[daip] Request for FITLD modification for DiFX data

[Walter Brisken]

OK -- I'll change the keyword to CORRELAT.

My brief perusal of FITLD.FOR suggest that once DIFX is detected as the 
correlator that the change will be very simple.

-Walter

On Wed, 11 Jun 2008, Eric Greisen wrote:

> Walter Brisken wrote:
>> The software correlator produces output data that is nearly identical to 
>> that of the hardware correlator.  I have found one difference that requires 
>> a minor change to FITLD.
>> 
>> First, one can identify data produced by DIFX by looking at the FITS 
>> header.  There will be a line
>> 
>> CORR    = 'DIFX'
>> 
>> at the top.  Feel free to suggest alternatives to this if this is not 
>> appropriate.  I continue to set TELESCOP = VLBA and ORIGIN = VLBA 
>> Correlator.
>> 
>> The change requested for DiFX is as follows:  The digital saturation 
>> parameter, called SATUR in FITLD, should always be set to 1.0 for data from 
>> DiFX.  This parameter is very tersely described in vlba scientific memo 12.
>> 
>> As far as I can tell, all of the other corrections made for VLBA correlator 
>> data also apply to DiFX correlated data.
>> 
>> Thanks,
>> 
>> Walter
>> 
>> 
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> CORR is used for correction too much.  At present we do not detect unknown 
> keywords so FITLD would have to recognize some new one.  OROGIN really is 
> supposed to be VLBA or perhaps NRAO an institution.  So we should have a 
> correlator keyword - how about CORRELAT or perhaps CORLATOR which is better 
> as a mnemonic if poorly spelled.  The former follows the rule of correct but 
> truncated spelling.
>
> As for actually making these changes - we will see - I know nothing about 
> SATUR.
>
> Eric
>