In apparatus for generating a Complementary Cumulative Distribution Function (CCDF) curve for an input signal, an analog to digital converter (ADC) samples the input signal at sampling points to provide a parameter value corresponding to a desired parameter of the input signal at each sampled point. A memory element provides a frequency count of occurrence of each received parameter value from an address in the memory corresponding to the received parameter value. An adder receives the frequency count, increments the count and provides the incremented count to an input of the memory element for writing back into the address corresponding to the received parameter value. A CCDF curve generating module reads the frequency count stored in the memory element corresponding to each parameter value and generates a CCDF curve therefrom.