View page
Talk page

Continuous calibration

Modified 15:30, 6 Nov 2015 by junya | Page History

    Version as of 15:52, 23 Nov 2024

    to this version.

    Return to Version archive.

    View current version

    Table with the current status of the EVN stations for the continuous calibration (band dependent)

     

    Current status of the continuous calibration implementation at the stations

     
      L Band C band M band X band K band Q band Last updated
    Ar              
    Bd              
    Ef Available Available Available Available Available Available 18-06-2015
    Hh Not yet Not yet Not yet Not yet Not yet N/A 18-06-2015
    Jb              
    KVN - - - - No No 10-06-2015
    Mc No(work in progress) No(work in progress) No(work in progress) No(work in progress) No(work in progress) - 11-06-2015
    Mh - - - No Tested in lab No 09-06-2015
    Nt              
    On Available Available Available Available No No 06-11-2015
    Sr Not yet   Not yet   Not yet   24-06-2015
    T6              
    Tr              
    Sh              
    Sv              
    Wb in progress in progress in progress in progress     06-11-2015
    Ys - 80 Hz 80 Hz 80 Hz not tested No 5-06-2015
    Zc              

     

    • The DBBC allows to detect synchronously an 80 Hz signal integrating the power from the cal off and cal on phases.
    • The 80 Hz signal can be obtained from output "Cont Cal".
    • Continuous cal can be enabled by typing:
      • cont_cal=on (at the FS)
    • In some cases the signal is inverted and you can get negative Tsys. This is a pending issue to be solved. It can be solved by patching the FS, but this solution should be avoided in the future and look for a cleaner one. The DBBC allows to invert the signal but this does not work at V105 version yet.
    • The file of station.prc should be ready to switch between continuous calibration for some bands and traditional calibration for others. How to properly set it? See the document of /usr2/fs/misc/dbbc.txt
    • Note that your noise source should have a Tcal on the level of ~1 K rather than ~10 K. 
    • Onsala -- we have just tested the latest firmvare DDC V105 (version on 2015 Jun 10) which allows to swap the total power sampling between the Cal-On and Cal-Off registers. Now, our FS can do the proper measurements of Tsys, On-off, and Fivept at Onsala. The system is functional now. We have switched it on during N15L3. We are going to reduce Tcal from ~10 K to ~1 K and then start to use it in the user experiments at L and C bands in session 1/2016. The X-band 80Hz calibration hardware is also ready now. while its usage may be delayed as we have to get agreement from our Geo-VLBI experts. 
    • Hart -- we are working on implementing this on our 15m first as a test bed to see how well our solution will work.  At the moment we are still waitin gon components for that.