Matched Filter Criteria and Range Weighting for Weather Radar

The effective weighting function for weather radar is defined. This weighting function considers the effects of both the transmitted signal and the receiver filter. It is used to assign effective ranges to samples taken at prescribed times. For uniformly distributed targets it is shown that "signal"-to-noise ratio depends on the receiver filter, transmitted signal envelope, and receiver noise spectral density. Maximization of this signal-to-noise ratio when range resolution constraints are imposed is discussed, and a receiver design approach specifically adapted for Doppler weather radars is developed.     

Susceptibility of DS/FH,M, Binary DPSK to Partial and Full Band Barrage Jamming

Spread spectrum signaling schemes have been proposed to counter unfriendly, electrical jamming threats. In order to establish their effectiveness, such schemes must be analyzed. This work takes a step in this direction by developing the susceptibility equation, or equivalently, the probability of error, of a direct sequence/frequency hopped (DS/FH), binary differential phase-shift keying (DPSK) system when subjected to a barrage jamming signal. Specific system models are established for the receiving system as well as for the jamming signal and the spread spectrum techniques. Both partial and full band jamming strategies are considered. Graphical results are presented with the conclusions summarizing the spread spectrum effectiveness and the deficiencies of the FH processing gain definition.     

Detection of polyphase pulse compression waveforms using the radon-ambiguity transform

The recently developed Radon-ambiguity transform (RAT) detects unknown linear frequency modulated (LFM) signals by computing line integrals through the origin of the signal's ambiguity function (AF) magnitude. It is shown that this method also detects the step LFM and frequency-derived polyphase pulse compression waveforms with varying performance degradation. Simulations are provided to estimate the detection loss relative to the LFM.     

Calibration of the MERIC full-polarimetric radar: theory and implementation

This paper describes the architecture and calibration design of the experimental ground based radar station MERIC. This full-polarimetric radar is conceived for the analysis and the recognition of non cooperative aircraft in flight.We carefully study how the full-polarimetric capability is obtained for a simultaneous transmit (simultaneous transmission of two linear FM with opposite slopes) radar system, using analogue deramping with a replica.The phase distortions of the signal propagating in the four polarimetric channels are carefully estimated. We define a phase calibrating method compatible with the outdoor measurements conditions and few constraints on reference targets.We show the phase accuracy obtained with the proposed calibration method on real measurements.     

涡轮发动机聚氧减重探索

本文在聚氧提高航机部件性能，总体性能的研究基础上，进一步探索航空发动机聚氧减重的规律，提供聚氧缩短压气机、燃烧室、涡轮轴向尺寸、减少发动机直径、减轻上述核心机部件和发动机总重量的理论依据，可供航机预研参考。     

A Correlation Polarimeter for Noise-Like Signals

Optimum estimation (tracking) of the polarization plane of a linearly polarized electromagnetic wave is determined when the signal is a narrow-band Gaussian random process with a polarization plane angle which is also a Gaussian random process. This model is Compared to previous work and is applicable to space communication. The estimator performs a correlation operation similar to an amplitude -comparison monopulse angle tracker, giving the name correlation polarimeter. Under large signal-to-noise ratio (SNR), the estimator is causal. Performance of the causal correlation polarimeter is evaluated for arbitrary SNR. Optimum precorrelation filtering is determined. With low SNR, the performance of this system is far better than that of previously developed systems. Practical implementation is discussed. A scheme is given to reduce the effect of linearly polarized noise.     

An Optimum Phase Reference Detector for Fully Modulated Phase-Shift Keyed Signals

Many modern telemetry systems which use phase-shift keying (PSK) have receivers which derive a coherent reference from the fully modulated PSK signal itself and thus conserve the energy which otherwise would be allocated to a discrete reference signal. In this paper, an optimum receiver structure for estimating a phase reference from the PSK signal itself is derived and its realization discussed. It is shown that at low signal-to-noise ratios, the optimum detector can be realized with a Costas loop. Since a Costas loop and squaring loop exhibit identical performance, it follows that either of these simple devices gives optimum performance for low-input signal-to-noise ratios.     

UV Irradiation Effect on the Electrical Properties of ZnO Thermal Control Coating Pigment

Electron concentration and Hall mobility have been investigated in pure zinc oxide single crystals, while in the dark and under ultraviolet (UV) excitation. Mode of scattering in ZnO has been determined by studying the temperature dependence of various electrical parameters in the range from -170 to 120°C. It has been observed that the degradation to the crystals by UV irradiation is limited only to the surface layer and shows up only at relatively lower temperatures, which is in contrast to the degradation behavior in thin films and powders.     

Silicon Solar Cell Performance at High Intensities

The theoretical and experimental work performed since 1960 in the area of high-intensity and high-temperature operation of silicon and gallium arsenide photovoltaic devices is reviewed. Test results for conventional 5-grid silicon cells, for specially designed 13-grid silicon cells, and for a GaAs cell are presented parametrically for the illumination intensity range from 0.07 to 2.8 W/cm2 and the temperature range from 30 to 1 50°C. The data cover the 3 points on the currentvoltage characteristic required to reconstruct the full characteristic in the power-generating quadrant. The 13-grid silicon cells showed much better performance than the GaAs cell.     

基于干扰观测器的新一代歼击机鲁棒飞行逆控制器设计

基于干扰观测器设计了新一代歼击机的鲁棒飞行逆控制器。根据时标分离的原则，将机动飞机分为快慢不同的回路。采用动态逆方法设计了快回路和慢回路控制器，并在慢回路用干扰观测器估计飞机所受的扰动，同时，用于在线补偿动态逆误差。仿真结果表明，该设计合理。