FIELDS


The FIELDS program uses the Green's functions calculated by SCOOTER or SPARC and produces a shade file that contains a sequence of snapshots of the acoustic field as a function of range and depth.

 

Files:

 

        Name           Unit         Description

Input

        *.FLP            1       FieLd Parameters

        *.GRN           20       GReen's function

Output

        *.PRT            6       PRinT file

        *.SHD           25       SHaDe file

 

 

EXAMPLE AND DESCRIPTION OF FLP FILE:

 

'RDB'                        ! 'R/X (coord), Lin/DB, Pos/Neg/Both'

200.0  220.0  501            ! RMIN, RMAX, NR

 

 (1) - OPTIONS

 

      Syntax:

         OPT

      Description:

         OPT(1:1): Coordinates

                  'R' Cylindrical (R-Z) coordinates.

                  'X' Cartesian   (X-Z) coordinates.

         OPT(2:2): Spectrum

                   'P' Positive (recommended)

                   'N' Negative

                   'B' Both positive and negative

The spectral integral should formally be done from all along the real k-axis, however the negative portion contributes significantly only in the near-field.  Run-time is less if it is neglected.

         OPT(3:3): Interpolation type

                  'O' POlynomial (for broadband runs) (default)

                  'A' PAde       (can produce better results for CW runs but is less reliable)

The Pade option (OPT(3:3)) is less robust. Use polynomial interpolation if an underflow/overflow occurs ...

         OPT(4:4): Selects a source beam pattern

                       '*' Read in a source beam pattern file.

                       'O' Omnidirectional (default).

 

 (2) - RECEIVER RANGES

 

       Syntax: RMIN  RMAX  NR

 

       Description:

          RMIN: First receiver range (km)

          RD:   Last  receiver range (km)

          NR:   Minimum number of receiver ranges

The actual number of ranges used is increased slightly to satisfy FFT sampling requirements.