U.S. DEPARTMENT OF THE INTERIOR / U.S. GEOLOGICAL SURVEY
                                
                                
        U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-13
                                
              International Phase of Ocean Drilling
                Seismic Line 1 Demultiplexed Data
               Cape Hatteras to Mid-Atlantic Ridge
                                
                            DISC ¯31

Demultiplexed Seismic Data

     Each file of seismic data is the disc-image of a SEG-Y
format tape output during the demultiplexing of the original
field data.  The data were written to tape using the 32 bit IBM
floating point format (Barry, and others, 1975).  As the data
were copied bit-for-bit to the CD-ROM file, this format was
preserved.  Each file of sesimic data is named IPD{number}, where
{number} is the first shotpoint in the file.  NOTE: FFID
indicates the Field File Identification Number assigned each shot
as it was recorded.

             file:  ¯IPD26210.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯136775036
   traces in file:  ¯21251
      first trace:  ¯422/13 FFID/trace
       last trace:  ¯866/47 FFID/trace


             file:  ¯IPD26432.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯132758972
   traces in file:  ¯20627
      first trace:  ¯866/47 FFID/trace
       last trace:  ¯296/34 FFID/trace


             file:  ¯IPD26647.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137302788
   traces in file:  ¯21333
      first trace:  ¯296/35 FFID/trace
       last trace:  ¯741/7 FFID/trace

                             1

             file:  ¯IPD26870.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137103272
   traces in file:  ¯21302
      first trace:  ¯741/7 FFID/trace
       last trace:  ¯184/44 FFID/trace



Observer Logs

     The following files are digitized versions of the original
observer's log sheets.  Each file is named OB{number}.{format},
where {number} is the first shot point on the page, and {format}
is the graphic format of the file: PCX, TIF, or GIF.  No {format}
extensions are shown with the file names given below.

OB26200
OB26250
OB26300
OB26350
OB26370
OB26370G
OB26420
OB26470
OB26520
OB26570
OB26620
OB26670
OB26720
OB26770
OB26820
OB26870
OB26920
OB26970
OB27020
OB27070



REFERENCE

Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended
     standards for digital tape formats: Geophysics, v. 40, p.
     344-352.



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