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Mt Pleasant 26m

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Ceduna-Hobart Interferometer




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OTTER is the name of the program that is used to control the receiver selection on the 26m telescope. There are two components - a server and client. The server accepts TCP connections and talks to the hardware while the client is a GUI that provides information on the current status.

To start the GUI, run ./ from a terminal on newsmerd. The program will then collect the current status of the receiver and display it. A screenshot is included below

The OTTER interface

The list of available commands is listed in the lower section of the GUI. The commands are entered by typing the character in the square brackets and pressing enter e.g to select the 8.4 GHz receiver, type 6 and then press enter. Some commands (such as interacting with the phase shifter) will return additional prompts for the user - please follow the listed instructions.

Selecting a receiver

Always make sure that the telescope is parked before changing receivers. Otherwise, there’s a serious risk of damage if cabling gets caught on the platform as it moves.

Check that the display in rack 3 shows the selected receiver number after a second or so. If you’ve changed from one receiver to another, the focus platform should start moving to the new focus position. If it does not, try toggling the switch above the Rx display from “Auto” to “Manual” and back again.

If you can’t change a receiver (after a power failure say), type “r” to reset the electronics in the focus cabin.

Using the Quadrature Hybrid & crossover switch

For most experiments (except at L-band) you should have the Quadrature Hybrid OUT (indicated by the Quad OUT line) and the crossover switch in “direct” mode (Direct). If the hybrid is in when it shouldn’t be, the recorded polarisations will not be circulars but rather some strange elliptical blend. If the display for SW2 shows it as crossed, then the recorded polarisations will be reversed from the nominal (so RCP will be in channel 2 rather than channel 1). The quadrature hybrid and crossver status can be toggled with the q and d commands respectively.

Checking cryogenic status

If everything is working, the multifeed 70K/20K readings should be ~60/30 and the L-band 70K/20K readings should be ~80/35. If any of the readings are more than ~10 degrees above these nominal values, it may indicate an impending problem. Getting in early saves a lot of time overall, so please let Brett and Eric know about this as soon as possible.

OTTER Server

The OTTER server runs on rx26m. If the GUI fails to start or returns error messages, please check that it is running (with ps -ef | grep OTTER as observer@rx26m). You can restart the server with sudo /etc/init.d/OTTER restart if there are any problems. The server is being continuous polled by MoniCA with the data being logged in the hobart database.

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Page last modified on May 04, 2015, at 01:04 AM