Radar can determine an object’s location, keep a record of past locations, and can give an estimate as to where this object, or target, will be. Radar measures a target by emitting an electromagnetic signal and measuring the reflection off of the target. By measuring the round trip time and Doppler frequency shift, this method measures distance and velocity very well, but measures angle very poorly. Sometimes rather than keep track of every aspect of a target’s trajectory, radar will instead use a simplified representation based on only one or two observables that are measured very accurately and precisely – range and Doppler frequency shifts.