摘要
The active reflector of FAST(five-hundred-meter aperture spherical radio telescope) is supported by a ring beam and a cable-net structure,in which nodes are actively controlled to form series of real-time paraboloids.To ensure the security and stability of the supporting structure,tension must be monitored for some typical cables.Considering the stringent requirements in accuracy and longterm stability,magnetic flux sensor,vibrating wire strain gauge and fiber bragg grating strain gauge are screened for the cable tension monitoring of the supporting cable-net.Specifically,receivers of radio telescopes have strict restriction on electro magnetic interference(EMI) or radio frequency interference(RFI).These three types of sensors are evaluated from the view of EMI/RFI.Firstly,these fundamentals are theoretically analyzed.Secondly,typical sensor signals are collected in the time and analyzed in the frequency domain,which shows the characteristic in the frequency domain.Finally,typical sensors are tested in an anechoic chamber to get the EMI levels.Theoretical analysis shows that Fiber Bragg Grating strain gauge itself will not lead to EMI/RFI.According to GJB151 A,frequency domain analysis and test results show that for the vibrating wire strain gauge and magnetic flux sensor themselves,testable EMI/RFI levels are typically below the background noise of the anechoic chamber.FAST finally choses these three sensors as the monitoring sensors of its cable tension.The proposed study is also a reference to the monitoring equipment selection of other radio telescopes and large structures.
The active reflector of FAST ( five-hundred-meter aperture spherical radio telescope) is suppor- ted by a ring beam and a cable-net structure, in which nodes are actively controlled to form series of real-time paraboloids. To ensure the security and stability of the supporting structure, tension must be monitored for some typical cables. Considering the stringent requirements in accuracy and long- term stability, magnetic flux sensor, vibrating wire strain gauge and fiber bragg grating strain gauge are screened for the cable tension monitoring of the supporting cable-net. Specifically, receivers of radio telescopes have strict restriction on electro magnetic interference (EMI) or radio frequency in- terference (RFI). These three types of sensors are evaluated from the view of EMIfRFI. Firstly, these fundamentals are theoretically analyzed. Secondly, typical sensor signals are collected in the time and analyzed in the frequency domain, which shows the characteristic in the frequency domain. Finally, typical sensors are tested in an anechoic chamber to get the EMI levels. Theoretical analysis shows that Fiber Bragg Grating strain gauge itself will not lead to EMI/RFI. According to GJB151 A, frequency domain analysis and test results show that for the vibrating wire strain gauge and magnetic flux sensor themselves, testable EMIfRF1 levels are typically below the background noise of the ane- choic chamber. FAST finally choses these three sensors as the monitoring sensors of its cable ten- sion. The proposed study is also a reference to the monitoring equipment selection of other radio tele- scopes and large structures.
基金
Supported by the National Natural Science Foundation of China(No.11173035,11273036,11303059)
关键词
张力传感器
电磁干扰
电缆
评价
球面射电望远镜
反射镜
光纤布拉格光栅
布拉格光纤光栅
five-hundred-meter aperture spherical radio telescope (FAST), cable tension mo-nitoring, magnetic flux, vibrating wire, fiber Bragg, electro magnetic interference (EMI)