To improve the performance of composite pseudo-noise （PN） code clock recovery in a regenerative PN ranging system at a low symbol signal-to-noise ratio （SNR）, a novel chip tracking loop （CTL） used for regenerati...To improve the performance of composite pseudo-noise （PN） code clock recovery in a regenerative PN ranging system at a low symbol signal-to-noise ratio （SNR）, a novel chip tracking loop （CTL） used for regenerative PN ranging clock recovery is adopted. The CTL is a modified data transition tracking loop （DTTL）. The difference between them is that the Q channel output of the CTL is directly multiplied by a clock component, while that of the DTTL is multiplied by the Ⅰ channel transition detector output. Under the condition of a quasi-squareware PN ranging code, the tracking （ mean square timing jitter） performance of the CTL is analyzed. The tracking performances of the CTL and the DTTL, are compared over a wide range of symbol SNRs. The result shows that the CTL and the DTTL have the same performance at a large symbol SNR, while at a low symbol SNR, the former offers a noticeable enhancement.展开更多
Noncoherent early-late processing （NELP） code tracking loops are often implemented using digital hardware for digital global positioning system （GPS） receivers. Noncommensurate sampling technology is widely used b...Noncoherent early-late processing （NELP） code tracking loops are often implemented using digital hardware for digital global positioning system （GPS） receivers. Noncommensurate sampling technology is widely used because it is viewed as an effective solution to cope with the drawback of digital effects. However, the relationship between the sampling rate and auto-correlation function （ACF） is not adequately characterized by traditional analysis. The principles for selecting the sampling rate are still not apparent. In order to solve this problem, we first analyzed the effects of different sampling rates on ACF and obtained the analytical form of a discrete auto-correlation function （DACF） for a noncommensurate sampling rate. Based on the result, the relationship between the step variation in DACF and NELP parameters such as sampling rate, integration time, and correlator spacing was determined. The maximum step variation size of DACF was also determined. However, considering the actual situation, additional factors such as code Doppler shift, precorrelation filter, and thermal noise may degrade the step variation of DACE The relationship between the step variation and these factors was analyzed separately. An appropriate sampling rate and appropriate correlator spacing were proposed to achieve the typical accuracy of measurement. The numerical simulation verified the validity of the above theoretical analyses, and finally, the conclusions and design constraints for the digital GPS receiver are summarized.展开更多
A modiΡed pseudo-noise（PN） code regeneration method is proposed to improve the clock tracking accuracy without impairing the code acquisition time performance.Thus,the method can meet the requirement of high accura...A modiΡed pseudo-noise（PN） code regeneration method is proposed to improve the clock tracking accuracy without impairing the code acquisition time performance.Thus,the method can meet the requirement of high accuracy ranging measurements in short time periods demanded by radio-science missions.The tracking error variance is derived by linear analysis.For some existing PN codes,which can be acquired rapidly,the tracking error variance performance of the proposed method is about 2.6 dB better than that of the JPL scheme（originally proposed by Jet Propulsion Laboratory）,and about 1.5 dB better than that of the traditional double loop scheme.展开更多
GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对...GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对比,判断是否存在欺骗干扰.常规SQM算法仅利用ELP三个信息,检测性能受限,为此提出多相关器联合功率(SQM detection of power combined Multi-correlator groups,SPCM)算法.以ELP之间多个等间隔相关器输出功率的加权为检测量,且取相关时刻与即时码时间差的反比为加权系数;进一步分析检测量的概率分布特性,并基于Neyman-Pearson理论确定最佳检测阈值,通过比较检测量与检测阈值的大小,判断是否存在欺骗干扰.基于美国德克萨斯大学奥斯汀分校公开的场景四数据集进行试验,结果表明:与Ratio和ELP等典型SQM算法相比,在不同虚警率条件下,所提出SPCM算法兼具高检测概率和快速预警响应时间性能.展开更多
