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 ¯01

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 Identifacation Number assigned each shot
as it was recorded.

             file:  ¯IPD101.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯143824200
   traces in file:  ¯15565
      first trace:  ¯1/1 FFID/trace
       last trace:  ¯252/3 FFID/trace


             file:  ¯IPD228.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯220793400
   traces in file:  ¯23895
      first trace:  ¯256/36 FFID/trace
       last trace:  ¯643/60 FFID/trace


             file:  ¯IPD422.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯144905280
   traces in file:  ¯15682
      first trace:  ¯643/61 FFID/trace
       last trace:  ¯897/56 FFID/trace

                               1



             file:  ¯IPD549.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯2250
      data length:  ¯9000 msec
  bytes per trace:  ¯9240
    bytes in file:  ¯58492800
   traces in file:  ¯6330
      first trace:  ¯897/57 FFID/trace
       last trace:  ¯999/62 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.

OB101
OB101G
OB151
OB201
OB251
OB311
OB311G
OB361
OB411
OB461
OB511
OB561


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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