CN210578508U - Real-time noise calibration system of radio telescope system - Google Patents
Real-time noise calibration system of radio telescope system Download PDFInfo
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- CN210578508U CN210578508U CN201920602569.3U CN201920602569U CN210578508U CN 210578508 U CN210578508 U CN 210578508U CN 201920602569 U CN201920602569 U CN 201920602569U CN 210578508 U CN210578508 U CN 210578508U
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Abstract
The utility model provides a radio telescope system's real-time noise calibration system, this system includes: the antenna comprises an antenna unit, a feed source, a calibration unit and a receiving unit. The feed source receives radio signals from a celestial body or a cold air gathered by the antenna unit and sends the radio signals to the calibration unit. The calibration unit is used for generating a noise calibration signal which changes periodically, coupling the noise calibration signal with the radio signal to generate a coupling signal, and then sending the coupling signal to the receiving unit. And the receiving unit acquires corresponding output power when the telescope points to cold air or a celestial body according to the coupling signal, and performs noise calibration on the telescope system according to the variation difference of the output power so as to acquire the absolute flow of the celestial body. The utility model discloses can improve the accuracy of radio telescope system's noise calibration.
Description
Technical Field
The utility model relates to a radio astronomy technical field especially relates to a real-time noise calibration system of radio telescope system.
Background
The radio telescope is used to receive radio signal radiated by celestial body in universe and to research the physical and chemical properties of celestial body. The radio telescope consists of two parts, antenna and receiving system. The common reflector antenna reflects and converges weak celestial body signals to a receiving system. The receiving system comprises a feed source and a receiver assembly: the feed source collects signals converged from the reflecting surface; the receiver comprises a low noise amplifier, a filter, a mixer, AD sampling and the like, and is used for amplifying, filtering and other series of processing on signals and finally processing astronomical data by using a computer, so that the information of a research celestial body is obtained.
When a radio telescope system is observed, the corresponding relation between the power value of a received signal and the power of a celestial body radiation signal needs to be accurately known, so that the absolute flow information of a celestial body is obtained, and astronomy research is carried out. Generally, the received signal includes sky background noise, atmospheric loss, antenna loss, noise generated by the receiver itself, and the like, in addition to the celestial body radiation signal, and is collectively referred to as telescope system noise. Meanwhile, the noise of the telescope system is different along with the different positions of the telescope pointing to the sky; even if the telescope is pointed at the same position, the system noise changes along with the change of the temperature along with the time. The noise calibration of the telescope system is a key step in the observation of the radio telescope system, and can determine the validity and usability of the observation data. Therefore, how to calibrate the system noise in real time is realized, so that the telescope system noise is removed from the received signals, the instability of the output noise of a noise source caused by the change of voltage and ambient temperature is reduced, the accurate celestial body absolute flow is obtained, and the method has important research significance.
SUMMERY OF THE UTILITY MODEL
The utility model provides a real-time noise calibration system of radio telescope system solves traditional radio telescope system and easily arouses noise source output noise unstability because of voltage and ambient temperature's change when carrying out the noise calibration, causes the unsafe problem of data that the noise calibration obtained, can improve the accuracy of the noise calibration of radio telescope system.
In order to achieve the above purpose, the utility model provides the following technical scheme:
a real-time noise calibration system for a radio telescope system, comprising: the antenna comprises an antenna unit, a feed source, a calibration unit and a receiving unit;
the feed source receives radio signals from a cold air or a celestial body converged by the antenna unit and sends the radio signals to the calibration unit;
the calibration unit is used for generating a noise calibration signal which changes periodically, and coupling the noise calibration signal with the radio signal to generate a coupling signal and then sending the coupling signal to the receiving unit when the telescope points to cold air or a celestial body;
and the receiving unit acquires corresponding output power when the telescope points to cold air or the celestial body according to the coupling signal, and performs noise calibration on the telescope system according to the variation difference of the output power so as to acquire the absolute flow of the celestial body to be detected.
