environmental software is interfaced with NTDS,
shipboard Aerographer’s Mates have indirect access to
the bathythermograph output.
On temporary
deployment, mobile environmental team members may
need to manually enter the bathythermograph output
into the Mobile Oceanography Support System
(MOSS) terminal.
The AN/BQH-7A may be connected to two
launchers at the same time, although only one is used for
each sounding.
This system uses both a hand-held
LM3A launcher (fig. 2-6) and the MX-8577/SSQ-61
through-the-hull launcher. The hand-held launcher
may also be used with all of the AN/SSQ-(series)
systems.
The same T-4 XBT probe is used with the
AN/BQH-7A system. In addition, the AN/BQH-7A
also accepts the T-5 6,000-foot-deep ocean scientific
probe, the T-7 2,500-foot improved sonar prediction
probe, and other specialized probes. By using any of
these probes, you can make the chart recording as either
a depth/temperature trace or as a depth/sound velocity
trace. Selection is made with the “strip chart output”
selector switch, located just above the chart door.
Sound velocity is internally calculated based on the
measured temperature and a standard salinity of 35%.
The tape may be replayed to produce either a
temperature or a sound velocity trace. Normally, the
temperature trace is recorded first, evaluated and
encoded for transmission, and then the sound velocity
trace is recorded for direct use by the shipboard Sonar
Technicians.
The AN/BQH-7A also uses a different type of
probe called an Expendable Sound Velocimeter (XSV)
probe. The standard model is the XSV-01, that
conducts sound velocity measurements to 2,790 feet
(850 meters), and is shown in figure 2-7. An XSV probe
uses a special sensor that produces an internal acoustic
signal. The integrated circuitry of the probe then
calculates the sound speed, factoring in the temperature,
pressure, and salinity of the water. The sound speed
values produced by an XSV are direct measurements.
When this probe is used, the chart output selector is
disabled and only a sound velocity profile is produced.
These probes are recommended in areas where the
salinity of seawater is historically different from the
standard 35%, and when salinity varies with depth.
When soundings are conducted by using this type of
probe, a standard temperature probe must still be
dropped to fulfill data collection requirements.
Detailed operating procedures are covered in the
operator/technical manual Technical Manual for
Figure 2-6.—LM3A hand-held launcher.
Bathythermograph/Sound Velocimeter AN/BQH-7A
Oceanographic Data System Surface Ship Application,
NAVSEA SE365-BA-MMO-010/BQH-7A.
Maintenance
Preventive and corrective maintenance are
thoroughly covered in the operator/technical manual.
Preventive maintenance includes recommended
weekly testing of the system output using a test probe,
a monthly launcher cleaning and inspection, a
quarterly test device performance procedure, a
semiannual recorder and processor cleaning and
inspection, and an annual check of the cable’s
signal/ground continuity and insulation resistance. At
the beginning of each sounding, the operator must
ensure that the ready-for-launch mode stylus alignment
is made. With an XBT probe in the “temperature”
mode, align the stylus at 62.0°F (±0.3°F). and with an
XSV probe, align the stylus at 4,962 feet per second.
Columns are predrawn on each recording chart for these
readings as well as for other calibration measurements.
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