CN112904257B - System and method for calibrating phase error of full link of synthetic aperture microwave radiometer - Google Patents
System and method for calibrating phase error of full link of synthetic aperture microwave radiometer Download PDFInfo
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- CN112904257B CN112904257B CN202110114673.XA CN202110114673A CN112904257B CN 112904257 B CN112904257 B CN 112904257B CN 202110114673 A CN202110114673 A CN 202110114673A CN 112904257 B CN112904257 B CN 112904257B
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Abstract
The invention provides a system and a method for calibrating the phase error of a full link of a synthetic aperture microwave radiometer, wherein the system comprises the following components: the system comprises a comprehensive aperture microwave radiometer, a directional calibration antenna, a Beidou time system, a Beidou positioning system, an azimuth pitching tracking driving system and ground equipment; the directional calibration antenna is arranged on the synthetic aperture microwave radiometer and used for directional calibration of the synthetic aperture microwave radiometer; the Beidou time system is used for providing time information for the calibration system; the Beidou positioning system is used for determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer; the azimuth elevation tracking drive system is used for driving the synthetic aperture microwave radiometer and the directional calibration antenna to track sky star motion; and the ground equipment is used for controlling the movement of the azimuth pitching tracking driving system and collecting and processing data. Compared with the prior art, the method can improve the calibration precision of the phase error of the full link.
Description
Technical Field
The invention belongs to the technical field of space microwave passive remote sensing radiometers, and particularly relates to a system and a method for calibrating a full-link phase error of a synthetic aperture microwave radiometer.
Background
The synthetic aperture microwave radiometer has the advantage of high spatial resolution and is a hotspot of research in the field of microwave remote sensing at present. The phase information of the synthetic aperture microwave radiometer is the key of the imaging of the synthetic aperture microwave radiometer system. The full link phase error of a conventional synthetic aperture microwave radiometer is calibrated by measuring the response of a point source in a dark room. However, the antenna aperture of the current synthetic aperture microwave radiometer is getting bigger and bigger, and far field conditions required during calibration are far. For example, the antenna aperture is 10 meters, the observation frequency is 6.9GHz, and the far-field condition needs 4600 meters. The phase error is calibrated by measuring a point source in a darkroom, the measurement precision is low, and the measurement method belongs to a near field area and does not meet far field conditions. The sky star target radiation signal is strong, meets far field conditions, and can be used for full link phase error calibration of a large-scale synthetic aperture radiometer system.
The synthetic aperture microwave radiometer includes: the system comprises an antenna, a receiver, a data acquisition system, a correlator, a load computer, a noise injection calibration system and the like; the antenna is used for receiving the star radiation signal; a receiver for amplifying and downconverting the satellite radiation signal; the data acquisition system is used for acquiring a star radiation signal; the correlator is used for calculating the phase difference between every two channels; the load computer is used for completing the issuing of the remote control and remote measurement instruction and the collection of the remote control and remote measurement state; and a noise injection scaling system for injecting noise signals into the respective channels.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a system and a method for calibrating the phase error of a full link of a synthetic aperture microwave radiometer.
The technical scheme of the invention is as follows:
a system for calibrating full-link phase errors of a synthetic aperture microwave radiometer, comprising: a synthetic aperture microwave radiometer, the synthetic aperture microwave radiometer further comprising: the system comprises a synthetic aperture microwave radiometer antenna, a receiver, a data acquisition system, a correlator, a load computer and a noise injection calibration system; the calibration system further comprises: the device comprises a directional calibration antenna, a Beidou time system, a Beidou positioning system, an azimuth pitching tracking driving system and ground equipment; wherein:
the directional calibration antenna is arranged on the synthetic aperture microwave radiometer and used for directional calibration of the synthetic aperture microwave radiometer;
the Beidou time system is used for providing time information for the calibration system;
the Beidou positioning system is used for determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer;
the azimuth elevation tracking drive system is used for driving the synthetic aperture microwave radiometer and the directional calibration antenna to track the sky star motion;
and the ground equipment is used for controlling the movement of the azimuth pitching tracking driving system and collecting and processing data.
