新疆天文台南山26米天线全息法测量系统
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摘要
南山25 m射电望远镜经过一年多的升级改造现已全面完成,主反射面直径增加至26 m,为保证Q波段(30~50 GHz)接收机的工作效率,望远镜的表面精度需达到较高的水平,微波全息法可对天线面形进行精确测量和调整,是望远镜面形首次和定期精调的首选,基于新南山26 m天线建立了一套全息法测量系统。整个系统包括参考天线、接收机、相关机、传输链路、时频参考、扫描控制和全息法处理软件等几部分,采用带通采样技术直接采集中频信号,减少了基带信号转换环节;采用高性能外部本振并利用氢钟输出的参考信号进行锁相,达到了极高的相位稳定度。目前整个系统已通过测试并取得了初步的测量结果,经处理分析,该系统工作正常,已达到应用要求。
The upgrade work of Nanshan 25 m telescope has been completed after more than one year with great efforts. The diameter of main reflector is increased to 26 meter. And to ensure the high observational efficiency of Q band receiver,we have to measure and adjustment the antenna penal elaborately. Microwave holography is the first choice for initial and periodical measurement of antenna surface due to the high precision of this method. So we build a holography system based on the new 26 m antenna,which includes reference antenna,receiver,correlator,transmission link,time and frequency reference,antenna control software and holographic processing software. Some techniques have been used for simplify the hardware and promote the performance of this system. We use band pass sampling theorem for IF signal direct digitization,which can save the hardware device of baseband converter and decrease the phase fluctuation due to microwave signal mixing,filtering and amplification. To get a better phase stability of the system,we use a high performance Phase-locked Dielectric Resonator Oscillator( PDRO) for satellite signal mixing,which can support a very stable phase by lock the 10 MHz reference signal from a hydrogen mazer. All parts of this system have been designed and tested,the result shows that the whole system works very well and meets the needs of application.
The upgrade work of Nanshan 25 m telescope has been completed after more than one year with great efforts. The diameter of main reflector is increased to 26 meter. And to ensure the high observational efficiency of Q band receiver,we have to measure and adjustment the antenna penal elaborately. Microwave holography is the first choice for initial and periodical measurement of antenna surface due to the high precision of this method. So we build a holography system based on the new 26 m antenna,which includes reference antenna,receiver,correlator,transmission link,time and frequency reference,antenna control software and holographic processing software. Some techniques have been used for simplify the hardware and promote the performance of this system. We use band pass sampling theorem for IF signal direct digitization,which can save the hardware device of baseband converter and decrease the phase fluctuation due to microwave signal mixing,filtering and amplification. To get a better phase stability of the system,we use a high performance Phase-locked Dielectric Resonator Oscillator( PDRO) for satellite signal mixing,which can support a very stable phase by lock the 10 MHz reference signal from a hydrogen mazer. All parts of this system have been designed and tested,the result shows that the whole system works very well and meets the needs of application.
引文
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[3]Rochblatt D J,Seidel B L.Performance improvement of DSS-13 34-meter beam-waveguide antenna using the JPL microwave holography methodology[C]//Jet propulsion Laboratory,Pasadena,California.TDA Progress Report 42-108,1991:253-270.
[4]Kesteven M.Parkes Holography[EB/OL].[2017-04-03].http://www.atnf.csiro.au/people/Michael.Kesteven/PKS_HOLO/pks_holo.html.
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[6]王锦清,虞林峰,范庆元,等.抛物面天线微波全息测量及结果分析[J].中国科学院上海天文台年刊,2011(1):136-146.Wang Jinqing,Yu Linfeng,Fan Qingyuan,et al.Holography measurement for parabolic antenna and the results analysis[J].Annals of Shanghai Observatory Academia Sinica,2011(1):136-146.
[7]王锦清,范庆元,李斌.微波全息测量中相关机的实现[J].天文研究与技术——国家天文台台刊,2009,6(4):280-291.Wang Jinqing,Fan Qingyuan,Li Bin.The implementation of a correlator for microwave holographic measurement[J].Astronomical Research&Technology——Publications of National Astronomical Observatories of China,2009,6(4):280-291.
[8]Nikolic B,Hills R E,Richer J S.Measurement of antenna surfaces from in-and out-of-focus beam maps using astronomical sources[J].Astronomy&Astrophysics,2007,465(2):679-683.
