For each of the baseband configurations the details of the spectral windows are included in the Baseband tab in the Spectral Windows panel. At the top a summary table provides an overview of the spectral windows that are defined for the baseband. Some of the spectral window parameters can be specified in the table by clicking in the table cells. Below the overview table, for each spectral window the full set of parameters can be displayed by selecting the spectral window's tab. A few input parameters are commented on below.
Clicking the Add button below the summary table, a SpectralWindow or a pair of SpectralWindows is added depending on the receiver type and the choice of Products & Sideband Separation value. Key parameters of all spectral windows defined in the baseband are displayed in the table. Details about some of these parameters are described below.
The value of the center frequency is constrained to multiples of approximately 32 kHz for the BL correlator and 4 kHz for the ACA correlator. The value typed into the table is adjusted automatically, while you need to click the Adjust button in the tab. In the spectral window table the colour of the offset turns red if the spectral window does not lie within the baseband. The field use USB and use LSB cannot be changed for single sideband (bands 1 and 2) or two sideband (bands 3-8) receivers, as the sideband is chosen by the OT according to the center and LO1 frequency. For a double sideband receiver (bands 9 and 10), sideband selection depends on the choice of Products & Sideband . For the AUTO_ONLY & NONE case, both LSB and USB are selected. This is due to the restriction that the signal of both sidebands cannotbe separated for auto correlation mode. For the CROSS_AND_AUTO & FREQUENCY_OFFSET_REJECTION case, either use LSB or use USB is selected according to the center frequency of the baseband and LO1 frequency, and the selection is not allowed to change. For the CROSS_AND_AUTO & FREQUENCY_OFFSET_SEPARATION or CROSS_AND_AUTO & PHASE_SWITCHING_SEPARATION case, two spectral windows are defined at a time as a pair, one in the LSB and the other in the USB. You can remove the check for either sideband you don't need. All the spectral window parameters except a few are common to the spectral windows defined as a pair and the parameters for the both sidebands are displayed and editable on a tab. Note that FREQUENCY_OFFSET_SEPARATION does not appear in the Product & Sideband Separation list box for an ACA spectral spec because the ACA correlator does not support this function.
There are restrictions between the nominal bandwidth and the nominal number of channels of the spectral window for the BL correlator. You will see 3 types of representation in the list box for those parameters: black characters, grey characters, and grey characters with a stroke.
Black characters are used to indicate that the value is valid against the setting of the other. When you see the list box for nominal bandwidth, choices in black are valid against the current value of number of channels, and vice versa. Choices in gray with or without stroke are invalid. Stroke means the value is available against none of the choices of the other. In other words, the value is not available for the settings of other parameters: polarization, correlation bits, oversampling, and quantization correction. Choices in grey without stroke will be valid and turn black when one of the valid choices is chosen for the other.
For every Spectral Window at least one Spectral Average Region needs to be set. For the case that spectral windows are defined as pairs, i.e. sideband separation is selected for a DSB receiver, a check box labeled Creates the same region in the mirrored window is displayed below theSpectral Average Region table. As the default this is checked and the regions displayed in the table are applied to the both sidebands. Remove the check if you want to set different spectral average regions to LSB and USB, then you will see columns labeled LSB and USB which allows you to select which sideband or both use the region.
After having created and filled out one or more Instrument Setup forms, clicking on the Resources/Instrument Setup folder shows a table with the available InstrumentSetups.