Preferably, the receiving unit calibrates the output power of the receiving unit according to the periodic variation difference of the output power when the telescope points to the cold space and the known equivalent noise temperature of the noise source, and calibrates the output power to obtain the noise temperature of the telescope system;
the receiving unit is also used for obtaining the brightness temperature of the celestial body to be measured according to the difference value of the output power when the telescope points to the celestial body and the output power when the telescope points to the cold space;
the receiving unit also determines the absolute flow of the celestial body to be measured according to the brightness temperature of the celestial body to be measured and the effective receiving area of the antenna unit, wherein the effective receiving area of the antenna unit is measured through a standard source in the radio astronomy.
Preferably, the calibration unit includes: the noise generation module, the coupling module, the control module and the power supply module;
the input end of the coupling module is connected with the output end of the noise generation module, the control end of the coupling module is connected with the output end of the control module, and the power supply module provides direct current power supply for each module;
the noise generation module is used for generating a noise calibration signal according to a set noise source;
the coupling module is used for coupling the noise calibration signal with the radio signal and generating the coupling signal which changes periodically;
the control module outputs PWM waves to control the coupling module to be opened and closed periodically, so that the noise calibration signal changes periodically.
Preferably, the coupling module includes: the device comprises a feed source interface, a receiver interface, a directional coupler and a microwave switch;
the directional coupler is connected with the feed source through the feed source interface, and the directional coupler is in signal connection with the receiving unit through the receiver interface;
the input end of the microwave switch is connected with the output end of the noise generation module, the output end of the microwave switch is connected with the coupling end of the directional coupler, and the control end of the microwave switch is connected with the output end of the control module;
the control module controls the noise calibration signal generated by the noise generation module to be switched on and off according to a set period through the microwave switch.
Preferably, the noise generation module includes: the circuit comprises a noise tube, a voltage stabilizing circuit, a bias circuit, a blocking capacitor, an attenuation circuit, a power interface and an output interface;
the input end of the voltage stabilizing circuit is connected with the power interface, the output end of the voltage stabilizing circuit is connected with the input end of the bias circuit, the output end of the bias circuit is connected with the input end of the noise tube, the output end of the noise tube is connected with one end of the blocking capacitor, the other end of the blocking capacitor is connected with the input end of the attenuation circuit, and the output end of the attenuation circuit is connected with the output interface;
the power supply module inputs direct current through a power supply interface, and the voltage stabilizing circuit and the bias circuit adjust the input current of the noise source in real time to enable the noise source to generate the noise calibration signal under constant current;
the blocking capacitor is used for isolating direct current signals, and the attenuation circuit is used for adjusting the output power of the noise tube.
Preferably, the noise generation module further includes: the constant temperature control circuit is used for controlling the noise tube to generate the noise calibration signal at a set temperature according to the ambient temperature.
Preferably, the noise tube includes: an avalanche diode operating in a reverse breakdown region to generate equivalent noise.
The utility model provides a real-time noise calibration system of radio telescope system, the noise calibration signal of the periodic variation who produces through calibration unit control noise source couples with the radio signal who comes from celestial body or cold air, and generates the coupling signal, utilizes the equivalent noise temperature of noise source to mark the output of receiving element to carry out the noise calibration to the telescope system according to directional celestial body and the change difference of output when directional cold air. The problem that when the traditional radio telescope system is used for noise calibration, noise source output noise is unstable due to changes of voltage and ambient temperature, so that data obtained by noise calibration is inaccurate is solved, and the accuracy of the noise calibration of the radio telescope system can be improved.
Drawings
In order to more clearly illustrate the specific embodiments of the present invention, the drawings used in the embodiments will be briefly described below.
Fig. 1 is a schematic structural diagram of a real-time noise calibration system of a radio telescope system provided by the present invention;
fig. 2 is a schematic structural diagram of a calibration unit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a noise generation module according to an embodiment of the present invention;
fig. 4a is a waveform diagram of a microwave switch control signal according to an embodiment of the present invention;
FIG. 4b is a waveform diagram of the output power of the receiving system as a function of time when the telescope is aligned with the radio source according to the embodiment of the present invention;
fig. 4c is a waveform diagram of the output power of the telescope alignment cold space time receiving system according to the embodiment of the present invention;
fig. 5 is a schematic diagram of a real-time noise calibration method for a radio telescope system according to the present invention.
