SMILS
The
Sonobuoy Missile Impact Location System (SMILS) combines airborne equipment with
prepositioned Deep Ocean Transponder (DOT) arrays located on the ocean floor in various
parts of the world to enable accuracy scoring of ballistic missile impacts during test
firings. It uses an array of sonobuoys launched from the support aircraft to gather
background acoustic information from the ocean environment and navigation information from
the DOTs, and transmit this information as audio via RF links to the aircraft where it is
recorded and a database is created. When the ballistic missile reentry vehicles (RVs)
impact in or around the sonobuoy array, the buoys transmit the impact audio to the
aircraft where it is recorded and combined with timing and the previously gathered buoy
navigation data to compute an impact location and time for each RV.
Mission
Description
A SMILS capable aircraft, one of two EC-18Bs in the ARIA
inventory, is flown to the DOT array where the missile is to be targeted. An ALASS probe
(described in the next major section of this appendix) is deployed, followed by an initial
complement of sonobuoys which will determine the ocean drift velocity vector and sound
velocity profile, as well as verify proper aircraft navigation to the center of the DOT
array. The ocean drift and sound velocity data are then used to determine the size and
location of the final array of sonobuoys to be launched, and the wind velocity vector from
the ALASS is used to determine sonobuoy launch points, especially during high altitude
sonobuoy launches (allowable sonobuoy launch altitudes range from 1,000 to 20,000 feet).
Next, the SMILS operator generates a set of waypoints for the aircraft flight pattern,
including the launch points, and sends them to the aircraft inertial navigation system
(INS) via a MIL-STD-1553 data bus. The aircraft flight crew then uses these waypoints to
either automatically or manually fly the aircraft through the launch pattern. During this
time, the launch technician loads the appropriate sonobuoys into the launch tubes at the
times designated by the launch controller, which automatically launches the buoys at the
proper waypoints. The final array consists of 16 buoys, all of which have their data
recorded on magnetic tape and 8 of which are navigated in real time by the acoustic
navigator. As the RV impacts occur, impact data from all 16 buoys is recorded for later
analysis and accuracy scoring, and the acoustic navigator uses the selected 8 navigated
buoys to compute a near real time score (number of impacts inside or outside the array
within 30 minutes, geodetic locations within 6 hours).
System Description
The onboard systems are grouped into two subsystems - the
sonobuoy subsystem and the instrumentation subsystem. The two subsystems are linked via a
MIL-STD-1553 data bus and various operator interfaces.
Sonobuoy Subsystem
The sonobuoy subsystem consists of hardware and software
necessary to launch sonobuoys and meteorological (ALASS) probes from the aircraft. It
includes a launch controller, two sonobuoy storage racks, five launch tubes, and an On Top
Position Indicator (OTPI).
Launch Controller
The launch controller is a microprocessor controlled
device which manages the launching of sonobuoys. It provides sonobuoy data and
subsystem status to the system controller (discussed later), and receives launch sequence
data and firing commands from the system controller, all via a MIL-STD-1553 data bus. It
also contains a keypad, displays, and indicators to provide an operator interface.
Sonobuoy Storage Racks
Two separate storage racks are provided for storage of
sonobuoys for up to three separate missions. The upper storage rack, located in the main
cabin, provides storage for up to 24 sonobuoys in their launch containers (SLCs). The
lower storage rack, located in the aft baggage compartment, provides storage for up to 48
additional sonobuoys.
Launch Tubes
Four size "A" (approx 5-inch diameter) launch
tubes are provided for ejecting size A sonobuoys from their SLCs. These tubes are
internally reloadable and pressurized, and are controlled by the launch controller.
Additionally, one size "B" launch tube is provided for gravity dropping ALASS
probes or other items up to 8-inches diameter. The aircraft must be depressurized to use
the gravity drop tube.
On Top Position
Indicator
The On Top Position Indicator (OTPI) is a receiver and
antenna system which when coupled to the aircraft automatic direction finder (ADF) allows
the pilot to locate a reference point directly over a sonobuoy dropped in the water. This
is used as an auxiliary aircraft navigation aid when the sonobuoy has been navigated
relative to the DOT array.
Instrumentation
Subsystem
The instrumentation subsystem consists of hardware and
software necessary to receive, record, and process the transmitted sonobuoy signals to
determine the accuracy of the ballistic missile impacts. It includes the following
equipment: sonobuoy receivers, patch panel, system controller, control and display
terminal, plasma display, acoustic navigator, digital tape recorder, two data recorders,
and a visicorder.
Sonobuoy Receivers
The sonobuoy receivers are used for reception of sonobuoy
signals on any of 31 preset VHF frequencies. Sixteen channels can be received
simultaneously.
Patch Panel
The patch panel, or signal distribution chassis, provides
signal interconnect, buffering, and conditioning for audio, timing, and test signals.
System Controller
The system controller, based on two Motorola MVME-135
CPUs, provides central computer control for the SMILS system. It accepts premission
initialization data from digital tape, IRIG-B timing from the ARIA timing system, and
navigational data from the INS. It provides for the 1553 data buses, computes buoy launch
waypoints and transmits them to the INS, transmits buoy launch commands to the launch
controller, and monitors system health and status.
Control and
Display Terminal
The control and display terminal (CDT) provides the
operator interface for controlling the instrumentation subsystem computerized functions.
It is an I/O gas plasma device with 100 programmable switches capable of generating
characters, symbols, graphics, and labels. It is used to display menus and receive command
inputs from the operator.
Plasma Display
The PD-3000 plasma display provides the main alphanumeric
and graphics displays to enable the operator to gather information on system and mission
status.
Acoustic Navigator
The acoustic navigator, based on three Motorola MVME133XT
CPUs, gives the capability of onboard near real-time RV impact scoring. It calculates and
stores the ocean sound velocity profile, monitors the received baseband acoustic signals
for significant events (including DOT interrogate pings, DOT response pings, sonobuoy
surface locator pings, and RV impacts), detects and classifies these events, and navigates
the sonobuoys in real time in order to fix RV impact locations and times.
Digital Tape Drive
The digital tape drive is used to load mission
initialization data (including mission date, sonobuoy inventory, DOT array center
location, DOT positions relative to center, and historic sound velocity data) into the
system controller.
Data Recorders
Two 14-track wideband group II tape recorders are used to
record baseband acoustic data from the sonobuoys and IRIG B timing. The recorders are
normally configured for 7.5 inches per second, all FM tracks, but can be reconfigured for
higher speeds and other combinations of direct and FM tracks.
Two associated systems are the Air Launched Atmospheric
Sounding System ALASS and the Optics
system. |
