Activity dips, also referred to as frequency perturbations, can be difficult to spot in oscillating crystals. However, a single activity dip can cause major problems in an application’s signal, including within GPS or missile systems. Imagine launching a missile and then losing control of its navigation. Or getting a very inaccurate GPS velocity reading of an aircraft. These (and many other problems) can be caused by a failure to spot frequency dips in crystals. It’s important to understand what activity dips are and how to avoid them from occurring in crystals...and that's exactly what you're going to learn right now!