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Application of pn code in Time Delay Measurement of Telephone Network

SENSORS 2025年第1期25卷 241页

作者： Jin, Xiaozhen Hua, Yu Chinese Acad Sci Natl Time Serv Ctr Xian 710600 Peoples R China Chinese Acad Sci Key Lab Precise Positioning & Timing Technol Xian 710600 Peoples R China

Telephone time service is a wired time service that transmits time signals through a telephone network, with the advantages of simple receiving equipment and wide coverage. But the performance of time service is not high, usually several milliseconds. The time delay measurement of the telephone network is an important factor limiting the improvement in timing performance. The existing telephone service systems measure time delay based on sending characters. The time fluctuation of modulating and demodulating characters and the low accuracy of detecting characters affect the uncertainty of time delay measurement. This article proposes a time delay measurement method based on sending pn codes. It utilizes the good autocorrelation properties of pn codes to improve detection accuracy and then improve the uncertainty of delay measurement. This article studies and designs the modulation, demodulation, and capture of pn codes. Simulation has verified that this method has strong anti-noise performance. Time delay tests have proved that this method can improve the uncertainty of delay measurement by an order of magnitude in different telephone network environments.

关键词： telephone time service time delay measurement pn code uncertainty of measurement

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A Modified Adaptive Filtering Acquisition Method for pn code with Data Modulation

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IEEE COMMUNICATIONS LETTERS 2011年第8期15卷 869-871页

作者： Liu, Yunzhi Pan, Yahan Yao, Fuqiang Nanjing Telecommun Technol Inst Nanjing Peoples R China

Adaptive filtering acquisition method has been proved to be an effective pseudo-noise (pn) code acquisition method in DS-SS system, which is especially useful for long pn code acquisition in low Signal to Noise Ratio (SNR) environment. In order to make use of this method in those pn code acquisition systems with data modulation, a modified adaptive filtering is proposed in this paper, where the effect of polarity reversion caused by data modulation on pn code is removed by employing absolutely successive difference technique in both the received signals and local generated pn code. Compared with the adaptive filtering acquisition method, even with data modulation, the proposed method can attain almost similar acquisition performance, which is tested by simulations.

关键词： Acquisition adaptive filtering LMS algorithm pn code

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Adaptive acquisition of pn code using excision CFAR detector in multipath fading mobile channels

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ELECTRONICS LETTERS 2004年第5期40卷 338-339页

作者： Song, Y Hu, G Shanghai Jiao Tong Univ Dept Elect Engn Shanghai 200030 Peoples R China

An adaptive acquisition of pn sequences is presented for DS/SS communications. The E-CFAR detector is introduced to excise strong signals before the cell-averaging operation. Performance of the proposed detector suffers almost no degradation under the benign environment, and the degradation is quite small under multipath fading, in comparison with a conventional cell-averaging method.

关键词： multiuser detection Multiple access communication pn code pn sequences E-CFAR detector codes excision CFAR adaptive signal detection constant false alarm rate multipath fading mobile channels DS-SS communications direct sequence spread spectrum communications multipath channels Radio links and equipment pseudonoise codes Signal detection spread spectrum communication adaptive acquisition fading channels cell-averaging operation code division multiple access excision CFAR detector

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A Novel pn code Acquisition Scheme Based on Sequential Estimation

A Novel PN Code Acquisition Scheme Based on Sequential Estim...

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17th Asia-Pacific Conference on Communications (APCC)

作者： Kim, Junhwan Chong, Dahae Lee, Youngpo Kang, Seung Goo Baek, Jeehyeon Yoon, Seokho Sungkyunkwan Univ Sch Informat & Commun Engn Suwon South Korea

ISBN: (纸本)9781457703881;9781457703898

In this paper, a novel pseudo noise (pn) code acquisition scheme based on sequential estimation is proposed, which can not only achieve code acquisition for both inverted and non-inverted pn codes, but also demodulate the spreading data. Simulation results show that the proposed scheme has approximately half the complexity of the conventional scheme while exhibiting a similar mean acquisition time performance to that of the conventional scheme.

关键词： code acquisition sequential estimation phase-shift-network pn code

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Modified pn code Laser Modulation Technique for Laser Measurements

Modified PN Code Laser Modulation Technique for Laser Measur...

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Conference on Free-Space Laser Communication Technologies XXI

作者： Sun, Xiaoli Abshire, James B. NASA Goddard Space Flight Ctr Greenbelt MD 20771 USA

ISBN: (纸本)9780819474452

Pseudo-noise (pn) modulation techniques have been used to modulate lasers for time of flight measurements and for profiling atmospheric backscatter. Compared to mono-pulse techniques, pn code modulation allows timing and backscatter measurements to be made with much lower laser peak powers and higher duty cycles. We have developed a new modified version of pn code modulation for laser measurements in which the laser pulse width and position may also be varied within the pn code bit interval. These allow more degrees of freedom for optimizing laser measurements. We have demonstrated these in laboratory measurements using a 974 nm laser diode, return to zero (RZ) pn code modulation at various laser pulse duty cycles, and a photon counting receiver. The results show significant improvements in the receiver signal to noise ratio, sensitivity, and ranging precision for the lower duty cycle RZ pn codes.

