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A Baseband Configuration summary table (see Fig
6.18
) is visible above the baseband specification forms. Apart from a few fields the table also shows the LO2 frequency and the instantaneous date rates that can be expected for each baseband configuration. Note that the LO2 frequency is determined within the OT, by the tool itself. This is an estimate to help the user in preparing a correlator setup - the actual LO2 used may vary depending on the time of observation, and is set by Control at execution time. for specifying the maximal four basebands.
Figure 6.18:
The
BaseBand
tabd for the ALMA BL in the SpectralSpec form of the Instrument Setup. The bottom part of the figure shows the overview table of the specified spectral windows
|
-
Baseband Name
: Set automatically, one of BB_1, BB_2, BB_3 or BB_4.
-
Desired Center Frequency
: The desired centre frequency (in sky units) for this BBC. Not needed for the Correlator Config, rather this is maintained as the users desire for the location of this BBC, and thus to calculate the LOs.
-
Actual Center Frequency (Rest)
: The actual centre frequency (in rest units) for this BBC.
-
Actual Center Frequency (Sky)
: The actual centre frequency (in sky units) for this BBC.
-
Products
: Allows the user to select both auto and cross correlation products or auto only or cross only. When the accumulation mode is ALMA_FAST, only the auto products are available. The default is CROSS_AND_AUTO.
-
LO2 Frequency Switching
: Check if frequency switching is to be performed at LO2. This will always be false unless FREQUENCY_SWITCHING is selected at the SpectralSpec level.
-
Number of Positions
: The number of switching positions in the switching setup, 1 (which is no switching), 2, 3,or 4.
-
Dwell Time
: Part of the setup for the "switching" definition. The dwell time is the data collecting duration at a given position. dwell time + dead time must be a multiple of 48 msecs. Dwell time is ignored if there is no switching (TBC).
Next:
Spectral Window Tabs
Up:
BaseBand Configuration
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LO Setup Preferences
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The ALMA OT Team, 2011 May 20