M. Antoniou

The concept of a forward scattering micro-sensors radar network for situational awareness

The concept of a novel forward scattering micro-radar wireless network for ground targets detection and recognition is presented. The system topology and structure are described first, followed by a summary of the systempsilas capabilities and applications. Signal processing strategies used for target detection, parameter estimation and automatic target recognition are briefly explained and supported with experimental results.

Space surface bistatic SAR with space-borne non-cooperative transmitters

This paper presents research results in space-surface bistatic synthetic aperture radar (SS-BSAR) with GNSS non-cooperative transmitters. The experimental-setup used to study the SS-BSAR is described. The signal processing algorithm that will be used to process the data collected from SS-BSAR is also discussed

Forward scatter RCS estimation for ground targets

Computer simulation models and techniques are proposed for RCS estimation of ground targets in a forward scattering micro radar network. A number of practical targets are considered as simulation examples over a wide range of radar carrier frequencies.

Vegetation clutter spectral properties in VHF/UHF bistatic doppler radar

A simple model of vegetation clutter creation mechanism is discussed for the bistatic and forward scattering Doppler radar configuration. The foliage is considered as a set of separate pendulums oscillating with different resonance frequencies. On the basis of this model, predictions of clutter spectral properties are made and compared with clutter data measured on different frequencies in the VHF and UHF bands.

Experiences Gained during the Development of a Passive BSAR with GNSS Transmitters of Opportunity

An electrode for a plasma arc torch comprises a copper holder having a lower end which mounts an emissive element serving as the cathode terminal for the arc during operation. A relatively non-emissive separator formed of silver alloyed with 0.5 to 4 percent of copper or other metals surrounds the emissive element and separates the emissive element from the copper holder at the exposed end face of the electrode. The separator serves to prevent the arc from detaching from the emissive element and attaching to the copper holder.

GNSS-based passive radar for maritime surveillance: Long integration time MTI technique

The exploitation of the Global Navigation Satellite Systems (GNSS) as transmitters of opportunity in passive radar systems for maritime surveillance is particularly attractive because of the main advantages consisting in a global coverage (even in open sea) and in the availability of multiple sources (different satellites and constellations). The main drawback stays in the restricted power budget provided by navigation satellites. This makes necessary to conceive, define and develop innovative moving target detection techniques specifically tailored for the system under consideration, in order to make this technology a powerful tool for persistent surveillance of sea areas of interest. To this aim, a long integration time Maritime Moving Target Indication technique is proposed in this work, and its effectiveness is proved against experimental data involving a small maritime target, not detectable by conventional MTI techniques. Obtained results prove the feasibility of a maritime MTI mode for GNSS based passive systems.

Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles

In bats it has been shown that they adjust their emissions to situational demands. Here we report similar findings for human echolocation. We asked eight blind expert echolocators to detect reflectors positioned at various azimuth angles. The same 17.5 cm diameter circular reflector placed at 100 cm distance at 0°, 45° or 90° with respect to straight ahead was detected with 100% accuracy, but performance dropped to approximately 80% when it was placed at 135° (i.e. somewhat behind) and to chance levels (50%) when placed at 180° (i.e. right behind). This can be explained based on poorer target ensonification owing to the beam pattern of human mouth clicks. Importantly, analyses of sound recordings show that echolocators increased loudness and numbers of clicks for reflectors at farther angles. Echolocators were able to reliably detect reflectors when level differences between echo and emission were as low as −27 dB, which is much lower than expected based on previous work. Increasing intensity and numbers of clicks improves signal-to-noise ratio and in this way compensates for weaker target reflections. Our results are, to our knowledge, the first to show that human echolocation experts adjust their emissions to improve sensory sampling. An implication from our findings is that human echolocators accumulate information from multiple samples.

Problems of surface change detection based on SS-InBSAR

SS-BSAR comprises of a space borne transmitter moving relative to an observed surface and a stationary receiver on the ground. Interferometric SS-BSAR (SS-InBSAR) contains two spatially separated receiving antennas and appropriate channels. SS-InBSAR can be used for a number of remote sensing applications and in particular for surface change detection. The SS-InBSAR CD compares two consecutive InBSAR images to detect changes in the earths surface. This is done by calculating the decorrelation between the two images. This can lead to decorrelation between images in SS-InBSAR CD even when there is no deformation of the acquired surface. This paper reports methods and results of the decorrelation investigation for SS-InBSAR.