Download the Full Article As Pdf ⬇︎
equipment
Let’s talk about Underwater Communications Systems PIXABAY / PUBLIC DOMAIN
Text by Michael Menduno mission-specific need. Others say they prefer a fact not lost on nature: many marine ani- to commune in silence. If you are wondering mals, especially cetaceans, use ultrasound to In 1977, a year after I got certified, whether your next diving project could benefit communicate and navigate. Conversely, with Soundwave Systems launched the from vox communication, it is useful to under- the exception of extremely low frequencies, stand a little about the technology, its imple- radio waves do not propagate through “Wetphone,” a voice-activated mentation and use. water. Today through-water sys- underwater communications device tems are called “half-duplex” (vs that promised to revolutionize sports Sounding off “full-duplex” ) because only diving, making it a “silent world” no There are two kinds of underwater one person can talk at the communication systems: hardwire same time on a given fre- more. I added it to my wish list along and wireless or “through-water” quency while the receiver with a Watergill At-Pac, the fore- comms. Hardwire systems are essen- listens just like a walkie-talk- runner of modern-day wings, and tially waterproof intercoms connect- ie or push-to-talk CB radio. an SAS drysuit. Soundwave filed for ing the diver to the surface, and are used primarily for divers on an History bankruptcy a few years later. umbilical and “blackwater diving.” Originally developed for
They are not designed for sport OCEAN REEF GROUP the US Navy in the late Today—nearly 40 years later—communi- use. In contrast, through-water ‘60s, early through-water cation systems have become standard kit systems use ultrasound (typically comms and their spinoffs for commercial, military, law enforcement, 25-33kHz) to transmit and receive such as the Wetphone, public safety, aquarium and scientific divers signals through water in the same used the circuitry found and videographers, but they remain a niche way that walkie-talkies or mobile in AM radios to encode product for recreational and technical divers. phones use radio waves. The voice conversations For many, the added complexity and cost of density of water, which is 784 times Ocean Reef M101A G.divers (0.3-4kHz) on an ultra- what is essentially an underwater walkie-talkie greater than air, makes it an excel- underwater receive-only unit fits sound carrier. However, BECKY SCHOTT / PHOTO COURTESY OF OTS outweighs the benefits in the absence of a lent conductor of sound energy— conventional mask straps and amplitude modulation Divers communicate through comms systems attached to full-face masks full-face mask models
58 X-RAY MAG : 81 : 2017 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO Divers with OTS full-face equipment mask
dual channels and are push-to-talk like a walkie-talkie, though some offer voice activation as an option. Their operational range varies from 150-1,500ft for sport
units to more than half a mile for profes- OCEAN REEF GROUP sional comms, depending on sea con- ditions and noise levels (special military
units can transmit more than three miles). W31 MARINER Vendors also sell receive-only units and a High Pressure Compressor Charging Rate: 105 or 140 lt/min variety of surface stations for surface-to- Working Pressure: 225/310 bar diver communications. Dimensions (CM): W44 L81 H52 Weight: 65 kg W32 CANOPY High Pressure Compressor Who was that masked man? Charging Rate: 180, 250 or 300 lt/min If you could just add comms without Ocean Reef Predator TDivers Working Pressure: 225/310 bar Dimensions (CM): W70 L100 H130 Alkin and Aykom changing anything else, it is likely that full-face mask Weight: 280, 290 or 300 kg Compressor Distributors many more sport divers would be talk- ing the talk. Unfortunately, it is not that the full-face mask when using comms, C & R Testing Ltd simple. In order to talk underwater, you which enables divers to breathe through Unit 1, Owenshaw Mills, Old Cawsey, Sowerby Bridge, Halifax HX6 2AF need an air-filled space to speak into their nose and mouth. Telephone: +44 (0) 1422 410 466 | Email: [email protected] (and place a mic), and the mouth must Website: www.candrtesting.co.uk be unencumbered. Early sport units like Full-face masks Opening Times: Monday to Friday 9.00 am - 17:00 pm the Wetphone utilized a “mouth mask,” Today, there are a variety of full-face Saturday and Sunday - Closed essentially a rubber pocket attached to masks on the market along with requisite the second stage regulator and strapped training