OTHR Impulsive Interference Suppression in Strong Clutter Background
External interferences can severely degrade the performance of an Over-the-horizon radar (OTHR), so suppression of external interferences in strong clutter environment is the prerequisite for the target detection. The traditional suppression solutions usually began with clutter suppression in either time or frequency domain, followed by the interference detection and suppression. Based on this traditional solution, this paper proposes a method characterized by joint clutter suppression and interference detection: by analyzing eigenvalues in a short-time moving window centered at different time position, clutter is suppressed by discarding the maximum three eigenvalues at every time position and meanwhile detection is achieved by analyzing the remained eigenvalues at different position. Then, restoration is achieved by forward-backward linear prediction using interference-free data surrounding the interference position. In the numeric computation, the eigenvalue decomposition (EVD) is replaced by singular values decomposition (SVD) based on the equivalence of these two processing. Data processing and experimental results show its efficiency of noise floor falling down about 10-20dB.
Adaptive HF-communication interference mitigation in HF-GWR
The high-frequency (HF)-communication interference in the HF ground wave radar (GWR) has the characteristics of high intensity, directivity, transient and homogeneity in its effects on all the rangecells of the HF-GWR, an adaptive HF-communication interference mitigation scheme based on those characteristics is proposed in this paper. The scheme uses the samples from the rangecells without echoes of the sea-surface to estimate the covariance matrix, then HF-communication interference is suppressed through the adaptive beamforming technique. By employing the measured data, the results show that the proposed sehme is effective in HF-communication interference mitigation.
Far-field dispersal modeling for fuel-air-explosive devices
A computer model for simulating the explosive dispersal of a fuel agent in the far-field regime is described and is applied to a wide variety of initial conditions to judge their effect upon the resulting fuel/air cloud. This work was directed toward modeling the dispersal process associated with Fuel-Air-Explosives devices. The far-field dispersal regime is taken to be that time after the initial burster charge detonation in which the shock forces no longer dominate the flow field and initial canister and fuel mass breakup has occurred. The model was applied to a low vapor pressure fuel, a high vapor pressure fuel and a solid fuel. A strong dependence of the final cloud characteristics upon the initial droplet size distribution was demonstrated. The predicted fuel-air clouds were highly non-uniform in concentration. 18 refs., 86 figs., 4 tabs.