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Finding the best delay offsets

FILE IN INTER_DATA:01-dec-1992 ! load the current data file
SET SUBBANDS L01 to L04        ! use all subbands, which
                               ! should be have close to equal phase offsets.
                               ! delay is more accurately determined. 
SET BAND LOWER                 ! select lower side band for instance
SET Y PHASE                    ! 
SET X I_FREQ                   ! Intermediate frequency  as X axis
SET SCAN 1234                  ! or SET NUMBER n 
FIND                           ! 
SOLVE DELAY /PLOT
The optimum delay is actually the differential delay between first and last antennas of the baseline in question. It should be entered in the data file for the first antenna, or its opposite entered in the data file for the second antenna (or possibly shared between them along these lines). Be careful to determine the delay with enough precision, in order not to introduce a slope in the phases (1 nanosecond produces 0.5 turn in the 500 MHz passband).



Gildas manager 2018-02-17