FTS Drive Module

The FTS Drive Module generates the time-line, physical and optical position vectors for the spectrometer scan. The user defines a band of operation for the instrument 

The maximum required optical path difference Smax is then given by the spectral resolution Av 

If N yq 1, which results on a finer optical delay, the maximum wavenumber of the system is then v = N yqVmax and the spectral resolution is conserved. 

The optical path difference vector 5 is a vector of N samples from 0 to Smax sampled every AS. Depending on the optics design, the physical position vector will range from 0 to x = Smax 12 (Martin-Pupplet configuration) or from 0 to x = Smax (modified Mach-Zehnder design). 

The time-line vector is then defined by the optical position and the optical velocity V ast = S/V. The optical velocity is derived from the driver velocity Vscan and the Optical System Level OSL), which depends on the band of interest and is described in Sect.4.5.5.2. With these parameters, the optical velocity is V = 2VscanOSL, and the factor 2 is because of the selected Martin-Pupplet configuration. 

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The first step is to generate a Sky Map to be fed to the subsequent modules in the Sky Generator Module and the corresponding photon noise, computed in the Sky Photon Noise Module. In parallel, given the parameters defined by the user for the instrument, an interferometric MV-map is created at the v-Map Generator Module from the position of the two telescopes. The FTS Drive module calculates the spectrometer scan parameters. Once a MV-map and the scan parameters are defined, the instrument beam is calculated at the Beam Generator Module. The sky map and the beam are then combined to recreate the observed sky map. 

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