Remote omnidirectional water vapor radiometer observation control system

Abstract

The application provides a remote omnidirectional water vapor radiometer observation control system, and belongs to the field of water vapor radiometer observation control. The system comprises hardware devices (antenna driving, receiver, calibration black body, bias source, intermediate frequency power attenuation module and chopping wheel driving, etc.), and further comprises software control (including a graphical display interface, a bias scanning control thread, an antenna tracking control thread, an observation thread, a remote communication thread, etc.). The application realizes rapid observation calibration based on the chopping mode, omnidirectional scanning, fixed-point scanning and various observation modes such as atmospheric Skydip, and transmits the observation data to a data service client through the Internet through an encrypted data transmission mode. Meanwhile, the application realizes continuous and real-time observation processing of terahertz atmospheric signals, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water vapor radiometer observation and control, specifically involving a high-sensitivity heterodyne, omnidirectional water vapor radiometer system based on a superconducting mixer (SIS) and its observation, control and operation methods. Background Technology

[0002] The primary purpose of a common water vapor radiometer (WVR) system is to directly measure the brightness temperature of water vapor absorption lines in the atmosphere. The actual water vapor content is then deduced from the brightness temperatures across different frequency bands, making it a direct measurement system. Currently, the most influential radiometer companies internationally are RPG (Germany) and Radiometers (USA). These systems typically employ Schottky semiconductor-based detection systems. Their significant advantage is ease of installation and measurement, but they suffer from a fatal flaw: excessive noise, often exceeding 1000K. Summary of the Invention

[0003] This invention addresses the issues of high noise and temperature, as well as system gain variation and nonlinearity in the aforementioned Schottky detector systems by providing a remote omnidirectional water vapor radiometer observation and control system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A remote omnidirectional water vapor radiometer observation and control system includes: an antenna driver, a receiver, a calibration blackbody, a bias source, an intermediate frequency power attenuation module, and a chopper wheel driver. The antenna driver is used to achieve pointing of the omnidirectional water vapor radiometer at any AZ and EL position. The receiver includes a local oscillator signal source, a SIS mixer, a CLNA amplifier, an intermediate frequency amplifier, and a synchronous detection circuit. The local oscillator signal source provides a pump signal to the SIS mixer, enabling the SIS mixer to generate an intermediate frequency signal. After amplification by the CLNA amplifier and the intermediate frequency amplifier, four channels are output. The intermediate frequency (IF) signal is detected by the synchronous detection circuit; the calibration blackbody includes a high-temperature blackbody and a room-temperature blackbody, used to calibrate the system gain of the receiver; the bias source is used to provide bias voltage to the SIS mixer; the IF power attenuation module is used to adjust the power of the four IF signals output by the IF amplifier so that its total power level is within the linear range of the synchronous detection circuit; the chopper drive is used to rotate the chopper, which provides pulse signals to the synchronous detection circuit, enabling the synchronous detection circuit to acquire the brightness temperature signals of the sky, the high-temperature blackbody, and the room-temperature blackbody.

[0006] Optionally, the operating temperatures of the high-temperature blackbody and the room-temperature blackbody are 60°C and 30°C, respectively.

[0007] Optionally, the ambient temperature intermediate frequency amplifier outputs four intermediate frequency signals, namely 0-2GHz, 2-4GHz, 4-6GHz and 6-8GHz.

[0008] Optionally, it also includes a graphical display interface, which has the function of displaying receiver, including the status display of SIS mixer voltage and current, CLNA amplifier voltage and current, and the total power of the four intermediate frequency signals.

[0009] Optionally, the graphical display interface also has the function of displaying an automatic weather station, including the display of atmospheric temperature, dew point temperature, heater temperature, wind speed and direction, relative humidity and atmospheric pressure.

