Odetics setup:OBS prep:OBS deployment:Shoot line:OBS recovery:Post deployment calibration:Data recovery:
OBS data acquisition
The general sequence of events for obs data acquisition:
Odetics setup:
- Setup the GPS antenna and odetics box, and check that it is acquiring satellites. The clock needs at least a few hours to get an accurate time.
- Run the BNC cable from the shot firing equipment (connected to the CBT (?) connector) to the shot logging laptop.
- Setup odetics box to control airgun shots, use 'shotlog.vi' (a Labview program) to log the shot times in GPS (GMT) time. Ensure that the position mode is set to DYNAMIC. The black odetics box seems to be the most reliable. The output pulse from the odetics box should be changed to a pulse width of 0.01s and a voltage of 4v.
OBS prep:
- Calibrate clock, and setup OBS software. Attach RAs, anchor, burn wire, and rope canister. Best to note all details in a spreadsheet at this point, instead of later.
OBS deployment:
- trun pinger on, log drop time, position and water depth.
Shoot line:
- have shotlogger set up and working prior to starting the actual line.
OBS recovery:
- have direction finders and acoustic control unit (pinger) ready.
- send release signal to OBS, and watch for ascent on the 12.5 kHz sounder.
- when at surface, retrieve with long pole or hook.
- note the time for signalling the OBS, start of ascent, time on surface, time recovered, and position recovered.
- condition o-rings in RAs (optionallly remove batteries), remove rope canister, wash off float and instrument.
Post deployment calibration:
- note CPU (heffler clock) offset, and measure offset using odetics clock. Capture all commands used on command line.
Data recovery:
- Details on downloading of datafiles and conversion to SEGY is discussed on ObsDataDownloading.