Detailed Description
In order to make those skilled in the art better understand the solution of the embodiments of the present invention, the embodiments of the present invention are further described in detail below with reference to the accompanying drawings and the implementation manner.
The telescope aims at the problems that signals received by a traditional telescope are easily influenced by environment temperature, equipment current and system noise, and obtained measurement data are unstable and inaccurate. The utility model provides a real-time noise calibration system and method of radio telescope system produces the noise calibration signal of periodic variation through calibration unit control noise source to carry out the coupling with the radio signal who comes from the celestial body or cold sky, and generate the coupling signal, utilize the equivalent noise temperature of noise source to mark receiving unit's output, and carry out the noise calibration to the telescope system according to directional celestial body and directional cold time output's change difference. The problem that when the traditional radio telescope system is used for noise calibration, noise source output noise is unstable due to changes of voltage and ambient temperature, so that data obtained by noise calibration is inaccurate is solved, and the accuracy of the noise calibration of the radio telescope system can be improved.
As shown in fig. 1, a real-time noise calibration system of a radio telescope system includes: the antenna comprises an antenna unit, a feed source, a calibration unit and a receiving unit. The feed source receives radio signals from a celestial body or a cold air converged by the antenna unit and sends the radio signals to the calibration unit. The calibration unit is used for generating a noise calibration signal which changes periodically, and coupling the noise calibration signal and the radio signal to generate a coupling signal and then sending the coupling signal to the receiving unit when the telescope points to cold air or a celestial body. And the receiving unit acquires corresponding output power when the telescope points to cold air or the celestial body according to the coupling signal, and performs noise calibration on the telescope system according to the variation difference of the output power so as to acquire the absolute flow of the celestial body to be detected.
Specifically, the receiving unit includes: receiver and computer, antenna element includes: a reflector antenna. When the radio telescope points at the celestial body to be measured or when the radio telescope is in cold air, radiation signals from the celestial body or noise signals from the cold air are converged to the feed source through the reflector antenna, enter the receiver through the noise calibration unit, and are finally transmitted to the computer for data processing to obtain the radiation power value of the celestial body or the cold air. The calibration unit controls the coupling module to be opened and closed periodically according to the control signal so that the noise calibration signal generates periodic change, the receiver receives the power of the periodic change, and the astronomical signal can be obtained by deducting the noise temperature of the telescope system obtained by calibration.
Further, the receiving unit calibrates the output power of the receiving unit according to the periodic variation difference of the output power of the telescope in the cold space and the known equivalent noise temperature of the noise source, and calibrates the output power to obtain the noise temperature of the telescope system; the receiving unit is also used for obtaining the brightness temperature of the celestial body to be measured according to the difference value of the output power when the telescope points to the celestial body and the output power when the telescope points to the cold space; the receiving unit also determines the absolute flow of the celestial body to be detected according to the brightness temperature of the celestial body to be detected and the effective receiving area of the antenna unit, wherein the effective receiving area of the antenna unit is measured through a standard source in the radio astronomy.
In one embodiment, the celestial body is observed by first aligning the celestial body, and the output power of the receiving system varies periodically due to the periodic variation of the noise calibration signal, as shown in FIGS. 4a-4 b. P1Including celestial body radiation power, telescope system noise power and output power of noise source. P2Including celestial radiation power and telescope system noise power. At this time, the ordinate P1And P2The calibration method is a digital calibration-free method, and the real power value corresponding to the ordinate needs to be calibrated by using the equivalent noise temperature of the noise source. Due to the fact thatPower is proportional to equivalent noise temperature, P1Equivalent to TS+TSYS+TNS，P2Equivalent to TS+TSYS. Wherein T isSIs the bright temperature of the celestial body, TSYSFor telescope equivalent system noise temperature, TNSIs the noise source equivalent noise temperature. P1And P2Difference value Δ P ofONI.e. equivalent to TNS。TNSIs a known parameter of the noise source, and therefore utilizes TNSI.e. calibrating delta PONThereby obtaining a vertical coordinate PONThe corresponding real power value, i.e. the output power of the receiving unit is scaled.
