Principles of Modern Radar - Volume 2 1891121537

7.3 Doppler Beam Sharpening Extensions 281d(u, t)2-D FFT(u, t)D(k u , ω)d(u, t)× e −jyChirp(u)d Dechirp (u, t)FIGURE 7-21DBS with RMC issimilar to DBS-ADbut preprocessesthe data with anRMC stage.× e −jyMig(u)1-D FFT(u)D RMC (k u , ω)D Dechirp (k u , t)2-D IFFT(k u , ω ) Mappingd RMC (u, t)f(x, r)The following simulation parameters were used to demonstrate the effect of the rangemigration and the benefit of RMC to DBS-AD:• Carrier frequency = 250 MHz• RF bandwidth = 7.5 MHz• Integration angle = 1.7 ◦• Resolution = 20 m (both dimensions)• Range to scene center = 50 km• Scene size = 2kmby2kmThe use of a low carrier frequency is designed to stress the scene size, as (7.25) indicatescross-range extent will be limited when operating with long wavelengths. Diagramsof the collection geometry and the location of point targets are provided in Figure 7-22.Along-Track (m)−1000Collection Geometry−800−600−400−200050 km range toscene center20040060080010000 1 2Aperturepositions3 4 5 6Cross-Track (m)× 10 4(a)Along-Track (m)−1000−800−600−400−20002004006008001000Scene GeometryScene limits2 km m by 2 km−1000−800−600−400−2000 800 600 400 800 1000Cross-Track (m)(b)FIGURE 7-22 Simulated DBS-AD-RMC geometry emphasizing (a) the overall collectiongeometry, and (b) point scatterer locations in the scene of interest.