[9]Nikolic B,Prestage R M,Balser D S,et al.Out-of-focus holography at the Green Bank Telescope[J].Astronomy&Astrophysics,2007,465(2):685-693.
[10]刘抗抗,叶骞,裴鑫.相位恢复全息-基于远场幅值的天线表面精度检测[J].中国科学:物理学力学天文学,2017,47(5):059513.Liu Kangkang,Ye Qian,Pei Xin.Phase retrieval holography-surface measurement based on the amplitude of the far field patterns[J].Scientia Sinica:Physica,Mechanica&Astronomica,2017,47(5):059513.
[11]裴鑫,李健,陈卯蒸,等.基于ROACH的微波全息法相关机设计[J].天文研究与技术,2015,12(1):54-62.Pei Xin,Li Jian,Chen Maozheng,et al.Design of a microwave holography correlator based on the ROACH board[J].Astronomical Research&Technology,2015,12(1):54-62.
[12]裴鑫,陈卯蒸,李健,等.基于相关机延迟测量法的VLBI时频信号光纤传输试验[J].天文研究与技术,2015,12(3):270-276.Pei Xin,Chen Maozheng,Li Jian,et al.An experiment of VLBI clock-signal distribution through optical fibers based on signal-delay measurement using a digital correlator[J].Astronomical Research&Technology,2015,12(3):270-276.
[2]Rochblatt D J,Seidel B L.DSN microwave antenna holography[J].Telecommunications&Data Acquisition Report,1984,40(6):27-42.
[3]Rochblatt D J,Seidel B L.Performance improvement of DSS-13 34-meter beam-waveguide antenna using the JPL microwave holography methodology[C]//Jet propulsion Laboratory,Pasadena,California.TDA Progress Report 42-108,1991:253-270.
[4]Kesteven M.Parkes Holography[EB/OL].[2017-04-03].http://www.atnf.csiro.au/people/Michael.Kesteven/PKS_HOLO/pks_holo.html.
[5]Serra G,Bolli P,Busonera G,et al.The microwave holography system for the Sardinia Radio Telescope[J].Processing of SPIE,2012,8444:1-15.
[6]王锦清,虞林峰,范庆元,等.抛物面天线微波全息测量及结果分析[J].中国科学院上海天文台年刊,2011(1):136-146.Wang Jinqing,Yu Linfeng,Fan Qingyuan,et al.Holography measurement for parabolic antenna and the results analysis[J].Annals of Shanghai Observatory Academia Sinica,2011(1):136-146.
[7]王锦清,范庆元,李斌.微波全息测量中相关机的实现[J].天文研究与技术——国家天文台台刊,2009,6(4):280-291.Wang Jinqing,Fan Qingyuan,Li Bin.The implementation of a correlator for microwave holographic measurement[J].Astronomical Research&Technology——Publications of National Astronomical Observatories of China,2009,6(4):280-291.
[8]Nikolic B,Hills R E,Richer J S.Measurement of antenna surfaces from in-and out-of-focus beam maps using astronomical sources[J].Astronomy&Astrophysics,2007,465(2):679-683.
[9]Nikolic B,Prestage R M,Balser D S,et al.Out-of-focus holography at the Green Bank Telescope[J].Astronomy&Astrophysics,2007,465(2):685-693.
[10]刘抗抗,叶骞,裴鑫.相位恢复全息-基于远场幅值的天线表面精度检测[J].中国科学:物理学力学天文学,2017,47(5):059513.Liu Kangkang,Ye Qian,Pei Xin.Phase retrieval holography-surface measurement based on the amplitude of the far field patterns[J].Scientia Sinica:Physica,Mechanica&Astronomica,2017,47(5):059513.
[11]裴鑫,李健,陈卯蒸,等.基于ROACH的微波全息法相关机设计[J].天文研究与技术,2015,12(1):54-62.Pei Xin,Li Jian,Chen Maozheng,et al.Design of a microwave holography correlator based on the ROACH board[J].Astronomical Research&Technology,2015,12(1):54-62.
[12]裴鑫,陈卯蒸,李健,等.基于相关机延迟测量法的VLBI时频信号光纤传输试验[J].天文研究与技术,2015,12(3):270-276.Pei Xin,Chen Maozheng,Li Jian,et al.An experiment of VLBI clock-signal distribution through optical fibers based on signal-delay measurement using a digital correlator[J].Astronomical Research&Technology,2015,12(3):270-276.