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It is natural to approach multi-channel SAR in terms of spatial diversity concepts developed for multiple-input-multiple-output (MIMO) communications and recent advances in MIMO radar. We introduce the MIMO SAR concept in this paper, and the goal here is to research the concept and potential design of a new SAR application based on MIMO theory and techniques. MIMO technology which were develop originally...
Airborne radar has evolved from early systems where almost all radar characteristics were fixed to todaypsilas highly flexible, software-driven systems. The most recent advance has been the widespread adoption of active electronically scanned array (AESA) antennas, which has given the system designer unprecedented control of antenna characteristics. However, in common with most conventional radars,...
The main idea that motivates this study is to improve the resolution of a radar mounted on an airplane, looking in the forward direction: this can be obtained by forming a synthetic array along the airplane line of flight. We term this new concept as ldquoForward-Looking Synthetic Aperture Radarrdquo (FLoSAR). We present a feasibility study that analyses the system geometry, evaluates the achievable...
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...
A new method for wideband spatio-temporal processing in the context of clutter mitigation and target detection is addressed in this paper. The frequency dependent, spatio-temporal steering vectors, are separated using a series expansion that depends on a sequence of Bessel function terms, and this is used to focus data vectors corresponding to various frequency components to a single frequency component...
It is commonplace to use an unweighted transmit aperture and a weighted receive aperture in radars utilising active electronically steered array (AESA) antennas. The preferred receive weightings are usually Gaussian or Taylor as these are perceived to give the best compromise between loss of main-beam directivity, minimised main-beam dilation and excellent sidelobe control. However, this is only part...
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...
Millimeter-wave band is the general trend for new communication, tracking radar and automotive systems. The crowd of RF frequency bands, the compactness of higher frequency radiating systems and the commercial availability of MMW components drive even more communications, tracking radars and automotive systems toward millimeter-wave band. Moreover, the antenna technology evolves from mechanical to...
The utilization of diversity in radar systems has shown improvements over conventional beamforming phased array radars in many aspects of the system performance including target detection probability, the number of identifiable targets, and beam-pattern synthesis. When linearly independent signals are transmitted, the signals received from targets at different locations are also linearly independent...
This paper describes an active electronically scanned array (AESA) FMCW radar with eight transceivers. Each transceiver has its own direct digital synthesizer (DDS) for signal generation which enables digital beam forming on transmit as well as on receive. The coherent operation of the eight transceivers and the capability to perform digital beam forming on transmit and receive is demonstrated. Also...
This paper discusses two adaptive spatial processing approaches that have been recently proposed for mitigating spread-Doppler clutter in skywave over-the-horizon (OTH) radar. The first is slow-time MIMO (SLO-MO) STAP which uses conventional waveforms that are phase-coded so as to be orthogonal after Doppler processing at the receiver, i.e. in ldquoslow-time.rdquo SLO-MO STAP is proposed as a means...
Coherent synthesis sparse aperture array radar can provide a long baseline with narrower beamwidth at the cost of grating lobes. In this paper, we propose a method to suppress grating lobes based on frequency MIMO technique. By transmitting M orthogonal waveforms with diverse frequencies from subaperture-to-subaperture, M beams can be formed with the same mainlobe direction. However, grating lobes...
The noise radar concept can be extended to an array of K transmit antenna and M receive antenna. When independent noise sources are transmitted from each antenna the approach may be viewed as a special case of MIMO radar and matched filters may be derived. In this contribution statistical properties of matched filters for MIMO noise radar are derived. For any array the concepts of the sum and difference...
Conformal arrays possess certain desirable characteristics for deployment on unmanned aerial vehicles and other payload-limited platforms: aerodynamic design, minimal payload weight, increased field of view, and ease of integration with diverse sensor functions. However, the conformal arraypsilas nonplanar geometry causes high adaptive losses in conventional space-time adaptive processing (STAP) algorithms...
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...
The concept of multiple-input multiple-output (MIMO) radar is recently proposed inspired by recent advances in MIMO communications. A recently proposed statistical MIMO radar configuration is considered here, in which the transmit array antennas are widely spaced to enable spatial diversity with respect to the targets, while the receiver is an uniform linear array with the elements spaced half a wavelength...
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...
Multiple-Input, Multiple-Output (MIMO) radars enhance performance by transmitting and receiving coded waveforms from multiple locations. To date, the theoretical literature on MIMO radar has focused largely on the use of ldquoorthogonal waveforms.rdquo Practical approaches to approximate orthogonality (e.g., via waveforms characterized by low cross-correlation and low autocorrelation sidelobe levels)...
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...
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