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 ¯27

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:  ¯IPD22498.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯136388876
   traces in file:  ¯21191
      first trace:  ¯317/31 FFID/trace
       last trace:  ¯759/5 FFID/trace


             file:  ¯IPD22719.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137676076
   traces in file:  ¯21391
      first trace:  ¯759/6 FFID/trace
       last trace:  ¯204/36 FFID/trace


             file:  ¯IPD22941.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137489432
   traces in file:  ¯21362
      first trace:  ¯204/37 FFID/trace
       last trace:  ¯257/38 FFID/trace

                              1
 
             file:  ¯IPD23128.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯134812056
   traces in file:  ¯20946
      first trace:  ¯257/39 FFID/trace
       last trace:  ¯694/8 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}
extension is shown with the file names given below.

OB22441
OB22521
OB22541
OB22591
OB22641
OB22691
OB22741
OB22791
OB22841
OB22891
OB22941
OB22991
OB23000A
OB23050
OB23100
OB23150
OB23200
OB23250
OB23300



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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