脉冲星信号相干消色散与非相干消色散的比较研究
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摘要
脉冲星信号在星际空间传播的过程中,由于星际介质的存在造成观测到的脉冲星信号发生色散,因此需要对接收的脉冲星信号进行消色散,以获得原始的脉冲星信号。目前,消色散方法主要分为两种:相干消色散和非相干消色散。相对来说相干消色散效果彻底,算法较简单,而且能保留原始数据的时间分辨率,不过计算量较大,但是现在快速进步的计算机技术已经使计算量的问题得到很好的解决。为了精确了解两种消色散方法的区别,利用相关系数的方法定量地比较了相干消色散、非相干消色散两种方法的效果:在一定的频率值之下,前者得到消色散效果优于后者。同时确定两种消色散方法在效果相同时的观测频率。
Spreading through in the interstellar space,pulsar signals,due to the existence of the interstellar medium,would be observed dispersively,therefore we need to remove dispersion of the received pulsar signals for obtaining the original pulsar signals.The current de-dispersion methods are mainly divided into two types,coherent de-dispersion and incoherent de-dispersion.Relatively speaking,the former is able to eliminate dispersion completely,which has simpler algorithm,and preserves the time resolution of the original signal.Although it has a larger amount of calculation,rapid progress of computer technology can solve such problem.In order to accurately understand the difference between the two methods of de-dispersion,this paper,adopting the method of coherence coefficient,quantitatively compares the effects of coherent dedispersion and incoherent de-dispersion:below a certain frequency,the former is better than the latter in obtaining the de-dispersion effects.Meanwhile,the observed frequency of the two de-dispersion methods at the same effect is determined.
Spreading through in the interstellar space,pulsar signals,due to the existence of the interstellar medium,would be observed dispersively,therefore we need to remove dispersion of the received pulsar signals for obtaining the original pulsar signals.The current de-dispersion methods are mainly divided into two types,coherent de-dispersion and incoherent de-dispersion.Relatively speaking,the former is able to eliminate dispersion completely,which has simpler algorithm,and preserves the time resolution of the original signal.Although it has a larger amount of calculation,rapid progress of computer technology can solve such problem.In order to accurately understand the difference between the two methods of de-dispersion,this paper,adopting the method of coherence coefficient,quantitatively compares the effects of coherent dedispersion and incoherent de-dispersion:below a certain frequency,the former is better than the latter in obtaining the de-dispersion effects.Meanwhile,the observed frequency of the two de-dispersion methods at the same effect is determined.
引文
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[2]徐永华,罗近涛,李志玄,等.基于MARK5B+DSPSR的基带数字脉冲星观测系统[J].天文研究与技术---国家天文台台刊,2013,10(4):352-358.
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[8]刘立勇,艾力·伊沙木丁,张晋.乌鲁木齐天文站建立脉冲星相干消色散观测系统[J].天文研究与技术---国家天文台台刊,2007,4(1):72-78.
[9]HANKINS T H,RICKETT B J.Pulsar signal processing[J].Methods in Computational Physics:Advances in Research&Applications,1975,14:55-129.
[10]托乎提努尔,张海龙,王杰.基于CUDA的射电天文多相滤波器组设计[J].天文研究与技术,2017,14(1):117-123.
(1)https://casper.berkeley.edu/wiki/The_Polyphase_Filter_Bank_Technique
[2]徐永华,罗近涛,李志玄,等.基于MARK5B+DSPSR的基带数字脉冲星观测系统[J].天文研究与技术---国家天文台台刊,2013,10(4):352-358.
[3]KRAMER M,STAIRS I H,MANCHESTER R N,et al.Tests of general relativity from timing the double pulsar[J].Science,2006,314(5796):97-102.
[4]SHAPPEE B J,SIMON J D,DROUT M R,et al.Early spectra of the gravitational wave source GW170817:evolution of a neutron star merger[J].Science,2017,358(6370):1574-1578.
[5]SHEIKH S I,HELLINGS R W,MATZNER R A.High-order pulsar timing for navigation[C]//Proceedings of Annual Meeting of the Institute of Navigation.2007:432-443.
[6]STAIRS I H,SPLAVER E M,THORSETT S E,et al.A baseband recorder for radio pulsar observations[J].Monthly Notices of the Royal Astronomical Society,2000,314(3):459-467.
[7]NAYANA B R,KUMAR S M.Application of coherent de-dispersion DSP algorithms in study of pulsar data[J].Digital Signal Processing,2012,4(10).
[8]刘立勇,艾力·伊沙木丁,张晋.乌鲁木齐天文站建立脉冲星相干消色散观测系统[J].天文研究与技术---国家天文台台刊,2007,4(1):72-78.
[9]HANKINS T H,RICKETT B J.Pulsar signal processing[J].Methods in Computational Physics:Advances in Research&Applications,1975,14:55-129.
[10]托乎提努尔,张海龙,王杰.基于CUDA的射电天文多相滤波器组设计[J].天文研究与技术,2017,14(1):117-123.
(1)https://casper.berkeley.edu/wiki/The_Polyphase_Filter_Bank_Technique