Continuous calibration

Current status of the continuous calibration implementation at the stations

• 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. Most likely, we will start to use it in EVN session 3/2015. 
• 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.