Radar/ARPA Image Generation And Function Improvement

Radar/ARPA simulator takes the important role in seafarer training, assessment of competence, etc. Radar simulator has been demanded higher performances along with rapid development of marine industry. And the explicit standards are clearly defined by STCW 78/95 Convention.Mimic image generation and display is the kernel part in the full computerized radar/ARPA simulator. At the same time all kinds of rada/ARPA functions must be simulated. Mimic image comprises of radar echoes and ARPA marks. Radar echoes include echoes of lands, islands, all kinds of moving targets, racon, SART and sea, etc. ARPA marks consist of fixed range marker, variable range marker, electronic bearing line, guard zone, heading-line, parallel index(4 navigation lines), vector lines(or PAD) and past track information of tracked target ships, marks of trial manoeuvres, ect.Initial coastline sampling data, racon position data and SART position data are acquired from sea chart by digitizer. All of the initial data are saved with predefined data structure in data files. For displaying the initial date aquired from sea chart correctly in three different display modes(relative head up motion,relative north up motion, true north up motion), a series of coordinate conversion are necessary .In the second chapter, data structure and various coordinates conversion are discussed in details .In the previous radar/ARPA simulator, both radar echoes and ARPA marks are generated with the algorithm of computing intersection point with scanline sweeping (abbreviated to ACIPSS), this does't accord with the mechanism of radar working. ACIPSS is fit for radar echoes generation. To generate ARPA marks, ACIPSS has its obvious fault. A better way is adoptingdifferent algorithm to generate radar echoes and ARPA marks, then drawing them on different surface.In the third chapter, it is illustrated that how to draw different contents on different surface based on the DirectX technique. In the radar/ARPA simulator, there are 12 surfaces generated for radar image display: FrontSurface# BackSuface# BaseSurface# MenuSurface# EchoSurface# Echo_BackSurface# MarkSurface# OverlaySurface# CorrSurface# CursorSurface# UnderCursorSurface and UnionCursorSurface. First, every part of current radar image is respectively drawed on different surfaces. Second, image on different surfaces are drawed on BackSurface in order. Last, display image through flipping between FrontSurfacd and BackSurface. It will be easy to add new image which is difficult to be generated before by adopting this method. It also provides a great future for the improvement of radar/ARPA function simulation.Improved algorithm for generated radar image are presented in chaper 4:1) ACIPSS is improved in radar echo generation. New method is to combine ACIPSS with single back buffer display. The combination realize high level simulation of true antenna sweep effect. All of the above will be explained in details in chapter 4 section 1.2) Simulation of sea echo determines the quality of radar echo image to a great extent. The random sea echo generation does't accord with the mechanism of sea echo generation. Research reveals that the intensity of sea echo accords with the Weibull distribution. It will be discussed in chapter 4 section 2 that how to generate sea echo accord with Weibull distribution.3) The initial coastline data which are acquired from chart by digitizer is a series of sampling point. Coastlines are simulated with polylinesbyconnecting two neibour sampling points. Nature coastline looks more like to be a polyline in a small range scale(such as 0.25) on the radar/ARPA screen. The coastline subdivision algorithm based on fractal algorithm could produce coastline with any level details without adding more sampling points. The subdivision algorithm will be listed in chapter 4 section 3. 4} Generation of radar interfrence image and target swap simulation improve the simulation of radar/ARPA simulator.