Rescue communication is a method used by divers to communicate with each other or with surf team members. In professional dives, communication is usually between a single working diver and a divers supervisor at a surface control point. This is considered important both for managing diving work, and as a safety measure to monitor the condition of the diver. Traditional communication methods are with line signals, but these have been replaced by voice communications, and line signals are now used in emergencies when voice communications have failed. Diver-supplied surfaces often carry closed-circuit video cameras on helmets that allow surface teams to see what divers do and engage in inspection tasks. It can also be used to send a hand signal to the surface if voice communication fails. Underwater whiteboards can be used to write text messages that can be shown to other divers, and there are some dive computers that allow some text messages to be programmed to be sent by water to other divers or surface personnel with compatible equipment.
Communication between divers and between surface and divers personnel is imperfect, and nothing is worst, as a consequence of the physical characteristics of water. This prevents the diver from showing up. Voice communication is the most common underwater format, because the visual form is more affected by visibility, and communication and written signing are relatively slow and limited by dive equipment.
Recreational divers do not usually have access to voice communications equipment, and generally do not work with standard scuba request valves, so they use other signals. Hand signals are commonly used when visibility allows, and there are a variety of commonly used signals, with some variations. These signals are often also used by professional divers to communicate with other divers. There are also various other special-purpose non-verbal signals, most of which are used for safety and emergency communications.
Video Diver communications
Function
For the sake of safety and efficiency, divers may need to communicate with others who are diving with them, or with their surface support team. The interface between air and water is an effective barrier for direct sound transmission, and natural water levels also become a barrier to visual communication throughout the interface due to internal reflection, especially when not very smooth. Tools used by divers and pressurized environments also provide a barrier to voice-based communications, and submarine loads, relatively low light levels, and low visibility of many dive environments also hinder visual communications.
Communication is critical in emergencies, where high levels of stress make effective communication more difficult, and emergencies can make physical communication more difficult. Voice communication is a natural and effective thing to do, and most people rely on it for fast and accurate communication in most circumstances.
The general requirement for an effective system for diver communication is that everyone who will use it has access to the system, which works effectively in certain environments, that people who want to use it are familiar enough to communicate quickly. , accurately and unambiguously with each other, and that the system has sufficient ranges to work when needed. Simple, logical, and broad-standard signaling systems are more effective at meeting these requirements. Some such systems have been developed using different equipment and are suitable for different situations. These include sound-based systems, visual systems and tactile systems.
Maps Diver communications
History
The original communication between divers and surface attendants is to draw the lifeline of divers. Then, the tube system spoke, patented by Louis Denayrouze in 1874, on trial; It uses a second hose with a diaphragm sealing each end to transmit the sound, but it does not work very well. A small number was made by Seibe-Gorman, but the phone system was introduced soon after this and because it worked better and safer, the talking tube was soon obsolete, and most of the helmets had been returned to the factory and changed. In the early 20th century a telephone system developed electricity that improved the quality of voice communications. The cables used are inserted into the line or air duct, and use one of the headsets worn inside the helmet or speakers mounted inside the helmet. Microphone can be mounted on the front of the helmet or contact-throat microphone can be used. Initially there was only the possibility for the diver to talk to the surface telephonist, but then a dual phone system was introduced which allowed the two divers to talk directly to each other, while being monitored by the clerk. Telephone divers are produced by Siebe-Gorman, Heinke, Rene Piel, Morse, Eriksson, and Draeger. The system was established in the mid-20th century, has been repaired several times as new technology is available, and is still commonly used for surface-supplied divers using light-weight helmet and full-face masks. The introduction of closed-circuit video to monitor the inside of a diving bell, and to provide a team of supervisors with direct feedback on work activities the divers has expanded the capacity to provide useful advice to working divers, and to track stand-by divers or nomadic activities in emergencies , making coordinated activities easier and more effective.
