User Tools

Site Tools


development:gnss_calibration

This wiki is not maintained! Do not use this when setting up AuScope experiments!

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
development:gnss_calibration [2020/11/18 03:23]
Tiege McCarthy
development:gnss_calibration [2021/01/25 00:42] (current)
Tiege McCarthy
Line 19: Line 19:
  
   * **Spectrum analyser traces:** When I got out here the spectrum analyser was not showing the expected spectrum despite L-band being on axis. Removing cable produced no change in the output, looks like after it was unplugged it needed to have the '​pre-set'​ button pushed (I think) in order for it to switch to the 'RF in' input. In the process of troubleshooting this I seem to have changed the behaviour of trace 1 and am not sure how to change it back to how it was. Trace 2 is still set to a 100 count average.   * **Spectrum analyser traces:** When I got out here the spectrum analyser was not showing the expected spectrum despite L-band being on axis. Removing cable produced no change in the output, looks like after it was unplugged it needed to have the '​pre-set'​ button pushed (I think) in order for it to switch to the 'RF in' input. In the process of troubleshooting this I seem to have changed the behaviour of trace 1 and am not sure how to change it back to how it was. Trace 2 is still set to a 100 count average.
-  * **Tracking testing:** Testing the shell wrapper calling the 5 minute block schedules. All seems to run fine so far - Looks like it takes between 60s and 120s for the telescope to settle between schedule blocks - will need to take this in account for when we should be pulling from the spectrum analyser. +  * **Tracking testing:** Testing the shell wrapper calling the 5 minute block schedules. All seems to run fine so far - Looks like it takes between 60s and 120s for the telescope to settle between schedule blocks - will need to take this into account for when we should be pulling from the spectrum analyser
-  * **Recording from Spectrum Analyser:** I have written a very ugly script that currently grabs trace outputs from the spectrum analyser every 5 seconds during valid time periods (currently from 90s past the start of the scan to the end time). Between the 5 minute blocks it averages all grabbed spectra together and writes them to a file with the timestamp of the scan.+  * **Late start tracks:** The current wrapper when run after the schedules start time will try each of the blocks in order until it finds one with a tracking point in the future - this is OK, but it takes a long time to iterate through all the previously observed blocks (~20s for each 5 min block - ~4 mins per hour of catchup). Not a big deal if you are only starting the track <1hr late, however, longer than this and you start to lose a significant amount of your observing time just catching up. Will need to look into a better solution for this - I have a solution which would work for python but need to look into what is possible in the shell script
 +  * **Recording from spectrum analyser:** I have written a very ugly script that currently grabs trace outputs from the spectrum analyser every 5 seconds during valid time periods (currently from 90s past the start of the scan to the end time). Between the 5 minute blocks it averages all grabbed spectra together and writes them to a file with the timestamp of the scan
 + 
 +**Nov 19, 2020:**: 
 +  * **Late start tracks:** The bash script generated during schedule generation has now been updated to include '​if'​ statements with time conditions - this should fix any issues with starting tracks late. Current version of the scripts can be found on my github in a repository named '​antenna_thrust_scripts'​ (https://​github.com/​tiegemccarthy/​antenna_thrust_scripts) (Tiege) 
 + 
 +**Dec 2, 2020:**: 
 +  * **Schedules** Two tracks prepared for this day - one for KOSMOS 2461 (R735) and one for GPS IIRM-8 (G050) (Tiege) 
 +  * This day was cancelled due to high winds - had a meeting with Lucia, Jamie and Guifre instead. Tracking postponed until next week. (Tiege) 
 + 
 +**Dec 8, 2020:** 
 +  * Another cancellation,​ this time due to post-LBA maintenance on the cryo system. (Tiege) 
 + 
 +**Dec 11, 2020:** 
 +  * **Remote track on GPS IIRM-8:** fixed a few issues with the observing setup. First issue was time stamps in the shell wrapper not working on newsmerd - the date command was for some reason reading them as GMT+7 timezone despite the default output of date being in UTC. This has since been fixed. (Tiege) 
 +  * Also fixed a bug in the recording script that occasionally caused a type error when writing out the data with numpy.savetxt(). (Tiege) 
 +  * Wrote a script for doing manual (not scheduled) recording using the spectrum analyser - will be useful for when we need to calibration scans on quasars. (Tiege) 
 + 
 +**Dec 15, 2020:** 
 +  * **Draft observing guide:** I have written a rough guide outlining the steps required in order to undertake the GNSS tracks and recording which currently exists [[https://​docs.google.com/​document/​d/​1ZQYY4cJqCG02h52L18jyCAuboBhCwgeG2JhKxVYTsHk/​edit?​usp=sharing|on my google drive]] (Tiege) 
 + 
 +**Jan 21, 2021:** 
 +  * **GPS050 tracks:** Finally have a run not being cancelled by weather. Running a full track of GPS050 today (and hopefully tomorrow pending weather) - trying a 3 degree offset on offsource scans as 1 degree was too little in our last run with valid data. Also trying some new spectrum analyzer settings - keeping RBW at 3 MHz and VBW at 10 MHz, but changing span to 999 MHz and sweep points to 333, this should remove the need to resample the data when reducing the data - should know by tomorrow. Ideally we will get another couple of tracks on this source next week to check experiment to experiment repeatability of the results. 
 +  * **Flux calibration** Assuming wind remains pleasant, will get some data on a couple of bright quasar sources - 1934-638 is a little too weak for our setup. Would also be good to get multiple sources so we can check SEFD estimations. Ended up getting a scan of 3C353. ​ (Tiege) 
 + 
 +**Jan 22, 2021:** 
 +  * **GPS050 tracks:** Have a full track from Yesterday and a few hours from today. Needed to extend offset to 4 degrees as 3 degrees still had evidence of both L1 and L2 signal in beam. 
 + 
 +**Jan 25, 2021:** 
 +  * **Script changes:** Have changed the recorder to throw out traces from the spectrum analyzer that do not have the expected length - this simplifies data reduction as these traces would need to be removed prior to analysis normally. 
 +  * ** Data reduction:​** Track from Jan 21 has been reduced and didn't seem to have many issues (other than incomplete traces) - off source scans with the 3 degree offset still have signal in them and therefore power levels are underestimated. Jan 22 data seems to have a little bit of signal still in the band unfortunately - not sure if its worth going to 5 degrees. Something seems to have happened in the second half of the track on Jan 22 - looks like L1 and L2 signal disappear completely after a certain time. Perhaps there was a windstow I missed, I will check the logs on newsmerd.
  