The telescope is deflected from the celestial body and aimed at the cold air, and the output power of the receiving system varies periodically due to the periodic variation of the noise calibration signal, as shown in fig. 4 c. P3Including telescope system noise power and output power of noise sources. P4I.e. telescope system noise power. Power is proportional to equivalent noise temperature, P3Equivalent to TSYS+TNS，P4Equivalent to TSYS。P3And P4Difference value Δ P ofOFFIs also equivalent to TNS. By TNSI.e. calibrating delta POFFThereby obtaining a vertical coordinate POFFThe corresponding real power value, i.e. the output power of the receiving unit is scaled. At the moment, the noise temperature T of the telescope equivalent system is also obtainedSYS。 P1And P3A difference of (A), or P2And P4Difference of (i.e. brightness temperature T of celestial body)S. To increase the integration time in astronomical observations, P can be used in the calculation1And P2Mean value of
And P3And P4Mean value of
The difference of (a) is taken as the bright temperature of the celestial body.
As shown in fig. 2, the calibration unit includes: the device comprises a noise generation module, a coupling module 11, a control module and a power supply module. The input end of the coupling module 11 is connected with the output end of the noise generation module, the control end of the coupling module is connected with the output end of the control module, and the power supply module provides direct current power supply for each module. The noise generation module is used for generating a noise calibration signal according to a set noise source. The coupling module 11 is configured to couple the noise calibration signal with the radio signal and generate the coupling signal with a periodic variation. The control module outputs PWM waves to control the coupling module to be opened and closed periodically, so that the noise calibration signal changes periodically.
Specifically, the control module may include: the upper computer can control the output of the single chip microcomputer through the computer interface, the single chip microcomputer controls whether a noise calibration signal output by the noise generation module enters or not through outputting a square wave signal, the noise source is connected when the square wave signal is at a high level, and the noise source is disconnected when the square wave signal is at a low level. The power module includes: the calibration unit comprises a direct current power supply and an alternating current interface, wherein an external power supply converts alternating current into direct current inside the direct current power supply through the alternating current interface, and the direct current power supply supplies power to each device of the calibration unit. It should be noted that the PWM wave output by the control module may have other waveforms, which are set according to actual requirements.
In practical application, the telescope is pointed to a bias celestial body to be measured and is pointed to cold air near the celestial body, the coupling module is periodically opened and closed under the control of square wave signals provided by the direct-current power supply and the control module, so that the noise calibration signal generates periodic change, the receiver receives the power of the periodic change, and the power value received by the receiver can be calibrated and the noise of a telescope system can be calibrated according to the change difference and the known equivalent noise temperature of the noise source. When the telescope points to the celestial body, the receiving unit obtains the brightness temperature of the celestial body to be measured according to the change difference value of the output power and the output power when the telescope points to the celestial body; and the receiving unit determines the absolute flow of the celestial body to be detected according to the brightness temperature of the celestial body to be detected and the effective receiving area of the antenna unit. Therefore, the system can calibrate in real time and calibrate the noise temperature of the telescope system corresponding to the real-time pointing direction of the telescope, thereby obtaining the absolute flow of the celestial body to be measured.
Further, the coupling module 11 includes: the device comprises a feed source interface, a receiver interface, a directional coupler and a microwave switch. The directional coupler is connected with the feed source through the feed source interface, and the directional coupler is in signal connection with the receiving unit through the receiver interface. The input end of the microwave switch is connected with the output end of the noise generation module, the output end of the microwave switch is connected with the coupling end of the directional coupler, and the control end of the microwave switch is connected with the output end of the control module. The control module controls the noise calibration signal generated by the noise generation module to be switched on and off according to a set period through the microwave switch.
Specifically, the calibration unit is located between a feed source and a receiver in a radio telescope signal receiving link, the feed source is connected with a feed source interface of the calibration unit, and the receiver is connected with a receiver interface of the calibration unit. The radio signals from celestial bodies or cold air converged by the reflector antenna are collected by the feed source, enter the noise calibration unit and then enter the receiver. The signal of the feed source sending radio signal entering the calibration unit enters the directional coupler, the noise calibration signal also enters the directional coupler through the microwave switch, and the noise calibration signal and the directional coupler are coupled and then output to the port of the receiver. The directional coupler has two signal paths inside, and the signal path from the through end to the input end is a through path of the signal, and the signal has only a small loss, and the loss depends on the insertion loss coefficient of the directional coupler, for example, the insertion loss is 1dB, which means that 80% of energy is transmitted. The coupling path of the signal from the coupling end to the input end is the path through which only a small amount of signal passes, and the coupling coefficient, for example, the coupling degree is 20dB, which depends on the directional coupler, represents that only 1% of the signal can be transmitted to the input port of the coupler. The directional coupler functions to combine the signals of the two paths together for output from the input port to the receiver. During astronomical observation, a celestial body signal enters a receiver through a coupler through path, and a noise signal for calibration enters the receiver through a coupling path.
