While his method using relativistic Doppler shift
a la Special Relativity is all right for such a preliminary analysis, in our opinion this method has a drawback that it uses "standard definition of Lorentz transformation" based on 2-dimensional problem of rod-on-rail as explained in numerous expositions of relativity theory .
Somehow the consequences of this well-known Doppler shift
were not fully taken into account by engineers before Cassini's 1997 launch.
Doppler radars, on the other hand, represent the class of radars specifically designed to select targets and reject clutter based upon the Doppler shift
in the return echo.
The radar, when looking down at airborne targets, uses the Doppler shift
to distinguish targets from clutter.
That wobble shows up as a Doppler shift
, pushing the wavelength of starlight alternately toward the bluer and redder end of the spectrum as the star moves toward and away from Earth.
By measuring Doppler shift
differences of bistatic radar signals among different receiving sites, the velocity vector and the heading of a flying target can be authentically identified.
These sources are used as the reference in extracting the Doppler shift
of the return signal, which is proportional to the radial motion of the target from which the transmitter signal is backscattered.
The test signal's frequency mimicked the Doppler shift
that would occur while Cassini flies past Titan, with its closest approach planned for 1,200 kilometers (750 miles).
This so-called Doppler shift
provides a view several kilometers deep into the Martian interior.
As the antenna moves, it imposes Doppler shift
on the arriving signal.
Target B that is closing at 500 m/s, (1640 ft/s) (32000 Hz true Doppler shift
, 2000 Hz apparent Doppler frequency) also is unobscured.
There were multiple absorption features, spread out in space (indicated by the Doppler shift
of the spectral lines), revealing that there were several clouds.