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Chaff, a typical passive deceivable interference, is commonly used to cheat radar reconnaissance by producing high fidelity echoes in military counter-mission. It is difficult and challenging to distinguish chaff from ship based on their echoes. Firstly a sparseness characteristic analysis is implemented about ship and chaff return in time-domain and frequency-domain, respectively, which conclude...
One of the most important issue in maritime international transport is the necessity of increasing the level of safe in vesselpsilas navigation. We can achieve this goal using various methods. One of them is the enlargement and enrichment of navigational data processed by own deck computer net and external systems AIS (Automatic Identification System) and VTS (Vessel Traffic Service). The radar image...
The article presents research results on the application of artificial GRNN neural network in the process of radar tracking in marine navigational radars. A comparison has been presented of the tracking process by means of a numerical filter implemented in a real radar device and a neural filter prepared by the authors. The test situation was registered on a real vessel and next introduced into a...
This work uses ordinary X-band marine radars to extract directional wave spectra and their related sea state parameters, as well as speed and direction of ocean surface currents, including tidal information. The used method analyzes the structure in frequency and wave number vector of the image spectra derived from of temporal sequences of marine radar images of the sea surface acquired by a marine...
Defence Research and Development Canada - Ottawa has developed an experimental airborne radar referred to as the X-band Wideband Experimental Airborne Radar (XWEAR). The radar was designed to support research into SAR imaging of fixed and moving targets (ocean and land), time-frequency analysis of moving targets, clutter suppression for GMTI radar, and ocean surveillance for small and large target...
HF radar signals rely on the ionosphere to achieve over-the-horizon surveillance, but this is obtained at the expense of subjecting the signals to a diverse range of scattering and modulation phenomena. Many of these effects are associated with multiple scattering, both in the ionosphere and near the earthpsilas surface. This paper reviews a variety of multiple scattering phenomena and shows how an...
In 1956, the Naval Research Laboratory completed a set of experiments that showed 1) that VHF and HF radar echoes could be coherently processed, and 2) that the ionosphere is often sufficiently stable for a radar operating in the high-frequency band (3 MHz to 30 MHz) to be capable of detecting and tracking targets beyond the normal microwave radar horizon. Later in 1961, the Naval Research Laboratory...
Doppler frequency shifts of sea echoes in bistatic shipborne surface wave radar (BS-SWR) are simultaneously modulated by the velocity components projected from the motion of both platforms, and therefore the Doppler spectrum is much more complex than its counterparts in monostatic mode. In this paper, based on the dynamic geometric relationship among bistatic platforms and first-order sea clutter...
In this paper we study the statistical distributions of bistatic scattering from Pierson-Moskowitz sea surfaces. The Monte Carlo simulation method is applied and the Maxwellpsilas equations are solved numerically using the Banded Matrix Iterative Approach. By assuming normal-distributed and correlated real and imaginary scattering components, we derive analytical probability density functions (pdfs)...
This paper briefly discusses a procedure to measure the radar cross section (RCS) of small boats at 94 GHz. It describes an extremely simple and moderately low cost set of hardware that was used to perform these measurements. An analysis of the calibration method including measurements of reference corner reflector returns and those from the sea were made throughout the trials. Results include polar...
Doppler analysis of radar sea-clutter is typically performed from a static cliff top location looking out to sea. This constrains the grazing angle to low values and the radar look direction with respect to the wind. Current research at the DSTO is interested in the properties of sea-clutter at medium to high grazing angles, over all azimuth directions, full polarisation and different spatial resolutions...
This paper deals with the problem of automatic target recognition (ATR) of non cooperative targets. Specifically the focus is on the ATR of ships in ISAR images. To fulfill this task a multifeature based technique is proposed which uses a number of features extracted from the ship radar image. Both cases of known/unknown target aspect angle and single/multiframe based processing technique are considered...
This paper presents a study of the effects of sea clutter on the performance of HF surface wave radar (HFSWR), operating in the band between 3 and 5 MHz, in the detection of two classes of ships: large freighters with gross registered tonnage (GRT) in the order of several tens of thousands of tons and small vessels with a GRT of about 1000 tons. The radar returns from both large and small ships are...
The relative detection performance of fast scan and slow scan radars utilizing frequency agile waveform transmission is examined. A real, wide bandwidth, sea clutter data set is compressed using a set of contiguous narrowband compression filters to create data sets corresponding to three or ten frequency steps. Both a non-coherent and coherent Kelly detection scheme are implemented and tested. A detection...
Rapid improvements in skill and spatio-temporal resolution of mesoscale numerical weather prediction models have recently created the ability to simulate notional radar design performance in four dimensional non-standard refractivity environments. This paper quantifies the engineering demands, relative to a standard atmosphere, placed on notional ship borne S band, C band and X band radars during...
This paper discusses three diverse topics in radar that have little relationship to one another, other than they represent what might be interesting for further exploration. These topics are: (1) a suggested origin for microwave sea echo (something not currently understood), (2) a different type of phased array radar architecture based on digital beamforming that can overcome a serious weakness of...
The sensitivity of track before detect processing to the choice of clutter model in the measurement correction stage was examined through processing of real and simulated data containing radar echo returns of a small maritime target in sea clutter. The potential for achieving significant detection performance improvements by utilizing K and KA distributed clutter models in place of the simpler Rayleigh...
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