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Systems and Sensors


Alvin maintains frequent communication with the support ship during each dive and at all operating depths.

Alvin’s UQC underwater telephone, which is compatible with Navy systems, can be used for both voice and code communications with Atlantis. An identical unit on Atlantis can interrogate the submersible for ranges, and Alvin may interrogate the support ship as well. Since Alvin has both “up-“ and “down-looking” transducers, the UQC may be used to echo range to the bottom to determine altitude, or to the surface to determine depth.

A VHF radio with all marine channels is used for communication when Alvin is on the surface. An all-channel portable VHF marine radio is carried as a backup and Atlantis is equipped with a marine VHF radio direction finder. The direction finder receives only marine VHF frequencies; users of VHF beacons should confirm reception capability before planning use of the direction finding equipment.

Kongsberg pan/tilt/zoom (PATZ) camera
(L-R): Framegrabber, navigation, command & control, sonar/science monitors


One of the biggest advantages of using a human-occupied vehicle for science is having the ability to take in the context of the environment firsthand -- to be able to see areas of concentration and sampling within the larger environment.  The addition of two pan & tilt-mounted 4K ultra-high definition cameras along with a real-time 4K and proxy (h.264) video recording system enables closer, more detailed observation and post dive analysis along with improved subsequent dive planning.

Alvin’s imaging system provides native support for twelve SDI video cameras (up to 12G-SDI), up to four HD IP cameras, and four independent pan & tilts.  Note: analog cameras are no longer natively supported.

An iPad imaging system user interface provides camera and pan & tilt controls, real time video monitoring, recorder control with active recording tally light, still image capture, and real time navigation and temperature sensor data display.

Two pan & tilt-mounted Deep Sea Power & Light Optim SeaCam 4K UHD 6,500m-rated cameras are located below the light bar on the port and starboard brow.  The Optim features a 15.5x/12x optical/digital zoom (240x combined), a 78°H x 48°V FOV (in water), and a 350mm minimum object distance at full telephoto that makes for stunning close-up images and brings out the smallest details. The in-hull iPad user interface provides pan & tilt  joystick and camera controls for focus (near/far and auto/manual), exposure mode (auto, manual, shutter priority and aperture (iris) priority), shutter speed, F-stop (iris), ISO (gain), white balance (pilot controlled), and zoom (tele/wide).

For shallow dives (<4,500m), two Kongsberg OE14-522 pan/tilt/zoom HD cameras may be located just above and slightly outboard of the forward-facing port and starboard observer viewports.  The OE14-522 is a high quality, high definition underwater video camera with a 10x optical zoom lens mounted on a movable platform inside the view port, giving pan and tilt functionality with no external moving parts.  The in-hull iPad user interface provides pan & tilt joystick and camera controls for focus (near/far and auto/manual), exposure mode (auto, manual, shutter priority and aperture (iris) priority), shutter speed, F-stop (iris), ISO (gain), white balance (pilot controlled), and zoom (tele/wide).  By default, the speed of the pan and tilt is coupled to the zoom position, i.e., when the lens is at the telephoto position the movements are slow; when in the wide position, the movements are quicker.

Four 6,500m-rated, fixed lens, Deep Sea Power & Light HD Multi SeaCam (domed optics) situational cameras are also installed: one aft looking, one down looking, one on the brow center below the light bar providing a wide field of view of the forward work area, and one dedicated for pilot use installed on a micro pan & tilt above the light bar.

Video Monitors

Along with the video monitoring provided by the iPad web browser user interface, Alvin also includes two Video Assist 7” 12G flat panel displays for in-hull viewing (one for each observer).  The displays (1920 x 1200 pixels) are super bright 2500nit HDR monitors that support 3D LUTs and feature professional scopes along with powerful focus assist and exposure tools that help observers accurately set focus, exposure and frame shots.

