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LBA Observations with AuScope Telescopes

Please use slogit.lbake.sh and slogit.lbayg.sh (on Newsmerd) to prepare the schedule files for Katherine and Yarragadee. The information below is off possible use in debugging and checking any problems with the configurations.

Old Information

With Katherine & Yarragadee joining the LBA, experiments using them in a non-geodetic mode are becoming more frequent. This is a rough guide to setting up the AuScope dishes for LBA observations. I’m using Katherine as the station and the v465a experiment in all the following examples. These notes assume some familiarity with the system from IVS observing. If you’re completely new to this, please have a read through the AuScope Wiki in parallel for definitions, etc.

The laborious work is drudging the schedules & preparing the DBBC configurations. These can be done ahead of time (and really do need to be as they’re quite time consuming).

Drudging the schedules

Nota bene - this procedure only applies to normal experiment files! Fringe check schedules require a few extra steps

First, download the vex files into /usr2/sched/ on pcfske. The easiest way is to use the following commands

cd /usr2/sched/
ncftpget ftp://ftp.atnf.csiro.au/pub/people/vlbi/v465/v465a/v465a.vex

The ftp address is on the ATNF wiki pages.

If any of the schedules have experiment names longer than 6 characters, drudg will refuse to deal with these. If it’s urgent, rename the file to something shorter but sensible but always let the LBA chat (and Chris Phillips & Cormac Reynolds by email) know.

Note that the VEX files contain the first LO frequencies for the AuScope antennas and, at time of writing, the default values are incorrect. The VEX files should be checked to make sure the LO frequencies are 1900 MHz for S-band and 7600 MHz for X-band before drudging. You can re-calculate the IF frequencies yourself later and edit the procedure files accordingly, but getting the VEX file right is probably safer.

For each experiment, run drudg v465a.vex and follow the prompts.

  • Select the relevant station
  • Select 12 to make the procedure (v465ake.prc)
  • Select 3 to make the SNAP file
  • Select 5 to print out the summary of the SNAP file (v465ake.snp)
  • Select 0 to quit from drudg

Open the v465ake.prc file in a text editor. The Mark5 mode in the setup01 procedure will need checking, the DBBC setup will need editing too.

Mark 5 mode

The mk5_mode in the drudged file may differ from the above. For example, for v252ae this is set to mk5b_mode=ext,0×0000CCCC. This mode must be consistent with DBBC settings. So it quite possible that, after setting up the DBBC configuration, you will have to edit the .prc file. For example, for v252ae the mode needs to be changed to mk5b_mode=ext,0×000000FF. The same must be done for the fringe .prc file. Full details are in the next (DBBC config) section. In a nutshell, the mk5b_mode is an 8-character hexadecimal word, where each character represents the recording mode. For example, the last F is equivalent to 1111 in binary, which stands for two-bit mapping in each of channels 1 and 2 (each 11 representing the fact that magnitude and sign get recorded; for one-bit sampling the equivalent would be 01 for each channel, or 0101 = 5 in hexadecimal for each channel pair).

DBBC config

The DBBC is now configured by the Field System so building and loading custom DBBC config files is no longer necessary. It will be necessary to modify the dbbc01d and ifd01 procedures to get the input bands, BBC channels etc configured correctly.

Additional procedures

Now you need to add in some preob, postob and systemp procedures. Run cat /usr2/proc/ke12m.prc >> v465ake.prc to attach the preob routine. For the postob routine, you need to know the number channels being recorded - check the ATNF wiki for the experiment. v465a records 8 channels, so the command to attach the postob routine is cat /usr2/proc/postob_8×16MHz_2 >> v465ake.prc. Here, 8×16MHz refers to the number of channels and bandwidth, and _2 to two-bit recording. Finally, systemp - v465a is recording S-band, dual polarisation so the command is cat /usr2/proc/systemp12srl >> v465ake.prc.

Finally, copy the edited procedure to the correct directory with mv v465ake.prc /usr2/proc/

Drudging Fringe-check schedules

First, download the vex files into /usr2/sched/ on pcfske. The easiest way is to use the following commands

cd /usr2/sched/
wget -c ftp://ftp.atnf.csiro.au/pub/people/vlbi/fringe-checks/vc171/vc171.vex

The ftp address is on the ATNF wiki pages.