courses. Most masks feature a majority circulates breathing gas across SCUBA_April17_07_CR_Testing.indd 1 28/02/2017 16:59 over the mouth; however, they have built-in oral nasal pocket to reduce CO2 the faceplate to keep it from fogging. proved to be largely unworkable. In- build-up, a built-in regulator, and a port to Full-face masks offer divers a number of stead, the community has standardized attach a comm system. In addition, the obvious advantages over scuba masks. They have a wider field of vision, they do not fog up, and they are warmer and more comfortable than a bite-mouth- piece. They also protect the diver’s air- ways in the event he or she goes uncon- scious underwater, which is a big safety factor. BECKY SCHOTT The disadvantages are subtler. Like any (AM), which transmits three simultaneous Single-sideband quickly became the de scuba mask, mask fit and obtaining a signals—a carrier and two sidebands— facto standard due to its near 100% intel- good seal is critical, especially since the suffered from poor intelligibility because ligibility under good conditions. full-face mask covers more of one’s face. the signals would get out of sync as they Today, there are several primary ven- Equalization can be more difficult and traveled through the water and were dors that build through-water comm so can mask clearing. With practice, gas reflected off various surfaces. Also, divers systems: granddaddy Ocean Technology consumption tends to be about the same had to remain nearly motionless in the Systems (OTS) founded in 1984, DiveLink with a full-face mask but goes up consid- water while talking; otherwise, voices Underwater Communications and Ocean erably when you are talking—good gas sounded garbled. Reef Group. Products range from all-in- management skills are required. None of this helped Wetphone’s case. one, half-watt cigarette pack-sized sport In addition, bailout is a little trickier, It was not until the mid-’80s that increas- transceivers that are powered by a 9v particularly in cold-water. Divers have to ingly miniaturized electronics made it pos- battery and mounted on the mask strap, remove their masks and regulators simul- sible to use sophisticated single-sideband to more powerful 5-watt walkie-talkie- taneously to go on an alternative breath- modulation, which transmits a single sized units that can be attached to a ing source. Ironically, full-face masks ultrasonic carrier signal to eliminate the diver’s harness and include cabling for present more challenges for technical reflection and multi-path problems of AM. the mic and earpiece. Most units feature PHOTO COURTESY OF KIRBY MORGAN divers. First, they complicate open-circuit Divers with Kirby Morgan M-48 full-face masks
59 X-RAY MAG : 81 : 2017 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO equipment The Full Monty of Underwater Communications Listen up. Today, all through-water other instead of relying on ineffective communications systems oper- Time Division Multiple Access (TDMA) ate in “half duplex” mode similar modulation, which assigns a specific to a walkie-talkie. The receiver is time slot for each distinct communicator. turned off when the user pushes For divers, it means they will no longer the talk button so as not to satu- have to push to talk, and a network of rate the receiver. Contrast this with divers can share the same frequency. your “landline” telephone, which operates in full duplex mode; both Simultaneous transmissions parties can talk at the same time. Data transmission rates depend solely Mobile phones give the illusion of full on the frequency and power of the duplex, but actually the transmitter underlying hardware. However, be- and receiver operate on slightly dif- cause a Dolphin-enabled point-to-point ferent frequencies. comm unit will be able to transmit and All that is about to change if receive simultaneously—for example, The Spectrum full face mask by OTS (above QinetiQ North America,1 has its way. Last transmitting data packets while receiv- and left) has a soft nose for easy equalizing, month, the privately held, Massachu- ing requests to resend specific missing and allows divers to use their own regulators. setts-based manufacturer, which pro- packets, as part of its error correction PHOTO COURTESY OF OTS duces some 200 protocols—throughput would show a 4x types of robots improvement, compared to half-duplex for the US military, communications. announced that “I envision a group of eight divers it had cracked that will all be able to communicate the holy grail of with each other at the same time, while wireless com- the divemaster would be able to have munications— private conversations with any specific