Video Recording

ProRes LT Encoded Video Data

Port and starboard video recorders are used to record and store ProRes LT 422 encoded video data (other encoder formats are available).  Each recorder has a total storage capacity of 4TB split over two 2TB solid state drives (SSDs).  The ProRes recorders feature a 12G-SDI connection and support recording SD, HD and Ultra HD (4K) formats up to 2160p60.  All recorded ProRes video contains embedded timecode that is synchronized to the in-sphere NTP time server.

Proxy H.264 Encoded Video Data

Port and starboard proxy video recorders are used to record and store the H.264 encoded 1080p30 proxy video.  Each proxy recorder has a minimum total storage capacity of 256GB split over two 128GB SD cards.  All recorded proxy video contains embedded timecode that is synchronized to the in-sphere NTP time server.

Additionally the in-sphere imaging server’s real-time processing engine generates copies of the port and starboard proxy video data, captures real time navigation metadata, and embeds the metadata in a series of subtitle files for each of the proxy video files.  The subtitle files contain dive details as well as an assortment of time stamped navigation data.

SeaLite Sphere LED lamp


Alvin has twelve independent lighting channels, each 10A, fused at 80A total.

Multiple 10,000 lumen DSP&L SeaLite Sphere 7200 LED lights can be mounted around the sub to illuminate the work area, with one down-looking at the aft end of the sub.  At least four lights mount around the basket and swing arm, with others mounted on the light bar on Alvin’s brow. Lighting can be configured as needed based on dive objectives. Constant current drivers allow flicker free operation, and they are fully dimmable via a GUI on the computer inside the sub.  We have two optional green LED lights on the light bar, which increase visibility at distance.

The Optim 4K pan and tilt-mounted cameras can each carry a pair of parallel lasers which can be used to help determine range, size or area of interest of targets observed on the associated camera.  The beams are 10 cm apart.


Alvin is fitted with two hydraulically powered manipulators on swing arms to increase reach.

The starboard ISE manipulator has six degrees of movement: shoulder pitch and yaw, elbow pitch, wrist pitch and rotate, and jaw open and close.  The manipulator has a maximum extension of 72 inches and a lift capacity of 100 pounds at maximum extension. Remote operation is controlled by a switch panel in the personnel sphere. The arm may be viewed from either the front or starboard side viewports during operation and can be fitted with a hydraulic actuator that can be used as a trigger mechanism to operate devices held by the jaw.

The port Schilling Titan 4 manipulator has the same six degrees of movement with the additional capability of wrist yaw. Maximum extension is 75 inches, with a fully extended lift capacity of 150 pounds. Wrist torque is rated at 30 ft/lbs and has a maximum rotational speed of 65 RPM. This arm is controlled by a position feedback master/slave mechanism, with the spatially correspondent master located in the personnel sphere allowing viewing and control through the front and port side viewports. This manipulator can also be fitted with an auxiliary hydraulic ram to trigger special equipment.  A second Titan 4 can be mounted on the starboard side in place of the ISE manipulator.

Manipulators on swing extensions arms
Alvin's manipulator operational workspace
Manipulator jaw dimensions and hydraulic actuator


Alvin’s primary navigation sensors are the Doppler velocity log (DVL) used in conjunction with the fiber optic gyroscope (FOG) and disciplined with ultra-short baseline (USBL) fixes.  Software integrates DVL information with data from all the other sensors on the sub and calculates the sub’s position and distributes the information to the Pilot in real time.  The Pilot can then dial in what the the sub should do:  maintain position over a certain spot to collect a sample (even in a strong current), hold a specified altitude or depth and ‘hover’ there, or follow a course or heading.  “Step” moves are also possible, where the Pilot enters a shift of a desired amount and the vehicle complies.  The scientist could say, ‘I want to spin in one spot’, and the Pilot could command the sub computers to make it happen.

