This paper proposed a kind of two-dimension partly coherent jamming style against Synthetic Aperture Radar (SAR) named stepped time-delay repeater jamming. Its repeated time-delay increases or ...deduces by a fixed increment during the irradiation of SAR. The research shows that the presented jamming style can obtain both range and azimuth coherent processing gains when through SAR system. In addition, its SAR imaging output covers some region which could be applied for distributed targets protection. Theoretical analysis and simulation experiments verify its validity.
This paper provides the evaluated results of transmitting efficiency concerning about non-contact electric power transmission via a repeater antenna using magnetic resonance method under high-speed ...driving conditions. First, we evaluated transmitting efficiency in installing a repeater antenna between a transmitting antenna and a receiving antenna to fully understand the effects of the repeater antenna. Second, we also experimentally evaluated and simulated transmitting efficiency at zero velocity when the repeater antenna was installed in our own evaluation system. Finally, we found out that transmitting efficiency decreased at a peripheral velocity over 60 km/h when both a transmitting side rotor and a repeater antenna rotated at the same peripheral velocity.
It has been claimed that MIMO radars perform better than conventional radars against repeater and hot clutter jammers (jammer signals reflected from the ground into the radar). It is shown here that ...conventional radars can perform as well if not better than MIMO radars against these jammers as well as against barrage noise jammers. The results are presented in tutorial form without heavy math. Instead physical explanations are given for these results. Applied here to reject the barrage jammer and hot clutter is the Adaptive-Adaptive Array Processing (AAAP) technique which makes use of the information available as to where the jammers are rather than assuming there location is not known as done for the classical sample matrix inversion (SMI) method. This is reminiscent of the KA-STAP technique used by DARPA. It also could be called Cognitive Adaptive Array Processing (CAAP). The method reduces the transient time (the number of time samples needed to calculate the interference covariance matrix) by orders of magnitude. Also the interference covariance matrix size is reduced by orders of magnitude and in turn the computation of its matrix inverse. Finally this method reduces the sidelobe degradation usually resulting from using the SMI method. The AAAP technique lends itself well to both the MIMO and conventional array systems when digital beam forming is used.
ABSTRACT
Using self‐reported but empirically verified repeater groups, we analyzed vast amounts of real test data across a wide range of administrations from a graduate admissions examination that ...was administered in a non‐English language to investigate repeater effects on score equating using the nonequivalent groups with anchor test (NEAT) design. Both linear and nonlinear equating models were considered in deriving the equating functions for various study groups. We evaluated scaled score differences between equating in the total group, the repeater group, and the first‐timer group using statistics of simple differences and subpopulation invariance measures developed and used widely in the last 10 years. Standard errors of statistics summarizing scaled score differences were estimated using a simulation approach to provide statistical criteria for evaluating the significance of equating differences. In addition, we used scaled score differences that were critical to admissions screening as criteria for evaluating the practical significance of equating differences. To put the investigation of repeater effects in proper perspective, we analyzed the repeater data for an in‐depth understanding of repeater performance trends. Overall, we found no significant effects of repeater performance on score equating for the exam being studied. Although many of the equating differences were practically significant, most of the practically significant differences were not statistically significant. However, further research with larger repeater samples is recommended to help explain the practical significance of equating differences consistently observed in this study for the repeater group. Potential problems associated with small repeater study sample sizes, issues of the practical criterion for evaluating the significance of equating differences, and study limitations are also discussed.
A same-frequency cellular repeater is proposed that uses adaptive signal processing to cancel the feedback path, thereby allowing high gain while maintaining stability. This technique has application ...wherever it is desired to boost signal strength in outlying areas of cell coverage, particularly inside homes and buildings. It is intended to provide useful gain without needing special donor/transmit antennas requiring directional gain, separation beyond a meter or so, or roof installation. A simulation of a 900-MHz repeater with 10-MHz bandwidth is presented that demonstrates the feasibility and determines the effect of parameter values on convergence and cancellation performance.
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