User Guide

Section 11: Akula Stations
11-23
When Active Intercept detects an active sonar ping, a line is seen on the
active intercept display on the bearing of the contact. The strength of the
signal is represented as a bank of colored lights directly below the display
that glow from green to red as the signal grows in strength.
In addition to the circular Active Intercept Display the Active Intercept
Station contains the following fields and buttons.
FREQUENCY (HZ): Displays the frequency of the intercepted signal.
(Active Sonar Frequencies for platforms and torpedoes as modeled in
S.C.S. – Dangerous Waters can be found in the USNI Browser in the
SENSORS entry.)
BEARING (DEG): Displays the bearing of the intercepted signal.
INTERVAL (SEC): Displays the interval between the last two signals.
AGE (SEC): Displays the time in seconds since the last signal.
MARK: Assigned a Contact ID on the selected signal and sends the
bearing information to TMA. Each time MARK is clicked when the signal is
selected, the current bearing of that contact is sent to TMA, and the Nav
and Fire Control maps.
 Click the signal lines in the Active Intercept Display to select it,
then click MARK.
SIGNAL STRENGTH: Indicates the strength of the selected signal. Green
indicates a weaker signal, red a stronger one.
Active Intercept Display: A line from the center of the circular display to its
outer edge indicates the bearing of an intercepted signal. Thick lines
indicate strong contacts.
AKULA SSP SONAR STATION
The Sound Speed Profile (SSP) Station displays the speed at which sound
is transmitted at various water depths in the area around Ownship. Ocean
water typically forms distinct layers of density that can profoundly affect
sonar transmissions. Warmer, less dense water forms the upper surface
duct—below this, temperatures fall off sharply and density increases. The
effect of this process is sound generated in one layer doesn’t tend to
transmit easily to the other layer, and vice versa. At the beginning of any
mission, always check the depth at which the surface duct separates from
the lower thermal. (See Training/Sonar School/Underwater Sound
Propagation for more information on thermal layers.)
The Sound Speed Profile is created from information returned from an
Expendable Bathythermograph (XBT) probe. When launched, the probe
reports depth and sound speed information in both graph and table form.
Launching an XBT probe
The results of the last XBT probe are visible in the display window and on
the tablet when the SSP station is first entered.