Vortex sensor amplitude information may be used to validate that a vortex signal being measured corresponds to an actual fluid flow and is not noise. The estimated amplitude of a sinusoidal vortex signal is used as a secondary means to determine the fluid flow based on vortex sensor characteristics. The original amplitude of the sinusoidal vortex signal is determined from a clipped voltage amplitude sinusoidal signal. The estimated velocity of the fluid in a pipe based on the original amplitude of the sinusoidal vortex signal is compared to the measured velocity of the fluid based on vortex velocity frequency. If the two determined velocities do not reasonably agree, the measured vortex signal is not a valid flow signal and adaptive filters are adjusted to reduce the effects of noise.