[0010] Optionally, the graphical display interface creates a receiver control thread, which includes control over the local oscillator signal source, SIS mixer, CLNA amplifier, and intermediate frequency amplifier. The graphical display interface sends the setting signals and parameters of the local oscillator signal source, SIS mixer, CLNA amplifier, intermediate frequency amplifier, and automatic weather station to the receiver control thread. After acquiring the total power voltage of the four intermediate frequency signals, the receiver control thread uses a moving average processing method to reduce noise, converts the acquired total power voltage into a power value, performs internal calibration to obtain the gain and brightness temperature values ​​of the four channels, and sends them to the graphical display interface for display.

[0011] Optionally, the graphical display interface creates a bias scan control thread for setting different bias voltages of the SIS mixer, thereby obtaining the voltage and current curves of the SIS mixer, which are then displayed through the graphical display interface. The graphical display interface sends scan parameters to the bias scan control thread, including the start point, end point, scan interval, and scan mode.

[0012] Optionally, the graphical display interface includes an antenna tracking control thread for real-time control of the radiometer's pointing direction and for providing receiver synchronization modulation signals, chopper rotation speed control, and status acquisition. The radiometer's azimuth and elevation control, as well as the chopper, share the same RS485 bus. The antenna tracking control thread has two operating modes: a tracking motion mode and a stationary mode.

[0013] Optionally, the graphical display interface creates an observation thread for measuring the brightness temperature variation at different azimuths or at a fixed location under the same atmospheric mass. The observation thread obtains multiple sets of observation data from four channels at each azimuth location, then performs numerical averaging to obtain the observation results. Finally, it creates an observation directory and observation data file based on the observation time, with the observation data file using ASCII file format. The observation thread transmits the observation data to the graphical display interface via vector, and the graphical display interface initializes the graphic coordinates and legend according to the data type, refreshes, and then displays the data.

[0014] Optionally, the graphical display interface creates a remote communication thread, which is a permanent communication thread using the publish-subscribe method. The communication protocol is TCPv4, and the encryption method is TLS encryption key authentication file. A new key is created each time the connection is reconnected, and the key generation adopts the Diffie-Hellman method. Multiple clients can connect to the remote communication thread simultaneously, establish communication connections through the scandataTopic topic keyword, and adopt a QoS quality observation strategy.

[0015] The beneficial effects of this invention are:

[0016] (1) This invention is based on a superconducting SIS mixer detector. The noise temperature of the entire system is less than 150K, which greatly improves the system's observation sensitivity. The system adopts a superheterodyne system architecture, which can detect water vapor absorption lines in the 183GHz frequency band. The intermediate frequency signal after down-conversion is amplified by four-way power division, and then the power of different frequency bands is detected, digitally amplified and acquired to obtain the shape of the water vapor absorption line in that frequency band. The specific water vapor content will be determined later.

[0017] (2) This invention addresses the common problem of radiometers primarily using a single calibration source, which, with increasing measurement accuracy, leads to an increasing number of internal calibration sources. In addition to liquid nitrogen and high-temperature blackbodies, a noise diode is added, providing multi-point calibration and eliminating the gain nonlinearity issue of the radiometer. This invention employs both high-temperature and room-temperature calibration sources, and the switching device uses a Chopper method, achieving real-time calibration and improving observation accuracy.

[0018] (3) This invention realizes multiple observation methods such as rapid observation calibration, omnidirectional scanning, fixed-point scanning and atmospheric Skydip based on chopping method, and transmits the observation data to the data service client via the Internet through encrypted data transmission method, realizing the functions of continuous and real-time observation and processing of terahertz atmospheric signals, and has broad application prospects. Attached Figure Description

[0019] Figure 1 This is a hardware block diagram of the remote omnidirectional water vapor radiometer observation and control system.

[0020] Figure 2 This is a software block diagram of the remote omnidirectional water vapor radiometer observation and control system.

[0021] Figure 3 This is a flowchart of the graphical display interface of the remote omnidirectional water vapor radiometer observation and control system.

[0022] Figure 4 This is a flowchart of the receiver control thread of the remote omnidirectional water vapor radiometer observation and control system.

[0023] Figure 5 This is a flowchart of the bias scan control thread of the remote omnidirectional water vapor radiometer observation and control system.

[0024] Figure 6 Flowchart of antenna tracking control thread for remote omnidirectional water vapor radiometer observation and control system.

