Maritime Radar Surface Surveillance Techniques and the High Grazing Angle Challenge (SET-185)
|Type||RTO Task Group|
|Scientific Report(s)||Scientific report not yet available.|
|Request Information||Contact STO/CSO Panel Office|
|Principal Military References|
|Covered Military Functions|
|Keywords||Maritime detection; sea clutter; coherent maritime detection; high grazing angle; polarimetric radar|
|Leading RTO Panel||SET|
|In Coordination with|
|Partner Nations Invited?|
a)Identify existing data sets and collect data over low to high grazing angles from stationary and moving platforms. This will include the collection of polarimetric, coherent, multi-phase centre and multi-static data sets. During course of ET sufficient data sets were identified to support initial investigations. b)Develop empirical and electromagnetic models for clutter and targets for high grazing angles. These models will assist the development of performance prediction methods, simulations, assessment of existing algorithms, design of new algorithms and radar procurements. The empirical models derived from the collected data will be used to characterize: - Temporal variability of short-lived clutter events (spikes) and their impact on the sea clutter spectrum and amplitude statistics - Spatial and temporal correlation of the sea clutter and clutter events - Polarimetric decomposition of clutter plus target signals - Clutter RCS and amplitude statistics at high grazing angles Scattering-physics-based models will also be developed with a goal to extend the predictions of the empirical models to a broader range of conditions and will benefit from comparison with empirical models. c)Develop new detection strategies (e.g. coherent detection, STAP, multi-static and imaging based discrimination). Evaluate these new detection strategies in comparison with existing detection strategies. Detection techniques will be tested against field data and used to identify effective detection approaches as well as evaluate fidelity of detection performance models. Shortcoming of approaches and outstanding issues will be identified.
Airborne wide area, maritime surveillance has traditionally been accomplished using non-coherent high bandwidth radar systems operating on low altitude aircraft at low grazing angles. At low grazing angles the signal to clutter ratios of typical maritime targets of interest are usually sufficiently large to allow the use of non-coherent approaches which can be implemented using simple lightweight radar designs with relatively low computational demands. Unfortunately, recent developments threaten to negatively impact the ability of these simple designs to meet future military needs. Two of the most significant changes are the development of the asymmetric threat spectrum and the migration of the radar systems to high altitude platforms. Asymmetric threats involve very small surface craft with low radar cross sections and the potential for high maneuverable dynamics. These craft can be utilized in suicide/swarm attacks against military fleets, and in piracy and smuggling operations. They are very difficult to detect using existing airborne radars. The problem of detection is further compounded by the intention of many nations to transition their airborne surveillance capabilities to jet aircraft and UAVs. In most cases these new platforms will operate at much higher altitudes leading to much steeper look down or grazing angles during surveillance missions. Grazing angles of 25o will lead to increases in clutter cross sections of 10-15dB with respect to typical low grazing angle geometries of less than 3o. Overwhelmingly, past research has focused on the low grazing angle case and very little is know about the characteristics of sea clutter in the medium to steep grazing angle regime other than the fact that clutter cross sections are dramatically increased. The adoption of radar approaches such as coherent, STAP, polarimetric, imaging and multi-static techniques, or combinations thereof, will be required to detect these new targets and accommodate the new platforms. These approaches are now feasible given recent advances in RF and computing technology. The proposed activity addresses: the Long Term Capability Requirements (LTCR) for Intelligence Surveillance & Reconnaissance (ISR) Collection Capability and Counter Underwater Threats (i.e. maintain periscope detection capability); UK6 – RTO taxonomy B06.01–RF-Sensors –Active; DAT item 2 for Protection of Harbors and Ports.
The broad objective of this team is to understand the military utility of different radar detection techniques against difficult targets (e.g. low RCS targets, semi-submersibles, speedboats, jet skis) viewed at high grazing angles against the background of sea clutter. To achieve this objective, the working parties will undertake the following parts: a)Identify existing high grazing angle (i.e. greater than 10o) sea clutter and small target data sets and conduct additional data collection trials to support the work of the Technical Team (TT). b)Extend the understanding of the phenomenology of sea clutter and target signatures. c)Develop mathematical models and simulation techniques to assist in the radar design, development and procurement activities. Validate models, where possible, against real data. d)Assess the performance of existing radar detection algorithms in this environment and develop new radar detection techniques (coherent, multichannel, polarimetry,…)