Clutter primarily comprises unwanted stationary ground reflections with limited relative motion with respect to the radar. Radar systems can minimize the occurrence of blind speeds either by employing multiple Pulse repetition frequency (PRF) schemes or by using high PRFs in which the radar may become range ambiguous. The main difference between PRF staggering and PRF agility is that the pulse repetition interval can be changed between consecutive pulses for the case of PRF staggering. The chapter addresses two quantities that are normally used to define the performance of Moving Target Indicator (MTI) systems. They are Clutter Attenuation (CA) and the Improvement Factor. Using the binomial coefficients with alternating signs produces an MTI filter that closely approximates the optimal filter in the sense that it maximizes the improvement factor, as well as the probability of detection. Target velocities that correspond to multiple integers of the PRF are referred to as blind speeds.