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operations:aum-hb

This is an old revision of the document!


Some background

the AUM experiments are designed to investigate and hopefully demonstrate the compatibility of the new wideband VGOS receiver with the existing S/X system. This is important for maintaining a global geodetic network during the transition to a fully global VGOS array.

The Hobart12 antenna now has a functional wideband system, with reasonable sensitivities. The initial observations of the AUM series will be made using the “VGOS”-mode DBBC3 software, recording channels with an (excessive) bandwidth of 32 MHz which will be dealt with in the correlation stage. If the current issues with the DBBC3 and its “Legacy”-mode software are resolved, we sill change over to use this instead, so the instructions may be updated - please check the page carefully each time you are starting or monitoring an AUM experiment.

Major Differences

The major differences for observing an AUM experiment rather than a standard S/X experiment are that there is no FS support for the hardware and that we need to run two DBBCs simultaneously to record the S- and X-band data. The recorder has also changed from the mark5B to a flexbuff which operates in a very different fashion. Preliminary scripts have been written to monitor the relevant parameters but again, these are likely to be changed and improved as needed.

Revised checklist

Taking the existing e-remote control checklists as a template, here is a listing of the significant differences.

Before the Experiment

  • Preparing the schedule file: Do not use the existing slogit scripts, but instead download the skd file directly to pcfshb and run drudg to generate the prc, snp and sum files and put them where they're needed.
cd /usr2/sched
wget ftp://cddis.gsfc.nasa.gov/vlbi/ivsdata/aux/2018/aum001/aum001.skd
drudg aum001.skd
   hb
   12
   3
   5
   0
scp /tmp/sched.tmp observer@ops-serv2:/vlbobs/ivs/logs/aum001hb.sum

The next step is to convert the existing snp file into one which will control the flexbuff recordings appropriately. This is done via a script at present - please use the following commands

cp aum001hb.snp aum001hb.orig.snp
/usr2/sched/snp2flexbuff.sh aum001hb.orig.snp aum001hb.snp hb

The newly created aum001hb.snp file retains the timing of the source commands, scan names and times but calls a script to run the recorder and omits many of the typical procedures like preob, etc. NB - do not use the line number entries in the sum file!

  • RF and IF paths configured/DBBC settings: The RF/IF/DBBC configuration has been compiled into a single script on pcfshb /usr2/sched/aum.32mhz.py. Running this should set up all the essential settings.
    • No RF configuration is needed for the X-band data recorded through the DBBC3, but it is necessary to set the inputs on the 26m's remote backend (e.g “the folly” or “PalfreymansBackend”. Go to the hobart26 VNC session (vncviewer newsmerd:1) and go to desktop 3. Refresh the Folly display with 'r' and confirm that S/X SRCP and S/X XRCP are highlighted for channels 1 and 2 respectively.
/home/www/auscope/opswiki/data/attic/operations/aum-hb.1532933362.txt.gz · Last modified: 2018/07/30 06:49 by Jamie McCallum