[0025] Figure 7 Flowchart of atmospheric opacity and azimuth scanning observation thread for remote omnidirectional water vapor radiometer observation and control system.

[0026] Figure 8 This is a flowchart of the remote communication thread of the remote omnidirectional water vapor radiometer observation and control system.

[0027] Figure 9a and 9b These are the implementation method and result diagram of the synchronous signal chopper wheel in the observation and control system of a remote omnidirectional water vapor radiometer.

[0028] Figure 10 It is the underlying synchronous detection program of the remote omnidirectional water vapor radiometer observation and control system. Detailed Implementation

[0029] The invention will now be described in further detail with reference to the accompanying drawings.

[0030] Figure 1 This is a hardware block diagram of the remote omnidirectional water vapor radiometer observation and control system. The entire receiver and antenna control uses a unified RS485 interface, employing a simplified version of the Modbus communication protocol. Communication messages use a variable-length RTU format, with a maximum length of 64 bytes (the standard Modbus RTU message length is 256 bytes; considering the insufficient internal RAM resources of the microcontroller, it has been simplified to the minimum message length required for the task). The receiver control unit (RCU), intermediate frequency unit (IFU), and local oscillator unit (LOU) are assigned independent device addresses to achieve single RS485 bus control.

[0031] The hardware architecture of the remote omnidirectional water vapor radiometer and its observation and control system mainly includes:

[0032] Antenna drive (AZ / EL): Used to enable the omnidirectional water vapor radiometer to point at any AZ (0~360°) and EL (0~90°) position.

[0033] Two calibration blackbodies: operating at 60℃ and 30℃ respectively, used to calibrate the receiver system gain.

[0034] One chopper wheel drive: with a rotation speed of 5Hz, the receiver can perform real-time calibration of the atmospheric intensity of the sky within one rotation cycle by changing the received optical path signal (sky, high temperature blackbody and normal temperature blackbody).

[0035] Bias source (SIS and CLNA): Used to provide bias voltage to the detector mixer in the receiver and to obtain bias current feedback for real-time detection of the operating status of the SIS mixer and CLNA amplifier.

[0036] Intermediate Frequency Power Attenuation Module: The intermediate frequency amplifier is the room temperature amplifier of the radiometer. The input signal is 0-8GHz, and the output is four intermediate frequency signals with a bandwidth of 2GHz (0-2GHz, 2-4GHz, 4-6GHz, and 6-8GHz), thereby realizing the detection of 183 water vapor continuous spectrum signal. The attenuation module is the power adjustment module of the intermediate frequency amplifier, so that the total power level of the four intermediate frequency signals is within the linear range of their respective detectors. At the same time, the DC voltage output by the detector is at the full scale of the ADC acquisition of the synchronous detection circuit, improving the accuracy of the detection circuit.

[0037] Local oscillator signal source: The system adopts a heterodyne receiver. The local oscillator signal source is used to provide a pump signal to the SIS mixer, which downconverts the 183GHz band signal to a 0-8GHz signal. Then, it is amplified and detected by a CLNA amplifier and a room temperature intermediate frequency amplifier.

[0038] Hardware components such as the system's synchronous detection and reading module: The synchronous detection circuit provides a 5Hz pulse signal through a rapidly rotating chopper wheel, enabling the synchronous detection circuit to accurately acquire three total power signals: the sky, the high-temperature blackbody, and the normal-temperature blackbody. Through calibration formulas, the gain variation of the omnidirectional radiometer is eliminated, improving the acquisition accuracy and processing speed of the sky radiation signal.

[0039] Figure 2 The graphical user interface features important functions such as system function display, system performance measurement, atmospheric observation mode selection, and scientific observation. It can perform detector performance diagnosis, atmospheric observation under different observation modes, and fitting of observation results. Detailed functions are as follows:

[0040] The graphical display interface shows antenna functions including: antenna command position, actual antenna position, and position error display; control functions include: setting antenna position, setting antenna offset position, and antenna null search, etc.

