Performance of Low-rank STAP detectors

In this paper the STAP detector based on the lowrank approximation of the normalized adaptive matched filter (LRNAMF) is investigated for its false alarm probability (FAP) performance. An exact formula for the FAP of the LRNAMF detector is derived using the g-method estimator [4]. The non CFAR behavior of this detector is shown via simulations using different models for the clutter-plus-noise covariance matrix. The detection probability is also evaluated, and the LRNAMF detector exhibits robustness in the presence of inhomogeneities consisting of interferers in the training data, for both non-fluctuating as well as fluctuating target models

Envelope-Law and Geometric-Mean STAP Detection

Two detectors for space-time adaptive processing (STAP) are proposed here. These are variants that use envelope-law and geometric-mean (GM) (or logarithmic) processing, both being well-known concepts from conventional constant false alarm rate (CFAR) square-law radar detection [212]. The variants are based on normalized adaptive matched filter (NAMF) STAP processing, and their CFAR property is established. Threshold setting for the detectors for specified false alarm probability (FAP) is accomplished using fast simulation based on importance sampling. Performance analyses of these detectors reveal almost indistinguishable loss in detection probability in homogeneous Gaussian interference compared with conventional square-law STAP detector versions. In addition, they exhibit robust detection performance in the presence of interfering targets in the training data for both nonfluctuating as well as fluctuating target models. Comparisons are made with the corresponding envelope-law and GM variants of the adaptive matched filter (AMF) detector previously proposed in a recent paper

Light weight digital array SAR

A light weight SAR has been designed, suitable for short range tactical UAVs, consisting of a fully digital receive array, and a very compact active transmit antenna. The weight of the complete RF front is expected to be below 3 kg, with a power consumption below 30 W. This X-band system can provide image resolution down to 10 cm at up to 5 km range. The system makes use of FMCW technology and digital beam forming in the horizontal direction, with 24 receive channels. A switchable transmit antenna is designed, to allow wide coverage with sufficient antenna gain. RF electronics for the receive panels have been realized and tested, as well as a low phase noise transmitter. Detailed antenna design has been performed, and critical issues such as bandwidth and transmit-receive isolation have been assessed by simulation

Life in Devil's Kitchen : microbial diversity of hydrothermal soils from the Mt. Hood volcano

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Extraction of DNA from acidic, hydrothermally modified volcanic soils

Acidic soils for microbial diversity studies were collected from Devil’s Kitchen, a fumarolic field on Mt Hood, USA. The very dense soils, which contain clay and other minerals, are derived from andesitic and dacitic rocks altered by volcanic heat and acidic, sulfur-rich hydrothermal steam. An initial attempt to extract biomass DNA using a mechanical-based cell lysis protocol was ineffective. However, by using various other protocols, DNA was successfully extracted, leading to the identification of several acidophilic Mt Hood extremophiles. The results emphasise the importance of testing different extraction procedures when dealing with apparently intractable samples.5 page(s

Compressive CFAR Radar Processing

In this paper we investigate the performance of a combined Compressive Sensing (CS) Constant False Alarm Rate (CFAR) radar processor under different interference scenarios using both the Cell Averaging (CA) and Order Statistic (OS) CFAR detectors. Using the properties of the Complex Approximate Message Passing (CAMP) algorithm, we demonstrate that the behavior of the CFAR processor is independent of the combination with the non-linear recovery and therefore its performance can be predicted using standard radar tools. We also compare the performance of the CS CFAR processor to that of an `1-norm detector using an experimental data set

Compressive CFAR radar detection

Abstract—In this paper we develop the first Compressive Sensing (CS) adaptive radar detector. We propose three novel architectures and demonstrate how a classical Constant False Alarm Rate (CFAR) detector can be combined with ℓ1-norm minimization. Using asymptotic arguments and the Complex Approximate Message Passing (CAMP) algorithm we characterize the statistics of the ℓ1-norm reconstruction error and derive closed form expressions for both the detection and false alarm probabilities. We support our theoretical findings with a range of experiments that show that our theoretical conclusions hold even in non-asymptotic setting. We also report on the results from a radar measurement campaign, where we designed ad hoc transmitted waveforms to obtain a set of CS frequency measurements. We compare the performance of our new detection schemes using Receiver Operating Characteristic (ROC) curves. I

A Culture-independent survey of the bacterial community in a radon hot spring

Paralana is an active, radon-containing hot spring situated in a region of South Australia's Flinders Ranges with a long history of hydrothermal activity. Our aim was to determine the bacterial composition of Paralana using a culture-independent, 16S rRNA-based technique. The presence of a diverse bacterial community was strongly suggested by the large number (~180) of different ribotypes obtained upon analysis of nine hot spring samples. DNA sequencing of Paralana 16S rRNA genes corroborated this observation, identifying representatives of seven confirmed and two candidate divisions of the domain Bacteria. These included Cyanobacteria, Proteobacteria (both β and δ subdivisions), the Cytophaga–Flexibacter–Bacteroides group, Low G+C Gram-positives, Nitrospira, green non-sulfur bacteria, green sulfur bacteria, OP8, and OP12. No known ionizing radiation-resistant Bacteria were identified. Only one Paralana 16S rRNA sequence type (recombinant B5D) was homologous to a sequence previously identified from a radioactive environment.16 page(s