  The propagation of signals in space-time is considered on the basis of the
notion of null (isotropic) vector field in spaces with affine connections and
metrics as models of space or of space-time. The Doppler effect is generalized
for these types of spaces. The notions of aberration, standard (longitudinal)
Doppler effect, and transversal Doppler effect are considered. On their
grounds, the Hubble effect appears as Doppler effect with explicit forms of the
centrifugal (centripetal) and Coriolis velocities and accelerations. Doppler
effect, Hubble effect, and aberration could be used in mechanics of continuous
media and in other classical field theories in the same way as the standard
Doppler effect is used in classical and relativistic mechanics.
