1. An apparatus for producing a phase component of a nonlinear frequency modulated (NLFM) chirp radar pulse, comprising: an input for receiving a set of parameter values defined externally of said apparatus; and a digital integration unit coupled to said input, said digital integration unit configured to perform a plurality of digital integration operations over a time interval defined by a width of the NLFM chirp radar pulse, said digital integration unit configured to perform each said digital integration operation by applying to a respectively corresponding one of said parameter values a respectively corresponding number of instances of digital integration, and said digital integration unit configured to produce said phase component based on said plurality of digital integration operations; wherein one of said parameter values is defined as a variable parameter value for variation during said time interval.