One of the limitations of conventional modal testing using a roving impact hammer is that the reference sensor (usually an accelerometer) must remain fixed throughout the test. Since the accelerometer must typically be connected by a wire to the data acquisition system. a very long wire may be required when testing a large structure. Furthermore, better quality signals are possible if each impact force is applied closer to the response accelerometer. Because it does not require a fixed reference sensor throughout the test, a Rapid Impact™ test is faster and easier to perform on any size structure.