599 research outputs found
Non-Linear Signal Processing methods for UAV detections from a Multi-function X-band Radar
This article develops the applicability of non-linear processing techniques
such as Compressed Sensing (CS), Principal Component Analysis (PCA), Iterative
Adaptive Approach (IAA) and Multiple-input-multiple-output (MIMO) for the
purpose of enhanced UAV detections using portable radar systems. The combined
scheme has many advantages and the potential for better detection and
classification accuracy. Some of the benefits are discussed here with a phased
array platform in mind, the novel portable phased array Radar (PWR) by Agile RF
Systems (ARS), which offers quadrant outputs. CS and IAA both show promising
results when applied to micro-Doppler processing of radar returns owing to the
sparse nature of the target Doppler frequencies. This shows promise in reducing
the dwell time and increase the rate at which a volume can be interrogated.
Real-time processing of target information with iterative and non-linear
solutions is possible now with the advent of GPU-based graphics processing
hardware. Simulations show promising results
Clutter removal of near-field UWB SAR imaging for pipeline penetrating radar
Recently, ultrawideband (UWB) near-field synthetic aperture radar (SAR) imaging has been proposed for pipeline penetrating radar applications thanks to its capability in providing suitable resolution and penetration depth. Because of geometrical restrictions, there are many complicated sources of clutter in the pipe. However, this issue has not been investigated yet. In this article, we investigate some well-known clutter removal algorithms
using full-wave simulated data and compare their results considering
image quality, signal to clutter ratio and contrast. Among candidate algorithms, two-dimensional singular spectrum analysis (2-D SSA) shows a good potential to improve the signal to clutter ratio. However, basic 2-D SSA produces some artifacts in the image. Therefore, to mitigate this issue, we propose “modified 2-D SSA.” After developing the suitable clutter removal algorithm, wepropose a complete algorithm chain for pipeline imaging. An UWB nearfieldSARmonitoring system including anUWBM-sequence sensor
and automatic positioner are implemented and the image of drilled
perforations in a concrete pipe mimicking oil well structure as a case
study is reconstructed to test the proposed algorithm. Compared to
the literature, a comprehensive near-field SAR imaging algorithm
including new clutter removal is proposed and its performance is
verified by obtaining high-quality images in experimental results
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Implementation of polarization diversity pulse-pair technique using airborne W-band radar
This work describes the implementation of polarization diversity on the National Research Council Canada W-band Doppler radar and presents the first-ever airborne Doppler measurements derived via polarization diversity pulse-pair processing. The polarization diversity pulse-pair measurements are interleaved with standard pulse-pair measurements with staggered pulse repetition frequency, this allows a better understanding of the strengths and drawbacks of polarization diversity, a methodology that has been recently proposed for wind-focused Doppler radar space missions. Polarization diversity has the clear advantage of making possible Doppler observations of very fast decorrelating media (as expected when deploying Doppler radars on fast-moving satellites) and of widening the Nyquist interval, thus enabling the observation of very high Doppler velocities (up to more than 100 m s−1 in the present work). Crosstalk between the two polarizations, mainly caused by depolarization at backscattering, deteriorated the quality of the observations by introducing ghost echoes in the power signals and by increasing the noise level in the Doppler measurements. In the different cases analyzed during the field campaigns, the regions affected by crosstalk were generally associated with highly depolarized surface returns and depolarization of backscatter from hydrometeors located at short ranges from the aircraft. The variance of the Doppler velocity estimates can be well predicted from theory and were also estimated directly from the observed correlation between the H-polarized and V-polarized successive pulses. The study represents a key milestone towards the implementation of polarization diversity in Doppler space-borne radars
Spectral and correlation analysis with applications to middle-atmosphere radars
The correlation and spectral analysis methods for uniformly sampled stationary random signals, estimation of their spectral moments, and problems arising due to nonstationary are reviewed. Some of these methods are already in routine use in atmospheric radar experiments. Other methods based on the maximum entropy principle and time series models have been used in analyzing data, but are just beginning to receive attention in the analysis of radar signals. These methods are also briefly discussed
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