Stern thrusters
Starboard aft thruster
Lift thruster


Alvin’s propulsion system provides precise maneuvering in three axes (X, Y, Z) and is accomplished through the use of seven electrically powered, ducted thrusters and an advanced control system. Thrusters are located as follows:

  • Three mounted at the stern provide forward/reverse thrust
  • Two mounted amidships provide vertical thrust
  • Two mounted horizontally, one at the stern & one forward of the sail, provide lateral thrust for side-to-side motion (“crabbing”) and rotational motion to turn about the sub’s vertical axis

Alvin’s primary positional control is an advanced digital system that incorporates a variety of input devices. Typically the Pilot uses three joysticks that provide proportional control of the sub’s motion in the three directions (X,Y,Z).

Alternate control is provided by a potentiometer/switch panel that allows scalar control along the three axes. Additionally, the system includes a number of propulsion modes including: auto heading, auto altitude, auto depth, auto X/Y, and “Stick Lock”. Selection of the various modes is available on the Command and Control touch screen and via dedicated push-button switches on the Pilot’s panel. The various modes and input methods may be utilized together to provide excellent maneuverability, including precise station keeping in the X,Y and Z axes and command of the sub in incremental steps along each of the axes.

The sub’s command architecture includes a variety of inherent redundancies to accommodate minor issues with the propulsion system and prevent significant impact on dive objectives.

Empty basket platform
Basket with sampling loadout

Science Workspace

Sampling tools are typically mounted to Alvin’s science ‘basket’, a robust and versatile platform located at the front of the vehicle, between the manipulators, and visible to all three occupants. The basket provides a 400-pound payload capability on 16 square feet (48” x 48”) of usable space for sample collecting, science tools, and specialized equipment.  The basket frame provides many mounting options and can be routinely reconfigured to meet the specific objectives of each dive.  The majority of basket preparation and configuration activity typically takes place the evening before a dive; minor adjustments and final preparation of sensitive experiments happen early in the morning prior to the dive.

The science basket assembly is designed to be jettisonable in an emergency, so any instruments on the basket which require hydraulic or electrical power must be fed through a release mechanism supplied by the Alvin Group.  Payload is attached to the basket with standard fasteners, and when possible should be designed with mounting flanges on the bottom that can accept ¼”-20 hardware.

The basket design is modular, and it can be modified for special uses.  The Alvin Group can also design and construct custom baskets or workspaces to accomplish cruise objectives.

Teledyne RDI Doppler Velocity Log (DVL)
Paroscientific depth transducer


Doppler Velocity Log

Alvin utilizes a Doppler Velocity Log (DVL) as a means to accurately measure the vehicle’s position and motion relative to the seafloor. Currently the submersible utilizes an RDI Teledyne Workhorse Navigator operating at an acoustic frequency of 600 KHz.

The DVL provides data at a high sample rate that includes position, velocity, heading (via a flux-gate magnetic compass), vehicle altitude (up to 90 meters above the seafloor), and vehicle attitude (pitch/roll).

When Alvin is near the bottom (<90 meters altitude) the unit achieves “bottom lock” to accurately track the vehicle as it moves along the seafloor. During descent and then again on ascent, the unit achieves “water lock” to track the vehicle as it transits through the water column.

Note that DVL-provided heading and attitude are used by the navigation system to calculate the vehicle’s position and motion. Primary vehicle heading and attitude are provided by the fiber optic gyro (see below). Both gyro and DVL heading as well as DVL altitude are displayed as a part of the Pilot’s command and control touchscreen interface. Other DVL data is available as a part of the vehicle’s output data set and viewable real time on the “Sensors” page of the command and control software.

Sensor accuracy is as follows:

Velocity: +/- 0.1 cm/s (+/- 0.2 %)
Flux-gate compass (Heading): +/- 2.0 degrees
Attitude (Pitch/Roll): +/- 0.5 degrees


Fiber Optic Gyrocompass

Primary vehicle heading and attitude are provided by an iXSea PHINS fiber optic gyro.  The unit provides accurate vehicle heading and attitude (pitch, roll) to the navigation software.

