The 230 GHz and 460 GHz wide band sidecab receivers are housed in a single cryostat. They have 4 GHz bandwidths (4-8 GHz IF) and synthesized local oscillators. They were installed in 2012 May.
These receivers are tuned automatically by a dedicated computer. Receiver tuning takes about a minute. For example to observe three CO isotopologues [12CO(2-1) in the USB flanked by 13CO(2-1) and C18O(2-1) in the LSB],
uip> instr rx230b
uip> lo 12co2-1 /if 5.28 /side up
uip> spectrometer /ffts1w 5.28 /ffts2 /restart
Both FFT spectrometers, FFTS1 and FFTS2, are available with these receivers. The AOS5 is not available. FFTS1 is switched between the receivers automatically. One half of FFTS2 (sub bands 1 and 2) is connected to the 230 GHz receiver and the other half (sub bands 3 and 4) is connected to the 460 GHz receiver.
To point using the FFTS2, specify the channel range corresponding to the appropriate sub band with the
HALF_WIDTH argument and
/CENTER option or with the
/RANGE option. For example, with FFTS2B3 (connected to the 460 GHz receiver):
uip> five_point 10 /range 16385 24576 /ffts2
The same pointing file (
230b_460b.pointing_setup) is used for both the 230 GHz and the 460 GHz receivers. In principle, the beams are coaligned.
When switching between the 230 GHz and 460 GHz receivers or to turn off the receiver at the end of night, use
uip> lo /off
With the 230 GHz receiver, observing at frequencies below 210 GHz requires manual installation of an extra low pass filter in the LO chain. Otherwise there will be spurious response at higher frequencies, near 4/3 x LO frequency. Please consult with the staff for details.
When using the 460 GHz receiver with FFTS1, verify the correct input (A3) is shown on the display panel of the FFTS1 IF processor.
If the receiver tuning completes but the receiver has no sensitivity on the sky, it is possible the synthesizer output is turned off. To reset the power level and reenable the output, switch to a different local oscillator (phase lock) system and back:
uip> lo /lock_loop default
uip> lo /lock_loop synthesized_lo
As long as the LO command is able to communicate with the receiver computer, you do not need to interact with it directly. If the LO command throws exceptions relating to communication with the receiver computer, reestablish the connection using
UIP> lo /restart
If you still receive exceptions after issuing the above command, you may have to reboot the receiver computer. The receiver computer is located in the backend room on the second floor. After reboot, the receiver control software will automatically start up. Issue the above command to establish the connection.
For engineering and troubleshooting purposes, the vncviewer can be used to control the receivers directly or watch debug messages. Consult staff.
$ vncviewer -shared XX.XX.XX.XX:1