K. Kabakchiev

Signal characterisation and processing in the forward scatter mode of bistatic passive coherent location systems

The transfer of the forward scatter (FS) concept to passive coherent location (FS PCL) systems provides a new emerging area of research. This article is dedicated to the investigation of various aspects of a bistatic passive coherent location (PCL) system operating in the FS mode. For efficient signal processing, appropriate FS PCL system analysis is presented. It is shown that using a relatively small modernisation of traditional signal processing algorithms, a PCL system may effectively operate against stealth and low profile targets crossing or being located in the vicinity of the radar baseline. The FS signals have been analysed in view of finding key effects and parameters influencing the waveforms and spectra which define the overall signal processing. Experimental results are given to validate the presented analysis.

Forward scatter radar mode for passive coherent location systems

The transfer of the forward scatter concept to passive coherent location systems provides an emerging area of research. This paper investigates aspects of such a system through analysis and discussion of previous dedicated forward scatter radar research, showing that indeed the addition of a forward scatter channel to existing passive systems would enhance the current capabilities.

Maritime FSR with moving receiver for small target detection

This paper is concerned with the new challenging multi-static and multi-frequency forward scatter radar (FSR) configuration in which one node (transmitter or receiver) is moving. A mathematical model for simulation of the received Doppler signature of the target in such a radar is presented. The experimental set-up and maritime measurements are described and a comparison of the simulated and measured results is given. The performance of the new configuration is analyzed at this initial stage of the research.

Detection and classification of objects from their radio shadows of GPS signals

The paper focuses on scientific issues related to new application of GPS in radar networks using the effect of Forward Scattering (FS) of electromagnetic waves to detect, locate and classify objects by their GPS radio shadows. The aim of the paper is to make experimental studies of GPS radio shadows of different objects irradiated by GPS signals and to develop methods and algorithms for automatic detection, estimation and classification of the shadows of these objects. The practical utility of the results obtained is to use a specific processing of the received signal in the GPS receiver, then to use the extracted information for positioning and classification of moving objects; for accurate assessment of the geographic location of fixed objects by method triangulation in systems for transport management, security of zones, subsequent identification of the detected objects from digital geographical maps.

Signal processing of GPS radio shadows formed by moving targets

This paper focuses on scientific issues related to new application of GPS in the construction and development of radar networks using the effect of Forward Scatter (FS) of electromagnetic waves for detection of objects by using of their GPS radio shadows. The paper theme is new, it combines two thematic areas: processing of GPS signals and processing of radar signals in FS radar systems.

Data mining classification of cars based on GPS shadows in Forward Scatter Radar systems

The goal of this paper is to introduce a new concept - using Data Mining approach for radar classification of vehicles, based on their GPS shadow signals detected in a GPS L1-based Forward Scatter Radar (FSR) system. Real data is used for the current experiments, recording the GPS radio shadows of several moving vehicles with commercial non-professional GPS equipment. The records are further processed in MATLAB computational environment in order to obtain the estimated parameters of the GPS shadows. Data Mining approach is then implemented for classifying the cars, comparing classifiers generated with different classification algorithms - a decision tree, a neural network, and a Bayesian classifier, for two different variants of the class variable, taking three or two possible values. The best results are achieved for the two values of the class variable and the best performing classifiers are the neural networks.

The study of target shadows using passive FSR systems

The paper describes one possible algorithm for object detection by using of Forward Scatter (FS) radio shadows created by objects. The algorithm is verified on the experimental data collected by a GPS receiver with a small commercial antenna. The results obtained show the possibility for object detection when its FS shadow is present.

Experimental parameter estimation of vehicles GPS shadows by Forward scattering systems

In this paper, we conduct an experimental study with the aim to obtain a large number of estimates of various parameters characterizing the GPS shadows created by three types of moving vehicles. The experimental cars have a similar size and therefore, the obtained estimates have similar values. From the results, it can be seen that the cars can be differentiated by means of their shadow parameters.

Experimental verification of target shadow parameter estimation in GPS FSR

In this paper we analyze the power budget and calculate signal to noise ratio (SNR) and radar cross section (RCS) for different ground targets using a forward scattering radar (FSR) system, which consists of a transmitter mounted on a satellite of GPS and a receiver located on the Earths surface. The FSR is a specific bistatic radar system where the bistatic angle is near 180o, and the target is located near the transmitter-receiver baseline. Theoretical and numerical calculations of SNR and RCS are presented for different ground targets when the GPS L1 signal is transmitted by satellites. The SNR and RCS are also estimated by using real records of the GPS signal shadows from different targets. The obtained numerical and experimental results are analyzed and discussed.