[0041] The graphical display interface shows the receiver's functions, including: SIS voltage and current, CLNA voltage and current, and the status of the total power (Hot, Ref, Sky, Tb, Gain) of the four channels after the intermediate frequency four-way division; the control functions include: selection of different channels, bias scan control (real-time monitoring control, scan mode control, scan file storage control, scan start point, end point, scan step size, scan single point duration and number of scanned points display, graphical display of scan results, etc.).

[0042] The graphical display interface shows the automatic weather station functions, including: atmospheric temperature, dew point temperature, heater temperature, wind speed and direction, relative humidity, and atmospheric pressure.

[0043] The graphical display interface shows the observation process, the real-time brightness temperature results from the four channels of the synchronous detector, the graphical display of the position and temperature at different azimuths for each complete Scan, and the graphical display of different atmospheric masses and temperatures after each Skydip observation.

[0044] In the graphical interface, a new receiver status acquisition thread and an antenna tracking control thread were created and started. The receiver status acquisition thread is a permanent thread that acquires the status of the entire observation system's receiver equipment in real time, including the voltage and current status of the SIS, the voltage and current status of the CLNA, the atmospheric parameters (temperature, humidity, pressure, wind speed, wind direction, dew point temperature) of the automatic weather station AWS, the status of the local oscillator signal source (voltage and current, attenuator voltage), and the intermediate frequency (IF) status (supply voltage and current, attenuator status). The graphical interface allows for control of the device parameter settings in the status acquisition thread, including bias voltage scanning control, CLNA bias source on / off, automatic weather station connection / disconnection, local oscillator signal source attenuator control, and IF attenuator control.

[0045] The antenna tracking control thread is also a permanent thread, used to constantly acquire antenna position information and antenna cabin status information (chopper rotation frequency, calibration blackbody temperature, etc.); the graphical display interface allows you to set the antenna's AZ and EL positions, and set the chopper rotation speed, etc.

[0046] A new clock thread is created in the graphical display interface to update the observation system time, initialize the observation control graphical display interface, and display the acquisition status on the interface in real time. In addition, offset scan control, stability testing, atmospheric opacity observation, and omnidirectional scan threads are created in the graphical display interface for control and observation of the main graphical display interface.

[0047] The observation thread primarily performs observations such as atmospheric opacity strategy and omnidirectional azimuth scanning. This thread mainly interacts with the receiver control thread and antenna thread for control and status communication, and displays the observation results on the graphical interface. The interaction between the observation thread and the antenna tracking control thread mainly involves setting the antenna position, reading the current position, and reading the standard blackbody temperature. The interaction with the receiver control thread mainly involves acquiring the status parameter information of the entire receiver (SIS voltage and current, CLNA voltage and current, LO voltage and current, IF voltage and current attenuation, meteorological station parameters, and the total power values ​​of the four channels of the synchronous detection circuit, each channel containing three total power voltages: atmospheric, high-temperature blackbody, and normal-temperature blackbody, etc.).

[0048] The main function of the bias scan control thread is to complete the setting of different biases, and then read the voltage, current and power values ​​at different bias points. Through graphical display, it determines whether the output power of the current SIS mixer and the entire receiver system is normal. As an important diagnostic method, when scanning, it first locks and stops the reading function of the current receiver normal status, and then starts continuous setting reading and writing. The setting commands are implemented by interacting with the receiver control thread, and the data reading is implemented by its own thread to improve scanning efficiency. After completing the scanning task, it exits and cancels the thread.

[0049] like Figure 3 As shown, the control method based on the remote omnidirectional water vapor radiometer observation and control system has the following specific implementation steps:

[0050] 1) Graphical display interface: First, a user-visual operation interface was created. Then, three permanent threads were created: antenna tracking control thread, receiver control thread, and time thread. The antenna tracking control thread and receiver control thread check whether all system hardware and drivers are normal before starting.

[0051] 2) The graphical interface creates remote “Skydata” Publish and “Scandata” Publish threads to enable remote transmission of scientific data from atmospheric observations.

[0052] 3) The graphical interface creates three non-permanent threads: “IVSweep”, “Skydip”, and “Scan”, for system performance testing and atmospheric science observations in different modes.

