天线阵大气相位扰动实时修正关键技术研究

When the weak signal of radio astronomy and deep space probe is received by antenna array composed by a large number of antennas, the combining efficiency will be seriously affected by the atmospheric phase fluctuations, which have to be calibrated real-timely. The research shows that improving the temporal resolution of the atmospheric wet delay measurement of the water vapor radiometer and combining with the technology of differential correction based on the global positioning system are the main research directions of the subsequent atmospheric phase disturbance correction technology. For this purpose, high-temporal, spatial-resolution water vapor radiometers will be developed, high-precision calibration techniques between remote water vapor radiometers will be established, and navigation receivers will be retrofitted to achieve real-time detection of atmospheric phase perturbation based on GPS+Beidou differentials. A set of practical atmospheric phase perturbation differential correction technology is obtained, with a measurement time resolution of 1 s and an accuracy of the order of mm. Using a 50-meter antenna at Miyun station and a 40-meter antenna at Kunming station, an experimental system consisting of the two large antennas, two GPS+Beidou receivers, and two microwave radiometers will be set up to achieve array corrections for atmospheric correction and weak radio signals. The research content of this topic can also be applied to passive radar, space debris detection and uplink antenna arrays.

在射电天文和深空探测中利用天线阵进行微弱信号接收时，大气相位扰动会严重影响信号的合成效率，必须对其进行修正。研究表明，提高水汽辐射计大气湿延迟测量的时间分辨率，并与基于导航卫星差分修正技术相结合，是后续大气相位扰动修正技术的主要研究方向。为此，将实现高时间、空间分辨率的水汽辐射计的研制，建立异地水汽辐射计之间的高精度定标技术；进行导航接收机的改造，实现大气相位扰动GPS+北斗差分实时探测的数据处理方法；获得一套可实用的大气相位扰动差分修正技术，测量时间分辨率达到1s，精度达到mm量级。利用密云站50米和昆明站40米天线，组建一套由2面大型天线、2台GPS+北斗接收设备和2台微波辐射计组成的实验系统，实现大气修正和微弱射电信号的组阵观测实验。本课题的研究内容，还可以应用到无源雷达、空间碎片探测和上行天线阵等技术领域。

在射电天文和深空探测中利用天线阵进行微弱信号接收时，大气相位扰动会严重影响信号的合成效率。为了克服气象辐射计时间、空间分辨率过低，无法直接应用于天线阵相位修正，且在阴雨天时存在失真和饱和的问题。通过增加观测频点、增大辐射计天线的口径、降低接收机噪声温度灯，提高了系统空间分辨率和灵敏度。通过水汽辐射计实时定标技术、误差校准和补偿技术，攻克了基于水汽辐射计的大气相位扰动高精度实时探测的关键技术。完成了时间分辨率为1s、单台大气传播延迟测量精度达15mm的原理样机的研制，并实现了VLBI台站的应用。提出了全球导航卫星系统差分的天线阵大气相位扰动实时修正方法，以高稳定度的原子钟作为外频标，利用导航卫星载波相位的单差与历元上的双差，并通过星历扣除由于卫星运动引起的相位变化，在周跳检测和修正后，通过长周期的拟合消除卫星轨道和站坐标误差的影响，最后通过双频或多频信号实现两地电离层和对流层扰动的实时测量。利用国家天文台密云站50米和昆明站40米天线，组建一套由2面大型天线、2台GPS+北斗接收设备和2台微波辐射计组成的实验系统，实现了大气修正和微弱射电信号的组阵观测实验，结果表明时间分辨率达到1s，大气相位差分探测精度达到1.9mm。