A comparison of two Crame/spl acute/r-Rao bounds for nonlinear filtering with P/sub d/<1

The paper presents a comparative study of two recently reported Crame/spl acute/r-Rao lower bounds (CRLBs) for nonlinear filtering, both applicable when the probability of detection is less than unity. The first bound is the information reduction factor CRLB; the second is the enumeration method CRLB. The enumeration method is accurate but computationally expensive. We prove in the paper that the information reduction factor bound is overoptimistic, being always less than the enumeration CRLB. The theory is illustrated by two target tracking applications: ballistic object tracking and bearings-only tracking. The simulations studies confirm the theory and reveal that the information reduction factor CRLB rapidly approaches the enumeration CRLB as the scan number increases.     

Comments on “The Cramer-Rao lower bounds for signals withconstant amplitude and polynomial phase”

For original paper see IEEE Trans. Signal Processing, vol.39, p.749-52 (March 1991). Different expressions for the Cramer-Rao lower bounds (CRLBs) of constant amplitude polynomial phase signals embedded in white Gaussian noise appear in the literature. The present paper revisits the derivation of the bounds reported by Peleg and Porat (1991) and indicates that the resulting expressions depend on the interval over which the signal is defined. The proper choice of the interval is the one that centers the signal around zero and results in the minimum lower bounds     

All-optical erasable programmable read-only memory (EPROM) based onLiNbO3 channel waveguides

The erasable programmable read-only memory (EPROM) consists of three channel waveguides. Two are made by the proton-exchange technique to construct a directional coupler as the read-in and read-out units. The third, placed in between the other two, is made by the Ti-indiffusion technique to function as the memory storage unit as well as the control channel. The operation principle is based on the combination of the directional coupler switch and the photorefractive effect. The EPROM also operates as an all-optical switch if a short-pulsed laser with high-energy density is used to write and erase, and the speed should be on the nanosecond time scale or even faster. Theoretical calculation of some typical designs shows that very small light energy (0.06-0.6 mJ) is needed for the device operation     

Cramer-Rao bound for nonlinear filtering with Pd<1 and itsapplication to target tracking

The paper investigates the Cramer-Rao bound for discrete-time nonlinear filtering in the case where the probability of detection of a sensor is less than unity. The theoretical formula involves the evaluation of exponentially growing number of possible miss/detection sequences. An approximation of the theoretical bound for practical applications, such as target tracking, where the number of sensor scans is large, is proposed. An application of the developed techniques to the well-known filtering problem of tracking a re-entry ballistic object is also presented     

Effect of radiation-induced oxide-trapped charge on mobility inp-channel MOSFETs

It is shown that radiation-induced oxide-trapped charge contributes to an increase in mobility in p-channel MOSFETs. A new scattering mechanism involving retardation of surface-roughness scattering due to oxide-trapped charge is proposed in order to explain the observed mobility increase     

Experimental study of anisotropy dependent geodesic lenses

The effect of anisotropy on focal lengths of geodesic lenses has been investigated with a novel experimental method. The measured relative difference for TE and TM (transverse electric and transverse magnetic)-mode focal lengths, for 10° off-axis propagation, was 6.33%; this compares well with the theoretical prediction of 6.6%