Remote omnidirectional water vapor radiometer observation control system

Abstract

The invention 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 equipment (an antenna drive, a receiver, a calibration black body, a bias source, an intermediate frequency power attenuation module, a chopper wheel drive and the like) and software control (comprising a graphic display interface, a bias scanning control thread, an antenna tracking control thread, an observation thread, a remote communication thread and the like). According to the invention, various observation modes such as rapid observation calibration, omnidirectional scanning, fixed-point scanning and atmosphere Skydip based on a chopping mode are realized, and observation data are transmitted to a data service client through the Internet in an encrypted data transmission mode; meanwhile, the functions of continuous and real-time observation and processing of terahertz atmosphere signals and the like are achieved, and the application prospect is wide.

Description

Technical Field

[0001] The present invention belongs to the field of water vapor radiometer observation and control, and in particular relates to a high-sensitivity heterodyne, omnidirectional observation water vapor radiometer system based on a superconducting mixer SIS and an observation, control and operation method thereof. Background Art

[0002] Commonly used water vapor radiometer (WVR) systems are primarily designed to directly measure the brightness temperature of water vapor absorption lines in the atmosphere. This direct measurement system uses brightness temperatures across different frequency bands to infer the actual water vapor content. Currently, influential radiometer companies in the world include RPG in Germany and Radiometers in the United States. These systems typically utilize Schottky semiconductor-based detection systems, which are distinguished by their ease of installation and measurement. However, they suffer from a significant drawback: high noise levels, typically exceeding 1000K. Summary of the Invention

[0003] The present invention aims to solve the problems of high noise temperature, system gain variation and nonlinearity of the above Schottky detector system and provides a remote omnidirectional water vapor radiometer observation and control system.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[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 realize the pointing of the omnidirectional water vapor radiometer at any AZ and EL position; the receiver includes a local oscillator signal source, an SIS mixer, a CLNA amplifier, an intermediate frequency amplifier, and a synchronous detection circuit; the local oscillator signal source is used to provide a pump signal to the SIS mixer, so that the SIS mixer generates an intermediate frequency signal, which is then amplified by the CLNA amplifier and the intermediate frequency amplifier and outputs four channels The intermediate frequency signal is sent to the synchronous detection circuit for detection; the calibration blackbody includes a high-temperature blackbody and a room-temperature blackbody, which are used to calibrate the system gain of the receiver; the bias source is used to provide a bias voltage to the SIS mixer; the intermediate frequency power attenuation module is used to power-regulate the four intermediate frequency signals output by the intermediate frequency amplifier so that their total power level is within the linear range of the synchronous detection circuit; the chopper wheel drive is used to rotate the chopper wheel, which provides a pulse signal to the synchronous detection circuit, so that the synchronous detection circuit can collect signals of the brightness temperatures of the sky, the high-temperature blackbody, and the room-temperature blackbody.

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

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

[0008] Optionally, a graphic display interface is further included, which has the function of displaying the receiver, including the status display of the SIS mixer voltage and current, the CLNA amplifier voltage and current, and the total power of the four intermediate frequency signals.

[0009] Optionally, the graphic display interface also has the function of displaying an automatic weather station, including 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 of 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 the receiver control thread collects the total power voltage of the four intermediate frequency signals, it uses a sliding average processing method to reduce noise, converts the collected total power voltage into a power value, performs internal calibration, obtains 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 a voltage-current curve of the SIS mixer and displaying it through the graphical display interface; the graphical display interface sends the scan parameters to the bias scan control thread, including the starting point, end point, scan interval, and scan mode.

[0012] Optionally, the graphical display interface creates an antenna tracking control thread, which is used to control the pointing of the radiometer in real time and provide receiver synchronization modulation signal, chopper wheel rotation speed control and status acquisition functions. The azimuth, pitch control and chopper wheel of the radiometer share the same RS485 bus; the antenna tracking control thread has two working modes: tracking motion mode and static mode.

[0013] Optionally, the graphic display interface is created with an observation thread for measuring the brightness temperature change at different azimuths or the brightness temperature change at a fixed position under the same atmospheric quality; the observation thread obtains multiple sets of observation data of 4 channels at each azimuth position, and then performs numerical averaging on them to obtain observation results, and finally creates an observation directory and observation data file according to the observation time, and the observation data file adopts ASCII file format; the observation thread transmits the observation data to the graphic display interface in a vector manner, and the graphic display interface initializes the graphic coordinates and legend according to the data type, and displays it after refreshing.

