Krzysztof Kulpa

Two Methods for Target Localization in Multistatic Passive Radar

This paper compares two algorithms for three-dimensional target localization from passive radar measurements. The algorithms use bistatic range measurements from multiple transmitter-receiver pairs to calculate the target position. The algorithms derived are based on the methods known for time-difference-of-arrival (TDOA) systems, namely spherical interpolation (SI) and spherical intersection (SX). Both algorithms rely on closed-form equations. A theoretical accuracy analysis of the algorithms is provided. This analysis is verified with Monte-Carlo simulations and a real-life example is presented.

Coherent MapDrift Technique

A new parametric autofocus technique with a high accuracy of flight-parameter estimation dedicated to strip-mode synthetic aperture radar (SAR) systems is presented. Most of the known autofocus techniques require high-reflectivity targets (man-made targets) to obtain a properly focused SAR image. The technique proposed in this paper allows flight parameters to be estimated effectively, even for a low-contrast scene (e.g., forests, fields, small paths, etc.). The autofocus technique is based on well-known MapDrift (MD) principles. The presented technique is a coherent one, which allows flight parameters to be estimated more precisely than in the other well-known parametric technique referred to as classical MD. The presented technique allows flight parameters to be estimated with accuracy that is independent of the initial velocity error. It can be used for real-time processing for both Earth imaging and moving-target indication.

Digital beamforming for Passive Coherent Location radar

The paper presents digital beamforming for Passive Coherent Location (PCL) radar. The considered circular antenna array is a part of a passive system developed at Warsaw University of Technology. The system is based on FM radio transmitters. The array consists of eight half-wave dipoles arranged in a circular array covering 360deg with multiple beams. The digital beamforming procedure is presented, including mutual coupling correction and antenna pattern optimization. The results of field calibration and measurements are also shown.

PaRaDe - PAssive RAdar DEmonstrator family development at Warsaw University of Technology

The paper presents a family of passive coherent location (PCL) radar demonstrators, called PaRaDe (passive radar demonstrator), which were developed at Warsaw University of Technology. The systems exploit commercial FM radio transmitters as illuminators of opportunity in order to detect and track airborne targets. In the paper, the details of demonstrator systems are described and the results obtained in tests are presented.

The CLEAN type algorithms for radar signal processing

A new class of signal processing algorithm based on CLEAN methods primary introduced in radio-astronomy is presented in the paper. The classical radar signal processing is based on match filtering concept, which is optimal in mean square sense in case, when single target echo is detected against white or colour Gaussian noise. Such approach was effective when pulse radar have been widely used. The introduction of pulse-compression technique changes significantly the signal model, but still the match filter have been widely. The introduction of continuous wave radars, and especially noise and passive radars changed dramatically the situation. In such radars all echoes are superimposed and interfere with each other and the simple model no longer fits to that case. The straightforward solution - use of inverse problem mathematical solutions such as solving the set of nonlinear equations to find all echoes in received signal - is usually computationally ineffective and often numerically not stable, so suboptimal methods are being developed to improve detections of weak signals in CW radars. One of possible solution is to use concept of CLEAN technique an remove all strong echoes from received signal. When only weak signals and white noise remains in is possible to use matched filter concept without significant loses of radar sensitivity. In the paper several techniques for radar signal processing utilizing CLEAN concept are shown.

Stretch Processing for Long Integration Time Passive Covert Radar

The paper presents a study of possibility of increasing the passive covert radar sensitivity by extending the coherent integration time. The long integration time induces the target range migration of moving targets. To overcome this problem, the usage of stretch processing is investigated. The paper shows, that even a simplified algorithm applying stretch processing concept, can significantly improve the radar sensitivity

DPCA Detection of Moving Targets in Airborne Passive Radar

A new approach to the passive coherent location (PCL) signal processing technique dedicated for use on mobile radar platforms is presented. The main goal of the research conducted was to present different aspects of an efficient space-time ground moving target indication (GMTI) algorithm for PCL radar mounted to airborne platforms. The algorithm described, based on displacement phase center antenna (DPCA), has been successfully tested with simulated and real-life data collected with an airborne passive radar demonstrator (PaRaDe).

Detection of Moving Targets With Continuous-Wave Noise Radar: Theory and Measurements

This paper investigates a radar using a narrowband continuous noise waveform as an illuminating signal for the detection of moving targets. First, the theory of noise radar is presented, including the properties of the noise waveform and signal model. Next, the signal processing for noise radar is described, consisting of adaptive filtering for clutter removal, calculation of the crossambiguity function, and detection. The presented concept is validated with real-life experiments, during which cars at ranges of hundred of meters and aircraft at ranges of a few kilometers were detected.

Detection of moving targets with multichannel airborne passive radar

Passive radars, i.e., radars that use existing transmitters as illuminators of opportunity, have witnessed a fast progress in the last decade. Recent developments in many countries [1-5] refer to systems that use commercial transmitters (e.g., FM radio, DAB, DVB-T, GSM) and apply advanced signal processing technology to the received signal. The technology, known also by passive coherent location (PCL), is reaching its maturity stage, as some final products appear on the market [6, 7]. Most of these systems are stationary, ground-based passive radars.

mm-Wave SAR demonstrator as a test bed for advanced solutions in microwave imaging

The capability of imaging and surveying ground areas with airborne and spaceborne sensors has a very high priority in many applications, both in the civilian and military sectors. One of the most essential uses of this capability is in disaster monitoring, where up-to-date, reliable images and data are vital for the undertaking and coordinating of rescue actions. Sensors in space are very accurate but typically have a long revisit time, and thus their use for continuous monitoring is limited. Manned aircrafts equipped with optical, infrared, and synthetic aperture radar (SAR) are costly, and their operation in poor weather conditions (like heavy storms) are limited due to concerns over pilot safety. Unmanned aerial vehicles (UAV) are ideal candidates for the safe and cheap surveillance and imaging of such areas. They can provide continuous monitoring at very low cost, be deployed very quickly, and pose no risk of the loss of life in the case of a platform malfunction caused by heavy weather conditions, technical problems, or human error. The disadvantage of small, unmanned platforms is that they only offer limited space for payloads and have a low electrical power supply. This lays down the conditions for the design of an airborne sensor for small- and medium-sized UAVs. The cheapest solution for UAV surveillance is the use of visual light cameras. Optical cameras are cheap, light, and require a low supply of power, but their usage is limited to the daytime and good weather conditions. The presence of heavy rain, clouds, fog, or smoke can significantly reduce their imaging distance, sometimes down to just a few meters. Far better results can be obtained using much longer electromagnetic waves. The use of far infrared (e.g. in the 10 μm region) can provide thermal information and can be used for the detection of people in both day and night conditions, but it does not provide satisfactory images of land and infrastructures. The use of millimeter and centimeter microwaves with active illumination, combined with SAR technology, can provide high resolution images in all weather conditions, day and night, at a distance of several kilometers.