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 ¯11

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:  ¯IPD5850.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯132897084
   traces in file:  ¯24411
      first trace:  ¯424/13 FFID/trace
       last trace:  ¯677/60 FFID/trace

             file:  ¯IPD6047.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯133942332
   traces in file:  ¯24603
      first trace:  ¯27/1 FFID/trace
       last trace:  ¯424/12 FFID/trace

             file:  ¯IPD6246.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯119395964
   traces in file:  ¯21931
      first trace:  ¯673/18 FFID/trace
       last trace:  ¯26/62 FFID/trace



                              1

             file:  ¯IPD6422.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯134067544
   traces in file:  ¯24626
      first trace:  ¯275/29 FFID/trace
       last trace:  ¯673/17 FFID/trace

             file:  ¯IPD6621.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1301
      data length:  ¯5204 msec
  bytes per trace:  ¯5444
    bytes in file:  ¯85648608
   traces in file:  ¯15732
      first trace:  ¯881/46 FFID/trace
       last trace:  ¯275/28 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.

OB5810
OB5860
OB5910
OB5960
OB6010
OB6060
OB6110
OB6160
OB6160G
OB6210
OB6260
OB6310
OB6360
OB6410
OB6460
OB6510
OB6560
OB6610
OB6660
OB6710


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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