[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 uses the TCPv4 version, and the encryption method uses the TLS encryption key authentication file. A new key is created after each reconnection, and the key generation uses the Diffie-Hellman method; multiple clients can connect to the remote communication thread at the same time, establish a communication connection through the scandataTopic topic keyword, and adopt the Qos quality observation strategy.

[0015] The beneficial effects of the present invention are:

[0016] (1) The present invention is based on a superconducting SIS frequency-mixing 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 down-converted intermediate frequency signal is amplified after four-way power splitting. The power of different frequency bands is then detected and digitally amplified and collected to obtain the shape of the water vapor absorption line in that frequency band. The specific water vapor content will be inferred later.

[0017] (2) This invention addresses the problem that commonly used radiometers primarily use a single calibration source. However, as measurement accuracy improves, the internal calibration source of radiometers becomes increasingly problematic. In addition to liquid nitrogen and a high-temperature blackbody, a noise diode is added, providing multi-point calibration and eliminating the gain nonlinearity problem of the radiometer. This invention utilizes both high-temperature and room-temperature calibration sources, and a chopper switching mechanism is employed, enabling real-time calibration and improving observation accuracy.

[0018] (3) The present invention realizes a variety of observation methods such as rapid observation calibration based on chopping, omnidirectional scanning, fixed-point scanning and atmospheric Skydip, and transmits the observation data to the data service client via the Internet through encrypted data transmission, realizing the functions of continuous and real-time observation and processing of terahertz atmospheric signals, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0021] Figure 3 It is a flow chart of the graphic display interface of the remote omnidirectional water vapor radiometer observation control system.

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

[0023] Figure 5 This is the flow chart of the bias scanning control thread of the remote omnidirectional water vapor radiometer observation control system.

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

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

[0026] Figure 8 It is a remote communication thread flow chart of the remote omnidirectional water vapor radiometer observation control system.

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

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

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

[0030] Figure 1 This is the hardware block diagram of the remote omnidirectional water vapor radiometer observation and control system. The entire receiver and antenna control system utilizes a unified RS485 interface, a simplified version of the Modbus communication protocol. Communication messages utilize a variable-length RTU format with a maximum length of 64 bytes (standard Modbus RTU messages are 256 bytes, but this is simplified to the minimum required to meet the mission requirements due to limited internal RAM resources in the microcontroller). Independent device addresses are assigned to the receiver control unit (RCU), intermediate frequency unit (IFU), and local oscillator unit (LOU) to enable control via a single RS485 bus.

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

[0032] Antenna drive (AZ / EL): used to realize the pointing of the omnidirectional water vapor radiometer at any AZ (0 to 360°) and EL (0 to 90°) position.

[0033] Two calibration blackbodies: operating temperatures are 60°C and 30°C respectively, used to calibrate the receiver system gain.

[0034] 1 chopper wheel drive: The rotation rate is 5Hz. By changing the receiving optical path signal (sky, high-temperature blackbody and room-temperature blackbody), the receiver can achieve real-time calibration of the sky atmospheric intensity within one rotation cycle.

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

[0036] IF power attenuation module: The IF amplifier is a room-temperature amplifier for the radiometer. Its input signal is 0-8 GHz, and it outputs four 2-GHz bandwidth IF signals (0-2 GHz, 2-4 GHz, 4-6 GHz, and 6-8 GHz), thereby enabling 183 water vapor continuum spectrum signal detection. The attenuation module is the power adjustment module of the IF amplifier, ensuring that the total power level of the four IF 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 range of the ADC acquisition of the synchronous detection circuit, improving the accuracy of the detection circuit.

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

[0038] The system's synchronous detection reading module and other hardware: Synchronous detection uses a rapidly rotating chopper wheel to provide a 5Hz pulse signal, achieving signal synchronization in the synchronous detection circuit. This allows the synchronous detection circuit to accurately collect three total power signals: sky, high-temperature blackbody, and room-temperature blackbody. A calibration formula eliminates gain variations in the omnidirectional radiometer, improving the acquisition accuracy and processing speed of sky radiation signals.