[0053] 4) Before the antenna tracking control thread and receiver control thread start, the graphical display interface connects these two threads, as well as the threads and the graphical display interface, with "signals" and "response functions". After completion, it initializes and connects the four non-permanent threads Skydip, IVSweep, Scan, and Stablity to establish direct signal and response function connections. Only in this way can complex functions such as automatic updating of user interface status, setting of user observation parameters, selection of user observation modes, and continuous scientific observation be realized.

[0054] 5) After the above work is completed, start the graphical display interface. The user can see the real graphical display interface. Start the antenna tracking control thread and receiver control thread. The user can see the status on the interface start to update.

[0055] 6) Reset the receiver state and tracking thread state to ensure that the entire system state remains consistent after each system startup, preventing abnormal user operations.

[0056] 7) After the thread starts, the antenna tracking control thread and the receiver control thread will update the status information to the user interface in real time through the signal channel.

[0057] Figure 4 The receiver control thread includes bias (SIS and CLNA) control, local oscillator (LOC) control, and intermediate frequency (IF) control. All devices share the same RS485 bus, employing a 1 / 8 frequency division method for status acquisition. A mutex lock method is used for control to ensure no bus conflicts occur at any given time. After acquiring the total power voltage from the four channels, a smooth moving average processing method is first used to reduce system noise. Then, the acquired power voltage is converted into a specific power value, and finally, internal calibration is performed to obtain the gain and brightness temperature values ​​for the four channels, which are then sent to the graphical display interface. To maintain a high acquisition rate, the receiver, weather station, and other statuses are acquired using a frequency division method, reducing the sampling rate of irrelevant devices and ensuring a high total power sampling rate (700ms), thereby improving observation efficiency.

[0058] The receiver control operations and receiver status acquisition operations, such as receiver bias setting, IV scan performance check, and scan parameter setting, adopt a mutex lock method to ensure that only one action is on the RS485 bus at any given time, thus ensuring the reliability of system control and preventing crashes.

[0059] Figure 5The bias scan control thread is primarily used to quickly and continuously set different bias voltages for the SIS (Self-Identifying Component), thereby obtaining the SIS's voltage-current curves and enabling the assessment of the SIS's performance. To maintain scan continuity, an interlocking mechanism is used between the scan thread and the receiver status thread. Before starting the scan, the receiver status thread task is paused, and then the SIS voltage and current scans are performed continuously. The scan parameters include the start point, end point, scan interval and interval time, scan mode control, and scan data storage and display functions. After the scan is completed, the scan lock is released, and the receiver control thread task resumes.

[0060] Figure 6 The antenna tracking control thread is primarily used for real-time control of the radiometer's pointing and providing synchronous modulation signals to the receiver, as well as controlling the chopper's rotation speed and acquiring its status. Azimuth, elevation, and the chopper share the same RS485 bus. The antenna tracking control thread has two operating modes: "tracking motion" mode and "stationary" mode. The chopper's operating status and the reference blackbody status use a "1 / 20 frequency division" method, thereby increasing the speed of radiometer direction control and improving the radiometer's pointing accuracy. This allows the entire antenna control frequency to reach 200ms. High-precision reduction gears and harmonic reduction motors are used for azimuth and elevation drives, respectively, achieving high-precision pointing of the radiometer.

[0061] Figure 7 The atmospheric opacity observation thread and scanning observation thread are mainly used to realize observations of different atmospheric measurement methods. They can realize three observation methods: "atmospheric opacity measurement" in the pitch direction, "atmospheric omnidirectional brightness temperature measurement" in the azimuth direction, and "fixed-point atmospheric change measurement" at a fixed location.

