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Examples of Device Table Setting for WHSF

Following examples show parameter settings of Device Table for WHSF spectrometer with a single-polarization 2SB receiver (CATS345=CATS3).

See the manual of Making Device Table for details of setting parameters.

FX Mode

2GHz bandwidth, CO(3-2) observation with USB

12CO(3-2) (f_rest=345.795991 GHz) at USB

• Frontend
Enter tracking frequency (Ftrack) at USB and IF frequency (Fif).
For example, when you enter Ftrack = 345.795991 GHz (rest frequency of 12CO(3-2)) at USB and Fif = 5.119875 GHz, center frequencies (Fcenters) of digital backend are set to 345.795991 GHz at USB and 335.556241 GHz at LSB. Fcenters are automatically calculated by pressing button.
• IF Port and MTX Switch
Refer to Analogue Backend in Making Device Table.
• FSel
Choose IF Ports of A/D Converters (X-IF1, X-IF2, Y-IF1, Y-IF2) into correlators (F0, F1, F2, F3).
USB signals flow into X-IF1 and X-IF2, and LSB signals flow into Y-IF1 and Y-IF2. You can choose any IF Ports to each correlator.
• Freq. calc
Push to see whether the setting is OK. If an error message displays on a pop-up Freq.calc window, correct them.

Fig 1. Example setting of 12CO(3-2) observation in FX 2GHz-BW mode

4GHz bandwidth, multi-line observation with USB and LSB

Simultaneous observation of 4 lines; HCN(4-3) (f_rest=354.505480 GHz) and HCO+(4-3) (356.734242 GHz) at USB, CS(7-6) (342.882866 GHz) and SO(8₈-7₇) (344.310792 GHz) at LSB.

• Frontend
Enter tracking frequency (Ftrack) at USB or LSB and IF frequency (Fif).
For example, when you enter Ftrack = 355.619861 GHz (average of HCN(4-3) and HCO+(4-3)) at USB and Fif = 6.144250 GHz, Fcenters are set to 355.619861 GHz at USB and 343.331361 GHz at LSB.
• IF Port and MTX Switch
Refer to Analogue Backend in Making Device Table.
• FSel
Choose IF Ports of A/D Converters (X-IF1, X-IF2, Y-IF1, Y-IF2) into correlators (F0 & F2, F1 & F3). In 4G-BW mode, F0 and F2 (or F1 and F3) process the same signal. USB signals flow into X-IF1 and X-IF2, and LSB signals into Y-IF1 and Y-IF2. You can choose two IF Ports of A/D Converters in FSel from pull-down menus. Choose either X-IF1 or X-IF2 from one menu, and either Y-IF1 or Y-IF2 from the other menu.
• Freq. calc
Push and Fcenters are calculated.
If "error" displays on a pop-up window, correct the settings.

Fig 2. Example setting of 4-line observation in FX 4GHz-BW mode

FFX Mode

At 1st stage, signals of USB and LSB are spectroscoped into 512 channels at each array of digital backend (X1, X2, X3, X4).
At 2nd stage, consecutive 8 channels of each array are further spectroscoped into 2048 channels.

2GHz bandwidth, multi-line observation and band merge

Simultaneous observataion of 12CO(3-2) (f_rest=345.795991 GHz) at LSB and HCO+(4-3) (f_rest=356.734242 GHz) at USB and band merge at 2nd stage.

Here we think of "band merge": connecting bandwidths of different arrays to gain wider bandwidth at 2nd stage.

• Frontend
Enter tracking frequency (Ftrack) at USB or LSB and IF frequency (Fif).
For example, when you set Ftrack = 345.795989 GHz at LSB and Fif = 5.12 GHz, center frequencies (Fcenter) of 1st stage are 356.033991 GHz at USB and 345.797991 at LSB.
• IF Port and MTX Switch
Refer to Analogue Backend in Making Device Table.
• FSel
We assume that correlators F0 and F1 are used for USB and F2 and F3 are for LSB. When we do band merge at arrays of 2nd stage, the arrays must process the same IF signal. If we use arrays X7 and X8 for band merge at USB, the IF signal of USB must be either X-IF1 or X-IF2. Here we choose X-IF1 for F0 and F1 and Y-IF1 for F2 and F3.
• Fcenters of 2nd stage
Enter Fcenters of arrays at 2nd stage.
Here we think of overlapping 2 channles of arrays X7 & X8 at USB centering on the frequency of HCO+(4-3), and X9 & X10 at LSB centering on the frequency of 12CO(3-2). We recommend that the nuber of overlapping channel is at least 1. Fig 3 illustrates the configuration of 2 arrays, X7 and X8 at USB. The total bandwidth of each sideband at 2nd stage is 14 channels (= 56 MHz ~ 50 km/s).
In this case, the center frequencies of X7 and X8 are 356.722242 GHz and 356.746242 GHz respectively.


Fig 3. Example of array configuration for band merge

• Freq. calc
After filling out, push to see whether the setting is OK. If there is no mistake, calculation program displays "ok" on a pop-up window and fine adjusts the Fcenters because of the limitaion of frequency resolution per one channel (4 MHz in FFX 2G-BW mode). In this case, Fcenters of X7 and X8 are adjusted to 356.723991 GHz and 356.747991 GHz respectively.

Fig 4. Example setting of band merge in FFX 2GHz-BW mode

Link

• ASTE WHSF Status Report
• WHSF Manual
• WHSF Tuning Guide
• Device Table for New Spectrometer WHSF
• Examples of Device Table Setting (F-FX)

updated: 2007-Dec-03