BY RALPH COBB
Historically, very few dollars have been directed toward research and development for fire service needs. Yet, the fire service can benefit greatly from transferring technology developed for the defense and aerospace industries to the fire service. Following are two examples of such technology available from this untapped resource.
THE TETHERED AEROSTAT
 Tethered aerostat. (Photo courtesy of BOSCH Aerospace Inc.) |
It happened suddenly without warning. A tornado watch had just been posted when the tornado swept down on the city. In less than five minutes, the storm cut a quarter-of-a-mile swath of destruction through five miles of sleeping subdivisions before ascending back into the clouds. As fate would have it, the storm also mangled the two communications antennae supporting the city’s 800 MHz radio system. Public safety communications were silenced.
However, the lack of communications was no cause for alarm. As soon as the fire department realized what had happened, a special small trailer was coupled to a fire department vehicle. The trailer was pulled to a predetermined location within the city near the disaster site. After the trailer was uncoupled, a valve was opened. In less than five minutes, a small airship, called an “aerostat,” was fully inflated and ready for deployment above the disaster site. The firefighter attached the antenna and released the tethered aerostat from its boom. When the aerostat reached 300 feet, the firefighter secured the tether, cranked the generator, and switched on the radio repeater. Several minutes after the trailer was positioned, emergency communications were available for police, firefighters, and emergency management personnel.
Using tethered aerostats to facilitate communication is a technology coming of age. In this age of rapidly expanding technology, who would have thought that the Smart Weapons Management Office of the U.S. Army Aviation and Missile Command would be funding, researching, and developing blimps? However, aerostats, both tethered and remotely controlled, can be used to keep a variety of communications platforms aloft for days for considerably less expense than cranking a helicopter or using fixed-wing aircraft. With regard to cost, the more applications identified for the technology, the cheaper it becomes for all users.
Tethered aerostats can serve a variety of communications and sensor needs for the fire service. They can provide aerial scene surveillance at hazardous-materials incidents. They are low maintenance, and there is no rotor wash that might spread contamination. They can be used for aerial observation at a host of important incidents and activities from accident and disaster scenes to large public gatherings. Using standard optics by day and thermal imaging by night, the site commander could observe crews’ movements around a disaster scene. Elevated thermal imaging could be used to spot casualties who may not be readily visible to ground crews.
In America’s new war against terrorists, scene security is becoming of paramount importance. Aerial observation can be used to spot intruders and looters at the scene. Such observations may thwart the success of secondary terrorist incidents, saving the lives of many responders. We are in an unprecedented era. As we face the ravages of fire before us, the greater threat may be approaching us from behind. We need all the help we can muster, and tethered aerostats have much to offer.
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In addition to requiring minimum maintenance, tethered aerostats are portable, require little training for users, have a long shelf life, and are relatively low in cost.
Laser Communications
Recent events have focused on the need for real-time situational awareness during emergencies. Although many lives were saved as a result of the heroic efforts of responders at the World Trade Center on September 11, 2001, additional lives might have been saved if emergency response officials had access to real-time imagery of the surrounding area immediately after the first attack. Laser communication (LaserCom) has many advantages that can significantly enhance emergency response teams and decision makers’ ability to respond appropriately and quickly during crises, be they the result of terrorist attacks, natural disasters, fires, or major accidents.
Communication lasers use the eye-safe wavelengths of the infrared band and provide the following advantages over radio frequency bands:
•Very large bandwidth. This allows for the simultaneous transmission of voice, data, and images. A throughput of up to 1.2 Gpbs from a 29 lb. LaserCom transceiver has recently been demonstrated. This is 1.2 billion bits per second. Technology that will enable much smaller and lighter transceivers with even greater bandwidth is currently in development. Table 1 gives equivalents of 1.2 Gpbs in information flow.
This bandwidth provides the following capabilities:
- simultaneous voice and data transmission without additional transceivers;
- live audio/video feed from the scene to other responding units, the dispatch center, the command post, or any other location; and
- broadband Internet access from any scene.
•Narrow beam width, unidirectional. This allows secure communications with a low probability of interception. LaserCom signals are extremely difficult to intercept and monitor. Terrorists could monitor radio frequency (RF) communications during an emergency and cause problems for emergency management through jamming, inserting false information, or other actions that would inhibit a timely response. Most importantly, LaserCom will replace current AVL systems and is capable of geo-location and tracking units in the field through the same transceiver.
•Less regulatory hassle. The Federal Communications Commission is finding it increasingly difficult to allocate frequencies. Laser communications do not have this characteristic or regulatory requirement. LaserCom also eliminates the problem with interference.
•Relatively low cost. While LaserCom may be more expensive than many RF systems, the cost of a LaserCom system will be considerably less than typical 800 MHz trunking systems. Also, technological developments (discussed below) will reduce the cost of LaserCom to below that of most RF systems.
•Portability. For a minimal investment, LaserCom communications packages can easily be stored, quickly transported to a scene, and rapidly deployed to support an emergency operation. A small, portable, quickly deployable tethered aerostat could also be used to deploy the portable transceiver where line-of-sight is a problem.
Since lasers are unidirectional and limited to line of sight, you may be wondering how LaserCom can provide all of these advantages. The key is Steered Agile Beams (STAB) technology being developed by the Defense Advanced Research Projects Agency (DARPA). The STAB device can automatically locate and track similar devices while mobile and transmit and receive data, voice, and imagery. Simply described, when a signal is transmitted, multiple laser beams are emitted and steered from the STAB device. When one beam senses the target transceiver, the beam locks on the target and communication occurs. A device that performs functions similar to those of the STAB device already exists, but it is a large, heavy system of gimbaled mirrors that is high in cost and limited in portability. New solid-state/microcomponent technologies such as optical microelectromechanical systems (MEMs), patterned liquid crystals, diffractive microoptics, and photonic crystals are being used to develop small, ultralight, rapidly steered laser beam subsystems of chip-scale size. Line-of-sight limitations could be overcome by a smart system’s relaying signals within a network between STAB devices, including airborne systems, where required, to achieve the required connectivity for elements currently not within the line of sight.
STAB technology developments are revolutionary and will greatly increase LaserCom’s utility and feasibility for multiple applications. This new technology will provide improvements in size, weight, cost, power requirements, simplicity, and performance. LaserCom has the potential to be a very useful complement to RF communications to support fire departments and other emergency response organizations.
For more information on this technology, contact Brian Matkin, Army Materiel Command Smart Weap-ons Office, Redstone Arsenal, AL, (256) 842-8912.
RALPH COBB is chief of Madison (AL) Fire & Rescue and a lieutenant colonel in the U.S. Army Reserve, serving at Logistics Support Activity, Redstone Arsenal. He is currently on military leave from his fire service position, called to active duty in support of Operation Noble Eagle. He has a master’s in education from Auburn University and is a graduate of the National Fire Academy’s Executive Fire Officer Program. He is vice president of the Alabama Association of Fire Chiefs.
