The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Junxing Ren - One of the best experts on this subject based on the ideXlab platform.
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stability analysis of gps carrier tracking loops by phase margin approach
Gps Solutions, 2013Co-Authors: Tian Jin, Junxing RenAbstract:Stability, which is significantly related to the loop parameters, is an important factor in the traditional GPS tracking loop design. Through the analysis of phase margin values in the discrete GPS PLL tacking loop, we are able to theoretically reveal the relationship between loop stability, equivalent Noise Bandwidth B n , predetection integration time T, and loop parameters. We calculate the theoretical limitations for B n T, that is, the product of equivalent Noise Bandwidth multiplied by predetection integration time, for second- and third-order phase-locked loop, respectively. The results are verified by actual data from GPS receivers.
Wu Lenan - One of the best experts on this subject based on the ideXlab platform.
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Extension to Shannon’s channel capacity —the theoretical proof
2007 6th International Conference on Information Communications & Signal Processing, 2007Co-Authors: Feng Man, Wu LenanAbstract:Shannon's channel capacity equation, a very important theory, defines the maximum transmission rate of communication systems. However, a new communication scheme, named ultra narrow band, is said to "break" Shannon's limit. During the research, a special kind of filters having different signal and Noise Bandwidth was found, therefore, the aim of our study was to extend Shannon's channel capacity formula in the case of different signal and Noise Bandwidth. Considering the conversion of time and space domain, a new capacity formula was deduced based on MIMO theory. Results indicated that extension equation is in good agreement with Shannon's channel capacity equation under the assumption of the same signal and Noise Bandwidth, but in different signal and Noise Bandwidth, capacity values calculated by this extension is larger than ones by Shannon's equation, which is the reason for "breaking" Shannon's capacity in ultra narrow band system.
G N Goltsman - One of the best experts on this subject based on the ideXlab platform.
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temperature dependence of the receiver Noise temperature and if Bandwidth of superconducting hot electron bolometer mixers
Superconductor Science and Technology, 2014Co-Authors: Wen Zhang, Wei Miao, Sheng-cai Shi, J Q Zhong, D J Hayton, N Vercruyssen, J R Gao, G N GoltsmanAbstract:In this paper we study the temperature dependence of the receiver Noise temperature and IF Noise Bandwidth of superconducting hot electron bolometer (HEB) mixers. Three superconducting NbN HEB devices of different transition temperatures (T-c) are measured at 0.85 THz and 1.4 THz at different bath temperatures (T-bath) between 4 K and 9 K. Measurement results demonstrate that the receiver Noise temperature of superconducting NbN HEB devices is nearly constant for T-bath/T-c, less than 0.8, which is consistent with the simulation based on a distributed hot-spot model. In addition, the IF Noise Bandwidth appears independent of T-bath/T-c, indicating the dominance of phonon cooling in the investigated HEB devices.
Wu Jiangxiong - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis of a novel kalman filter-based signal tracking loop
Proceedings of the 2nd International Conference on Robotics Control and Automation - ICRCA '17, 2017Co-Authors: Wang Wentong, Li Chuanjun, Wu JiangxiongAbstract:Though the GNSS receiver baseband signal processing realizes more precise estimation by using Kalman Filter, traditional KF-based tracking loops estimate code phase and carrier frequency simultaneously by a single filter. In this case, the error of code phase estimate can affect the carrier frequency tracking loop, which is vulnerable than code tracking loop. This paper presents a tracking architecture based on dual filter. Filters can performing code locking and carrier tracking respectively, hence, the whole tracking loop ultimately avoid carrier tracking being subjected to code tracking errors. The control system is derived according to the mathematical expression of the Kalman system. Based on this model, the transfer function and equivalent Noise Bandwidth are derived in detail. As a result, the relationship between equivalent Noise Bandwidth and Kalman gain is presented. Owing to this relationship, the equivalent Noise Bandwidth for a well-designed tracking loop can adjust automatically with the change of environments. Finally, simulation and performance analysis for this novel architecture are presented. The simulation results show that dual Kalman filters can restrain phase Noise more effectively than the loop filter of the classical GNSS tracking channel, therefore this whole system seems more suitable to working in harsh environments.
Tian Jin - One of the best experts on this subject based on the ideXlab platform.
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stability analysis of gps carrier tracking loops by phase margin approach
Gps Solutions, 2013Co-Authors: Tian Jin, Junxing RenAbstract:Stability, which is significantly related to the loop parameters, is an important factor in the traditional GPS tracking loop design. Through the analysis of phase margin values in the discrete GPS PLL tacking loop, we are able to theoretically reveal the relationship between loop stability, equivalent Noise Bandwidth B n , predetection integration time T, and loop parameters. We calculate the theoretical limitations for B n T, that is, the product of equivalent Noise Bandwidth multiplied by predetection integration time, for second- and third-order phase-locked loop, respectively. The results are verified by actual data from GPS receivers.