The SRT inclinometer for monitoring the rail and the thermal gradient effects on the alidade structure
The SRT inclinometer for monitoring the rail and the thermal gradient effects on the alidade structure
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DOI：
10.1117/12.2055556
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发表时间：
2014-07
期刊：
影响因子：
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通讯作者：
T. Pisanu;F. Buffa;S. Poppi;P. Marongiu;G. Serra;G. Vargiu;R. Concu
中科院分区：
文献类型：
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作者：
T. Pisanu;F. Buffa;S. Poppi;P. Marongiu;G. Serra;G. Vargiu;R. Concu
本文介绍了SRT照准仪倾斜仪的硬件和软件设计。这是一种商用设备，它基本上使用两个类似陀螺仪的传感器来测量两个角度，从这两个角度可以很容易地推断出天线指向误差。这种倾斜仪安装在靠近天线仰角轴的SRT照准仪平面上，以测量由于轨道的不完美平坦度和照准仪钢梁上的温度梯度效应而引起的方位角和仰角轴倾斜。去年夏天，在夜间进行了一些测试，首先检查了SRT上测量装置中的倾斜仪，然后监测了主要由于轨道粗糙度引起的轴倾斜。倾斜仪记录了几次测量结果，同时天线在方位角方向上以恒定速度移动360度旋转。结果表明，与我们在实验室测试中得到的结果很好地一致，轨道被证明是计划在预期的精度，这意味着产生的指向误差约为±2弧秒。最后，倾斜仪测量和天文观测同时进行。倾斜仪测量和天线指向偏移主要是由于热效应已被记录，而SRT是在23 GHz的观测到的环极校准源后，日出了许多小时。已经发现两组测量值之间的良好一致性，如下所示。
Here we present the hardware and software of the inclinometer chosen to be installed on the SRT alidade. This is a commercial device which basically uses two pendulum-like sensors to measure two angles from which the antenna pointing errors can be easily inferred. Such an inclinometer was installed on the plane of the SRT alidade close to the antenna elevation axis to measure the azimuth and elevation axis tilts due to the not-perfect flatness of the rail and to the temperature gradient effects on the alidade steel beams. Last summer some tests were carried out during night time, allowing first to check the inclinometer in a measurement set-up aboard on SRT, and then, to monitor the axis tilt due mainly to the rail roughness. Several measurements were recorded by the inclinometer, while the antenna was moving at constant speed in the azimuth direction for a 360-degrees rotation. The results showed a good agreement with those we got during the laboratory tests, and the rail turned out to be plan within the expected accuracy, which means a resulting pointing error of about ±2 arc-sec. Finally inclinometer measurements and astronomical observations have been performed all at once. The inclinometer measurements and the antenna pointing offsets due mainly to thermal effects have been recorded, while SRT was observing at 23 GHz toward a circumpolar calibrator source for many hours after the sunrise. A good agreement between the two set of measurement has been found as will be shown here following.