Recently, water systems have been developed that do not use cables to transmit signals. They were first developed for the US Navy in the late 1960s. The initial system for recreational scuba, Wet Phone, was launched by Sound Wave Systems in 1977, but failed. In the mid-1980s electronic miniatures made it possible to use single sideband modulation, which greatly improved the clarity in good conditions. In 1988 several systems using one-side bands were found satisfactory by the US Navy for clarity and range, and were largely satisfactory for ergonomics, reliability and maintenance. Through the water system allows limited distance communication between the diver and the surface, usually using a push to talk system, which minimizes power consumption by simply sending on demand. They have not been used generally by recreational divers because of the cost and the need for a full face mask.
Coverage
The surface-supplied dives use the widest variety of tools and methods. In 2018, loud cable (cable) communications are still the primary method, supported in major commercial applications by one-way closed-circuit video but the channel pull signal is also used as an emergency backup, and a water-based sound system can be used. as an emergency reserve for closed diving bells. Local communication between divers includes hand signals and text written on the board.
Scuba diving can be done with voice cable communications, but restrictions on mobility make this an unusual choice. Water voice communication does not have the same limits on the mobility of divers, which is often the reason to choose scuba for professional diving, but it is more complex, more expensive, and less reliable than hard-wired systems. There are several recreational applications for voice communication over water for scuba, but this method is commonly used for professional applications such as military and scientific dives, and almost all recreation diving depends on hand signals, light signals and whiteboards for divers-to-communication divers very little communication between the diver and the surface is limited by the preceding emergency signal. A breath-hold diver uses a subset of recreational diving hand signals where applicable, and has some additional hand signals specially for freediving.
The presence of divers in the water during diving operations exposes divers to the risk of passing waterborne traffic, and there are signs of international-standard shapes, lights and flags to show that the dive support vessels are limited in their ability to maneuver and that there are divers in the water.
Voice communication
Both hard-wired and through-water electronic voice communication systems can be used with the diving provided surfaces. Cable systems are more popular because there are physical connections to divers for gas supplies in any case, and adding cables does not make the system different to handle. Cable communications systems are still more reliable and simpler to manage than water systems, and do not require divers to carry a power source. Communication equipment is relatively easy and may be of type two wire or four wire. Two wire systems use the same wiring for surfaces for divers and divers to surface messaging, while four wire systems allow diver messaging and surface operator messages to use separate pairs of cables, allowing simultaneous conversations in both directions. The default setting with wired diver communication is to have a normal dive side, so the surface team can hear anything from the diver at any time except when the surface sends messages on a two-wire system. This is considered an important safety feature, as the surface team can monitor dive breathing sounds, which can provide early warning of developing problems, and confirm that the diver is still alive.
Water communication systems are more suitable for scuba because divers are not burdened by communication cables, but they can be mounted to the surface of the equipment provided if desired. Most water systems have a push to talk system, so high power is only used to transmit a signal when a diver has something to say. For commercial dive applications, this is a disadvantage, because the supervisor can not monitor the conditions of the diver by hearing them breathe.
The water communication system consists of two basic types. The acoustic system provides one-way communication from the surface to the diver. The audio signal emitted by the sinking transducer moves through the water to the diver, which can hear the sound directly, without the signal receiving equipment. Amplitude modulated (AM) and single sideband (SSB) systems provide two-way communication between divers and between surfaces and divers. Both the AM and SSB systems require electronic transmissions and receiving equipment worn by divers, and sinking transducers connected to surface units. The SSB system performs better around obstacles, and the AM system provides stronger and often clearer signals for the same power, but is restricted to line-of-sight use.
The diver's speech is taken by the microphone and converted into a high-frequency sound signal transmitted to the water by an omnidirectional transducer. Signals can bounce from the bottom and other surfaces and obstructions, which can extend the range around the obstructions, but will also decrease the signal due to interference effects caused by different path lengths of different routes. When the receiver transducer picks up the signal, the ultrasonic signal is converted into amplitude modulated power signal, amplified and converted into sound by earphone. The water-based communication device carried by the diver has battery power.