If any of the schedules have experiment names longer than 6 characters, drudg will refuse to deal with these. If it’s urgent, rename the file to something shorter but sensible but always let the LBA chat (and Chris Phillips & Cormac Reynolds by email) know.

For each experiment, run drudg vc171.vex and follow the prompts.

  • Select the relevant station
  • Select 11 to set the receiver type
    • Enter 16 14 1 1 to set the rack to Mark5, recorder to Mark5B, and to set no secondary recorder
  • Select 15 to set the “Data Transfer Override” - this controls exporting little snippets of data for fringe-checking.
    • Enter 10 /data/
    • Enter 0 to return to the main menu
  • Select 12 to make the procedure (vc171ke.prc)
  • Select 3 to make the SNAP file
  • Select 5 to print out the summary of the SNAP file (vc171ke.snp)
  • Select 0 to quit from drudg

Open the vc171ke.prc file in a text editor and edit the setup01 procedure - remove all references to pcal, tpi, vsi, vc or ifd.

Before
define setup01 00000000000x
pcaloff
tpicd=stop
mk5b_mode=ext,0×0000FFFF,1
mk5b_mode
vsi4=geo
vsi4
vc01d
ifd01
bank_check
tpicd
enddef

After
define setup01 00000000000x
mk5b_mode=ext,0×0000FFFF,1
mk5b_mode
bank_check
enddef

Now you need to add in the preob. Run cat /usr2/proc/ke12m.prc >> vc171ke.prc to attach the preob routine. There is no postob or systemp procedure for fringe-checks.

Finally, copy the edited procedure to the correct directory with mv vc171ke.prc /usr2/proc/

Setting up the DBBC

There are two steps to setting up the DBBC - the first is the working out which IFs are needed and then setting the channels appropriately. The setups below list the most common setups & how to get them working. I’ve switched to specific examples from previous experiments where possible. These should work for 16 MHz bandwidth observations with either 4 or 8 channels. Anything different from this needs much more work…

N.B. The red sections are what needs to be done when you’re setting up for the experiment itself. Creating the new configuration files (black text) needs to be done well ahead of time, so that they are ready before experiment startup.

X-band, single polarisation

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-7600). Using v271k as an example, channel 1′s lower band edge is 8200 MHz. The first line in the dbbc_config_file_v271k.txt is then 1 dbbc2.bit 600.00 16. Repeat for all needed channels and leave unused channels alone.
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v271k.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • Set up the IF inputs. I’ve assumed that the observing frequencies for X-band are between 8112 and 8624 MHz which is normal for the LBA.
    • If using XRCP, send these commands:
      dbbcifa=1,agc,1
      dbbcifb=4,agc,1
      pps_sync
    • If using XLCP, send these commands:
      dbbcifa=2,agc,1
      dbbcifb=1,agc,1
      pps_sync
  • Confirm that the crossover switches are in the direct position. It’s easiest to do this by starting up a system monitor. Connect to ops4 with shh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”
  • Check the mk5b_mode line in the /usr2/proc/v271kke.prc file. For 4 channels only, it should read as mk5b_mode=ext,0×000000FF,0 while for 8 it should be mk5b_mode=ext,0×0000FFFF,1.

X-band, dual polarisation

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Put all of the channels at one polarisation in lines 1–4 and have lines 5–8 for the other polarisation. If the schedule shows the channels as alternating between RCP and LCP, tell the LBA chat (Cormac and Chris by email) that the recorded channel ordering will be different.
    • Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-7600). As an example, if channel 1′s lower band edge is 8200 MHz then the first line in the dbbc_config_file_v999a.txt is then 1 dbbc2.bit 600.00 16. Repeat for all needed channels and leave unused channels alone.
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v999a.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • up the IF inputs. I’ve assumed that the observing frequencies for X-band are between 8112 and 8624 MHz which is normal for the LBA.
    • If using XRCP, XLCP, send these commands:
      dbbcifa=1,agc,1
      dbbcifb=1,agc,1
      pps_sync
    • If using XLCP, XRCP send these commands:
      dbbcifa=2,agc,1
      dbbcifb=4,agc,1
      pps_sync
  • Confirm that the crossover switches are in the direct position. It’s easiest to do this by starting up a system monitor. Connect to ops4 with shh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”
  • Check the mk5b_mode line in the /usr2/proc/v999ake.prc file. For 4 channels only, it should read as mk5b_mode=ext,0×000000FF,0 while for 8 it should be mk5b_mode=ext,0×0000FFFF,1.

