稻城圆环阵太阳射电望远镜(Daocheng Solar Radio Telescope,DSRT)作为子午工程二期太阳-行星际探测子系统的重要部分,工作在150-450 MHz频段,可提供高空间、高时间分辨率的太阳爆发亮温图像.针对DSRT天线的高精度指向测量以及对指向误差批量标定和校正的需求,首先根据DSRT独有的三轴座架系统,通过四元数旋转变换法建立了天线3参数编码器零点误差模型;然后提出了基于射电源的漂移扫描法获得16个单元天线功率方向图,并根据2维方向图确定波束中心的方法精确测量了DSRT天线指向误差;最后用最小二乘法拟合得到模型参数,并通过天线控制软件重新调整各个轴的零点,后对调整结果进行验证.结果表明指向校正方法可靠有效,校正后16个天线的指向精度为0.5.之内,明显优于校正前3.5.的指向误差,满足误差小于DSRT天线最高工作频率下的1/10波束范围内的要求.
Batch Measurement and Calibration Method of DSRT Three-axis Low Frequency Antenna Pointing Error
Daocheng Solar Radio Telescope(DSRT)is an important part of the Solar Interplanetary exploration subsystem of the second phase of The Chinese Meridian Project.It operates in the 150 MHz to 450 MHz frequency band and provides high-resolution spatial and temporal images of solar eruption brightness and temperature.Aiming at the high precision pointing measurement of the DSRT antenna and the requirement of batch calibration and correction of pointing errors,this paper establishes the 3-parameter,antenna encoder zero point offset pointing error model by quaternion rotation transformation method according to the unique three-axis mount system of DSRT.In this paper,the drift scanning method based on radio source is proposed to obtain the radiation pattern of 16 antennas and determine the boresight according to the two-dimensional power pattern to accurately measure the pointing error of the DSRT antenna.Finally,the least square method is used to get the model parameters,and the antenna control software is used to adjust the encoder zero point of each axis,and then the adjustment results are verified.The results show that the pointing calibration method is reliable and effective.The pointing accuracy of 16 antennas after correction is within 0.5°,which is significantly better than the pointing error of 3.5° before calibration,and the error is less than one-tenth of HBPW(half power beam width)under the maximum working frequency of the DSRT antenna.
radio telescope:pointing error,antenna power patternsun:radio radiation,methods:data analysis
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