Krzysztof Kulpa

• professor
• Professor at Warsaw University of Technology

The paper focuses on the results of experimental research on the possibility of passive space object detection using a single radio telescope from the European Low‐Frequency Array (LOFAR) network of astronomical radio telescopes. Commercial digital television (DVB‐T) transmitters were used as illuminators of opportunity in this radar system. In the...

This paper explores the problem of severe multipath propagation of underwater acoustic signals in a swimming pool. The problem appeared in a study that examined a system used to signal emergency situations (i.e, pre-drowning symptoms detected by a wearable device on a pool user’s wrist) and locate the signal source. A swimming pool acoustic environ...

This article presents detailed geometric analyses of ground clutter in bistatic passive airborne radars. Analytic closed-form solutions are derived for finding the intersection of iso-ranges and iso-velocities. This allows clutter bistatic coordinates to be easily converted to its Cartesian coordinates. Based on those solutions, a theoretical clutt...

In this paper, a brief overview of hardware platforms with multiple RF input channels that can be employed in the area of Passive Coherent Location (PCL) and passive Synthetic Aperture Radar (SAR) is given. Two families of the platforms are considered, i.e. Field-Programmable Gate Array (FPGA) based development boards, and generalpurpose Software-D...

The 14 papers (from 29 submitted) published in the Special Issue “Radar and Sonar Imaging Processing (2nd Edition)” highlight a variety of topics related to remote sensing with radar and sonar sensors. The sequence of articles included in the SI deal with a broad profile of aspects of the use of radar and sonar images in line with the latest scient...

This article deals with the problem of detection performance prediction for passive bistatic radars that use illuminators of opportunity, such as radio or television transmitters. First, a simplistic free-space propagation model is introduced. Next, the effects of the transmitter and receiver antenna patterns are analyzed. Then, the influence of th...

Passive bistatic radar does not emit energy by itself but relies on the energy emitted by illuminators of opportunity, such as radio or television transmitters. Ground-based passive radars are relatively well-developed, as numerous demonstrators and operational systems are being built. Passive radar on a moving platform, however, is a relatively ne...

The paper presents a new idea of using a low-frequency radio-telescope belonging to the LOFAR network as a receiver in a passive radar system. The structure of a LOFAR radio-telescope station is described in the context of applying this radio-telescope for detection of aerial (airplanes) and space (satellite) targets. The theoretical considerations...

This paper presents the results of investigations on the beamforming of a low-frequency radio-telescope LOFAR which can be used as a receiver in passive coherent location (PCL) radars for aerial and space object detection and tracking. The use of a LOFAR radio-telescope for the passive tracking of space objects can be a highly cost-effective soluti...

Classical radars use deterministic waveforms, such as linear frequency modulated pulses. Noise radars, on the other hand, use random waveforms, or waveforms that resemble random signals. The randomness of the signal provides certain advantages, such as limiting or avoiding range/velocity measurement ambiguity, or better resistance to jamming. This,...

This paper presents the application of the time-frequency (TF) reassignment technique in passive forward scattering radar (FSR) using Digital Video Broadcasting – Terrestrial (DVB-T) transmitters of opportunity operating in the Very High Frequency (VHF) band. The validation of the proposed technique was done using real-life signals collected by the...

The 21 papers (from 61 submitted) published in the Special Issue “Radar and Sonar Imaging Processing” highlighted a variety of topics related to remote sensing with radar and sonar sensors. The sequence of articles included in the SI dealt with a broad profile of aspects of the use of radar and sonar images in line with the latest scientific trends...

The paper is focused on Doppler-spread clutter removal in mobile passive radar. The presented algorithm is based on CLEAN technique, which was developed for radio astronomy, but is commonly used for passive radar. The algorithm was designed for application in a passive radar placed on a moving platform and equipped with an array antenna system for...

The paper offers new application of a Multi-channel Forward Scatter Radar (MFSR), which uses GPS signals for detection of air targets on their GPS radio shadows. The multi-channel GPS MFSR detector consists of several channels, which process information from several satellites simultaneously. The phenomena of diffraction in the near area is used fo...