S-band, single polarisation

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-1900). As an example, channel 1′s lower band edge is 2209 MHz then the first line in the dbbc_config_file_v999a.txt is then 1 dbbc2.bit 309.00 16. Repeat for all needed channels and leave unused channels alone.
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v999a.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • Set up the IF inputs.
    • For either single S-band polarisation, use
      dbbcifa=4,agc,2
      dbbcifb=2,agc,2
      pps_sync
  • Confirm that the crossover switches are in the correct position. For SLCP, the switches should be direct, while SRCP you need to have the switches crossed. If you do change this, please leave a note for the next observer!. To check the status, it’s easiest to do this by starting up a system monitor. Connect to ops4 with shh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”
  • Check the mk5b_mode line in the /usr2/proc/v999ake.prc file. For 4 channels only, it should read as mk5b_mode=ext,0×000000FF,0 while for 8 it should be mk5b_mode=ext,0×0000FFFF,1.

S-band, dual polarisation - 4 channels maximum

This is the configuration that is most fraught with hazard. It requires either physical recabling of the dbbc to put the correct S-band inputs into CoMos A and B, or requires the following (untested) procedure. If you use recabling, follow the X-band notes but use 1900 when working out dbbc frequencies.

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Put all of the channels at one frequency in lines 1–4 and have lines 9–12 for the other polarisation. If the schedule shows the channels as alternating between RCP and LCP, tell the LBA chat (Cormac and Chris by email) that the recorded channel ordering will be different.
    • Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-1900). As an example, if channel 1′s lower band edge is 2209 MHz then the first line in the dbbc_config_file_v999a.txt is then 1 dbbc2.bit 309.00 16 as is the ninth line. If channel 2′s lower band edge is 2225 MHz then the second and tenth lines will be 1 dbbc2.bit 325.00 16.
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v999a.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • Set up the IF inputs.
    • Send these commands:
      dbbcifa=4,agc,2
      dbbcifc=2,agc,2
      pps_sync
  • Confirm that the crossover switches are in the correct position. For SLCP/SRCP, the switches should be direct, while for SRCP/SLCP you need to have the switches crossed. If you do change this, please leave a note for the next observer!. To check the status, it’s easiest to do this by starting up a system monitor. Connect to ops4 with shh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”
  • Edit the mk5b_mode line in the /usr2/proc/v999ake.prc file. For 4 channels only, it should read as mk5b_mode=ext,0×00F0000F,1.

S-band, dual polarisation - 8 channels maximum

This is the configuration that is most fraught with hazard. It requires either physical recabling of the dbbc to put the correct S-band inputs into CoMos A and B, or requires the following (untested) procedure. If you use recabling, follow the X-band notes but use 1900 when working out dbbc frequencies.

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that one in the next step. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Put all of the channels at one polarisation in lines 1–4 and have lines 9–12 for the other polarisation. If the schedule shows the channels as alternating between RCP and LCP, tell the LBA chat (Cormac and Chris by email) that the recorded channel ordering will be different.
    • Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-1900). Using v444b as an example, channel 1′s lower band edge is 2244 MHz. The first line in the dbbc_config_file_v444b.txt is then 1 dbbc2.bit 344.00 16. The second RCP channel has a lower band edge of 2260 MHz and so the second line is 1 dbbc2.bit 360.00 16. Lines 9–12 in the file are the same as lines 1–4 (as this sets these channels to matched frequencies)
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v444b.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • Set up the IF inputs.
    • Send these commands:
      dbbcifa=4,agc,2
      dbbcifc=2,agc,2
      pps_sync
  • Confirm that the crossover switches are in the correct position. For SLCP/SRCP, the switches should be direct, while SRCP/SLCP you need to have the switches crossed. If you do change this, please leave a note for the next observer!. To check the status, it’s easiest to do this by starting up a system monitor. Connect to ops4 with shh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”
  • Edit the mk5b_mode line in the /usr2/proc/v999ake.prc file to read mk5b_mode=ext,0×0FF000FF,1