[0039] Figure 2 The graphical display interface has important functions such as system function display, system performance measurement, atmospheric observation mode selection and scientific observation. It can realize detector performance diagnosis, atmospheric observation under different observation modes and observation result fitting. The detailed functions are as follows:

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

[0041] The graphical display interface shows the following receiver functions: SIS voltage and current, CLNA voltage and current, and the status of the four-channel total power (Hot, Ref, Sky, Tb, Gain) derived from the four-channel IF frequency division. Control functions include: channel selection, bias sweep control (real-time monitoring control, sweep mode control, sweep file storage control, sweep start point, end point, sweep step size, single-point sweep duration, number of scanned points display, and graphical display of sweep results).

[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 shows the observation process, the real-time display of the four-channel brightness temperature from the synchronous detection, the graphical display of the position and temperature at different directions of each complete scan, and the graphical display of different atmospheric masses and temperatures after each Skydip observation.

[0044] In the graphical display interface, a receiver status acquisition thread and an antenna tracking control thread were newly established 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 and CLNA, atmospheric parameters (temperature, humidity, pressure, wind speed, wind direction, and dew point temperature) of the AWS, local oscillator signal source status (voltage and current, attenuator voltage), and intermediate frequency (IF) status (power supply voltage and current, attenuator status). The graphical display interface allows control of device parameter settings in the status acquisition thread, including bias voltage sweep control, turning the CLNA bias source on and off, connecting and disconnecting the AWS, and controlling the local oscillator signal source attenuator and intermediate frequency attenuator.

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

[0046] A new clock thread has been created in the graphical display interface to update the observation system time, initialize the observation control graphical display interface, and display the acquisition status in real time. Additionally, a bias scan control thread, a stability test thread, an atmospheric opacity observation thread, and an omnidirectional scan thread have been created for control and observation of the main graphical display interface.

[0047] The observation thread primarily performs observations such as atmospheric opacity strategies and omnidirectional azimuth scanning. This thread primarily interacts with the receiver control thread and antenna thread for control and status, and displays observation results on a graphical display interface. Interactions between the observation thread and the antenna tracking control thread primarily involve setting the antenna position, reading the current position, and reading the standard blackbody temperature. Interactions with the receiver control thread primarily involve obtaining status parameter information for the entire receiver (SIS voltage and current, CLNA voltage and current, LO voltage and current, IF voltage and current attenuation, weather station parameters, and the synchronous detection circuit's four-channel total power values, each containing three total power voltages: atmospheric, high-temperature blackbody, and room-temperature blackbody).

[0048] The main function of the bias scan control thread is to complete the settings of different biases, and then read the voltage, current and power values ​​of different bias points. Through graphical display, it can be used to determine 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 normal state of the receiver, and then starts continuous setting reading and writing. The setting command interacts with the receiver control thread, and the data reading is implemented by its own thread to improve the scanning efficiency. After completing the scanning task, the thread is exited and canceled.

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

[0050] 1) Graphical display interface: First, a user visual operation interface is created, and then three permanent threads are created: antenna tracking control thread, receiver control thread, and time thread. Between the startup of the antenna tracking control thread and the receiver control thread, all system hardware and drivers are checked to see if they are normal.

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

[0052] 3) The graphical display interface creates three non-permanent threads, "IVSweep", "Skydip", and "Scan", which are used to implement system performance testing and atmospheric science observations in different modes.

[0053] 4) Before the antenna tracking control thread and the receiver control thread are started, the graphical display interface connects the "signals" and "response functions" between the two threads, and between the threads and the graphical display interface. After completion, the four non-permanent threads (Skydip, IVSweep, Scan, and Stablity) are initialized and connected for direct signal connections and response function connections. This allows for complex functions such as automatic user interface status updates, user observation parameter settings, user observation mode selection, and scientific continuous observations.

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

[0055] 6) Reset the receiver status and tracking thread status so that the entire system status remains consistent after each system startup to prevent abnormal user operations.

[0056] 7) After the thread is started, 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 a single RS485 bus, using a 1 / 8 frequency division method for state acquisition. Control employs a mutex lock to ensure bus conflicts at all times. After acquiring the four-channel total power voltage, a "Smooth" sliding average process is first applied to reduce acquisition system noise. The acquired power voltage is then converted to specific power values. Finally, internal calibration is performed to obtain the gain and brightness temperature values ​​for the four channels, which are then displayed on a graphical display. To maintain a high acquisition rate, the receiver, weather station, and other status signals are acquired using a frequency division method, reducing the sampling speed of unrelated devices and ensuring a high sampling rate (700ms) for the total power, thereby improving observation efficiency.