The push-to-talk (PTT) method is the most widely available system for water communication, but some equipment allows continuous transmission, or voice-activated mode (VOX).
Push to talk is simple, efficient, and the preferred mode of many divers. It only transmits when the button is pressed, and saves power by not sending when the diver does not have anything to say, but requires the diver to use the hand to transmit. Users take turns to talk and listen. It is a normal communication protocol, and it encourages clear communication, but it does not allow audio monitoring of divers between communications.
Sound activated means that the unit is meant to transmit when the sound of the diver activates the microphone. If there is sufficient sound level generated in the microphone, the unit will send. This will lower the battery faster when the background noise level is sufficient to activate the transmission, but allows hands-free communication.
Continuous transmission is a mode in which one diver transmits continuously. It is a free hand, but all audible voices will be heard by others on the same channel and within reach. The open-circuit breathing apparatus generally produces a sufficiently large bubble of breathing.
The system through water is also used for back-up to communications cables via umbilical which are commonly used in closed dive bells. This system is used in case of cable system failure, and does not depend on the integrity of the umbilical bell, so it will function if the umbilical is disconnected and the bells are lost. They operate between battery-powered transducers on the bell and surface units using the same acoustic signal as those used for wireless divers communication. Single-band-suppressed drive system can be used, and frequency of 27kHz with typical 4.2kHz bandwidth. Helium breathing diverters may require a decoder system (also called unscrambling), which reduces the frequency of sound to make it easier to understand.
Voice communication protocol
The underwater voice communication protocol is like a radio communication protocol. The parties take turns talking, using clear and short sentences, and indicating when they are finished, and whether responses are expected. Like radio, this is done to ensure that the message has a fair chance to be understood, and the speaker is not distracted. When more than one receiver is possible, the caller will also identify the intended recipient via a calling message, and will usually also identify itself. The surface caller must also provide the opportunity for the diver to suspend or slow the breathing, or stop using noisy equipment, since the breath sound generated by the gas stream through the inlet sound and the bubbles from the exhaust is often so loud that the message can not hear it.
Hyperbaric speech distortion
The process of speaking underwater is influenced by the internal geometry of life support equipment and constraints on the communication system as well as the physical and physiological effects of the environment on speech and the production of vowel sounds. The use of respiratory gas under pressure or containing helium causes problems in the clarity of the diver's sound due to distortions caused by different sound velocities in different gas and gas densities compared to air at surface pressure. This parameter induces changes in the vocal formant, which affects timbre, and a slight pitch change. Several studies have shown that the loss of clarity is primarily due to changes in formants.
The difference in respiratory gas density causes a non-linear shift in low-pitch vowel resonance, due to resonance shift in the vocal cavity, giving nasal effect, and linear shift of vowel resonance which is a function of audible velocity in gas, known as the Donald Duck effect. Another effect of higher density is the relative increase in the intensity of the voiced sound relative to the unspoken voices. The contrast between the sound is closed and open and the contrast between the voiced consonant and the adjacent vowel decreases with increasing pressure. The change in sound velocity is relatively large in relation to the increase in depth in shallow depth, but this effect decreases as the pressure increases, and at greater depth the change in depth makes the difference smaller.
Ungkambler helium speech is a partial technical solution. They increase the clarity of the talks delivered to the surface personnel.
Video communication
The closed-circuit video is often mounted on a commercially-supplied commercial dive helmet to inform the surface team of the progress of the work performed by the diver. This allows the surface personnel to direct the diver more effectively to facilitate task completion. Voice communication is always provided when video diver is used. The communication cable for this system is part of the umbilical divers. Videos can also be used to monitor the dwelling of closed diving bells.