As shown in fig. 3, the noise generation module includes: the circuit comprises a noise tube, a voltage stabilizing circuit, a bias circuit, a blocking capacitor, an attenuation circuit, a power interface and an output interface. The input end of the voltage stabilizing circuit is connected with the power interface, the output end of the voltage stabilizing circuit is connected with the input end of the bias circuit, the output end of the bias circuit is connected with the input end of the noise tube, the output end of the noise tube is connected with one end of the blocking capacitor, the other end of the blocking capacitor is connected with the input end of the attenuation circuit, and the output end of the attenuation circuit is connected with the output interface. The power supply module inputs direct current through a power supply interface, and the voltage stabilizing circuit and the bias circuit adjust the input current of the noise source in real time, so that the noise source generates the noise calibration signal under constant current. The blocking capacitor is used for isolating direct current signals, and the attenuation circuit is used for adjusting the output power of the noise tube.
Further, the noise generation module further includes: the constant temperature control circuit is used for controlling the noise tube to generate the noise calibration signal at a set temperature according to the ambient temperature.
In practical applications, the thermostatic control circuit may include: the constant temperature control chip is adopted to control the ambient temperature of the noise tube to be constant at a set temperature, so that the instability of noise output noise of a noise source caused by temperature difference is avoided. In an embodiment, the noise generating unit includes a circuit board, a thermostatic control chip circuit board, and a housing. The main circuit board mainly includes: the device comprises a direct-current power supply interface, a voltage stabilizing circuit, a biasing circuit, a noise tube, a blocking capacitor, an attenuation chip and a noise source output interface. The constant temperature control chip is tightly attached to the noise tube to provide constant temperature for the noise tube. The design of the main circuit board is mainly to make the noise tube work at a proper DC bias point, so as to generate noise with certain power. The equivalent noise temperature of the noise is related to the current intensity passing through the noise tube, and the current input to the noise tube is adjusted by means of the voltage stabilizing circuit and the bias circuit. The blocking capacitor is used for isolating the direct current signal from entering the output end of the noise source; the attenuator chip reduces the output power of the noise tube on one hand, so that the noise tube meets the requirement of noise calibration of a radio telescope system, and on the other hand, the reflection loss condition of an output port can be improved.
The noise tube includes: an avalanche diode operating in a reverse breakdown region to generate equivalent noise.
In practical application, the calibrated noise signal is generated by a noise source, and the microwave switch plays a role in controlling the on-off of the noise signal generated by the noise source into the directional coupler so as to enable the noise calibration signal to generate periodic variation. The core device of the noise source is an avalanche diode, reverse breakdown voltage is applied to the avalanche diode, the avalanche diode works in a reverse breakdown region, internal electrons collide violently due to the avalanche effect to generate a large amount of noise, and the equivalent noise temperature reaches tens of thousands to hundreds of thousands of Kelvin.
It is visible, the utility model provides a real-time noise calibration system of radio telescope system produces the noise calibration signal of periodic variation through calibration unit control noise source to with come from celestial body or the radio signal in cold air carries out the coupling, and generates the coupling signal, receiving element basis the coupling signal obtains at the directional cold air of telescope or corresponding output in celestial body time, and carries out the noise calibration to the telescope system according to output's change difference. The problem that when the traditional radio telescope system is used for noise calibration, noise source output noise is unstable due to changes of voltage and ambient temperature, so that data obtained by noise calibration is inaccurate is solved, and the accuracy of the noise calibration of the radio telescope system can be improved.
