ISARLAB - Inverse Synthetic Aperture Radar Simulation - Defence ...

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DSTO-GD-0210results in the production of 1-D range profiles or 2-D ISAR images. Division of thesignal processing in this way allows ISARLAB to process experimentally collectedradar data as well as simulated data.Raw Radar ReturnsRangeWindowingRangeAlignmentRangeCompressionMotionCompensationGenerate RangeProfilesPhaseCompensationRange ProfilesDopplerWindowingDopplerProcessingDopplerProcessingImage DataFigure 4: Radar signal processing steps.The processing of the return signal is achieved in three steps. The first step, calledrange processing or range compression, essentially deconvolves the return signal usingknowledge of the transmitted signal. This provides the impulse response of the target(range profile). The second step is radial motion compensation that attempts toremove the relative radial movement between the radar and target. A number ofphase compensation algorithms are supported by ISARLAB [9]–[11]. The third andfinal step in the ISAR image production is Doppler processing. Here a spectralanalysis is performed in each range resolution cell to estimate the distribution ofDoppler frequencies and hence the cross-range positions of target scatterers. Various18
DSTO-GD-0210signal processing windows can be applied before both the range and Dopplerprocessing stages [12].6. Display ProcessingDisplay processing is performed in four steps. These are illustrated in Figure 5.First, the data output from the signal processing stage is converted to decibels (dB).This change from a linear scale to a logarithmic scale makes a large dynamic rangeeasier to visualise. This results in more detail being apparent in the final image.ProcessingConvertintensitiesto dBmaximum dBExtractuser-defineddynamicrangeLinearlyscale intointegersUse integers toindex into currentcolormap to getRGB valuesusermaximumdata fromsignalprocessingdata todisplayuserminimumminimum dBImage of largedynamic range.Intensity is alinear scale.Image of largedynamic range.Intensity is alogarithmic scale.Image of limiteddynamic range.Intensity is stilllogarithmic.Image of limiteddynamic range.Intensity is nowintegers 0 to 255.RGBvaluesFigure 5: Display processing steps.Next, a subset of the dynamic range is selected from the data for closer inspection.This is necessary because the dynamic range of the display device is much less thanthat of the radar data. Values outside of this range are clipped. If the range starts fromthe maximum intensity image pixel, which is arbitrarily set to zero, then this is calledautoscaling. Autoscaling is the default supported by ISARLAB. Alternatively, amaximum intensity (in dB) can be specified and clipping occurs above this maximumand under the dynamic range below this maximum.The next step is to linearly map these intensities (which are real numbers) into therange of integers that index the current colormap. The current colormap is the set of19
Page 1 and 2: ISARLAB - Inverse Synthetic Apertur
Page 3 and 4: ISARLAB - Inverse Synthetic Apertur
Page 5: AuthorsBrett HaywoodSurveillance Sy
Page 8 and 9: Proyecto LIFE: Eco-Mining[LIFE04 EN
Page 10: DSTO-GD-0210TablesTable 1: Informat
Page 13 and 14: DSTO-GD-0210sampling resolution, in
Page 15 and 16: DSTO-GD-0210resulting synthetic ran
Page 17 and 18: DSTO-GD-02103.1.1 Gross MotionIn ge
Page 19 and 20: DSTO-GD-0210The format for linear m
Page 21 and 22: DSTO-GD-0210⎡ A T P ⎤r r r⎢
Page 23 and 24: DSTO-GD-0210small changes in elevat
Page 25 and 26: DSTO-GD-02104. Getting Data and Inf
Page 27: DSTO-GD-02104.3 Saving and Loading
Page 31: DSTO-GD-0210RadarSignalScattererMod
Page 34 and 35: DSTO-GD-02108.2.2 The Graphical Use
Page 36 and 37: DSTO-GD-0210Panel. These menus are
Page 38 and 39: DSTO-GD-02109.1.2.5 ExitExiting ISA
Page 40 and 41: DSTO-GD-02109.1.4.1 Display TypeThe
Page 42 and 43: DSTO-GD-02109.2.2 Using this window
Page 44 and 45: DSTO-GD-0210paths or browse through
Page 46 and 47: DSTO-GD-0210Figure 16: The Data Imp
Page 48 and 49: DSTO-GD-0210traversed in an anticlo
Page 50 and 51: DSTO-GD-0210Figure 19: The Sinusoid
Page 52 and 53: DSTO-GD-0210induced motion paramete
Page 54 and 55: DSTO-GD-021012.2 Changing How it’
Page 56 and 57: DSTO-GD-0210frame (i.e. no overlap)
Page 58 and 59: DSTO-GD-0210Figure 23: The Classifi
Page 60 and 61: DSTO-GD-0210Figure 24: The Display
Page 62 and 63: DSTO-GD-021010. To see the Target i
Page 64 and 65: DSTO-GD-0210Appendix A: 3-D Linear
Page 66 and 67: DSTO-GD-0210Appendix C: UnitsThe in
Page 69 and 70: DISTRIBUTION LISTISARLAB − Invers
Page 71 and 72: State Library of South AustraliaPar

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