关键词： single photon counting pn code laser ranging lidar

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Positioning error correction for DS-CDMA IVC under location oriented pn code allocation scheme

Positioning error correction for DS-CDMA IVC under location ...

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15th International IEEE Conference on Intelligent Transportation Systems (ITSC)

作者： Namiki, Taro Ogata, Satoshi Sakakibara, Sho Ohno, Kohei Itami, Makoto Tokyo Univ Sci Facil Ind Sci & Technol Dept Appl Elect Noda Chiba 2788510 Japan

ISBN: (纸本)9781467330633

This paper discusses the IVC (Inter Vehicle Communication) system for ITS. DS-SS (Direct Sequence Spread Spectrum) is used for the IVC because it has CDMA (code Division Multiple Access) capability. However, efficient pn code allocation scheme is a problem to solve because the vehicles communication directly without base stations. In this paper, the location oriented pn code allocation scheme is adopted for the DS-SS IVC system. The influence of the positioning error for the communication performance is evaluated. The improved performance is shown even when the positing error exists in the IVC system. To improve the performance, the positioning error correction scheme is proposed. The distance between the vehicles are estimated by using the received signal strength after de-spreading. From the simulation result, the positioning error can be mitigated by using the proposed technique.

关键词： component Direct Sequense Spread Spectrum Inter Viecle Communication Location Oriented pn code Signal Power Strength

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A pn code parallel acquisition algorithm for CDMA communication and its implementation on FPGA

A PN code parallel acquisition algorithm for CDMA communicat...

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IEEE International Symposium on Microwave, Antenna, Propagation and EMC Technologies for Wireless Communications

作者： Zhang, X Sun, GL ConSymp Elect Sci & Technol Co Ltd R&D Ctr Chengdu 610041 Peoples R China

A novel pn code parallel acquisition algorithm for CDMA communication is presented in the paper. Using the mapping methodology from algorithm to architecture, our algorithm is successfully implemented in FPGA chips to... 详细信息

ISBN: (纸本)0780391284

关键词： pn code parallel acquisition integrate-dump algorithm mapping digital correlator

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A New Method for pn code Synchronization in the Direct Sequence Spread Spectrum Communication Systems 11

A New Method for PN Code Synchronization in the Direct Seque...

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11th International Conference on Computer Science & Education (ICCSE)

作者： Li, Tiejun Shangguan, Yali Shao, Guifang Jimei Univ Informat Engn Coll Xiamen Peoples R China Xiamen Univ Dept Automat Xiamen Peoples R China

ISBN: (纸本)9781509022182

Pseudo-Noise (pn) code synchronization is of crucial for receiver in direct sequence spread spectrum (DSSS) communication. What's more, acquisition and tracking are two important parts of the synchronization process. To meet the need of a lower power consumption and higher performance, there is a trend to design the digital match filter by using the field programmable gate array (FPGA) or the application specific integrated circuit (ASIC). This paper proposes a new pn code synchronization method based on FPGA and software radio technology. The adaptive threshold detection technology is first used at the acquisition stage to realize the relative judgment. Then the phase demodulation loop based on 1/2 lead-lag code is introduced to the tracking stage, which can guarantee the strictly synchronization between the local pn code and the received code. Simulation and actual experiment results validate the performance of the proposed method.

关键词： pn code adaptive threshold detection digital match filter phase tracking FPGA

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Narrowband interference suppression for pn code acquisition in a DS/CDMA overlay environment

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IEICE TRANSACTIONS ON COMMUNICATIONS 2000年第8期E83B卷 1631-1639页

作者： Kim, JY SK Telecom Cent Res & Dev Ctr Dev Grp IMT 2000 Pundang Gu Sungnam City 463020 Kyunggi South Korea

In this paper, performance of a PW code acquisition scheme is analyzed and simulated for a DS/CDMA overlay system where a CDMA user and a narrowband user coexist in the same frequency band. A narrowband user is modelled as a narrowband interference (NBI) located at the fraction of a CDMA user's bandwidth. To suppress the NBI. an interference suppression filter is employed at the receiver front-end. Acquisition performance is evaluated in terms of mean acquisition time using state transition diagram for acquisition process. To apply for a DS/CDMA mobile cellular environments, multiple access interference and imperfection of power control are taken into account in the analysis of acquisition performance. The imperfect power control is considered by modelling the power of each user to be lognormally distributed about nominal received power. From the simulation results, it is shown that for the cases of perfect and imperfect power control, the interference suppression filter is very effective for supprssion of the NBI and rapid pn code acquisition in a DS/CDMA overlay environment. It is also shown that the one-sided tap number of 5 for interference suppression filter is sufficient to suppress the NBI. And, capacity estimates are compared based on acquisition and BER performance. The analysis in this paper call be applied to the practical situations for a DS/CDMA overlay environment.

关键词： narrowband interference pn code acquisition DS/CDMA overlay

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A Novel pn code Acquisition Scheme Based on Sequential Estimation

A Novel PN Code Acquisition Scheme Based on Sequential Estim...

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Asia-Pacific Conference on Communications

作者： Junhwan Kim Dahae Chong Youngpo Lee Seung Goo Kang Jeehyeon Baek Seokho Yoon School of Information and Communication Engineering Sungkyunkwan University

ISBN: (纸本)9781457703898

关键词： code acquisition Sequential estimation Phase-shift-network pn code

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