PHINS accuracy is as follows:

Heading: +/- 0.2 degrees


Depth/Pressure Transducers

Alvin is equipped with two Paroscientific pressure/depth transducers. Both are temperature-compensated, precision quartz transducers, mounted symmetrically on the submersible (one on the port and starboard side of the vehicle at the same height and distance from the vehicle center of gravity).  Measured external ambient hydrostatic pressure is used to calculate vehicle depth. The resultant depth data is displayed to the observers on the in-hull tablets in the Metadata section of the imaging system and Sealog interfaces. This information is also available to the pilot on the primary command and control screen and on the “Sensors” page of the C&C software. Depth transducers are routinely calibrated by the manufacturer (typically on a 24-month cycle).

Note: A digital readout for the starboard depth sensor is available to the pilot on the port side of the personnel sphere. This is a redundant gauge that does not utilize the Fofonoff algorithm to convert pressure to depth and is therefore more conservative and less accurate. Users are directed to ignore this readout.

Sensor resolution: 0.1 meter

The Alvin command and control software logs calculated depth in meters and external hydrostatic pressure (PSI). Local parameters (salinity, temperature, latitude corrections) combined with raw pressure may be used to calculate depth (user post-processing).

Pressure conversion is based on: "Algorithms for Computation of Fundamental Properties of Seawater", by N.P. Fofonoff and R.C. Millard Jr. This algorithm assumes a latitude of 30 degrees, a salinity of 35 ppt, and a temperature of 0°C. According to this publication, "the correction for the actual density distribution would be 2 meters or less".

The following table can be used to refine the observed and logged depth by applying a correction for the actual latitude of the dive.

Depth (m)
1000 2000 3000 4000 5000
Latitude 0 1.3 2.6 4.0 5.3 5.9
10 1.2 2.3 3.5 4.6 5.2
20 0.7 1.4 2.1 2.8 3.2
30 0.0 0.0 0.0 0.0 0.0
40 -0.9 -1.7 -2.6 -3.4 -3.9
50 -1.8 -3.6 -5.3 -7.1 -8.0
60 -2.6 -5.3 -7.9 -10.6 -11.9
70 -3.3 -6.7 -10.0 -13.4 -15.0

Obstacle-Avoidance Sonar

A Kongsberg Mesotech 1171 sonar is available for search and obstacle avoidance.  This has a typical search range of over 100m and selectable scan sector width and position.


The trim system allows the pitch angle of the submersible to be adjusted by pumping as much as 500 pounds of ballast between tanks located in the bow and stern.  Normally, this system is used to maintain a level attitude as the load in the science basket varies during a dive, but it also permits the submersible to intentionally pitch bow up or bow down.

Variable Ballast

The variable ballast (VB) system is a fixed displacement, variable mass system that allows the Pilot to adjust the buoyancy of the submersible while at depth in order to achieve neutral, negative or positive trim, as well as provide reserve buoyancy for sampling payloads depending on the mission requirement at the time.

Salt water is added or removed from spherical titanium ballast tanks to effect a weight change of up to 10 pounds per minute. This system can be used to neutralize the submersible’s rate of vertical motion, thus allowing it to hover in the vicinity of a cliff or underwater structure.

Vertical travel may then be accomplished using the lift thrusters. For routine, near-bottom transits, the submersible is ballasted to be near neutral buoyancy. In cases where the bottom consists of light sediment, the Pilot may ballast about 10 pounds “light”, thus allowing the vertical thrusters to be consistently used in a manner which directs their water jets upwards. To prevent drift caused by currents, the Pilot may use the variable ballast system to get 50 to 100 pounds heavy. The amount of variable ballast weight available on each dive is not a fixed number and is affected by the payload on the dive. With advance notice, the ballast system can be configured to provide as much as 500 pounds of variable ballast. An additional negative force of up to 300 pounds can be applied by downward thrust of the lift thrusters for short periods of time. The VB system is both power- and time-consuming, and numerous trim changes will reduce bottom “work” time.