ILLUSTRATION COURTESY OF ILLUSTRATION QINETIQ simultaneous diver and also get a read of diver’s gas gas switching: divers must use quick dis- also offers their Predator TDivers mask built transmission and supplies and their biometrics,” explained connects and/or a gas block to switch for Team Blue Immersion founded by PADI receiving (STAR) Greg Folts, QinetiQ’s Director of Business to their decompression gas or bailouts Territory Director Jonas Samuelsson for a using their unique Development for Maritime Systems who without removing their masks. Second, cold-water tech expedition. They also use patented can- is also a diver. despite added airway safety, the use of a it for their support divers. celation technol- Other applications include creat- full-face mask with rebreathers is, at best, ogy called DOL- ing “continuous” sonar versus discrete problematic for a number of reasons. In conclusion PHIN, which was “pings” and listening, making it possible Finally, comm gear is not inexpensive: Today, recreational and technical divers developed in to reduce peak power requirements by A full-face mask with comm system can tend to use full-face masks and comms DOLPHIN Acoustic Communications and Sonar partnership with Optimal Systems Labo- 1000x or 30dB. The same goes for Fish- cost up to US$1,000-2,000 per diver. for mission-specific applications, and ratory, Inc. In addition, DOLPHIN creates finders. It could also eliminate the under- Some new and older masks are de- some say the uses are growing. Some a unique identification wrapper for each the-boat blind spot in side-scan sonar. signed to address some of these issues. examples are diving in cold or dirty water; nals to convey essential information, and voice, making it possible to granularly In addition, DOLPHIN can be used with The new OTS Spectrum offers a soft oral outfitting support divers who need to be do their talking after the dive. manage communications. Until now, the radio frequency (RF) applications such nasal pocket, which makes equalization able to speak with the surface; use in very problem was considered unsolvable. as radar. The company plans to license easier; divers can pinch their nose just like long decompressions or remote in-water Michael Menduno is an award-winning QinetiQ’s technology will make it its technology to interested manufactur- when wearing a scuba mask. In addition, recompression; and, of course, the occa- reporter and technologist based in Cali- possible to create extensive undersea ers, i.e. “QinetiQ Inside.” it is designed to use divers’ existing sec- sional underwater wedding. They are also fornia, USA, who has written about diving wireless networks for data and voice The company’s biggest challenge? ond stage regulator, which reduces the favored by gear geeks. and diving technology for more than 25 communications, solving numerous “Our biggest problem is convincing cost. Similarly, the Kirby Morgan M48 Mod There is no doubt that being able to years and coined the term “technical challenges for the military, commercial people it is real,” said Folts, who is work- 1 Modular FFM has a removable oral na- talk underwater adds a layer of safety, diving.” He was the founder and publisher and even consumer users. The Navy, for ing to convince the military and others sal pocket that makes bailout and under- coordination and control that cannot of aquaCORPS: The Journal for Technical example, will be able to operate swarms to rewrite their wireless comm specs. The water gas switches easier. Company co- be achieved otherwise. That is why they Diving (1990-1996), which helped usher of autonomous underwater vehicles that company will be trialing DOLPHIN with founder Bev Morgan began working on have become indispensable tools for technical diving into the mainstream of will constantly communicate with each the US Special Operations Command the design back in the early days of tech- working divers. But given their added sports diving, and organized the first Tek, 1 Note to tekkies: QinetiQ NA’s parent (SOCOM) in November. Keep your ears nical diving in response to the need to be complexity and cost, most sport divers are EUROTek and AsiaTek conferences, as well company, British-based QinetiQ Group Plc, open for this space.
able to make gas switches. Ocean Reef still content to rely on hand and light sig- as Rebreather Forums 1 and 2. developed the gaseous CO2 sensor
60 X-RAY MAG : 81 : 2017 EDITORIAL FEATURES TRAVEL NEWS WRECKS EQUIPMENT BOOKS SCIENCE & ECOLOGY TECH EDUCATION PROFILES PHOTO & VIDEO PORTFOLIO