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 ¯13

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:  ¯IPD7682.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132298244
   traces in file:  ¯24301
      first trace:  ¯565/1 FFID/trace
       last trace:  ¯71/13 FFID/trace


             file:  ¯IPD7935.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132330908
   traces in file:  ¯24307
      first trace:  ¯71/1 FFID/trace
       last trace:  ¯577/19 FFID/trace


             file:  ¯IPD8188.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132369016
   traces in file:  ¯24314
      first trace:  ¯577/20 FFID/trace
       last trace:  ¯83/45 FFID/trace

                             1

             file:  ¯IPD8441.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132216584
   traces in file:  ¯24286
      first trace:  ¯83/46 FFID/trace
       last trace:  ¯592/43 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.

OB7650
OB7700
OB7750
OB7800
OB7850
OB7900
OB7950
OB8000
OB8050
OB8100
OB8131
OB8131G
OB8181
OB8231
OB8281
OB8331
OB8431
OB8481
OB8531
OB8581
OB8631
OB8681


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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