FarSounder's Technology Blog
From time to time, FarSounder's development team likes to toot their own horn and tell the world about some of the cool things they are working on. We can't share all our secrets and development plans, but we can share some of the excitement that our engineers experience every day working for FarSounder.
Due to natural variations in fluid characteristics (such as water temperature, salinity and density) and the presence of small in-water reflectors (such as moving currents, marine life, and bubbles), the underwater environment is acoustically dynamic and often unpredictable. That’s why we at FarSounder have committed ourselves to building incrementally smarter tools to help keep our customers on the edge of technology and as far from harm’s way as possible. As a result, we’re happy to give a sneak peek of our most intelligent underwater collision avoidance system yet, capable of stabilizing in-water targets detected by the sonar and providing you with the most accurate representation of the water in front of your vessel to date. Our new stabilization feature relies on tracking in-water targets detected across multiple transmit/receive cycles (i.e. “pings”). By grouping these detections and monitoring their movements over time, we can use that information to both filter out unreliable targets, and fill in gaps where we are confident targets should be seen.
As more and more yachts choose expedition style itineraries, the risk of collision with poorly charted obstacles or wrongly placed obstacles (due to GPS malfunctions) increases significantly. Groundings with large underwater structures such as rocks, reefs, sandbanks and shoals are unfortunately significant risks for the adventurer. Having a navigation sonar installed which is capable of detecting such hazards at long range is important in these scenarios. More importantly, the detection range of the installed sonar should be suitable for the vessel. In this blog posting, we discuss how to calculate a suitable detection range for your ship's obstacle avoidance sonar.
Not all forward looking sonars are created equal. Most only produce a view of a single 2 dimensional slice. Some use scanning technology to build an image from multiple pings. Few employ 3D technology. FarSounder sonars are the only look-ahead sonars which produce a true 3-dimensional image at navigationally significant ranges. They do this with a single ping enabling a fast update rate. Clearly, range is an important metric. However, one number alone cannot fully describe a sonar's range capabilities. A navigation sonar should specify its range not only in terms of maximum detection range for a given in-water target size, but also maximum range at which it can map the bottom. This blog posting explains what drives this limit and how these same concepts can explain other “unexpected” echo reflections.
Throughout the centuries that man has taken to the seas, ship (and crew/passenger) safety has been a critical concern. In both known and unknown waters, groundings and collisions have cost the lives of countless souls. These accidents have significant economic impacts with loss of ships and cargo as well as environmental impacts due to oils spills and destruction of marine habitats. Over these centuries, incremental improvements to navigation have improved safety at sea. In particular, the 20th century saw huge leaps forward in safety technologies and regulations, saving lives, cargo, and ships. In today's world, one would not even think of operating large vessels without the use of radar, depth sounders, ECDIS, and/or electronics charts with GPS. But still these technologies are missing an important piece of information. They can't tell the ship operator what is under the water in front of the ship right now. FarSounder navigation systems provide this missing piece of the puzzle. They detect sand shoals, rocky shores, ice, coral, and whales - things that passenger ships (or any ship) should never touch.
When considering one of our forward facing navigation or diver detection sonars, customers are often curious about the sonar's impact on the performance of their vessel. Most people are familiar with the general concepts of streamlining with reference to their car. Such effects when operating in air are described by the vehicle's aerodynamics. Similar effects as they relate to ships and boats traveling through water are called hydrodynamics. In this blog posting, we'll be discussing the general concepts that should be considered with evaluating the hydrodynamic impact of a particular installation.
Navigation in and around ice is a very important topic for vessels destined for the arctic or antarctic waters. The rise of adventure cruising, scientific expeditions, and commercial shipping through these areas is keeping the topic in the forefront of many conversations. Ship operators in these areas are interested not only in detecting and avoiding icebergs but in some cases also knowing how close they can get to ice that is clearly visible above the water. Navigation in such areas is clearly reliant on seaman experience. Since the sinking of the RMS Titanic, engineers around the world have been working on ways to detect icebergs using various sonar technologies. In this blog post, we summarize how FarSounder's 3D sonars can be used to navigate in sea ice conditions and how our obstacle avoidance sonars can be installed on ice classed vessels.
The ultimate purpose of our 3D sonar products is very simple. We want to let users see dangers hidden under the water's surface. With our forward looking navigation sonars, this means seeing the obstacles that ship operators want to avoid. In terms of our ship protection systems, this also means seeing underwater intruder threats. This objective seems straight forward. However, the marine world is a complicated environment with lots of objects that can reflect sonar signals. Sometimes localized environmental conditions can even prevent sonar signals from propogating effectively. We want to make sure that the output from our sonars reflect (pun intended) the reality of what is under the water. This means that somehow we need to get an idea of what is actually there to determine if the outputs of our sonars are correct. This information is called "Ground Truth" and is the bain (or bounty) of every scientist and engineer who works on sensing technologies.
Ship strike is a major cause of death for great whales. Our sonars can be used to help avoid these ship strikes, but we need to be sure we do so without introducing new problems. Motivation for FarSounder's technology began with an interest in helping vessels avoid hitting whales. We've done this by developing sonar products able to detect many types of whale sized objects. There are many types of sonars, and some are generally believed to be harmful. Our sonar products, however, are not in that class. Our systems operate at sound levels, frequencies, and durations that are safe for marine mammals and are environmentally benign.
Given an echo returned from an environment within sonar's field of view, the ultimate goal of a FarSounder product is to decide whether the echo corresponds to a true target in the 3D space. The target could be the sea floor, an in-water obstacles, marine life, a diver, etc. This detection problem is fundamental to all of our products irrespective of their purpose: navigation or threat detection. FarSounder engineers have developed several tools that make their life easier when they need to unravel the complexity of underwater detection problems. One of the tools central to research and development at FarSounder is our sonar performance prediction tool, code named: DAMUS.
As FarSounder's customer base grows, we are continually learning about new applications for our navigation sonar products. As a marine company focused on engineering unique technologies, we obviously have an interest in the greater world of marine science. Though we do not study the occean per se, our products can be used as tools to help others study the ocean. This blog entry is intended to highlight some of the applications of our 3D navigation sonars for Research Vessels. With these products, we hope not only to provide safer navigation to users but also add some compelling reasons to add our tool to the researcher's arsenal of tools.