Optionally, the directional calibration antenna is parallel to the synthetic aperture microwave radiometer antenna and is interfaced to a receiver of the synthetic aperture microwave radiometer to receive sky star radiated energy.
A method for calibrating phase errors of a full link of a synthetic aperture microwave radiometer comprises the following steps:
s1: establishing a full link phase error calibration system of the synthetic aperture microwave radiometer;
s2: arranging the synthetic aperture microwave radiometer on the open air, and determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer by adopting the Beidou positioning system;
s3: the Beidou time system is connected to the ground equipment, and a sky star target to be observed is preselected;
s4: the positioning device calculates the azimuth pitching value of the sky star target in real time according to the time information provided by the Beidou time system and the position coordinate of the sky star target; the ground equipment controls the azimuth pitching driving system according to the azimuth pitching value of the sky star target, scans the sky star target and obtains azimuth and pitching direction scanning data from the data acquisition system;
s5: after scanning is finished, fitting the scanning data of the azimuth and the pitching direction according to a formula (1) to obtain the pointing errors of the azimuth and pitching tracking driving system in the azimuth and the pitching direction;
wherein, a is the detection voltage of the receiver output, k1Is the amplitude coefficient, k2Is a pointing error, k3Is a linear proportionality coefficient, k5The bias voltage of the receiver and p are pointing errors of the azimuth and pitch tracking driving system in azimuth and pitch;
s6: adding the pointing error into the correction to the azimuth-elevation tracking drive system;
s7: a receiving channel of the receiver is switched to an antenna channel, and the sky star signal enters a correlator after being amplified and down-converted by the receiver; the correlator calculates to obtain the phase difference between every two antenna channels, and the phase difference is integrated to obtain an average phase difference matrix
S8: the receiving channel of the receiver is switched to a noise channel; after the noise signal is amplified and down-converted by a receiver, the noise signal enters the correlator; the correlator calculates to obtain the phase difference between every two noise channels, and the phase difference is integrated to obtain an average phase difference matrix
S9: will be provided with
Minus one (C) of
Obtaining a full link phase error at an angle
Optionally, the calibration method further comprises:
s10: and changing the angle relation between the antenna directional diagram of each receiving channel of the receiver of the synthetic aperture microwave radiometer and the sky star target through the azimuth rotation of the azimuth pitching tracking driving system, repeating the steps S6-S9, obtaining the full link phase error of each angle, and storing the full link phase error.
Compared with the prior art, the invention has the following beneficial effects:
1) the invention utilizes the sky star as a far-field calibration source, and avoids the error caused by the unsatisfied far-field condition when the large-scale synthetic aperture radiometer measures.
2) The invention does not need a large darkroom and has lower cost.
3) The invention separates the active phase error (phase error of the receiver and the link after the receiver) from the passive phase error (link between antenna and receiver).
4) The invention can improve the calibration precision of the phase error of the whole link.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a block diagram of a system for calibrating phase errors of a full link of a synthetic aperture microwave radiometer according to an embodiment of the present invention;
fig. 2 is a flowchart of a method for calibrating a full link phase error of a synthetic aperture microwave radiometer according to an embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
As shown in fig. 1, the present embodiment discloses a system for calibrating a full-link phase error of a synthetic aperture microwave radiometer, which includes: the system comprises a comprehensive aperture microwave radiometer pointing calibration antenna, a Beidou time system, a Beidou positioning system, an azimuth pitching tracking driving system and ground equipment; wherein:
the synthetic aperture microwave radiometer further includes: the system comprises a synthetic aperture microwave radiometer antenna, a receiver, a data acquisition system, a correlator, a load computer and a noise injection calibration system; meanwhile, the synthetic aperture microwave radiometer is also a calibration object.
The directional calibration antenna is arranged on the synthetic aperture microwave radiometer and used for directional calibration of the synthetic aperture microwave radiometer; the directional calibration antenna is parallel to the synthetic aperture microwave radiometer antenna and is interfaced to a receiver of the synthetic aperture microwave radiometer to receive sky star radiated energy.
The Beidou time system is used for providing time information for the calibration system; for example, the Beidou time system can provide accurate time information for the ground equipment.
