Dual sideband spectral coordinate system description DSBSpecFrame
"
lower side band"
(LSB) and one from the "
upper
side band"
(USB). Corresponding LSB and USB frequencies are connected by the fact that
they are an equal distance on either side of a fixed central frequency known as the "
Local Oscillator"
(LO) frequency.
When quoting a position within such a spectrum, it is necessary to indicate whether the quoted position is the USB position or the corresponding LSB position. The SideBand attribute provides this indication. Another option that the SideBand attribute provides is to represent a spectral position by its topocentric offset from the LO frequency.
In practice, the LO frequency is specified by giving the distance from the LO frequency
to some "
central"
spectral position. Typically this central position is that of some
interesting spectral feature. The distance from this central position to the LO
frequency is known as the "
intermediate frequency"
(IF). The value supplied for IF can
be a signed value in order to indicate whether the LO frequency is above or below the
central position.
AlignSideBand: Should alignment occur between sidebands?
DSBCentre: The central position of interest.
IF: The intermediate frequency used to define the LO frequency.
ImagFreq: The image sideband equivalent of the rest frequency.
SideBand: Indicates which sideband the DSBSpecFrame represents.