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lbaops:parkesobservingsummary [2015/03/23 14:37]
chris.phillips
lbaops:parkesobservingsummary [2018/09/05 16:26] (current)
chrisphillips [Overview]
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- +======  Parkes Observing ======
-======  Mopra Observing ======+
  
 =====  Overview ===== =====  Overview =====
  
-Mopra antenna control and IF setup is all run from terminal based program called vlobsThis is similar //but not the same// as caobs at Narrabri. The VLBI backend consists of two "LBA DAS" which sample and filter the IF and the LBADR recorder which captures the sampled data, formats it in software and writes to local or remote disk (or streams for eVLBI). The DAS setup is controlled via the "DAS GUI" and the recorder via "cdisko2"Some antenna control is one via the simple GUI "attest" (focus, stow, changing attenuation). These are the same for ATCA, Parkes and Mopra and some documentation is available at:+Parkes antenna control is via command line program called atsnapatsnap will run a simple schedule and can take commands to stow/unstow the antenna etc. IF setup is done seperately - normal observers would not normally worry about this. Attenuation is done via the "loGUI" software. The VLBI backend consists of two "LBA DAS" which sample and filter the IF and the LBADR recorder which captures the sampled data, formats it in software and writes to local or remote disk (or streams for eVLBI). The DAS setup is controlled via the "DAS GUI" and the recorder via "cdisko2" These are the same for ATCA, Parkes and Mopra and some documentation is available at:
  
-http://www.atnf.csiro.au/vlbi/wiki/index.php?n=Main.ObservingNotes+https://www.atnf.csiro.au/vlbi/dokuwiki/doku.php/lbaops/observingnotes 
 + 
 +All Antenna and VLBI control is from the joffrey:1 VNC. The joffrey :2 VNC is not used.
  
 =====  Antenna control ===== =====  Antenna control =====
  
-The antenna is controlled via a terminal based program called vlobs on bigrockIf it is not running just type "''vlobs''" on a terminal on bigrock To start a schedule type:+The antenna is controlled via a commandline program called atsnap, run on joffreyAll LBA schedules should be in the directory ''~pksobs/lba''Assuming the antenna is unstowed you can simply run a schedule as:
  
- > file <SCHEDULENAME+  cd ~/lba 
- > start+  atsnap vt999a.psn
  
-The schedule name will generally be the name of the experiment. When you type "file" check carefully it really loaded the schedule - if you have a typo in the schedule name or the schedule does not exist there is not an obvious error issued. There is no need to "unstow" the antenna.+where vt999a, in this example, is the name of the experiment.
  
-The useful vlobs commands are:+====  Stowing ====
  
-||align=centre border='1px solid black' width=70% +To stow the antenna, make sure atsnap is not running (^C if it isand on a terminal on joffrey type:
-| file <SCHEDULE> | Load schedule called SCHEDULE.sch | +
-| start | Starting running the loaded UT schedule | +
-| lo_disable |  Stop vlobs adjusting the frequency (use with caution | +
-| lo_enable  | Allow vlobs to adjust frequency based on the running schedule | +
-| set att servo off | Disable vlobs adjusting the IF attenuation. This is the default |+
  
-To stow the antenna, stop the running schedule and stow from attest (see below).+  > atsnap stow
  
-=====  attest =====+Monitor in FROG that the antenna stows.
  
-Use attest to focus the antenna, stow the antenna and adjust attenuation+====  Unstowing ====
  
-====  Stowing ====+Check first on FROG the antenna really is stowed. If so, on a terminal on joffrey type: 
 + 
 +  > atsnap unstow 
 + 
 +Monitor on FROG that the antenna moves out of stow position. The takes a few minutes - do not attempt to move the antenna until the unstow is complete. Note that atsnap does not return error messages - you can only tell the unstow failed by looking at FROG.
  