[0062] The atmospheric opacity observation thread is primarily used to measure brightness temperature under different atmospheric masses, and simultaneously obtains the atmospheric opacity in the zenith direction after fitting. This thread selects 16 elevation positions (14.5°–81°) and can perform bidirectional scanning to improve observation efficiency. At each elevation position, multiple sets of observation data (Sky, Ref, Hot, Gain, Tb, Thot, and Tref) from four channels can be obtained. These data are then numerically averaged to obtain observation results with lower noise. Finally, a specific observation directory and new observation data files are created based on the observation time. The data files use ASCII file format to improve readability, and the file format consists of a data header + data fitting results + original observation data, facilitating subsequent data processing. The saved files are displayed graphically. Data is transmitted to the graphical display interface via vectors. The graphical display interface re-initializes the graph coordinates, legend, etc., according to the data type, and refreshes before displaying on the main interface. The graphical display interface allows for common operations such as zooming in and out using the mouse, providing a user-friendly interface. Finally, the observation results and status information are encapsulated, encrypted, and sent to a remote client, thus achieving dual-location data storage and improving data reliability.

[0063] The scanning observation thread is used to measure the brightness temperature variation at different azimuths or at a fixed location under the same atmospheric mass. Azimuth scanning employs a reciprocating cyclic scanning method, acquiring multiple sets of observation data (Sky, Ref, Hot, Gain, Tb, Thot, Tref, and observation time ObsTime) from four channels at each azimuth location. These data are then numerically averaged to obtain observation results with lower noise. Finally, a specific observation directory and new observation data files are created based on the observation time. The data files use ASCII file format to improve readability, and the file format includes a data header, data fitting results, and original observation data for easy post-processing. The saved files are displayed graphically. Data is transmitted to the graphical display interface via vectors. The graphical display interface re-initializes the graph coordinates, legend, etc., according to the data type, and refreshes before displaying on the main interface. The graphical display interface allows for mouse-based zooming and other user-friendly operations. Finally, the observation results and status information are encapsulated, encrypted, and sent to a remote client, thus achieving dual-location data storage and improving data reliability. The fixed-point observation method is based on a scanning observation thread with a fixed orientation. The only difference is that the orientation is in a fixed position, and the data recording rate is faster.

[0064] Figure 8The remote communication thread employs the Fast-DDS method, a persistent communication thread using a publish-subscribe approach. The communication protocol is TCPv4, and encryption uses TLS with a key authentication file. A new key is created after each reconnection, generated using the Diffie-Hellman method, enabling remote data transmission and control over the internet. Multiple clients can connect to a single communication thread simultaneously, establishing connections via the "scandataTopic" topic keyword. For reliability, a QoS monitoring strategy is employed, including data retransmission and data history length confirmation, improving communication reliability. Within the Subscribe thread, data acquisition and storage are achieved by monitoring network ports for data and heartbeat data. Upon data acquisition, a directory and new data file are automatically created, saving the data in the same format as the locally observed data, significantly improving data analysis efficiency.

[0065] like Figure 9a and 9b As shown, in synchronous detection, the sky signal, after passing through the 100mm primary mirror of the radiometer and the ellipsoidal folding mirror, is fed into the subsequent receiving optical path via a two-bladed rotating chopper at the beam waist position, along with the low-temperature and high-temperature blackbodies on both sides of the beam, in a time-division manner. The signal acquisition at the back-end receiver requires synchronous detection mode, using a constant-temperature blackbody (40°C) and a high-temperature heated blackbody (65°C) as two known calibration sources. The chopper rapidly switches between sky / reference / sky / high-temperature modes sequentially, and the synchronous detection and subsequent analog circuitry output S, R, and H signals.

[0066] The chopper wheel is driven by an HTS6010 servo motor, and the zero-point signal is generated through a baffle and an SPX307 optical switch. The zero-point signal is sent to a microcontroller interrupt, and software is used to generate the timing sequence for the R, S, and H synchronization selection signals. The primary operation of the zero-point synchronization interrupt is to reset the three synchronization counters (R / S / H). The timer interrupt handles the generation of the R / S / H signal timing (decrementing the corresponding counters, performing judgments, and toggling levels, etc.).

