7.1 Maritime Target and Sea Clutter Measurements with a Coherent Doppler Polarimetric Surveillance Radar
By: A. J. E. Smith, S.J. Gelsema, L.J.H.M. Kester, H.W. Melief, and A. Theil
TNO Physics and Electronics Laboratory
and: G. Premel Cabic, E. Woudenberg
Thales Naval Nederland B.V. | Abstract: Doppler polarimetry in a surveillance radar for the maritime surface picture is considered. This radar must be able to detect low-RCS targets in littoral environments. Measurements on such targets have been conducted with a coherent polarimetric measurement radar in March 2001 and preliminary results from that campaign are presented. The system provides estimates of the scattering matrix per range-Doppler bin. Several physical quantities that can be exploited to discriminate target echoes from sea clutter responses are discussed and an impression is given on their effectiveness. |
7.2 Chaotic Behaviour and Non-Linear Prediction of Airborne Radar Sea Clutter Data
By: Michael K. McDonald
Defense Research Establishment
and: Vinay Varadan and Henry Leung
University of Calgary | Abstract: The potential to model sea clutter radar returns using chaos theory is examined. Chaotic systems display qualitative similarities to sea clutter returns such as broad flat spectrums, bounded and irregular temporal behaviour. In this report several key parameters of chaotic systems, namely correlation dimension, Lyapunov spectrum and Lyapunov dimension are calculated from real sea clutter returns and found to be consistent with a chaotic interpretation. The airborne high-resolution data (less than one meter) produces a correlation coefficient with an average value of 4.63 and an embedding dimension of 6-7. Lyapunov dimensions are consistent with correlation values. A local linear technique and a radial basis function (RBF) are used to construct a one step non-linear predictor. A Mean Square Error (MSE) of approximately 0.0032 between the predicted and normalized (i.e. maximum +/- 1 range) real time series is measured. |
7.3 SAR Image Formation Uncorrupted by Multiple-Bounce Artifacts
By: David A. Garren
Science Applications International Corp. | Abstract: This analysis develops an innovative image reconstruction technique for synthetic aperture radar (SAR) based upon the removal of multiple-bounce (MB) artifacts. The basic concept is that the phase history measurements include the realistic effects of MB interactions. These measured phase history data are decomposed into contributions due to the desired single-bounce (SB) scattering events and the undesirable MB interactions. An enhanced quality image can be constructed by retaining only the SB contributions. |
7.4 Deconvolution Approach to Terrain Scattered Interference Mitigation
By: Anders Nelander
Swedish Defence Research Agency | Abstract: Terrain scattered interference or hot clutter is a recent problem in radar ECCM, especially for airborne radar with low sidelobe antennas and conventional adaptive sidelobe cancellation. In this paper a deconvolution approach is proposed to mitigate terrain-scattered interference. This approach is based on obtaining an estimate of the complex multipath impulse response from a short time interval in the received signals. The impulse response estimate is then convolved with a direct path reference signal to generate an estimate of the received terrain scattered interference signal. This interference signal estimate is then subtracted from the received main beam signal to generate a main beam signal with mitigated terrain scattered interference. |
7.5 Monte-Carlo Simulation of Ionospheric Scintillation
By: Paul D. Mountcastle and Michael D. Martin
Xontech, Inc. | Abstract: The ionosphere is an important consideration in the design of radars, especially those that operate at UHF frequency and below. In this paper, a statistical model of ionospheric scintillation is developed on the basis of data analysis and known empirical results. From a mathematical point of view, we model the effect of scintillation on radar signals via a constructed stationary random process. The complex PDF and autocorrelation of the process are designed to match the observed phenomenon. The resulting scintillation algorithm can be used to model ionospheric effects in real and simulated radar data. |