[0058] Receiver bias setting, IV scan performance check, scan parameter setting and other receiver control operations and receiver status acquisition operations use a mutual exclusion lock method to ensure that there is only one action on the RS485 bus at any time, 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 SIS bias voltages, thereby obtaining the SIS's voltage and current curves and, in turn, enabling SIS performance assessment. To maintain scan continuity, an interlocking mechanism is employed between the scan thread and the receiver status thread. Before starting a scan, the receiver status thread task is paused, and then the SIS voltage and current scan is continuously performed. Scan parameters include the start and end points, scan interval and interval time, scan mode control, and scan data storage and display. After the scan is complete, the scan lock is released, resuming the receiver control thread task.

[0060] Figure 6 The antenna tracking control thread is primarily responsible for real-time control of the radiometer's pointing direction, providing synchronous modulation signals for the receiver, and controlling the chopper wheel's rotation speed and collecting its status. The azimuth, elevation, and chopper wheels share the same RS485 bus. The antenna tracking control thread has two operating modes: "tracking motion" and "stationary." The chopper wheel's operating state and reference blackbody state utilize a "1 / 20 frequency division" scheme, which increases the speed of the radiometer's directional control and, in turn, its pointing accuracy. This results in a total antenna control frequency of 200ms. The azimuth and elevation drives utilize high-precision reduction gears and harmonic reduction motors, respectively, to achieve high-precision pointing for 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 position.

[0062] The atmospheric opacity observation thread is primarily used to measure brightness temperature under varying atmospheric masses and, through fitting, derive zenithal atmospheric opacity. This thread selects 16 elevation positions (14.5° to 81°) and enables bidirectional scanning, improving observation efficiency. At each elevation position, multiple sets of observation data from four channels (Sky, Ref, Hot, Gain, Tb, Thot, and Tref) are acquired. These data are then numerically averaged to produce lower-noise observations. Finally, a specific observation directory and new observation data files are created based on the observation time. The data files use an ASCII file format for improved readability. The file format consists of a data header, data fitting results, and raw observation data, facilitating subsequent data processing. The saved files are then displayed graphically. Data are then transferred to the graphical display interface via vectors. The graphical display reinitializes the graph coordinates and legend based on the data type and, after refreshing, is displayed on the main interface. The graphical display interface supports mouse operations for daily operations such as zooming in and out, providing a user-friendly interface. Finally, the observation results and status information are encapsulated, encrypted, and sent to the remote client, enabling dual-location data storage and improving data reliability.

[0063] The scanning observation thread measures brightness temperature variations at different azimuths or at fixed locations under the same atmospheric mass. Azimuth scanning utilizes a reciprocating cycle, acquiring multiple sets of observation data from four channels (Sky, Ref, Hot, Gain, Tb, Thot, Tref, and the observation time, ObsTime) at each azimuth. These data are then numerically averaged to produce a lower-noise observation result. Finally, a specific observation directory and new observation data files are created based on the observation time. The data files use an ASCII file format for improved readability. The file format consists of a data header, data fitting results, and raw observation data, facilitating subsequent data processing. The saved files are then displayed graphically. The data is then transferred to the graphical display interface via vectors. The graphical display reinitializes the graph coordinates and legend based on the data type, and then refreshes and displays the data on the main interface. The graphical display interface supports mouse operations for daily operations, such as zooming in and out, providing a user-friendly interface. Finally, the observation results and status information are packaged, encrypted, and sent to the remote client, enabling dual-location data storage and improving data reliability. The fixed-point observation method is based on the scanning observation thread of the azimuth. The only difference is that the azimuth is at a fixed position and the data recording rate is faster.

[0064] Figure 8The remote communication thread adopts the Fast-DDS method and is a permanent communication thread in the publish-subscribe mode. The communication protocol adopts the TCPv4 version, and the encryption method adopts the TLS encryption key authentication file. A new key is created after each reconnection. The key generation adopts the Diffie-Hellman method, thereby realizing remote data transmission and control via the Internet. Multiple clients can connect to a communication thread at the same time, and establish a communication connection through the "scandataTopic" topic keyword. The Qos quality observation strategy is adopted for reliability to realize data retransmission and data history length confirmation, thereby improving the reliability of communication. In the Subscribe thread, by monitoring whether there is data and heartbeat data on the network port, the received data is obtained and saved. After obtaining the data, a directory and a new data file are automatically created and saved in the same format as the local observation data, greatly improving the efficiency of data analysis.

