Performance of pulse-pair method of Doppler estimation

Because of its simplicity, the pulse-pair method is usually used in the estimation of Doppler from backscattered acoustic signals. In the literature, various improvements to the basic pulse-pair estimate have been proposed. The statistics of these improved methods have also been derived using simplified assumptions for the signal and noise. By developing a multiplicative noise model for the backscatter signal, in this work, the variance of the Doppler estimate is derived under all signal scenarios. The dependency of the variance on the amplitude correlation length of the data is also discussed. It is demonstrated that the use of parabolic window in the estimate is the proper method of Doppler evaluation under all conditions     

Some peculiarities of the wave beams in wireless power transmission

Some wave beam peculiarities which usually are wasted are useful in wireless power transmission systems. These peculiarities-the focusing of the beam, the taper distribution of the radiating field, and the discontinuous antenna-are discussed     

VLF Loop Antennas for Pulse Reception

This paper describes an approach to the realization of a VLF loop-type antenna system. The theoretical analysis is applied to a four-loop system for Loran-C reception.     

Automatic Light Control Electro-Optical CCDTV Systems

For electro-optical TV systems, a simplified method of analysis has been developed for an automatic light control (ALC) loop preliminary ary design and performance trade-offs. With iris and shutter control mechanization incorporated, not only does the input light range increase, but the video response overshoot and settling time are reduced as well. This study shows that the appealing notion of heavily damped response is not often true, particularly in the realtime ime airto-ground surveillance of targets with varying backgrounds. In addition, with exponential and geometric feedback functions introduced, the resultant ALC dynamics are independent of the input light level. To verify the assumptions made and to demonstrate the feasibility of a working model, a complete system simulation is performed.     

Passive localization of moving emitters using out-of-planemultipath

The purpose of this work is to establish how a moving emitter, such as a jammer, can be localized by a passive receiver through the use of out-of-plane multipath signals reflected by the terrain. This is a novel localization technique that assumes no a priori knowledge of the localization of the multipath sources. The emitter parameters of range, heading, velocity, and altitude are estimated by exploiting the correlation between the direct-path signal and the delayed and Doppler modulated signals. Two basis assumptions about the scattering properties of the terrain lead to different maximum likelihood estimators (MLEs). The Cramer-Rao lower bounds (CRLB) are used to study estimator performance versus emitter velocity for each case. The proposed estimators are successfully demonstrated using field data collected at White Sands Missile Range (WSMR) during the DARPA/Navy Mountaintop program     

An approximated method of calculating the cellular insert influence in the carrying capacity of the direct-flow labyrinth seal

A method for calculating the flowrate of the gas flowing through the cellular insert cells over the labyrinth seal strip is proposed. The gas density is taken to be average with respect to the decisive section. It is assumed that jets flowing out of cells disrupt the direct flow of the labyrinth seal. A practical implementation of the method is confirmed by the known experimental data.     

Numerical study of transient interchamber processes when reaching the SPRE operational conditions

A comprehensive numerical study of transient interchamber processes occurring when reaching the SPRE operational conditions is carried out. A conjugate problem under consideration includes nonstationary operation of an igniter heating, ignition and subsequent nonstationary and turbulent burning of a solid-propellant charge; nonstationary three-phase homo-heterogeneous flow of combustion products in the combustion chamber, nozzle and downstream of the nozzle block of a rocket engine; motion of a nozzle block cover. The calculation results are presented.