The Beidou positioning system is used for determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer;
the azimuth elevation tracking drive system is used for driving the synthetic aperture microwave radiometer and the directional calibration antenna to track sky star motion;
and the ground equipment is used for controlling the movement of the azimuth pitch tracking driving system and collecting and processing data.
Specifically, the power data obtained by the data acquisition system of the synthetic aperture microwave radiometer is collected and processed to obtain information such as pointing error and link phase.
As shown in fig. 2, this embodiment also discloses a method for calibrating phase errors of all links of a synthetic aperture microwave radiometer, which includes the following steps:
s1: establishing a full link phase error calibration system of the synthetic aperture microwave radiometer;
s2: the synthetic aperture microwave radiometer is arranged on an open space, and the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer are determined by the Beidou positioning system;
s3: the Beidou time system is connected to the ground equipment, and a sky star target to be observed is preselected; in specific implementation, a measurer selects a sky star target to be observed; in this embodiment, Mars is selected as the sky star target.
S4: the measuring equipment calculates the azimuth pitch value of the sky star target in real time according to the time information (in the embodiment, the time is Beijing time) provided by the Beidou time system and the position coordinate of the sky star target; the ground equipment controls the azimuth pitching driving system according to the azimuth pitching value of the sky star target, scans the sky star target and obtains azimuth and pitching direction scanning data from the data acquisition system;
it should be noted that the calculation method of the azimuth pitch value involved in this step is a method commonly used in the art, and therefore, further description is omitted here.
S5: after scanning is finished, fitting the scanning data of the azimuth and the pitching direction according to a formula (1) to obtain the pointing errors of the azimuth and pitching tracking driving system in the azimuth and the pitching direction;
where a is the detected voltage, k, of the receiver output1Is the amplitude coefficient, k2Is a pointing error, k3Is a linear proportionality coefficient, k5The bias voltage of the receiver and p are pointing errors of the azimuth and pitch tracking driving system in azimuth and pitch;
s6: adding the pointing error into the correction to the azimuth-elevation tracking drive system; it should be noted that how to add and correct the pointing error into the azimuth-elevation tracking driving system in this step is a common method in the art, and therefore, further description is omitted here.
S7: a receiving channel of the receiver is switched to an antenna channel, and a sky star signal (namely a signal radiated by a sky star target) enters a correlator after being amplified and down-converted by the receiver; the correlator calculates to obtain the phase difference between every two antenna channels, and the phase difference is integrated to obtain an average phase difference matrix
Corresponding to passive phase error;
s8: the receiving channel of the receiver is switched to a noise channel; after the noise signal (sent out by a noise injection calibration system) is amplified and down-converted by a receiver, the noise signal enters the correlator; the correlator calculates to obtain the phase difference between every two noise channels, and the phase difference is integrated to obtain an average phase difference matrix
Corresponding to active plus passive phase errors;
s9: will be provided with
Minus
Obtaining a full link phase error at an angle
S10: and changing the angle relation between the antenna directional diagram of each receiving channel of the receiver of the synthetic aperture microwave radiometer and the sky star target through the azimuth rotation of the azimuth pitching tracking driving system, repeating the steps S6-S9, obtaining the full link phase error of each angle, and storing the full link phase error.
The number of repetitions can be determined according to specific needs, and in this embodiment, the steps S6-S9 are repeated 99 times to obtain the full link phase error of 100 angles, and the full link phase error is stored in a file.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (4)
1. A system for calibrating full-link phase errors of a synthetic aperture microwave radiometer, comprising: a synthetic aperture microwave radiometer, the synthetic aperture microwave radiometer further comprising: the system comprises a synthetic aperture microwave radiometer antenna, a receiver, a data acquisition system, a correlator, a load computer and a noise injection calibration system; characterized in that the calibration system further comprises: the device comprises a directional calibration antenna, a Beidou time system, a Beidou positioning system, an azimuth pitching tracking driving system and ground equipment; wherein:
the directional calibration antenna is arranged on the synthetic aperture microwave radiometer and used for directional calibration of the synthetic aperture microwave radiometer;
the Beidou time system is used for providing time information for the calibration system;
the Beidou positioning system is used for determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer;
the azimuth elevation tracking drive system is used for driving the synthetic aperture microwave radiometer and the directional calibration antenna to track sky star motion;
and the ground equipment is used for controlling the movement of the azimuth pitching tracking driving system and collecting and processing data.
