[daip] [!7690]: AIPS - How to remove the 'RFI' in VLBA continumm observation data?

[Hui Zhang]

Hui Zhang updated #7690
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              Status: Open (was: Response Overdue)

How to remove the 'RFI' in VLBA continumm observation data?
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           Ticket ID: 7690
                 URL: https://help.nrao.edu/staff/index.php?/Tickets/Ticket/View/7690
           Full Name: Hui Zhang
               Email: hzhang at shao.ac.cn
             Creator: User
          Department: AIPS Data Reduction
       Staff (Owner): -- Unassigned --
                Type: Issue
              Status: Open
            Priority: Default
                 SLA: NRAO E2E
      Template Group: Default
             Created: 03 December 2015 11:32 AM
             Updated: 14 December 2015 09:06 AM
                 Due: 16 December 2015 09:06 AM (2d 0h 0m)
      Resolution Due: 15 December 2015 11:40 AM (1d 2h 33m)



Hi, Amy and Eric,
       Thank you for your reply very much. It is very useful for me,  now I roughly know how to use task 'RFLAG' to flag the 'RFI'. But there was some problems still puzzled me.
When I use the task  'RFLAG', I can set the FPARM(9) and FPARM(10) to control the threshold of NOISE and SCUTOFF,  but it is still hard to 
adjust these two parameters (or other parameters of FPARM) to get perfect results (keep all good data and get rid of all bad data). From the results plotted  by POSSM, there
are still some bad channels  existed, I think it is impossible to get rid of all of them just use 'RFLAG', and even I use 'EDITR' to flag the bad data for each 
baseline, these bad channels still exist.    Such as the figure in the attachment:  I use 'RFLAG' to flag the RFI, and then I use 'EDITR' to flag the obvious
bad data for each baseline, each IF and each Pol,  but when I apply the final  'FG' table to 'POSSM', the bad channels still exist, only have a little change.

       So my questions are:  
        (1) What's the usually method to flag the remained bad data  after I used the task 'RFLAG'?
        (2) When should we flag the 'RFI'?  After or before the amplitude calibration? Or even after the fringe fitting?
        (3) When should we stop flagging the remained RFI without affect the result too much? Especially when the data is very large, 
               it is time consuming to flag the remained RFI for all the baselines one by one.

        Thank you very much for your help.

Best Regards,
Hui Zhang 
     



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