文摘To improve the performance of composite pseudo-noise （PN） code clock recovery in a regenerative PN ranging system at a low symbol signal-to-noise ratio （SNR）, a novel chip tracking loop （CTL） used for regenerative PN ranging clock recovery is adopted. The CTL is a modified data transition tracking loop （DTTL）. The difference between them is that the Q channel output of the CTL is directly multiplied by a clock component, while that of the DTTL is multiplied by the Ⅰ channel transition detector output. Under the condition of a quasi-squareware PN ranging code, the tracking （ mean square timing jitter） performance of the CTL is analyzed. The tracking performances of the CTL and the DTTL, are compared over a wide range of symbol SNRs. The result shows that the CTL and the DTTL have the same performance at a large symbol SNR, while at a low symbol SNR, the former offers a noticeable enhancement.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFB0501301)the Key Laboratory for Fault Diagnosis and Maintenance of Spacecraft in Orbit(Grant No.SDML_OF2015006)
文摘Noncoherent early-late processing （NELP） code tracking loops are often implemented using digital hardware for digital global positioning system （GPS） receivers. Noncommensurate sampling technology is widely used because it is viewed as an effective solution to cope with the drawback of digital effects. However, the relationship between the sampling rate and auto-correlation function （ACF） is not adequately characterized by traditional analysis. The principles for selecting the sampling rate are still not apparent. In order to solve this problem, we first analyzed the effects of different sampling rates on ACF and obtained the analytical form of a discrete auto-correlation function （DACF） for a noncommensurate sampling rate. Based on the result, the relationship between the step variation in DACF and NELP parameters such as sampling rate, integration time, and correlator spacing was determined. The maximum step variation size of DACF was also determined. However, considering the actual situation, additional factors such as code Doppler shift, precorrelation filter, and thermal noise may degrade the step variation of DACE The relationship between the step variation and these factors was analyzed separately. An appropriate sampling rate and appropriate correlator spacing were proposed to achieve the typical accuracy of measurement. The numerical simulation verified the validity of the above theoretical analyses, and finally, the conclusions and design constraints for the digital GPS receiver are summarized.
基金supported by the National Natural Science Foundation of China (60904090)the Postdoctoral Science Foundation of China(20080431306)the Special Postdoctoral Science Foundation of China (20081458)
文摘A modiΡed pseudo-noise（PN） code regeneration method is proposed to improve the clock tracking accuracy without impairing the code acquisition time performance.Thus,the method can meet the requirement of high accuracy ranging measurements in short time periods demanded by radio-science missions.The tracking error variance is derived by linear analysis.For some existing PN codes,which can be acquired rapidly,the tracking error variance performance of the proposed method is about 2.6 dB better than that of the JPL scheme（originally proposed by Jet Propulsion Laboratory）,and about 1.5 dB better than that of the traditional double loop scheme.
文摘GNSS民用信号因其公开性和脆弱性易受外界欺骗干扰.作为欺骗干扰检测的有效方法,信号质量监测(signal quality monitoring,SQM)技术通过检测接收机跟踪环路早码、即时码、晚码(early late phase,ELP)的相关结果,与无欺骗时的相关特性对比,判断是否存在欺骗干扰.常规SQM算法仅利用ELP三个信息,检测性能受限,为此提出多相关器联合功率(SQM detection of power combined Multi-correlator groups,SPCM)算法.以ELP之间多个等间隔相关器输出功率的加权为检测量,且取相关时刻与即时码时间差的反比为加权系数;进一步分析检测量的概率分布特性,并基于Neyman-Pearson理论确定最佳检测阈值,通过比较检测量与检测阈值的大小,判断是否存在欺骗干扰.基于美国德克萨斯大学奥斯汀分校公开的场景四数据集进行试验,结果表明:与Ratio和ELP等典型SQM算法相比,在不同虚警率条件下,所提出SPCM算法兼具高检测概率和快速预警响应时间性能.
