation.

[0088] Data acquisition and system control unit

[0089] The unit consists of a microprocessor module, a receiver control and data acquisition module, a power control module, and a bus communication module. It is responsible for collecting scientific data, temperature data, angle coding signals, and antenna status signals of the receiver unit, and adjusting the receiver channel gain according to the data processing results. At the same time, it controls the scanning drive and angle coding circuits to work in the primary or backup state, and controls the switches of each channel of the receiver through data injection. In addition, the unit also receives and executes remote control instructions from the digital control subsystem, controls the working state of the system, and formats the data and sends it to the digital control subsystem. In terms of data processing, the unit is responsible for the processing of calibration source voltage data and the validity judgment of data packets.

[0090] Power supply unit

[0091] The power supply unit receives +28V from the primary bus and converts the primary power supply into secondary power supply to supply power to each unit of the system. The unit supports the main and backup switching through external instructions, and adopts protection measures such as double fuses, current limiting resistors and surge suppression circuits to ensure the safety and stability of the power supply system.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of the claims of the present invention.

Claims

1. A manned aircraft microwave radiation measurement and calibration system, characterized in that: include: Microwave radiometer antenna feed and receiver module, temperature measurement and calibration module, data acquisition and system control module, GPS receiving module and data preprocessing and display module, among which, The microwave radiometer antenna feed and receiver module has two working modes: traditional channel and fine spectrum channel, and receives and separates scientific data of different frequencies; The temperature measurement and calibration module adopts a dual-source design of high and low temperature calibration sources, and is used to realize on-orbit real-time periodic temperature control calibration and temperature measurement through a PID control algorithm; The data acquisition and system control module is used to collect antenna status information, receive and process scientific data and temperature data, determine the validity of data packets based on the data acquired by the GPS receiving module, send the processed data to the data control subsystem, and receive and execute remote control instructions of the data control subsystem; The GPS receiving module is used to obtain the geographical location and flight speed of the manned aircraft; The data preprocessing and display module is used to process and display various data results in the manned machine.

2. The manned aircraft microwave radiation measurement and calibration system according to claim 1, characterized in that: The microwave radiometer antenna feed and receiver module adopts a scanning flat antenna and a fixed parabolic antenna, 50-60GHz is set as a horizontal polarization channel, 183GHz and 229GHz are vertical polarization channels, including a 50-60GHz receiver, a 166 / 183GHz receiver and a 229GHz receiver, and the antenna feed is connected to each receiver.

3. The manned aircraft microwave radiation measurement and calibration system according to claim 2, characterized in that: The microwave radiometer antenna feed and receiver module adopt polarization wire grid and waveguide duplexer to realize frequency separation of two frequency bands of 50-60GHz and 166 / 183GHz-229GHz.

4. The manned aircraft microwave radiation measurement and calibration system according to claim 3, characterized in that: The microwave radiometer antenna feed and receiver module includes a receiver unit. Each frequency point receiver adopts a single sideband system, and the local oscillator adopts a phase-locked technology. Each frequency point receiver is added with a pre-LNA and a filter is added near the frequency multiplier.

5. The manned aircraft microwave radiation measurement and calibration system according to claim 1, characterized in that: The conventional channel is a filter bank channel, and the fine spectrum channel is a digital spectrometer channel with a bandwidth of 2 GHz.

6. The manned aircraft microwave radiation measurement and calibration system according to claim 4, characterized in that: The temperature measurement and calibration module includes a calibration unit and a temperature control unit, wherein: The calibration unit includes a high and low temperature calibration source, each of which includes a microwave absorber, a temperature measurement circuit and a shielding cover. The calibration body substrate is installed on the bottom plate of the receiver unit and is heat-insulated. The calibration body platinum resistors are respectively distributed at different positions of the center and edge of the black body, and the shielding cover adopts a composite material inner wall metallization. The calibration unit obtains the physical temperature of the black body by weighted calculation according to the actual measurement value of the temperature measurement circuit for the temperature measurement point and the temperature gradient distribution of the absorbing material. The temperature control unit is used to achieve a temperature control accuracy better than ±0.1K through a PID control algorithm.

7. The manned aircraft microwave radiation measurement and calibration system according to claim 1, characterized in that: The data acquisition and system control module is also used to adjust the receiver channel gain and control the related states of the microwave radiometer antenna feed and the receiver module according to the scientific data, the temperature data output by the temperature measurement and calibration module, and the collected angle coding signal and antenna status signal.

8. The manned aircraft microwave radiation measurement and calibration system according to claim 1, characterized in that: The processing and display of the data preprocessing and display module includes: equipment status judgment, original voltage reading and display, GPS real-time demonstration, calibration result demonstration and route data statistics.

9. The manned aircraft microwave radiation measurement and calibration system according to claim 1, characterized in that: The system further comprises a power supply module, which is used to convert the primary power supply into a secondary power supply to supply power to each module of the system.

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