[0065] like Figure 9a and 9b As shown in the figure, the sky signal in synchronous detection passes through the radiometer's 100mm primary mirror and ellipsoidal folding mirror, then passes through a two-blade rotating chopper wheel at the beam waist. It is then time-shared with the low-temperature reference and high-temperature reference blackbodies on either side of the beam and fed into the subsequent receiving optical path. The back-end receiver signal acquisition uses synchronous detection mode, using a constant-temperature reference blackbody (40°C) and a high-temperature heated blackbody (65°C) as two known calibration sources. The chopper wheel rapidly switches between sky / reference / sky / high-temperature sequentially. Synchronous detection and subsequent analog circuitry output the S, R, and H signals.

[0066] The chopper wheel is driven by an HTS6010 servo motor. A zero-point signal is generated via a barrier and an SPX307 optical switch. This zero-point signal is fed into a microcontroller interrupt, which generates the R, S, and H synchronization selection signal timing using software. The zero-point synchronization interrupt primarily resets the three synchronous counters R / S / H. A timer interrupt handles the R / S / H signal timing (decrementing, checking, and level-flipping the corresponding counters).

[0067] Figure 10In the program, the timing of the S, R, and H selection signals is achieved by setting the initial counts for the three selection signals S, H, and R, and then updating and judging the S, H, and R counts in real time in the timer interrupt program. To allow for fine-tuning of the timing, two Modbus registers are set in the program 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 ~25mm@18dB. With a chopper wheel center radius of 90mm, the beam diameter accounts for 25 / (2*90*π)≈5%. If the chopper wheel rotates at a constant frequency of 5Hz, the blanking portion before and after the signal will account for (200ms / 4)*5%=2.5ms, and the signal efficiency can reach approximately 95%, which is another advantage of a large chopper wheel.

[0068] Based on a 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 deduct the front and rear blanking times from the 50ms width.

[0069] Since the chopper wheel synchronization point (Sync) is set midway between Hot and Sky, the sky signal is roughly centered in the 50ms signal observation pulse when the synchronization pulse arrives. At this point, S = 0, R = 1, and H = 1 are set, meaning synchronous detection selects the sky signal path for integration, with both reference paths in a hold state. The subsequent changes are for S to switch from 1 to 0, R to switch from 0 to 1, and H to remain at 0. Setting the initial delay from the synchronization pulse to the subsequent high-to-low transition of S to TskySync, the initial delay for the low-to-high transition of the reference path, TrefSync, is TskySync + Tblank, and the low-to-high transition delay of the hot path, ThotSync, is TrefSync + 100ms.

[0070] During program initialization, set TcalOn = TskyOn = 50ms - Tblank (effective integration time excluding the preceding and following half-blanking periods), TskyOff = 100ms – TskyOn = 50ms + Tblank, and TcalOff = 200ms – TcalOn = 150ms + Tblank, as well as the TskySync, TrefSync, and ThotSync values. TskyOn is the effective integration time of the S signal after blanking (H / A = sampling), while TskyOff is the ineffective time of the S signal (H / A = hold). TcalOff represents the ineffective time of the calibration source R / H (since TcalOn = TskyOn, TcalOn is not defined separately). Setting three independent counters, TskySync, TrefSync, and ThotSync, simplifies the interrupt program design for generating the SHR synchronization signal. The Sky sync signal is a 10Hz periodic signal with an active low level and a 50% duty cycle. The AD1 output level takes 300ms for three cycles to fully charge the subsequent integration circuit. The Ref sync signal is a 5Hz periodic signal with an active low level and a 25% duty cycle. The AD2 output level takes 600ms for three cycles to fully charge the circuit. The Hot sync signal is a 5Hz periodic signal with an active low level and a 25% duty cycle. The AD3 output level takes 600ms for three cycles to fully charge the circuit.

[0071] Based on the aforementioned independent detection principle, the remote omnidirectional water vapor radiometer observation and control system uses a chopper wheel to generate a synchronization signal. The method is as follows: By adjusting the blanking time (Tblink), sky observation synchronization time (Tskysyn), and acquisition time (Tsample), a 10Hz sky synchronization signal and 5Hz room-temperature reference and high-temperature reference synchronization signals are generated at a chopper wheel rotation speed of 5Hz. After synchronous detection and amplification circuits, analog signals of the brightness temperatures of the sky, room-temperature blackbody, and high-temperature blackbody are simultaneously obtained. The actual power signal is then obtained through nonlinear calibration and voltage-power calibration. Finally, the calibration formula is used to obtain the sky brightness temperature and system gain in real time.