Hand Signal
Hand signals are a form of sign system used by divers to communicate while underwater. Hand signals are useful when divers can see each other, and some can also be used in poor visibility when in close proximity, when the receiver can sense the signature of the signaling hand and thus identify the given signal. At night, the signal can be illuminated by the light of the diver. Hand signals are the main method of underwater communication for recreational scuba divers, and are also used generally by professional divers, usually as a secondary method.
Divers who are familiar with sign language such as American sign language and who are equals can find it under water which is useful, but there are limitations because of the difficulty of doing some clear movement under water with gloved hands and often when trying to hold something.
RSTC hand signal
The member institutions of the Scuba Recreation Training Council (RSTC) in the United States have recognized a set of standard hand signals devoted to universal use, taught to explore students at the beginning of their initial dive courses.
These hand signals provide the following information:
- I'm out of breath! Hands show up and down chest.
- Go in that direction: Boxing with one hand, thumb extended and pointing in the direction shown.
- Go below, above or around: With palms down, hand gestures are used to indicate routes intended to go down, above or around obstacles.
Signals and other hand variations commonly used
The dive signal sometimes differs between groups of divers. There are regional variations and variations related to this type of diving. One of the items with the largest variation variation is how the diver shows the remaining gas pressure in the cylinder. Some variations include:
- Cut marks: "common danger" or "emergency".
- Tap the funnel: "share the air".
- Referring to the ear: "listen!"
- Hand cupped behind ear: "listen!"
- Refer someone to change the reference of the next signal from "I" to the designated diver.
- A flat hand sweeps the top of the head, palm down: "I have a ceiling". This could indicate the divers has entered a decompression obligation or there is an overhead of a solid obstruction. When it goes up it means "stop here". (This is my decompression ceiling, or we rise too fast, or just generally stop up at this depth).
- Move around the body in wave motion: "Current"
Divers sometimes find local signals for local situations, often to indicate local wildlife. As an example:
- I saw hammerhead sharks: Both sides of the head
- I see a lobster: Boxing with your index finger and middle finger pointing out horizontally and alternately swaying up and down
- I see an octopus: The back of the hand or wrist covering the mouth, all the fingers pointing out of the mouth and squirming
- I see sharks: Average hand, vertical fingers, thumb on forehead or chest
- I see a turtle: A flat hand one on top of one another, palms down, waving thumbs up and down together
Instructor signal:
- You (all) watched me. (usually before demonstrating the skill): Point the diver (s) with the index finger, point your own eyes with the forefinger and middle finger, point your chest with your index finger.
- You try it now , or do it again: Gestures with palms open toward students after showing skills.
Torch/flashlight signal
The focused torchlight can be used for basic signaling as well.
- OK signal: Draw a circle on the ground in front of you.
- Caution please! Wave the torch up/down.
- emergency! Fast, repeating, forward and backward horizontal motion
Usually a diver does not turn on a flashlight/flashlight in the eyes of another diver but directs the light into his own hand signal.
Line signals
Also known as rope signals, these are generally used in low visibility conditions where divers are connected to others, other divers or surface tenders, by rope, airline hose or umbilical diver. This date goes back to the time of use of standard wetsuits. Some of these signals, or pre-arranged variants, can be used with surface placement buoys. The diver pulls down on the buoy line to make the buoy bob in a pattern that is equivalent to the rope signal. Effective line signals require free line without much leeway - before attempting to line signal, slack must be taken, and line drawn strong. Most signals are recognized by returning the same signal, indicating that the signal is received accurately. Continuing failure to admit may indicate a serious problem and should be resolved as an urgent matter. There are several systems that are used, and there needs to be an agreement between the diver and the tender before the dives.
English Sub-Aqua Club
BS-AC has a very small set of rope signals. Most of them have the same meaning as the equivalent commercial or Royal Navy signals.
Tenders for divers
- One attraction on the phone: Are you okay?
- Two attractions - Stay here.
- Three attractions - Down.
- Four attractions: Rise at normal levels.
- Five or more attractions: Emergency, up to the surface.
