CiteULike: Forfatter Bobrovsky

Mean Time to Lose Lock for a PLL with Loop Delay under Thermal and Phase Noise Conditions

U Yehuday — 2008-05-09T23:56:03-00:00

Communications, 2007. ICC '07. IEEE International Conference on (2007), pp. 2888-2893.

The growing demand for reliable communications leads to the need for very large mean time to lose lock (MTLL) of PLL based synchronization subsystems. These large MTLLs, of the order of months, cannot be simulated or tested in a lab. In this work a systematic approach is given to computing the MTLL of a second order PLL with parasitic delay at low SNR and high phase noise. Computed and simulated results are shown to be in good agreement for values that can be simulated.

Anti multipath cellular radio location for DS/CDMA systems using a novel EKF subchip RAKE tracking loop

E Fishler — 2008-05-09T15:42:49-00:00

Military Communications Conference Proceedings, 1999. MILCOM 1999. IEEE, Vol. 2 (1999), pp. 1328-1332 vol.2.

This paper discusses an improved method for localization in a DS-CDMA based cellular-phone communication link. This method suggests an optimization for code synchronization, which allows for TDOA (time difference of arrival) estimations to be solved for the position of a mobile phone. It is known that the time delay of a received DS signal, derived from the classical DLL, may express severe timing errors due to multipath effects. A new anti multipath multi-tracking extended Kalman filter loop is shown to achieve far better results especially in the environment of specular multipath. Specifically, this new loop minimizes the errors due to multipath components by letting the EKF decide upon the best weights of its sub-chip processing branches, resulting in a RAKE-like tracking loop. This loop tracks not only the line of sight path, but also the other multipath components as well as their power and phase. It is shown that the implementation of this technique converges to the classical non-coherent code tracking DLL structure when no multipath is assumed, but results in a new and efficient tracking loop structure in the more realistic fading channel case. The application of this technique to the EIA IS-95 system is considered, where accurate location estimations as well as power management utilities are treated

A Simple Asymptotically Optimal Filter Over An Infinite Horizon

P Chigansky — 2007-09-18T15:27:43-00:00

. A filtering problem over an infinite horizon for a continuous time signal and discrete time observation in the presence of non Gaussian white noise is considered. Conditions are presented, under which a nonlinear Kalman type filter with limiter is asymptotically optimal in the mean square sense for long time intervals given provided the sampling frequency is su#ciently high. 1.

Very low-frequency heart rate variability wave amplitude and sympathetic stimulation-characterization and modeling

RJ Leor-Librach — 2007-02-28T15:10:20-00:00

Biomedical Engineering, IEEE Transactions on, Vol. 50, No. 7. (2003), pp. 797-803.

The purpose of this study was to assess the relationship between very low-frequency heart rate variability (LFHR) wave amplitude and the degree of sympathetic stimulation. We developed a computerized system for the controlled increase of heart rate (HR) by isoproterenol (ISP), with which we obtained a series of stabilized HR levels in conscious freely moving rats. We found that LFHR amplitude rises gradually as a function of the average HR for each level until it reaches a point where additional increases in average HR are associated with gradual decrease in LFHR amplitude. We successfully built and fitted a model of LFHR amplitude to the experimental results. The fact that our model fits the experimental data well may suggest a possible relationship between our LFHR amplitude findings and the basic physiologic properties of the HR-ISP system inherent in our model.