-Click the "stow" tab on the attest gui. Press "Go" 
  
 ====  Attenuation ==== ====  Attenuation ====
  
-Click the "attentab in attestGenerally you will not have to adjust the coarse attenuation. There are 4 "fine attenvalues corresponding to 2 pols and 2 IFs (A1, B1, A2, B2 where A and B are the two polarisations). Note that the value shown in attest are not necessarily the current valuesThe attest fine value are in steps of **CHECK** 2dB, while the values seen in MoniCA are the actual attenuation in dB. E.g. a fine atten of 3 is actually 6 dB.+Attenuation can be adjusted from "loGUI"If it is not running in one of the VNC windows you can start it from the "Observing Toolsmenu at the bottom left of the VNC 
 + 
 +**//ALWAYS//** remember to click "refresh" on loGUI (bottom left of window) to be sure the settings are up to date.
  
-Generally automatic attenuation  is disabled as it causes various problemsAs the observer you need to monitor the power levels and adjust attenuation as necessaryNote the power levels can be a little off nominal so the attenuation does not usually need to be adjusted more that occasionally if at all.+Use the "C12att" attenuations and "C40att" to adjust attenuation. The C12 attenuators are in two pairs. Usually the left hand pair is connected to the VLBI backend and control each polarisation on both DAS/frequency chainFor some receivers the 3rd and 4th C12att are connected to the VLBI backend. The only way to know is ask (or be told). You can try changing the attenuation and see which has an affect but be sure to remember to set it back to the original value if it had no affect.
  
-  *  The GTP values should be roughly between 1.0 and 5.0 and the SDO values something similar. If these values are way off, the Tsys measurement will fail. +The four C40 attenuations control the two polariation of each DAS separatelyUsually the most left hand C40 controls DAS1 IFP#1 (pol A), the next DAS1 IFP#2 (pol B) etcHowever it is not unusual for there to be a swap between the two polarisaionsWhen you change the values just note which DAS input is affected.
-  *  The DAS "IF level" should be roughly centredThe DAS will cope as long as the IF level is not at the extreme high or low end.+
  
-If either GTP/SDO or DAS levels are too high, add some fine attenuation to the appropriate IF. Similarly if the power levels are too low, remove attenuation.  Note however it is sometime impossible to get a "good" power level for the GTP/SDO and DAS simultaneously.+You should preferably use the C12 attenuations to adjust levels but as these change the values for both DAS you may need to adjust the C40 to allow for DAS specific differences
  
 =====  Monitoring ===== =====  Monitoring =====
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 You should regularly monitor the following every 10-15 minutes You should regularly monitor the following every 10-15 minutes
  
-  *  ATDRIVEMON shows antenna is tracking +  *  Any message on portal chat 
-  *  vlobs is running +  *  FROG shows no errors 
-  *  vlobs Tsys values are sensible (particularly non-zero - see troubleshooting) +  *  atsnap is running 
-  *  GTP/SDO values are within range+  *  Tsys values from MoniCA look sensible
   *  DAS IF level within range   *  DAS IF level within range
   *  Recorder still running   *  Recorder still running
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 =====  Troubleshooting ===== =====  Troubleshooting =====
-  *  **atdrivemon says drive error**: Is it very windy? May be a hardware windstow. If so just wait it out +  *  **cdisko freezes**Try killing the GUI (via window manager or ^C fro starting terminal) and restarting. Killing the GUI should not interrupt the recording 
-  *  **vlobs Tsys shows 0 for one or more IF**. Check SDO/GTP values and adjust attenuation. +  *  **DAS IF power level is out of range**: Adjust attenuation in loGUI (see above) 
-  *  **Frog complains about Focus**: Adjust focus in attest +  *  **Recmon says recorder not connected**: See Recorder Notes
-  *  **vlobs does not start - random characters on terminal**. Try again (and again, and again and again). +
-  *  **cdisko freezes** Try killing the GUI (via windo manager or ^C fro starting terminal) and restarting. Killing the GUI should not interrupt the recording+
  
  
  
lbaops/parkesobservingsummary.1427081872.txt.gz · Last modified: 2015/12/18 16:39 (external edit)