Diversification for tenders
- One attraction: I'm fine.
- Two attractions: I'm still.
- Three attractions: I'm going down.
- Four attractions: I came.
- Five or more attractions: Emergency, take me to the surface (no response is required)
Public Safety Divers
General safety rescuers and recreational divers use the following line signals when performing a circular search and bow underwater.
Tenders for divers
- One attraction on the phone: Are you okay?
- Two attractions: Stop, remove the slack, the opposite direction
- Three attractions: Came to the surface
- Four attractions: Stop, get ready, do not move (there may be danger ahead or boat entering the search area)
Diver for tender
- One pull in the line: OK
- Two pull: Pay more rows
- Three pulls: Object found
- Four or more tugs: Needed help
Commercial diving
The rope signal used in UK and South Africa includes the following:
Signal is a combination of pull and bell , Pull is a relatively long stable voltage on the line. The bells are always given in pairs, or couples followed by the odd bells left. They are a short tug, and a pair is separated by short intervals, with longer intervals to the next pair or single bells. Technique and nomenclature comes from the sound of a ship's bell every half hour during the watch, which is also done in pairs, with the last odd bell. One buzzer is not used as a dive signal as it is difficult to distinguish it from a jolt caused by a transient drag.
Divers:
General signal:
- 1 drag - Call to call attention, are you okay
- 2 pull - I send the end of the string (or other pre-arrangement items)
- 3 pulls - you've stepped too far, backed down until we stopped you
- 4 pull - Rise
- 4 drag and 2 bells - Immediately to the surface (often for surface decompression)
- 4 drag and 5 bells - Your buoy line appears
Signal direction:
- 1 drag - Find where you are
- 2 bells - Go along the jackstay line or distance, or jump straight out of the tender
- 3 bells - Facing shots or soft, go right
- 4 bells - Facing shot or soft, left
- 5 bells - Return to shooting or soft lines, or back along the jackstay.
Diving into the clerk:
General signal:
- 1 drag - To attract attention, or complete the last instruction.
- 2 pull - Send the end of the string or other pre-arrangement item
- 3 pull - I'll go down
- 4 pull - I want to show
- 4 pulls and 2 bells - Help me
- 5 or more pull - Emergency, pull me immediately
- succession 2 bells - I am violated and need a ready-made diver to help
- succession 3 bells - I am violated but can be clear without help
- 4 drag and 4 bells - I try to communicate with voice communication
Working signal:
- 1 drag - Hold or stop
- 2 bells - Drag
- 3 bells - lower
- 4 bells - Take the void on the lifeline or the lifeline is too tight
- 5 bells - I've found, started or finished the job
All signals start with a pull to attract attention, and this must be acknowledged before the actual signal is made. Royal Navy (RN) signals include short and paired "bells" and "pull" longer. The RN signal is almost identical to the rope signal used by commercial divers in England and South Africa.
The US Navy also has a standard set of line signals. This includes common signals from divers to tenders, search signals and emergency signals. Signals to change from general to search signal or vice versa are seven pulls, and the meaning of the signal can vary depending on whether it is assigned by the diver or the tender. Most signals are recognized by returning the same signal, confirming that the signal is received correctly.
Slate
Messages written on a whiteboard can be used to convey complicated messages with a low risk of misunderstanding. Slates are available in various sizes and are usually hard white plastic with a matte finish, perfect for pencil writing. They can be stored in various ways, but in pocket or bungeed to wrist is a popular method. Cut to the diver by the lanyard is another method, but there is a greater turning risk. Rows can be used to record information that will be used on diving, such as decompression schedules, to discuss important matters that are not sufficient for hand signals, and to record data collected during dives. The wet-record waterproof paper is a compact equivalent, and pre-printed waterproof data sheets and clip-board are routinely used by scientific divers to record observations.
