Yoann Paichard

Passive radar using a software-defined radio platform and opensource software tools

This paper presents a prototype passive radar system that utilises FM radio transmitters for target detection. The system is based on the Universal Software Radio Peripheral (USRP) hardware platform and the opensource GNURadio software-defined radio (SDR) toolkit. The hardware components that were required to implement the passive radar receiver are introduced. The signal processing software that was written to make target detection possible is briefly discussed. The experimental site and the geometry of the receiver, transmitters in the area, and incoming air traffic are described. The experimental data and the results after performing the required signal processing is presented. It is shown that the passive radar system has the ability to detect commercial passenger aircraft at short ranges.

A quantitative method for mono- and multistatic radar coverage area prediction

The prediction of radar coverage as a function of the position of the radar has always been a key step in radar network planning. In the past, simple geometric models backed up by the deployment of siting radars were the only options for potential site evaluation, but the development of sophisticated propagation models (e.g. AREPS [1]) has moved the technology forward to another level of prediction accuracy. Modelling takes into account atmospheric refraction, as well as terrain effects and clutter. In previous papers [2], [3] we have shown that the modelling can also cater for multistatic radar systems. In this paper we have extended our modelling to give a statistical measure of the effectiveness of a site that measures the signal to noise ratio (SNR) or (for multistatic radar) the signal to interference ratio (SIR) over regions of interest. The area is pixellated into values of SNR and SIR, and pixels meeting the required SNR and / SIR are counted. We show some results for a multistatic radar. We conclude by indicating how we plan to include ground clutter. We mention how this method of obtaining quantitative coverage performance can be used with all forms of radar, and will be able to improve future networks of cognitive radars.

Orthogonal multicarrier phased coded signal for netted radar systems

Orthogonal multicarrier radar waveforms have been designed for netted radar systems, where several radar stations are active simultaneously. The waveforms are phase-coded using orthogonal Golay complementary sets, derived from Reed Muller codes. These codes constrain the PMEPR of the signal to a maximum a 3 dB. Besides, ambiguity functions and cross-ambiguity functions with low sidelobes have been obtained. The possibility to encode data relative to the transmitter configuration (position, direction of the beam,…) in the radar waveform is also demonstrated.

Null placement in a circular antenna array for Passive Coherent Location systems

Passive Coherent Radar (PCL) is heavily constrained by the level of direct signal illumination. This paper investigates null steering techniques for a circular array antenna. An 8-element circular array has been designed and a method is proposed to steer multiple nulls in different directions. We present computed performance for two nulls achieved simultaneously. An 8 element dipole array has been constructed and the VSWR results are presented. This antenna will form the basis of practical null formation measurements.

A new probabilistic data association filter based on composite expanding and fading memory polynomial filters

This paper presents the use of composite expanding and fading memory polynomial filters performing tracking in conditions of heavy clutter and low probability of detection. The composite expanding and fading memory polynomial filters are modified to incorporate probabilistic data association, and a simulation study shows that this new type of filtering offers performance comparable to the linear Kalman filter in a high clutter density and low detection probability environment.

OFDM waveforms for multistatic radars

In this paper, the benefits of OFDM waveforms are analyzed for multistatic radar systems, where several radar stations cooperate in the same frequency band. The signal is coded over a 2D pattern, in the time and the frequency domains, using orthogonal Golay complementary sets derived from Reed-Muller codes. Binary data are also encoded in the signal. The obtained ambiguity and cross-ambiguity functions show that the OFDM signal structure is well adapted for radar applications. Transmitted waveforms have relatively low interference and sidelobe levels in the range and Doppler axis.

Autonomic subsystems for cognition in Passive Coherent Location

In a previous paper [1] we mentioned that Passive Coherent Location (PCL) can be thought of as Cognitive Radar[2]. The deployment of PCL systems (also known as Passive Bistatic Radar-PBR) is fraught with difficulty, even in the situation of a spatially static network of transmitters and receivers. It is well known that PCL systems have to take into account the strong, direct signals of cooperative and opportunistic transmitters used, and try to use terrain or antenna nulls[3] to mitigate the receiver dynamic range requirements. Receiver position in the terrain also influences the coverage. This results in a complex planning environment requiring propagation prediction tools to assist in selection of the best site [4]. The situation becomes worse when the network of transmitter and receivers becomes dynamic. In this paper, we discuss the cognition and networking requirements for PCL systems consisting of moving transmitters and receivers, forming a cognitive, sensor network. We show that a sensible approach would use the structure of human intelligence, which consists of a higher level integrating function, together with autonomic[5], lower level, subsystems.

A signal level simulator for netted radar waveforms evaluation

When evaluating the performances of radar waveforms, it is crucial to understand how the signal is affected by multiple interactions with the environment and the system hardware. Analysis of complex radar systems, such as multistatic and netted designs (see Fig. 1) is often intractable without the application of a dedicated radar simulation system. Recent research into radar simulation has focused primarily on synthetic aperture radar (SAR) systems and is not entirely applicable to traditional radar systems concerned with the location and tracking of remote targets. A complete simulator has been designed for the accurate simulation of raw returns in complex, multistatic and netted radars and is applicable to pulsed and continuous wave (CW) systems, and both active and passive radar systems. The Flexible Simulator for Multistatic Radars (FERS) can be used to simulate radar systems with arbitrary waveforms and arbitrary numbers of receivers, transmitters and scatterers. In this paper, algorithms for the simulation of raw radar return signals are presented, based on interpolation and modification of the transmitted signal and modelling of the radar hardware and environment. The algorithms are expected to be especially valuable for the simulation of emerging radar technologies, such as Passive Coherent Location (PCL), netted radar and phased array radar. Preliminary results, presented in this paper, suggest that these algorithms can simulate physical systems with excellent accuracy.

Signal level Simulator for netted text radar waveforms evaluation

When evaluating the performances of radar waveforms, it is crucial to understand how the signal is affected by multiple interactions with the environment and the system hardware. Analysis of complex radar systems, such as multistatic and netted designs (see Figure 1) is often intractable without the application of a dedicated radar simulation system. Recent research into radar simulation has focused primarily on synthetic aperture radar (SAR) systems [1] and is not entirely applicable to traditional radar systems concerned with the location and tracking of remote targets. A complete simulator has been designed for the accurate simulation of raw returns in complex, multistatic, and netted radars, and is applicable to pulsed and continuous wave (CW) systems, and both active and passive radar systems. The Flexible Simulator for Multistatic Radars (FERS) can be used to simulate radar systems with arbitrary waveforms and arbitrary numbers of receivers, transmitters, and scatterers. Herein, algorithms for the simulation of raw radar return signals are presented, based on interpolation and modification of the transmitted signal and modeling of the radar hardware and environment. The algorithms are expected to be especially valuable for the simulation of emerging radar technologies, such as Passive Coherent Location (PCL) [2], netted radar and phased array radar. Preliminary results, presented herein, suggest that these algorithms can simulate physical systems with excellent accuracy.