ESTIMATION OF THE CAPABILITIES OF BROADBAND RECEIVERS FOR DETECTING BROADBAND SIGNALS

Рассмотрена задача обнаружения радиолокационных дискретных составных частотных сигналов широкополосными приемниками с программными обнаружителями. Данный тип сигналов нашел большое применение в радиолокации благодаря высокой помехоустойчивости и энергетической скрытности. Для их обнаружения часто используют широкополосный энергетический обнаружитель, который измеряет энергию принятого сигнала, сравнивая ее с пороговым уровнем, и на основе этого выносит решение о наличии либо отсутствии сигнала. Недостатком таких устройств является факт срабатывания их на одиночные отчеты, которые могут и не являться полезным сигналом. За счет того, что обнаружение ведется в широкой полосе частот, ухудшаются возможности приема таких сигналов. Для повышения возможностей приема составных частотных сигналов применяются программные обнаружители. За счет определенных правил принятия решения возрастает качество обнаружения, а одиночные отчеты более не воспринимаются. В результате была разработана методика, позволяющая провести оценку вероятности правильного и ложного обнаружения сигналов широкополосным приемником с программным обнаружителем в системах связи с применением широкополосных сигналов на примере радиолокационных дискретных составных частотных сигналов. Показано преимущество применения программной обработки We considered the problem of detecting radar discrete composite frequency signals by broadband receivers with software detectors. This type of signal is widely used in radar due to its high noise immunity and energy secrecy. To detect them, a broadband energy detector is often used, which measures the energy of the received signal, comparing it with a threshold level, and, based on this, makes a decision on the presence or absence of a signal. The disadvantage of such devices is the fact that they are triggered for single reports, which may not be a useful signal. Due to the fact that the detection is carried out in a wide frequency band, the ability to receive such signals is impaired. To improve the reception capabilities of composite frequency signals, software detectors are used. Due to certain decision rules, the quality of detection increases, and single reports are no longer accepted. As a result, we developed a technique that makes it possible to assess the probability of correct and false signal detection by a broadband receiver with a software detector in communication systems using wideband signals using the example of discrete composite frequency radar signals. Here we show the advantage of using software processing

An Automated Radio-Telemetry System (ARTS) for Monitoring Small Mammals

Point 1: The study of animals in nature is essential for developing an ecologically valid understanding of behavior. Small mammals, however, are often fossorial and exceedingly difficult to monitor in the wild. This limits both the taxonomic scope of field observation, and excludes species that are powerful models for the study of behavioral mechanisms.Point 2: Here, we implement an automated radio telemetry system (ARTS) designed to track small fossorial mammals. Our ARTS uses an isotropic antenna array coupled with broadband receivers. We characterized transmission at our study site and tested the ARTS’ ability to track 48 prairie voles.Point 3: We compared position estimates from nonlinear least squares, nonparameteric, and Bayesian trilateration methods and found Bayesian trilateration to have the smallest error. To examine the ability of the system to track biologically significant behavior we used ARTS data to investigate circadian rhythms of freely behaving prairie voles. We used Lomb-Scargle analysis to estimate periodic patterns from irregularly sampled time series of speed. Prairie voles demonstrated ultradian movement at periods of approximately 45 and 90 min, observations on a time scale not possible using data from traditional methods.Point 4: This ARTS offers a new tool to observe rodent field behavior at time scales and in environments which have not been previously possible, such as investigating social and spatial behaviors on the scale of minutes, hours, and days in natural environments.

The Imbricated Foreshock and Aftershock Activities of the Balsorano (Italy) Mw 4.4 Normal Fault Earthquake and Implications for Earthquake Initiation

Foreshocks in the form of microseismicity are among the most powerful tools to study the physical processes that occur before main earthquakes. However, their detection and precise characterization is still sparse, especially for small-to-moderate-size earthquakes (Mw<6). We present here a detailed foreshock analysis for the 7 November 2019, Balsorano, Italy, normal fault earthquake (Mw 4.4). To improve the detection of the microseismicity before and after the mainshock, we use six three-component broadband receivers at distances of less than 75 km from the targeted seismicity, through template matching. To improve the understanding of the physical mechanism(s) behind the earthquake initiation process, as well as other accompanying phenomena, we also detail the spatiotemporal evolution of the sequence associated with this medium-sized earthquake, using waveform clustering and hypocenter relocation. Clear differences between foreshocks and aftershocks are revealed by this analysis. Moreover, five distinct spatiotemporal patterns associated with the different seismic activities are revealed. The observed spatiotemporal behavior shown by the foreshocks highlights a complex initiation process, which apparently starts on an adjacent unmapped antithetic fault. Finally, the aftershock activity comprises four different clusters with distinct spatiotemporal patterns, which suggests that the different clusters in this sequence have distinct triggering mechanisms.