Cave marker
Arrow cave, Line arrow or Dorff marker (after Lewis Holtzendorff) is a plastic arrow marker connected to the cave line by wrapping a line around the arrow through the slot. They are used to show directions to the exit, and can be identified by feelings. The message is simple, but very important, as if a diver does not know which way to go at the crossroads, there is the risk of serious trouble. Line arrows are also used at intersections on permanent lines, and at disposal, so when the diver returns to the tie, he or she can identify which way to go.
Personal non-directional and hybrid line markers are used to indicate the identity of a diver who has crossed the line and has not yet returned to that point. They cling to the lines in the same way as the cave arrows, and are deployed on the way to the cave, usually at critical points like forks or jumps, and used to show to other divers that someone is further along the line. They are marked to identify the diver, and are recovered by the diver on the way out. Cookies (round markers), rectangular outbound markers and pegs of clothing are used for this purpose. Round and rectangular markers stick to the lines in the same way as arrows, and can be personalized in any way that the owner can easily recognize. Colors are often used, but because there are a limited number of standard colors, and they are often indistinguishable in dark, user-modifiable modes that can be recognized by touch.
Arrows should always be placed on the side of the intersection because this is not ambiguous. Sometimes there is more than one way out of the junction. Both should be marked with arrows, but a preferred outlet can be marked with two serial arrows. The arrows are always pointing along the line to the exit.
Light and gas signals for dives provided on the surface
There are emergency signals typically associated with wet and enclosed bells that can be used by surfaces and bellman to exchange limited information that may be important for the safety of divers. They are used when the voice communication system fails, and provides enough information that the buzzer can be recovered with minimal risk for the diver. These signals are generally not applicable to divers directly supplied by the umbilicals from the surface, but if umbilical snagged and rope signals can not be transmitted, these signals may be supplied by a flash cap light and flush helmet in a continuous stream by opening the free flow valve or pressing the cleaning button).
- Two lights blinking on the bell mean the surface does not receive voice communications from the bell. The waiter responded by blowing the gas bell twice, creating two huge bursts of bubbles visible on the surface, then reminding the diver and preparing to coat.
- When the bell is ready to appear and voice communication is not working, the maid will blow the bell gas four times.
- If there is a problem during the ascent, a long continuous blowdown is a signal to stop.
Miscellaneous emergency signal
The pat code, created by tapping the hull, is used to communicate with divers stuck in closed bells or submarine or submarine residents during rescue.
A scuba divers who deploys Pending Surface Markers (DSMB) at the end of a dive can use pre-arranged color codes to show the surface support crew if there are any problems that require assistance. In some circles, the yellow DSMB is considered an emergency signal, and red means OK. In most circles, a second DSMB propagated on the same line will indicate a problem. DSMB can also be used to carry slate with message, but this is impossible to notice unless there is a special arrangement made.
Other minor emergency signals include the use of mirrors, inflatable signal tubes, floating ribbons, compressed air sirens, whistles, and other noise makers to alert surface problem support personnel.
VHF radios and personal emergency seekers are available that can send distress signals to nearby ships and withstand pressure to the depth of recreational diving, so that they can be carried by divers and activated on the surface if not visible from the vessel.
Lower signal
Flag
A diver flags down, or a scuba flag, is a flag used on water to indicate that there are divers below. Two flag styles are being used. Internationally, the "alpha" code flag, which has a white hoist and a blue fly fly, is used to signal that the ship has a diver down and other vessels must remain clear at slow speeds. In North America a red flag with a white diagonal line from the upper left corner to the lower right corner is conventionally used. The purpose of this flag is to notify other vessels to avoid the safety of divers and to avoid possible collisions with submarines that may not be able to maneuver.
Light and shape signals
A ship that supports dive operations may not be able to take avoidance measures to prevent collisions, as it may be physically connected to water diver by lifeline or umbilical, or may be maneuvering near divers, and necessary to demonstrate these constraints by international maritime law, using signals of light and shape are specified, and other vessels shall remain clear, both for the safety of divers, and to prevent collisions with dive support vessels. These signals and the rules for responding to them are set out in Rule 27 of the International Regulations to Prevent Sea Collisions, also known as COLREGS, and "Road Rules", as cited below.