The system consists of two subsystems:  a seawater portion and an auxiliary hydraulic control portion.  The seawater system directs and controls seawater flow and consists of three titanium spheres, a saltwater pump, one hydraulically-operated isolation valve, a flow control valve, a hydraulically-operated directional control valve, a system relief valve, two manual isolation valves, and interconnect tubing. The auxiliary hydraulic system operates the Pilot-actuated seawater isolation valves and directional control valve.

The system is not utilized for any safety-related functions, so its failure will not compromise the vehicle’s ability to return to the surface and be recovered.

Scientific Equipment Interface

The design of the Alvin electrical system includes the capability to interface to a wide variety of science equipment.  In general, though Alvin personnel will do their best to perform the final installation of the equipment onto the submersible, the specific condition or configuration of the vehicle may make one or more of these capabilities unavailable.  To make this go as smoothly as possible, proper planning, testing and communication with the Alvin Group is recommended (also see Pressure Testing for User-Supplied Equipment).  When delivering equipment to the Alvin Group, it is important to provide adequate documentation, including schematics, wire colors, connector types, and test documents (where necessary).

The available volume for additional in-hull equipment is very limited.  In general, only small hand‑held equipment should be considered for in-hull use.  It is best for these to include a connector for their interface cable, so they can be disconnected for storage.


There are a total of 46 through-hull wires available for science equipment use.  These are all 16ga, fused at 10A (fast), and some are in twisted pairs.  Because of wiring constraints, circuits using these conductors must be able to tolerate up to 1 ohm of end-to-end resistance on each wire.  These wires are terminated in-hull in AMP 206838-1 circular plastic connectors (CPCs); the mating connector for this is AMP 206837-1.  Outside, these terminate in one of the Science Basket J-boxes.


There are six power channels available for outside science equipment use.  Each of these is 24V at up to 150W, though full power may not be available from them all at once.  Power channels terminate in one of the Science Basket J-boxes, and are controllable through the in-hull GUI controls.

A high-power channel is also available that can provide 120V at up to 10A.  Specific arrangements must be made before planning to use this power channel.

Additional power channels may be available for in-hull science equipment use, provided through the Data Power Controller.  Voltages of 5V, 12V or 24V may be available, depending on other submersible equipment requirements.

Data System and Acquisition

The Alvin data system consists of sensors, a data transport layer and data acquisition/storage in the form of in-hull computers.  The majority of the sensors are permanently installed, including depth, altitude, CTD, etc., and are serial devices that use a serial to Ethernet bridge (Moxa) to transport data in-hull.  Science wires are available and assigned as needed on a cruise-by-cruise basis if this architecture is not appropriate for your application.  Data can be sent to any address on the network for logging and/or processing.  The in-hull network can be accessed using the installed Alvin computers or via science-provided equipment.

There are four through-hull serial data channels available for external science equipment interfacing.  Each of these channels is full‑duplex RS232, up to 115 Kbaud. Outside the hull these channels are accessible in one of two Science Basket J-boxes. Inside the hull these channels are terminated in a DB-9S connector.  They can also be made available on the submersible's network using a Moxa device.

Data may be accessed in-hull via the submersible’s network, using wired and wireless connections via a UDP transport layer, or it can be converted back to RS232 serial data.  USB to serial adapters are available for use with laptops that lack RS232.  If science wires are used, those connections are made available inside the sub through the Science Panel interface.

There are several options for computing in-hull.  First, there is a dedicated science computer running Windows 7 or Linux in a dual-boot configuration.  This computer has Alvin network access and has limited peripherals available (one USB and one serial port).  Alternately, the Alvin group can supply a toxicity/flammability-tested Windows laptop.

If these options are not acceptable scientists may supply their own device, though this requires pre-cruise toxicity and flammability testing. In these cases please contact the Alvin Group as early as possible to review and schedule the testing procedure.

