Interference from the instrument frame

Instruments that measure velocities at a point have to be mounted on something. Ideally they are deployed so as to minimize the likelihood of the instrument being in the wake of any frame components. You can check for wakes by looking for a consistent directional dependence of TKE that is not consistent with the general flow dynamics. You can also check for vortex shedding from the frame by looking at the spectra to check for unexplained peaks.