[0072] The present invention has the characteristics of real-time detection of atmospheric opacity measurement in a specific direction, multi-mode atmospheric measurement, and the ability to quickly realize local and remote data backup functions. It can realize multi-mode observation of the terahertz atmosphere and provide important technical reference for atmospheric observations 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 based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart 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, IF power attenuation module and chopper wheel driver; The antenna drive is used to realize the 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 is used to provide a pump signal to the SIS mixer, so that the SIS mixer generates an intermediate frequency signal, which is then amplified by the CLNA amplifier and the intermediate frequency amplifier, and outputs four intermediate frequency signals to the synchronous detection circuit for detection; the calibration black body includes a high-temperature black body and a room-temperature black body, which are used to calibrate the system gain of the receiver; the bias source is used to provide a bias voltage to the SIS mixer; the intermediate frequency power attenuation module is used to power adjust the four intermediate frequency signals output by the intermediate frequency amplifier so that their total power level is within the linear range of the synchronous detection circuit; the chopper wheel drive is used to rotate the chopper wheel, and the chopper wheel provides a pulse signal to the synchronous detection circuit, so that the synchronous detection circuit can collect the bright temperature signals of the sky, the high-temperature black body and the room-temperature black body.

2. The remote omnidirectional water vapor radiometer observation and control system according to claim 1, characterized in that: The operating temperatures of the high-temperature blackbody and the normal-temperature blackbody are 60° C. and 30° C. respectively.

3. The remote omnidirectional water vapor radiometer observation and control system according to claim 1, characterized in that: The room temperature intermediate frequency amplifier outputs four intermediate frequency signals of 0-2 GHz, 2-4 GHz, 4-6 GHz and 6-8 GHz respectively.

4. The remote omnidirectional water vapor radiometer observation and control system according to claim 1, characterized in that: It also includes a graphic 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 4-channel intermediate frequency signals.

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

6. The remote omnidirectional water vapor radiometer observation and control system according to claim 4, characterized in that: The graphical display interface creates a receiver control thread, which includes control of 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 the receiver control thread collects the total power voltage of the four intermediate frequency signals, it uses a sliding average processing method to reduce noise, converts the collected total power voltage into a power value, performs internal calibration, obtains the gain and brightness temperature values ​​of the four channels, and sends them to the graphical display interface for display.

7. The remote omnidirectional water vapor radiometer observation and control system according to claim 4, characterized in that: The graphical display interface creates a bias scan control thread for setting different bias voltages for the SIS mixer, thereby obtaining the voltage-current curve of the SIS mixer and displaying it through the graphical display interface; the graphical display interface sends the scan parameters to the bias scan control thread, including the starting point, end point, scan interval, and scan mode.

8. The remote omnidirectional water vapor radiometer observation and control system according to claim 4, characterized in that: The graphical display interface creates an antenna tracking control thread, which is used to control the pointing of the radiometer in real time and provide receiver synchronization modulation signals, chopper wheel rotation speed control and status acquisition functions. The azimuth and pitch control of the radiometer and the chopper wheel share the same RS485 bus; the antenna tracking control thread has two working modes: tracking motion mode and static mode.

9. The remote omnidirectional water vapor radiometer observation and control system according to claim 4, characterized in that: The graphical display interface is created with an observation thread for measuring brightness temperature changes at different locations or brightness temperature changes at a fixed location under the same atmospheric quality; The observation thread obtains multiple sets of observation data of 4 channels at each azimuth position, then performs numerical averaging on them to obtain observation results, and finally creates an observation directory and observation data file according to the observation time. The observation data file adopts ASCII file format; The observation thread transmits the observation data to the graphic display interface in a vector manner. The graphic display interface initializes the graphic coordinates and legend according to the data type and displays it after refreshing.

10. The remote omnidirectional water vapor radiometer observation and control system according to claim 4, characterized in that: The graphical display interface creates a remote communication thread, which is a permanent communication thread using the publish-subscribe method. The communication protocol uses the TCPv4 version, and the encryption method uses the TLS encryption key authentication file. A new key is created after each reconnection, and the key generation uses the Diffie-Hellman method. Multiple clients can connect to the remote communication thread at the same time, establish a communication connection through the scandataTopic topic keyword, and adopt a Qos quality observation strategy.

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