2. The calibration system of claim 1, wherein the directional calibration antenna is parallel to the synthetic aperture microwave radiometer antenna and is interfaced with a receiver of the synthetic aperture microwave radiometer to receive sky star radiated energy.
3. A method for calibrating phase errors of a full link of a synthetic aperture microwave radiometer is characterized by comprising the following steps:
s1: establishing a full link phase error calibration system for a synthetic aperture microwave radiometer according to any of claims 1 or 2;
s2: arranging the synthetic aperture microwave radiometer on the open air, and determining the longitude, the latitude and the altitude of the position of the synthetic aperture microwave radiometer by adopting the Beidou positioning system;
s3: the Beidou time system is connected to the ground equipment, and a sky star target to be observed is selected in advance;
s4: the positioning device calculates the azimuth pitching value of the sky star target in real time according to the time information provided by the Beidou time system and the position coordinate of the sky star target; the ground equipment controls the azimuth pitching driving system according to the azimuth pitching value of the sky star target, scans the sky star target and obtains azimuth and pitching direction scanning data from the data acquisition system;
s5: after scanning is finished, fitting the scanning data of the azimuth and the pitching direction according to a formula (1) to obtain the pointing errors of the azimuth and pitching tracking driving system in the azimuth and the pitching direction;
where a is the detected voltage, k, of the receiver output1Is the amplitude coefficient, k2Is a pointing error, k3Is a linear proportionality coefficient, k4Linear proportionality coefficient, k, of detection voltage to pointing position5For the receiver bias voltage, p for the azimuth pitch tracking drive systemPointing errors in azimuth and pitch;
s6: adding the pointing error into the correction to the azimuth-elevation tracking drive system;
s7: a receiving channel of the receiver is switched to an antenna channel, and the sky star signal enters a correlator after being amplified and down-converted by the receiver; the correlator calculates to obtain the phase difference between every two antenna channels, and the phase difference is integrated to obtain an average phase difference matrix
S8: the receiving channel of the receiver is switched to a noise channel; after the noise signal is amplified and down-converted by a receiver, the noise signal enters the correlator; the correlator calculates to obtain the phase difference between every two noise channels, and the phase difference is integrated to obtain an average phase difference matrix
S9: will be provided with
Minus
Obtaining a full link phase error at an angle
4. The calibration method of claim 3, further comprising:
s10: and changing the angle relation between the antenna directional diagram of each receiving channel of the receiver of the synthetic aperture microwave radiometer and the sky star target through the azimuth rotation of the azimuth pitching tracking driving system, repeating the steps S6-S9, obtaining the full link phase error of each angle, and storing the full link phase error.
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| EP1315282A3 (en) * | 1996-12-03 | 2004-05-12 | Raytheon Company | Microwave radiometer |
| CN101349719B (en) * | 2007-07-20 | 2011-02-09 | 中国科学院空间科学与应用研究中心 | Full polarization synthetic aperture microwave radiometer |
| CN102075227A (en) * | 2009-11-24 | 2011-05-25 | 中国移动通信集团公司 | System and method for controlling satellite finding antenna |
| CN103022692B (en) * | 2012-11-14 | 2014-09-17 | 广东隆伏通讯设备有限公司 | Communication-in-motion satellite pointing, capturing and tracking method and system thereof |
| CN108375758B (en) * | 2018-02-05 | 2020-05-19 | 华中科技大学 | Mirror image synthetic aperture radiometer error correction method based on external single-point source |
| CN109828249A (en) * | 2019-02-22 | 2019-05-31 | 北京遥感设备研究所 | A kind of calibrating method for synthetic aperture radiometer array |
| CN111929651B (en) * | 2020-07-30 | 2024-03-15 | 西安空间无线电技术研究所 | Phase residual calibration method for comprehensive aperture radiometer system |
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