S/X-band, single polarisation

  • Create a new configuration file in C:\DBBC_CONF of dbbcke if needed. If the experiment shares a configuration with a previous experiment (same frequencies, polarisations, channel order) then you should be able to use that. Otherwise, read on.
    • Copy the basic layout from dbbc_config_file_lba.txt to your new file and then edit the frequencies. Start by checking the listed frequencies of each channel on the ATNF Wiki. In the corresponding entry in your experiment’s config file change the frequency to (lower band edge-7600). Using v469a as an example, channel 1′s lower band edge is 8409 MHz. The first line in the dbbc_config_file_v469a.txt is then 1 dbbc2.bit 809.00 16. Repeat for all needed channels and leave unused channels alone.
  • Load the configuration into the DBBC with the DBBC Client command load=dbbc_config_file_v469a.txt
  • Reconfigure the DBBC with reconfig
  • Use the DBBC Client to send the command dbbcform=geo
  • Set up the IF inputs. I’ve assumed that the observing frequencies for X-band are between 8112 and 8624 MHz which is normal for the LBA.
    • Send these commands:
      dbbcifa=1,agc,1
      dbbcifc=2,agc,2
      pps_sync
  • For RCP, confirm that the crossover switches are in the direct position. It’s easiest to do this by starting up a system monitor. Connect to ops4 with ssh -X observer@ops4 and run monitor_system.pl. Select the relevant telescope & check the settings of the “Cross-over switches”. For LCP, the crossover switches should be crossed.
  • Check the mk5b_mode line in the /usr2/proc/v469ake.prc file. For 8 channels it should be mk5b_mode=ext,0×0FF000FF,1.

Starting and monitoring the schedule

Once the schedule is prepared and the DBBC config file is ready, you should be able to start up the experiment following the usual recipes for IVS observations (Auscope Wiki. I’ve included the link to the older documentation which describes using the VNC sessions to control the system. If the observation is being monitored from the AuScope control room, use e-remote control, but generally the VNC sessions are fine.

If you’re starting a fringe check, be aware that there will be no autocorrelation spectra produced. The exported files will be put into /data/ on mk5ke.

A short checklist is

  • Start the FS on pcfske
  • Configure the DBBC (as above)
  • Load the procedure with the oprin commands proc=v465ake and setup01
  • Run fmset if needed (from am oper@pcfske terminal, not the operator input)
  • Make a test recording & check the Autocorrs & bit stats (if using the main schedule). Use these commands in the oprin (leave a few seconds between each)
    • disk_record=on
      disk_record=off
      scan_check
      postob
  • Check difference between results of clkoff and maserdelay are nominal (difference should be <0.3 microseconds and stable)
  • Start the schedule with schedule=v465ake

During the run, make sure that

  • The telescope is onsource
  • There are no mark5 recording errors
  • clkoff and maserdelay are within 0.3 microseconds of eachother
  • That the autocorrs/bit stats look sensible
  • Systemp readings are nominal (Tsys readings are kludged in. If the experiment is recording a single polarisation both tsysS and tsysX will report whatever that is. For dual pol, tsysS is RCP and tsysX is LCP)

One difference from usual observing is that the postob procedure will also pop up a window listing the bit statistics of the recorded data. The observer should check this regularly to make sure it stays at near to the nominal 18/32/32/18 distribution (±2%).

If monitoring from Mt. Pleasant, use pmSTALMke.sh to monitor the alarms. If you want the station alarms to go off when there’s an error (rather than playing a sound through the speakers), use pmSTALMke.newsmerd.sh. I’d recommend changing the title of the terminal window to make it clear which alarms are from which station…

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Page last modified on August 14, 2013, at 01:12 AM