As shown in fig. 5, the present invention further provides a real-time noise calibration method for a radio telescope system, comprising:
s1: when the telescope points to the celestial body or is in a cold space, acquiring a radio signal of the celestial body or the cold space;
s2: a noise calibration signal is generated for the periodic variations.
S3: and when the telescope points to the celestial body or is cold, the noise calibration signal is coupled with the radio signal, and a coupling signal is generated.
S4: and obtaining corresponding output power when the telescope points to cold air or the celestial body according to the coupling signal, and carrying out noise calibration on the telescope system according to the variation difference of the output power so as to obtain the absolute flow of the celestial body to be measured.
Specifically, during astronomical observation, a radio signal is acquired by pointing a telescope to a celestial body to be detected or a cold air, a noise calibration signal is generated by a set noise source, a coupling module is controlled to be opened and closed periodically, so that the noise calibration signal and the coupling signal generated by the radio signal are changed periodically, a receiver receives the power of the periodic change, the power of the signal is calibrated by using a known noise source according to a change difference value, the received power value can be calibrated, and the noise temperature of a telescope system obtained by calibration is deducted to obtain the celestial body signal.
The method further comprises the following steps:
s5: and adjusting the input current of the noise source in real time to enable the noise source to generate the noise calibration signal under a constant current, and/or controlling the noise source to generate the noise calibration signal under a set temperature according to the ambient temperature.
In practical application, under the action of constant voltage and constant temperature control, the temperature and current of the noise tube are constant, so that the output noise is stable. The accuracy of the noise calibration signal provided by the noise source is made higher.
Further, the noise calibration is carried out on the telescope system according to the variation difference of the output power, and then the absolute flow of the celestial body to be measured is obtained, which includes: the telescope is pointed to cold air, and the output power of the receiving unit is calibrated according to the periodic variation difference of the output power of the pointed cold air and the known equivalent noise temperature of the noise source, so as to obtain the noise temperature of the telescope system through calibration; pointing the telescope to the celestial body, and obtaining the brightness temperature of the celestial body to be measured according to the difference value of the output power when pointing to the celestial body and the output power when pointing to the cold space; and determining the absolute flow of the celestial body to be measured according to the brightness temperature of the celestial body to be measured and the effective receiving area of the telescope system, wherein the effective receiving area is measured by a standard source in the radio astronomical.
It is visible, the utility model provides a radio telescope system's real-time noise calibration method produces periodic variation's noise calibration signal through the control noise source to carry out the coupling with the radio signal who comes from celestial body or cold air, and generate the coupling signal, utilize the equivalent noise temperature of noise source to mark receiving element's output, and then according to directional celestial body and directional cold air time output's difference carry out the noise calibration to the telescope system. The problem that when the traditional radio telescope system is used for noise calibration, noise source output noise is unstable due to changes of voltage and ambient temperature, so that data obtained by noise calibration is inaccurate is solved, and the accuracy of the noise calibration of the radio telescope system can be improved.
The structure, features and effects of the present invention have been described in detail above according to the embodiment shown in the drawings, and the above description is only the preferred embodiment of the present invention, but the present invention is not limited to the implementation scope shown in the drawings, and all changes made according to the idea of the present invention or equivalent embodiments modified to the same changes should be considered within the protection scope of the present invention when not exceeding the spirit covered by the description and drawings.
Claims (7)
1. A real-time noise calibration system for a radio telescope system, comprising: the antenna comprises an antenna unit, a feed source, a calibration unit and a receiving unit;
the feed source receives radio signals from a cold air or a celestial body converged by the antenna unit and sends the radio signals to the calibration unit;
the calibration unit is used for generating a noise calibration signal which changes periodically, and coupling the noise calibration signal with the radio signal to generate a coupling signal and then sending the coupling signal to the receiving unit when the telescope points to cold air or a celestial body;
and the receiving unit acquires corresponding output power when the telescope points to cold air or the celestial body according to the coupling signal, and performs noise calibration on the telescope system according to the variation difference of the output power so as to acquire the absolute flow of the celestial body to be detected.
