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

DSTO-GD-0210Rather than specifying 3-D vectors, it is easier to visualise, easier to describe and morecommon to encounter situations that can be described using the following quantities(the names below correspond to those seen in the ISARLAB software):1. For linear motion:• X position (m)• Y position (m)• altitude (m)• heading (degrees)• velocity (ms -1 )• acceleration (ms -2 )• climb rate (ms -1 )X position, Y position and altitude; together constitute the 3-D position in the globalcoordinate system. Heading is measured parallel to the X-Y plane. Zero (0) degrees isdefined to be the same direction as the X-axis and heading increases positively in aclockwise direction looking along the Z-axis towards the origin. Velocity andacceleration are scalar quantities and both apply in the direction specified by heading.The climb rate is the velocity in the Z-axis direction. Velocity and acceleration are withrespect to the ground and not the air or sea.2. For circular motion:• X position (m)• Y position (m)• X position of centre (m)• Y position of centre (m)• altitude (m)• speed (ms -1 )X position and Y position define the position on the circumference of a circle centred atX position of centre and Y position of centre. The circle is parallel to the X-Y plane andhence the altitude applies to both the position and position centre. The motion aboutthis circle is anticlockwise if speed is positive and clockwise if speed is negative.Speed is the magnitude of the instantaneous tangential velocity and is proportional tothe rate of rotation. Speed is with respect to the ground and not the air or sea.In our implementation of gross motion, we translate either the linear or circularquantities into an augmented array of three 3-D vectors that are interpreted differentlyaccording to the context of linear or circular motion. These arrays (shown below) areour representation of the radar’s or target’s gross motion.8