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
A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale...A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale. Using non-integer chip to sample time ratio, noncommensurate sampling was seen as an effective solution to cope with the drawback of digital effects. However, researchers only paid attention to selecting specific ratios or giving a simulation model to verify the effectiveness of the noncommensurate ratios. A qualitative analysis model is proposed to characterize the relationship between the range accuracy and the noncommensurate sampling parameters. Moreover, a method is also presented which can be used to choose the noncommensurate ratio and the correlation length to get higher phase delay distinguishability and lower range jitter. The simulation results indicate the correctness of our analyses and the optimal ranging accuracy can be up to centimeter-level with the proposed approach.展开更多
As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communicati...As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communication and ranging,we present a bit-level composite signal for simultaneous ranging and communication.In this composite method,through a specially designed mapping scheme using low-weight codewords,the information sequence is converted to a sparse sequence which is then superimposed on the ranging code.For ranging,the correlation characteristics of the ranging code component can be maintained to calculate the transmitter-receiver distance.For communications,the sparse sequence can be extracted without interference by eliminating the ranging code component.Simulation results show that the proposed composite signal can support communication and ranging simultaneously with limited sacrifice of ranging performance,and the performance loss of ranging can be controlled and minimized by lowering the density of information sequences using different sparsification encoding methods.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
This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） dire...This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.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Project(60904090) supported by the National Natural Science Foundation of China
文摘A high-precision pseudo-noise ranging system is often required in satellite-formation missions. But in an actual PN ranging system, digital signal processing limits the ranging accuracy, only level up with meter-scale. Using non-integer chip to sample time ratio, noncommensurate sampling was seen as an effective solution to cope with the drawback of digital effects. However, researchers only paid attention to selecting specific ratios or giving a simulation model to verify the effectiveness of the noncommensurate ratios. A qualitative analysis model is proposed to characterize the relationship between the range accuracy and the noncommensurate sampling parameters. Moreover, a method is also presented which can be used to choose the noncommensurate ratio and the correlation length to get higher phase delay distinguishability and lower range jitter. The simulation results indicate the correctness of our analyses and the optimal ranging accuracy can be up to centimeter-level with the proposed approach.
基金This work was supported in part by National Natural Science Foundation of China(61671324)the Director’s Funding from Pilot National Laboratory for Marine Science and Technology(Qingdao)(QNLM201712)Zhan Xu was supported in part by National Natural Science Foundation of China(61620106001).
文摘As the complexity of space exploration missions augments,how to enhance the overall performance of communication,ranging or other functions has become a challengeable problem.Considering the integration of communication and ranging,we present a bit-level composite signal for simultaneous ranging and communication.In this composite method,through a specially designed mapping scheme using low-weight codewords,the information sequence is converted to a sparse sequence which is then superimposed on the ranging code.For ranging,the correlation characteristics of the ranging code component can be maintained to calculate the transmitter-receiver distance.For communications,the sparse sequence can be extracted without interference by eliminating the ranging code component.Simulation results show that the proposed composite signal can support communication and ranging simultaneously with limited sacrifice of ranging performance,and the performance loss of ranging can be controlled and minimized by lowering the density of information sequences using different sparsification encoding methods.
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.
基金supported by the National Natural Science Foundation of China (10776040 60602057)+4 种基金Program for New Century Excellent Talents in University (NCET)the Project of Key Laboratory of Signal and Information Processing of Chongqing (CSTC2009CA2003)the Natural Science Foundation of Chongqing Science and Technology Commission (CSTC2009BB2287)the Natural Science Foundation of Chongqing Municipal Education Commission (KJ060509 KJ080517)
文摘This paper presents an approach of singular value de- composition plus digital phase lock loop to solve the difficult problem of blind pseudo-noise （PN） sequence estimation in low signal to noise ratios （SNR） direct sequence spread spectrum （DS-SS） signals with residual carrier. This approach needs some given parameters, such as the period and code rate of PN sequence. The received signal is firstly sampled and divided into non-overlapping signal vectors according to a temporal window, whose duration is two periods of PN sequence. An autocorrelation matrix is then computed and accumulated by those signal vectors one by one. The PN sequence with residual carrier can be estimated by the principal eigenvector of the autocorrelation matrix. Further more, a digital phase lock loop is used to process the estimated PN sequence, it estimates and tracks the residual carrier and removes the residual carrier in the end. Theory analysis and computer simulation results show that this approach can effectively realize the PN sequence blind estimation from the input DS-SS signals with residual carrier in lower SNR.