Additionally, there are also two Ethernet data lines available for outside science equipment integration.  Though these provide 100Base-T signaling, experience has shown they may actually provide significantly less data throughput.  Outside the hull, these Ethernet lines are accessible in one of the two Science Basket J-boxes. Inside the hull, these lines are terminated in RJ-45 connectors.

Optical Fibers

Two optical fibers (SMF-28 or equivalent, Single-Mode, 9/125 micron) are available for science equipment use.  These are terminated in ST inside the hull and in the optical junction boxes.  Though virtually any wavelength may be used, for compatibility it is recommended to have the in-hull equipment transmitting at 1310nm and the outside equipment transmitting at 1550nm.

Real-Time Processing

In-hull computing resources are available to minimize the need for separate scientific computers.  Access to a computer (either installed or tablet) can be made available to run science equipment applications.  In general, these machines have modest computing capability, USB ports, and are on the submersible’s network.  They are satisfactory for data logging and instrument control applications, though computationally-intensive functions should be saved for post-dive processing.


The Alvin video system can handle multiple inputs of varying formats.  In addition to the standard compliment of imagers, the system is flexible enough to allow the user to integrate custom-designed and commercially available video and still cameras both inside and outside the personnel sphere.

Outside Cameras

With prior concurrence, additional user-supplied cameras can be added to Alvin’s imaging system.

Inside Cameras

The Alvin Group provides an in-hull, hand-held still/video camera.  Additionally, the Group also maintains a supply of GoPro cameras that can be provided upon request.

If the user would like to provide their own in-hull camera, it is recommended that it be battery powered and internally recording.  If the camera provides a a video output it may be able to be integrated into the vehicle’s video system for display and recording. Prior arrangements must be made to ensure compatibility of this signal with the submersible's video system.  User supplied in-hull cameras can be used but must be cleared with the Alvin Operations Group and must pass toxicity and flammability testing protocol.


Hydraulic systems can be an efficient method of supplying large amounts of mechanical force almost instantaneously. Hydraulic systems are also robust and reliable. Alvin utilizes hydraulics for several functions.

Alvin’s hydraulic system is designed to supply hydraulic power for both submarine-specific functions and science applications. The system is used to power the manipulator arms, trim adjustment, and variable ballast control. The hydraulic system can also power any science gear that uses hydraulics. Power is generated by two 6HP hydraulic power units.  The Pilot distributes power via electronically-controlled valves.

Four independent hydraulic control valves are available for science use. They are all directional proportional valves which can supply up to 2GPM at 1800 PSI.  All science circuits have 2500 PSI relief pressure.  These relief valves provide load locking to the limit of the relief.

When the manipulator arm is activated, oil flow priority is given to the manipulator. The port arm requires up to 3 gpm and can use all the available flow for short periods of time.  This can cause interruptions and/or reductions of performance in other hydraulic functions that are operating.  If uninterrupted use of science hydraulic operations is required, the manipulator arm should not be used when the science hydraulic system is on.

The Alvin system uses Royal Purple Marine Hydraulic Oil. High pressure 10 micron and water removal filtration is provided.

Note: Despite taking many precautions, the Alvin hydraulic system should not be considered “clean”.  Science equipment must be robust enough to operate with potentially contaminated oil.

Alvin uses flexible hydraulic supply hoses which are connected to hydraulic manifolds with 1/4" Swagelok fittings. Hoses used to supply equipment mounted on the science basket must pass through a disconnect plate to allow emergency release of the basket.

For the latest information on the hydraulic system, please contact the Alvin Group in advance of intended use of the science hydraulic system.

Basic light bar enables customization
Standard loadout

Light Bar

The light bar is a 1-inch aluminum tube structure located on the brow of the sub.  Alvin lights and cameras are mounted to the bar but there is also limited space available for mounting science equipment. Equipment mounted on the light bar must have relatively low mass due to mounting constraints and to minimize effect on stability. The light bar is best for small instruments which need to be higher up on the front of the sub. If space in the light bar is required, the user should contact the Alvin Group for specifics on mounting requirements. The science user must supply the proper mount to attach the gear securely.