{charge, resistance, capacitance, voltage} Output quantity divided by the input acceleration Reference Frequency Test Frequency {X,Y, Z} Acceleration (m/s²) Excitation Voltage UUT is placed in a device, normally a shaker, which then moves in a single axis direction at a known acceleration at the reference frequency. Then the frequency is changed to the Test Frequency and difference in sensitivity is expressed as a ratio (Test Frequency / Ref Frequency).