This study presents the concept of multistatic passive images. Theoretical considerations are illustrated by the results obtained by imaging a small general aviation plane using DVB-T signals. These results are compared with simulated images derived from the same scenarios in real-life tests. The results described here show that it is possible to o...

In this paper, by comparing the GPS shadow parameters of the same cars obtained from the same satellites and recorded by the two different systems under the same conditions, the Stereo dual GNSS front end (NSL's) and the GPS recording system of the Colorado University, we assess indirectly the capabilities of the new system for FSR applications.

In this paper, the possibility of GPS-based Forward Scatter Radar (GPS FSR), where satellites are exploited as sources of signals, to detect falling cosmic objects is examined. It is known that in FSR systems, the signal re-reflected by falling cosmic objects as masked by a much stronger direct signal. The goal of the article is to evaluate signalt...

An approach and algorithm are proposed for separating the useful signal from a moving cosmic target and the direct signal transmitted by GPS satellites, on the background of the receiver noise. The algorithms for separating the useful signal will be based on the principle of separation in speed of two GPS signal sequences, the first - with a satell...

The history of rockets starts in antiquity, and has continued through to modern times. The modern rocket era started before World War II (WWII), when amateur rocket engineers were building and launching their rockets. During WWII rocket technology was closely associated with weapon development, with the famous V2 rocket as the most notable example....

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-profess...

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...

Today the main applications of ground based passive coherent location (PCL) systems are in the domain of air traffic surveillance–air target detection, tracking, and localization. Interest in using PCL radars in these applications is expressed primarily by military users, mainly because of the great advantages of silent and covert operation that pa...

The paper presents a concept of a versatile signal processor designed for a modern, active electronically scanned array (AESA) radar. The flexibility of the design is high enough to support most advanced modes of operation, including multiple-input multiple-output (MIMO) modes and cognitive radar control, reacting in real time to changing air situa...

This paper presents the design, implementation, and validation tests of a C-band analog-front-end (AFE) for the frequency modulated continuous wave (FMCW) radar. The system was designed to be used in various radar applications, including short rage mode, synthetic aperture radar (SAR) and moving target indication (MTI) mode. The AFE presented here...

In this letter, pioneering experimental results of passive synthetic aperture radar (SAR) imaging are presented. The classical active SAR radar operates in monostatic geometry. The SAR sensor presented in this letter is a passive radar utilizing commercial Digital Video Broadcasting—Terrestrial transmitters as illuminators of opportunity. It works...

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 Earth's surface. The FSR is a specific bistatic radar system where t...

WIFIRAD is a passive radar demonstrator developed in the Digital Signal Processing laboratories of the Warsaw University of Technology. It utilizes the signals from WIFI networks as sources of illumination. As WIFI signals are not continuous and the duty cycle depends on the amount of transmitted data, the paper is focused on the impact of the duty...

This study presents an analysis of micro-Doppler signatures of helicopters obtained using a network of passive radar receivers utilising multistatic geometry. In the multistatic scenario, for each passive radar receiver the target is visible from different bistatic angles, which results in different micro-Doppler signatures. This feature allows add...

The work is devoted to fusion of radar and radiometer images. Noise waveform SAR generates radar images of reflective objects of its field of view. A bistatic radiometer with synthetic aperture estimates the thermal radio emissions of the objects along their angular coordinates and even range. The estimated brightness temperatures of rough and smoo...

Detection of small changes in natural formations and human-made constructions is a promising application of synthetic aperture radar (SAR). This paper deals with a specific radar, which is a ground-based SAR using noise waveform. Being fully coherent, SAR provides both phase and amplitude information for every pixel in the mapped area. This gives r...

In this paper preliminary results of radar imaging measurements using a narrowband signal in the low terahertz band are presented. Measurement system architecture as well as the narrowband imaging technique are also discussed. Verification of the theoretical method of acquiring images by the use of narrowband signal through its application to real...