An abandoned vessel for maneuverability, except for ships performing mine-operated operations, should indicate:
- all three lights in vertical lines where they can be seen. The highest and lowest light from these lights should be red and the middle light is white;
- three day form in the best viewed vertical line. The highest and lowest of these forms are the ball and the middle is the diamond;
- when making a way through the water, masthead or lamp lights, spotlight and sternlight, other than the lights specified in subparagraph 1;
- when anchored, in addition to the lights or shapes specified in subparagraphs 1 and 2, the light, lamp, or shape specified in Rule 30.
A ship dredging or underwater operations, when restricted in its ability to maneuver, shall indicate lamps and forms specified in subparagraphs (1, 2 and 3 above) of this Rule and shall be added , when there is a barrier , the exhibit:
- two red lights or two balls in a vertical line to show the side where the obstruction is;
- two green lights two or two diamonds in a vertical line to show the side where other vessels can pass;
- at anchor, lamp or form specified in this paragraph, not the lamp or form specified in Rule 30.
Whenever the size of the vessel involved in the diving operation makes it impractical to display all lamps and forms specified in paragraph (above) of this Rule, the following shall be exhibited:
- three lights in a vertical line where they can be seen. The highest and lowest lights of these lights should be red and white light;
- the rigid replica of the International Code "A" is not less than 1 meter (3.3Ã, ft) in height. Steps should be taken to ensure all-round visibility.
Buoy of surface marker
Buoyant or inflatable buoy buoys can permanently be used to identify and/or mark the presence of divers below. It may be tethered, as a shotline, and shows a common area with a diver, or tethered to one of the divers by a line, indicating the location of the group to the people on the surface. These buoys are usually brightly colored for visibility, and may be fitted with one of the dive flag signals.
Bullet surface markers (SMB) tethered to the diver are usually drawn on a thin line attached to a reel, spool or other device that allows the diver to control the length of the line, so an excessive slack line can be avoided.
A portable or delayed buoy surface marker (DSMB) is a blowing marker flown by divers when it is underwater and sends it to the end of the line to indicate its position, and it is usually good that it rises or there is a problem. The use of DSMB is common when divers wish to decompress stops from fixed references, or will appear in areas with vessel traffic, or need to indicate their position to the submarine or surface team.
A cluster of tethered surface buoy can be used to demarcate the area where dives occur. This is more likely to be used by commercial, scientific or public divers to cover work or search areas, or accidents or crime scenes.
Ultrasonic accessories
The Buddy-Watcher is a wake-up warning device mounted on the wrist that sends an ultrasonic signal when the button is pressed, at least 20 meters (66 ft) through the water to a matching unit on a dive buddy, which will generate a silent vibration and visual signal reminding the diver that their friend want attention. There is no direct indication to the sender whether the signal has been received and there is no indication of distance or direction to a friend. This device is waterproof up to 40 meters (130Ã, ft), and therefore suitable for recreational scuba diving use, but not technically dive.
UDI-28 and UDI-14 wrist decompression computers feature communication between wrist and surface units that include distress signals, a set of unlimited text messages and a homing signal.
References
Source
- Hollien, H.; Rothman, H. B. (2013). "Diver Communication". In Drew, E. A. Underwater Research . Elsevier. pp.Ã, 1-78. ISBN: 9780323150316.
- Prosser, Joe; Gray, H.V. (1990). Diving Cave Communications (PDF) . Branford, Florida: Cave Diving Division of the National Speleological Society, Inc . Retrieved September 13 2016 .
- US Navy (December 1, 2016). US. Navy Diving Revision Manual 7 SS521-AG-PRO-010 0910-LP-115-1921 (PDF) . Washington, DC.: US Naval Naval Systems Command.
Source of the article : Wikipedia
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