2. The real-time noise calibration system for a radio telescope system as claimed in claim 1,
the receiving unit calibrates the output power of the receiving unit according to the periodic variation difference value of the output power of the telescope in the cold space and the known equivalent noise temperature of the noise source, and calibrates the output power to obtain the noise temperature of the telescope system;
the receiving unit is also used for obtaining the brightness temperature of the celestial body to be measured according to the difference value of the output power when the telescope points to the celestial body and the output power when the telescope points to the cold space;
the receiving unit also determines the absolute flow of the celestial body to be measured according to the brightness temperature of the celestial body to be measured and the effective receiving area of the antenna unit, wherein the effective receiving area of the antenna unit is measured through a standard source in the radio astronomy.
3. The real-time noise calibration system for a radio telescope system as claimed in claim 1, wherein the calibration unit comprises: the noise generation module, the coupling module, the control module and the power supply module;
the input end of the coupling module is connected with the output end of the noise generation module, the control end of the coupling module is connected with the output end of the control module, and the power supply module provides direct current power supply for each module;
the noise generation module is used for generating a noise calibration signal according to a set noise source;
the coupling module is used for coupling the noise calibration signal with the radio signal and generating the coupling signal which changes periodically;
the control module outputs PWM waves to control the coupling module to be opened and closed periodically, so that the noise calibration signal changes periodically.
4. The real-time noise calibration system for a radio telescope system as claimed in claim 3, wherein the coupling module comprises: the device comprises a feed source interface, a receiver interface, a directional coupler and a microwave switch;
the directional coupler is connected with the feed source through the feed source interface, and the directional coupler is in signal connection with the receiving unit through the receiver interface;
the input end of the microwave switch is connected with the output end of the noise generation module, the output end of the microwave switch is connected with the coupling end of the directional coupler, and the control end of the microwave switch is connected with the output end of the control module;
the control module controls the noise calibration signal generated by the noise generation module to be switched on and off according to a set period through the microwave switch.
5. The real-time noise calibration system for a radio telescope system according to claim 3, wherein the noise generation module comprises: the circuit comprises a noise tube, a voltage stabilizing circuit, a bias circuit, a blocking capacitor, an attenuation circuit, a power interface and an output interface;
the input end of the voltage stabilizing circuit is connected with the power interface, the output end of the voltage stabilizing circuit is connected with the input end of the bias circuit, the output end of the bias circuit is connected with the input end of the noise tube, the output end of the noise tube is connected with one end of the blocking capacitor, the other end of the blocking capacitor is connected with the input end of the attenuation circuit, and the output end of the attenuation circuit is connected with the output interface;
the power supply module inputs direct current through a power supply interface, and the voltage stabilizing circuit and the bias circuit adjust the input current of the noise source in real time to enable the noise source to generate the noise calibration signal under constant current;
the blocking capacitor is used for isolating direct current signals, and the attenuation circuit is used for adjusting the output power of the noise tube.
6. The real-time noise calibration system for a radio telescope system according to claim 5, wherein the noise generation module further comprises: the constant temperature control circuit is used for controlling the noise tube to generate the noise calibration signal at a set temperature according to the ambient temperature.
7. The real-time noise calibration system for a radio telescope system as claimed in claim 5, wherein the noise tube comprises: an avalanche diode operating in a reverse breakdown region to generate equivalent noise.
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| CN (1) | CN210578508U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110113066A (en) * | 2019-04-29 | 2019-08-09 | 中国科学院国家天文台 | A kind of the real-time noise calibration system and method for radio telescope system |
| CN112003570A (en) * | 2020-08-31 | 2020-11-27 | 中电科仪器仪表有限公司 | Millimeter wave noise source with high-frequency broadband and preparation method thereof |
-
2019
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110113066A (en) * | 2019-04-29 | 2019-08-09 | 中国科学院国家天文台 | A kind of the real-time noise calibration system and method for radio telescope system |
| CN110113066B (en) * | 2019-04-29 | 2023-12-01 | 中国科学院国家天文台 | Real-time noise calibration system and method for radio telescope system |
| CN112003570A (en) * | 2020-08-31 | 2020-11-27 | 中电科仪器仪表有限公司 | Millimeter wave noise source with high-frequency broadband and preparation method thereof |
| CN112003570B (en) * | 2020-08-31 | 2022-07-19 | 中电科思仪科技股份有限公司 | Millimeter wave noise source with high-frequency broadband and preparation method thereof |
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