Appendix A10:  Reading OBSIP log files and segy files
Included in this appendix are the following:
Description of the shot log files and matlab function to read this format.  
Description of the SEGY file naming and channel labeling conventions and SEGY documentation
MATLAB files to read the segy files
Shot Log Files
For each line in the seismic survey there is a shot log.  These log files are named according to the convention: MBL0910_###.obsip.  Where ### is the seismic line number followed by a letter (A or R) as necessary.  This naming convention is described in Appendix A2:  MGL0910 Seismic Survey Summary.
WHOI provided the following description of the OBSIPshotFile        
MATLAB function to read_obsip_shotlog.m
SEGY files
SEGY file naming convention
SIO SEGY files contain one channel per file.   For each OBS there are four SEGY files. The naming of the SEGY files and and numbering of the data channels is as follows (where ## is the OBS Number):
  OBS##_L28X/Y_etomo.segy     Channels 0 & 1     = horizontals
  OBS##_L28Z_etomo.segy     Channel 2     = vertical
  OBS##_HYD_etomo.segy     Channel 3    = hydrophone

* For the experimental sites A and B replace 'L28' with 'Tril' and 'HYD' with 'DPG'
** Note: This is different from the numbering system used in the WHOI SEGY headers.  The WHOI channel numbering convention is the one we are currently using in Upicker.

Note: Emilie Hooft felt that there was a problem with the ranges inserted in the SIO SEGY headers.  Distances in the EW direction appeared to be too large.  Distances in the NS direction appeared to be too small.  She could not determine the source of this error in a quick look at the code used.
WHOI SEGY files contain all four channels in one file.   For each OBS there is one SEGY files. The naming of the SEGY file and the numbering of the data channels is as follows :  
obs##_etomo_D$$.segy (where ## is the OBS Number and $$ is the WHOI instrument number)
  Channel 1     = vertical
  Channels 2 & 3    = horizontals
  Channel 4    = hydrophone
* This is different from the numbering system used in the SIO SEGY headers
Note: This channel numbering convention is the one that we are currently using in Upicker.

1/2010: New SEGY file downloaded for OBS 3 from WHOI, this incorporates the correct new clock correction.

Documentation on the SEGY format
WHOI provided the following library: segy.h
MATLAB functions to read the binary segy files used by upicker.  This was modified to:
1.  read_segy.m will load one of four channels of the SEGY data where:
  Channel 1     = vertical
  Channels 2 & 3    = horizontals
  Channel 4    = hydrophone
2. read_segy.m will load either the shot range specified or all shots corresponding to the sequence number of a particular line if the shot number entered is less than 100.
3. make_filename.m  will make the names of the SEGY files using the information in the table whoi_obs.mat.
read_segy.m
make_filename.m
whoi_obs.mat