  Three dimensional numerical simulations of the response of a Lorentz factor
2.5 relativistic jet to precession at three different frequencies have been
performed. Low, moderate and high precession frequencies have been chosen
relative to the maximally unstable frequency predicted by a Kelvin-Helmholtz
stability analysis. Transverse motion and velocity decreases as the precession
frequency increases. Although helical displacement of the jet decreases in
amplitude as the precession frequency increases, a helical shock is generated
in the medium external to the jet at all precession frequencies. Complex
pressure and velocity structure inside the jet is shown to be produced by a
combination of the helical surface and first body modes predicted by a normal
mode analysis of the relativistic hydrodynamic equations. The surface and first
body mode have different wave speed and wavelength, are launched in phase by
the periodic precession, and exhibit beat patterns in synthetic emission
images. Wave (pattern) speeds range from $0.41c$ to $0.86c$ but beat patterns
remain stationary. Thus, we find a mechanism that can produce differentially
moving and stationary features in the jet.