[0067] Figure 10In this design, the timing of the S, H, and R selection signals is achieved by setting initial counts for the three selection signals and then updating and judging these counts in real time within a timer interrupt routine. To accommodate fine-tuning of the timing, two Modbus registers are used for precise setting of the synchronization time Tsync and the blanking width Tblank. According to the design, the beam diameter at the chopper center is approximately 25mm at 18dB, and the chopper wheel center radius is 90mm. Therefore, the beam diameter percentage is approximately 25 / (2*90*π)≈5%. If the chopper wheel rotates at a constant frequency of 5Hz, the blanking portion of the signal will occupy (200ms / 4)*5% = 2.5ms, achieving a signal efficiency of around 95%. This is an advantage of using a large chopper wheel.

[0068] Based on the 5Hz chopper wheel rotation frequency (200ms rotation period), signal S is observed twice within 200ms (50ms On / Off), and reference R and high-temperature blackbody H are observed once each (50ms On, 150ms Off). The effective integration time in the above observations needs to be deducted from the blanking time before and after within a 50ms width.

[0069] Since the chopper synchronization point (Sync) is set between Hot and Sky, the sky signal is approximately in the middle of the 50ms signal observation pulse when the synchronization pulse arrives. At this moment, S=0, R=1, and H=1 should be set, meaning the synchronization detector selects the sky signal path for integration, and both reference paths are held. The subsequent changes are S path from 1 to 0, R path from 0 to 1, while H path remains unchanged at 0. The initial delay for the subsequent high-to-low switching of S path from the synchronization pulse is set to TskySync. Therefore, the initial delay for the low-to-high switching of the reference path is TrefSync = TskySync + Tblank, and the low-to-high switching delay of the high-temperature path is ThotSync = TrefSync + 100ms.

[0070] During program initialization, TcalOn = TskyOn = 50ms - Tblank (the effective integration time excluding the first and second half-blanking times), TskyOff = 100ms - TskyOn = 50ms + Tblank, TcalOff = 200ms - TcalOn = 150ms + Tblank, and the values ​​of TskySync, TrefSync, and ThotSync are set. TskyOn refers to the effective integration time count of the S-signal after blanking (H / A = sampling), and TskyOff refers to the invalid time count of the S-signal (H / A = holding). TcalOff represents the invalid time count of the calibration source R / H (since TcalOn = TskyOn, TcalOn is not defined separately). Setting three independent counters, TskySync, TrefSync, and ThotSync, is to simplify the interrupt program design for generating the SHR synchronization signal. The Sky synchronization signal is a 10Hz periodic signal, active low, with a 50% duty cycle. The AD1 output level can fully charge the subsequent integrating circuit in 3 cycles (300ms). The Ref synchronization signal is a 5Hz periodic signal, active low, with a 25% duty cycle. The AD2 output level can fully charge in 3 cycles (600ms). The Hot synchronization signal is a 5Hz periodic signal, active low, with a 25% duty cycle. The AD3 output level can fully charge in 3 cycles (600ms).

[0071] Based on the aforementioned independent detection principle, the remote omnidirectional water vapor radiometer observation and control system employs a chopper wheel synchronization signal. The method is as follows: By using three parameters—the blanking time (Tblink), the sky observation synchronization time (Tskysyn), and the acquisition time (Tsample)—a 10Hz sky synchronization signal and 5Hz ambient temperature and high temperature reference synchronization signals are generated at a chopper wheel rotation speed of 5Hz. After passing through the synchronization detection and amplification circuit, analog signals of the brightness temperatures of the sky, the ambient temperature blackbody, and the high temperature blackbody can be obtained simultaneously. Then, the actual power signal is obtained through nonlinear calibration and voltage power calibration. Finally, the sky brightness temperature and system gain value are obtained in real time using the calibration formula.

[0072] This invention features real-time detection of atmospheric opacity in a specific direction, multi-mode atmospheric measurement, and rapid local and remote data backup capabilities. It enables multi-mode observation of the terahertz atmosphere and provides important technical references for atmospheric observation in other frequency bands.

