shiftfreq.pro

NRAO GBTIDL
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shiftfreq.pro

Last modification date:: Wed Sep 28 13:27:11 2016

shiftfreq

function shiftfreq(freq, voffset, [veldef=string])

Shift a frequency using a velocity offset. Note that because of the nature of the non-true velocity definitions, this is not a simply reversable shift for anything by a TRUE velocity. Namely, f=shiftfreq(shiftfreq(f,voffset),-voffset) will not result in the same value of f as you started out with for anything except veldef='TRUE'. If you want to undo a frequency shift using the same voffset, use unshiftfreq.

Returns: the shifted frequencies in Hz.
Version: $Id$

Parameters

freq
in, required
double The frequencies, in Hz, to shift.

voffset
in, required
double The velocity offset (m/s) to add to the frequencies (resulting frequencies are then appropriate for a frame moving at voffset relative to the original frame of freq).

Keywords

veldef
in, optional
string (def. 'RADIO') The velocity definition from one of RADIO, OPTICAL or TRUE.

Produced by IDLdoc 1.6 on Wed Sep 28 13:27:39 2016

Parameters
freq in, required double	The frequencies, in Hz, to shift.
voffset in, required double	The velocity offset (m/s) to add to the frequencies (resulting frequencies are then appropriate for a frame moving at voffset relative to the original frame of freq).

Keywords
veldef in, optional string (def. 'RADIO')	The velocity definition from one of RADIO, OPTICAL or TRUE.