  
 **TO DO**: **TO DO**:
-  * **prepare tracks** for 5 min on source off source (for 1 satellite at a time); probably try 1 sec updates; how does sattrack handle this? code up 5 minute tracks to load after each other (run in sequence) - after the track finished, the antenna sits at the final az/el+  * <del>**prepare tracks** for 5 min on source off source (for 1 satellite at a time); probably try 1 sec updates; how does sattrack handle this? code up 5 minute tracks to load after each other (run in sequence) - after the track finished, the antenna sits at the final az/el</​del>​
   * **define spectral analyser output** - pulling & scripting seems to work - but what and how long to write out data?; question what resolution and freq span? Why is TRACE output always 500 points? https://​cdn.rohde-schwarz.com/​pws/​dl_downloads/​dl_common_library/​dl_manuals/​gb_1/​f/​sfl_1/​FSL_OperatingManual_en_12.pdf   * **define spectral analyser output** - pulling & scripting seems to work - but what and how long to write out data?; question what resolution and freq span? Why is TRACE output always 500 points? https://​cdn.rohde-schwarz.com/​pws/​dl_downloads/​dl_common_library/​dl_manuals/​gb_1/​f/​sfl_1/​FSL_OperatingManual_en_12.pdf
   * **SEFD calibration** - need to work out how to do this? VirgoA or Hydra is strong - use on/offs and spec an. Nominal SEFD about 400-500 Jy   * **SEFD calibration** - need to work out how to do this? VirgoA or Hydra is strong - use on/offs and spec an. Nominal SEFD about 400-500 Jy
Line 31: Line 61:
   * **get value table ready** - try to replicate the tracking table Peter Steigenberger sent through; figure out boresight angle etc (Lucia to ask Ron/Peter)   * **get value table ready** - try to replicate the tracking table Peter Steigenberger sent through; figure out boresight angle etc (Lucia to ask Ron/Peter)
   * **have a look at subsequent estimation** - get all the necessary values together, code an estimator? first understand the code   * **have a look at subsequent estimation** - get all the necessary values together, code an estimator? first understand the code
-  * **next track**: booked in next Wednesday (Nov 18) for more tests+  * <del>**next track**: booked in next Wednesday (Nov 18) for more tests</​del>​
   * **next catchup**: booked in Wednesday (Dec 4)    * **next catchup**: booked in Wednesday (Dec 4) 
  
/home/www/auscope/opswiki/data/attic/development/gnss_calibration.1605669836.txt.gz · Last modified: 2020/11/18 03:23 by Tiege McCarthy