[0073] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A remote omnidirectional water vapor radiometer observation and control system, characterized in that, include: Antenna driver, receiver, calibration blackbody, bias source, intermediate frequency power attenuation module and chopper wheel driver; The antenna driver is used to achieve pointing of the omnidirectional water vapor radiometer at any AZ and EL position; the receiver includes a local oscillator signal source, a SIS mixer, a CLNA amplifier, an intermediate frequency amplifier, and a synchronous detection circuit. The local oscillator signal source provides a pump signal to the SIS mixer, enabling the SIS mixer to generate an intermediate frequency signal. After being amplified by the CLNA amplifier and the intermediate frequency amplifier, four intermediate frequency signals are output to the synchronous detection circuit for detection; the calibration blackbody includes a high-temperature blackbody and a room-temperature blackbody, used to calibrate the system gain of the receiver; the bias source provides a bias voltage to the SIS mixer; the intermediate frequency power attenuation module adjusts the power of the four intermediate frequency signals output by the intermediate frequency amplifier, ensuring that its total power level is within the linear range of the synchronous detection circuit; the chopper wheel driver rotates the chopper wheel, which provides a pulse signal to the synchronous detection circuit, enabling the synchronous detection circuit to acquire the brightness temperature signals of the sky, the high-temperature blackbody, and the room-temperature blackbody; It also includes a graphical display interface, which has the function of displaying the receiver, including the status display of SIS mixer voltage and current, CLNA amplifier voltage and current, and the total power of the four intermediate frequency signals. The graphical display interface creates a receiver control thread, which includes control over the local oscillator signal source, SIS mixer, CLNA amplifier, and intermediate frequency amplifier. The graphical display interface sends the setting signals and parameters of the local oscillator signal source, SIS mixer, CLNA amplifier, intermediate frequency amplifier, and automatic weather station to the receiver control thread. After acquiring the total power voltage of the four intermediate frequency signals, the receiver control thread uses a moving average processing method to reduce noise, converts the acquired total power voltage into a power value, performs internal calibration to obtain the gain and brightness temperature values ​​of the four channels, and sends them to the graphical display interface for display. The graphical display interface has an observation thread for measuring the change in brightness temperature at different locations or at a fixed location under the same atmospheric mass. The observation thread obtains multiple sets of observation data from four channels at each azimuth position, then performs numerical averaging to obtain the observation results, and finally creates an observation directory and observation data file based on the observation time. The observation data file adopts the ASCII file format. The observation thread transmits the observation data to the graphics display interface via vectors. The graphics display interface initializes the graphic coordinates and legend according to the data type, and then refreshes and displays the data.

2. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The operating temperatures of the high-temperature blackbody and the room-temperature blackbody are 60℃ and 30℃, respectively.

3. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The intermediate frequency amplifier outputs four intermediate frequency signals, namely 0~2GHz, 2~4GHz, 4~6GHz and 6~8GHz.

4. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The graphical display interface also has the function of displaying an automatic weather station, including the display of atmospheric temperature, dew point temperature, heater temperature, wind speed and direction, relative humidity and atmospheric pressure.

5. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The graphical display interface creates a bias scan control thread to set different bias voltages for the SIS mixer, thereby obtaining the voltage and current curves of the SIS mixer, which are then displayed through the graphical display interface. The graphical display interface sends scan parameters to the bias scan control thread, including the start point, end point, scan interval, and scan mode.

6. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The graphical display interface has an antenna tracking control thread, which is used to control the radiometer's pointing in real time and provide functions such as receiver synchronization modulation signal, chopper rotation speed control, and status acquisition. The radiometer's azimuth, elevation control, and chopper rotation speed control share the same RS485 bus. The antenna tracking control thread has two working modes: tracking motion mode and stationary mode.

7. The remote omnidirectional water vapor radiometer observation and control system as described in claim 1, characterized in that: The graphical interface creates a remote communication thread, which is a permanent communication thread using the publish-subscribe method. The communication protocol is TCPv4, and the encryption method is TLS encryption key authentication file. A new key is created after each reconnection, and the key generation adopts the Diffie-Hellman method. Multiple clients can connect to the remote communication thread simultaneously, establish communication connections through the scandataTopic topic keyword, and adopt a QoS quality observation strategy.

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