The XBT/XSV system uses
a sea water ground. As soon as an
electrode within the nose of the
expendable probe makes contact with
the water, the circuit is complete and
temperature or sound velocity data can
be telemetered to the ship-board data
processing equipment. Data are recorded
and displayed in real time as the probe
falls. The nose of each expendable
probe is precision weighted and the
unit spin-stabilized to assure a
predictable rate of descent. From
this rate of descent, probe depth is
determined to an accuracy of +2%.
When the probe reaches its rated
depth (a function of ship speed and
the quantity of wire contained within
the shipboard spool) the profile is
completed and the system is ready
for another launch.