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Through-the-wall radar imaging attempts to image complex scenes within enclosed structures. While most of the high-resolution imaging techniques assume point targets, indoor imaging requires dealing with single or multiple walls which are extended targets in nature and violate the point-target assumption. In order to provide high quality imaging, we need to consider point targets and extended targets...
Planar electromagnetic lenses like the Rotman lens are attractive candidates for beambeam forming networks forming networks because of their high bandwidth of operation and their capability to form multiple beams at lower cost as comparable electronic phase shifting networks. The principles of Rotman lenses have been studied for several decades and examples have been successfully built using different...
Based on nonuniform L-shaped array, the paper presents a new time-space processing method for joint estimation of the frequency and 2D arrival angles of coherent signals over a wide frequency band, which is called wide-band time-space smoothing (WTSS) algorithm. The algorithm can precisely estimate 3D parameters of coherent signals with same digital frequency. Getting rid of the costly multidimensional...
To check the capabilities of a dasiashared aperturepsila, at FGAN the PALES experimental system is built up. Especially array signal processing with a multibeam system is investigated. In this paper the basics of signal detection by square law detectors are discussed. The proposed signal detection method is based on a time frequency representation. Besides signal detection also the PRF of the received...
Australia has been developing and fielding phased array applications since the early 1950s. The application areas range from radio astronomy and atmospheric sciences, through over-the-horizon radar, surface wave, microwave ship and airborne systems. Given Australia's unique geographical size, position, single continent and national identity, it is not surprising that much of this effort has been focussed...
In this paper we combine advanced STAP algorithms and concepts for adaptive guard channels with subarrayed planar arrays together with the theoretical results available in the field of adaptive detection (GLRT, AMF, ACE tests). The aim is to define a robust adaptive sidelobe blanking detector against combined impulse and CW interference as well as strong clutter discretes. For the selection of the...
This paper describes work carried out at QinetiQ to demonstrate real-time operation of space-time adaptive processing (RTSTAP) for airborne phased array radar, in a laboratory environment. RTSTAP processing is performed using field programmable gate array (FPGA) hardware and controlled via a MATLABcopy graphical user interface. The FPGA hardware is connected to the PACER (phased array concepts evaluation...
Calculating accurate low-rank covariance estimates for sensor arrays with a large number of elements is a common task in signal processing. Many algorithms make use of the exact spectral decomposition of the empirical covariance structure-but the singular value decomposition is often too costly in practice, owing to array size or constraints on computation. Recent approaches geared toward the approximate...
In the frequency modulated continuous wave radar systems, when the transmitter uses periodic linear symmetric triangular wave modulation, the received signal after processed by the mixer will have many harmonics. In the single target detection, this effect can be ignored. However, in the multi-target detection, targets with different ranges and velocities lead to overlapping of the harmonics. Using...
Cross-range resolution in spotlight synthetic aperture radar (SAR) is primarily a function of the angular extent (Deltathetas) over which data is collected. In [1], the authors proposed a method for improving cross-range resolution for a given Deltathetas by use of frequency diverse array (FDA) techniques. The goal was to exploit an apparent increase in Deltathetas to improve cross-range resolution...
In this paper, a new spectral estimation method, which is based on the rank-deficient sample covariance matrix, is proposed. The new method applies the amplitude and phase estimation (APES) filter and the Capon weight simultaneously on the data matrix to obtain the complex amplitude estimate of the spectral line of interest. Because the sample covariance matrix is singular, a rank-deficient version...
In this paper we introduce a batch frequency domain scheme for wideband jammer nulling with multichannel synthetic aperture radar (SAR). This is compared to the wideband extension of the SLC approach. We analyze the nulling performance for several image acquisition modes and interference scenarios and show that both algorithms are adequate in terms of cancellation level. The frequency domain approach...
Modern 2D spectral estimation techniques can be used for SAR imaging. The aim of those techniques is to improve the SAR image quality at the expense of an additional processing load. This paper focuses on applying the 2D minimum variance power spectrum estimation method (MVM) to SAR raw data. MVM process improves the image ISLR and reduces speckle noise. MVM was found to be particularly useful in...
New operational requirements for stealth targets detection in dense & inhomogeneous clutter are emerging (littoral warfare, low altitude asymmetric threats, battlefield in urban area...). Classical radar approaches for Doppler & array signal processing have reached their limits. We propose new improvements based on advanced mathematical studies on geometry of SPD matrix (symmetric positive...
A demonstration of multiple-input multiple-output over-the-horizon radar is presented. Transmitter signal beam- forming on a multi-element array has been created, not conventionally before transmission at the transmitter facility, but, after radar signal transmission, skywave propagation, target scattering, return signal propagation, and reception using an over-the-horizon radar receiver. Transmitter...
In this paper, we describe a new parameter estimation methodology called transpose domain filtering (TDF). TDF is a processing formulation that that is different from conventional processing (e.g., beamscan processing) in that the weight vector is applied in the domain that lies transpose to the signal model. For a typical radar array processing problem, this means TDF would apply the weight vector...
This paper introduces innovative SAR system concepts for the acquisition of high resolution radar images with wide swath coverage from spaceborne platforms. The new concepts rely on the combination of advanced multi-channel SAR front-end architectures with novel operational modes. The architectures differ regarding their implementation complexity and it is shown that even a low number of channels...
Passive radar systems using emitters of opportunity for target detection and tracking have received significant interest recently, especially those which exploit frequency modulated (FM) radio stations and TV transmitters as signal sources. This paper is concerned with passive radar systems that utilize signal sources in the high frequency (HF) band (3-30 MHz), where due to long-distance ionospheric...
With the advent of new forms of true time delay wideband beamformers -both photonic and digital-the effect of noise within the beamformer channels must be taken into account. As an example, in this paper, a multibeam photonic beamformer for a phased array working in receive mode using linear frequency modulated pulses is analyzed. A general expression is obtained showing the effect of the optical...
This paper evaluates the performance of several adaptive beamforming techniques applied to the problem of cancelling interference in a high frequency (HF) radar with transmitter and receiver physically separated by large distances. The difficulties posed by mitigating interference in a HF radar are fundamentally different in many aspects from the adaptive cancellation problem in more conventional...
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