We present an algorithm for the detection of candidate astronomical pulses. It is implemented in several steps. First, a spectrogram of a dispersed astronomical pulse is linearized in observing frequency followed by application of the Radon transform. The result of the transformation is displayed as a two-dimensional function. Next, the function is smoothed using a spatial low-pass filter. Finally, the maximum of the function above 90-deg angle is compared to the maximum of the standard deviation of the noise below 90-deg angle and a decision in favor of an astronomical pulse present or absent is made. Once pulse is detected, its dispersion measure (DM) is estimated by means of a basic equation relating the slope of the linearized dispersed pulse and the DM value. Performance of the algorithm is analyzed by applying it to a set of simulated fast radio bursts, experimental data of Masui pulse, and of seven rotating radio transients. The detection algorithm demonstrates results comparable to those by the conventional pulse detection algorithm.
KEYWORDS: Signal detection, Interference (communication), Signal processing, Phased arrays, Radio astronomy, Astronomy, Data modeling, Signal to noise ratio, Statistical analysis, Receivers
In this paper we develop two statistical rules for the purpose of detecting pulsars and transients using signals from phased array feeds installed on a radio telescope in place of a traditional horn receiver. We assume a known response of the antenna arrays and known coupling among array elements. We briefly summarize a set of pre-processing steps applied to raw array data prior to signal detection and then derive two detection statistics assuming two models for the unknown radio source astronomical signal: (1) the signal is deterministic and (2) the signal is a random process. The performance of both detectors is analyzed using both real and simulated data.
This paper considers a problem of distributed function estimation in the case when sensor locations are modeled as Gaussian random variables. We consider a scenario where sensors are deployed in clusters with cluster centers known a priori (or estimated by a high performance GPS) and the average quadratic spread of sensors around the cluster center also known. Distributed sensors make noisy observations about an unknown parametric field generated by a physical object of interest (for example, magnetic field generated by a ferrous object and sensed by a network of magnetometers). Each sensor then performs local signal processing of its noisy observation and sends it to a central processor (called fusion center) in the wireless sensor network over parallel channels corrupted by fading and additive noise. The central processor combines the set of received signals to form an estimate of the unknown parametric field. In our numerical analysis, we involve a field shaped as a Gaussian bell. We experiment with the size of sensor clusters and with their number. A mean square error between the estimated parameters of the field and the true parameters used in simulations is involved as a performance measure. It can be shown that a relatively good estimate of the field can be obtained with only a small number of clusters. As the number of clusters increases, the estimation performance steadily improves. The results also indicate that, on the average, the number of clusters has more impact on the performance than the number of sensors per cluster, given the same size of the total network.
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