Survival radio
Encyclopedia
Survival radios are carried by ships and aircraft to facilitate rescue in an emergency. They are generally designed to transmit on international distress frequencies
. Maritime systems have been standardized under the Global Maritime Distress Safety System
.
Type 241, circa 1920. These operated using Morse code
on 500 kHz, the international distress frequency at the time. This frequency had the advantage of long range due to ground-wave propagation and was constantly monitored by all large ships at sea after the Titanic sinking. However, due to its wavelength of 600 meters, a long antenna was required to achieve good range. Long wires on the order of 1/4 wavelength held up by kites or balloons were often used. Spark-gap continued to be used in lifeboats long after the technology was banned for general communication.
s and was crystal-controlled
. The radio case curved inward in the middle so that a user seated in an inflatable life boat could hold it stationary, between the legs and above the knees, while the generator handle was turned. The distress signal, in Morse code, was produced automatically as the crank handle was turned. An NS2 unit was captured by the British in 1941, who produced a copy, the Dinghy Transmitter T-1333. Britain gave a second captured unit to the United States, which produced its own copy, the SCR-578. United States Army Air Forces
aircraft carried the SCR-578 on over-water operations. Named the Gibson Girl
because of its 'hour-glass' shape, it was supplied with a fold-up metal frame box kite
, or a balloon with a small hydrogen generator, for which the flying line was the aerial wire. Power was provided by a hand cranked generator. The transmitter component was the BC-778. The frequency was 500 kHz at 4.8 watts, giving it a range of 200 mi (321.9 km; 173.8 nmi). Keying could be automatic SOS
, or manual. Crystals were a scarce item for the U.S. during the war and the SCR-578 was not crystal-controlled.
A post-World War II version, the AN/CRT-3, which added a frequency in the 8 MHz range, was in use by ships and civil aircraft until the early 1970s.
in World War II brought line-of-sight VHF radios into use. The much shorter wavelengths of VHF allowed a simple dipole
or whip antenna
to be effective. Early devices included the British Walter, a compact single vacuum tube oscillator design operating at 177 MHz (1.7 meter wavelength), and the German Jäger (NS-4), a two-tube master oscillator power amplifier design at 58.5 and, later, 42 MHz. These were small enough to include in life rafts used on single-seat fighter aircraft.
Post-war designs included the British Search And Rescue And Homing beacon (SARAH) beacon, the U.S. AN/URC-4 and the Soviet R 855U. These operated on the aircraft emergency frequencies
of 121.5 and 243 MHz (2.5 and 1.2 meter wavelengths).
on board went down in 1972 and could not be found, the U.S. began requiring all aircraft to carry an Emergency Locator Transmitter (ELT) that would turn on automatically in the event of a crash. Initially these units sent beacon
signals on the 121.5 MHz aircraft emergency frequency. These are being phased out in favor of rescue beacons that use a 406.025 MHz signal, which can be picked up by the Cospas-Sarsat
international satellite system for search and rescue. Each 406 MHz beacon has a unique digital ID code. Users are required to register the code with the Cospas-Sarsat, allowing inquiries to be made when a distress signal is picked up. Some advanced models can transmit a location derived from an internal GPS or GLONASS
receiver.
Maritime practice has shifted from rescue radios on 500 kHz distress frequency (which is no longer officially monitored) to the Global Maritime Distress Safety System
, which includes use of the Cospas-Sarsat
system and other measures, including radar transponders and hand-held marine VHF radio
s.
(DME), Global Positioning Satellite receivers, and satellite communication. United States military survival radios include:
International distress frequency
Since early in the 20th century, the radio frequency of 500 kilohertz has been an international calling and distress frequency for Morse code maritime communication. The unit kilohertz was not introduced until 1960...
. Maritime systems have been standardized under the Global Maritime Distress Safety System
Global Maritime Distress Safety System
The Global Maritime Distress and Safety System is an internationally agreed-upon set of safety procedures, types of equipment, and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft....
.
History
The use of radio to aid in rescuing survivors of accidents at sea came to the forefront after the sinking of the RMS Titanic in 1912. Lifeboats were equipped with spark gap transmitters such as the MarconiMarconi Company
The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...
Type 241, circa 1920. These operated using Morse code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
on 500 kHz, the international distress frequency at the time. This frequency had the advantage of long range due to ground-wave propagation and was constantly monitored by all large ships at sea after the Titanic sinking. However, due to its wavelength of 600 meters, a long antenna was required to achieve good range. Long wires on the order of 1/4 wavelength held up by kites or balloons were often used. Spark-gap continued to be used in lifeboats long after the technology was banned for general communication.
The Gibson Girl
During World War II, Germany developed a hand-crank 500 kHz rescue radio, the "Notsender" (emergency transmitter) NS2. It used two vacuum tubeVacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...
s and was crystal-controlled
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...
. The radio case curved inward in the middle so that a user seated in an inflatable life boat could hold it stationary, between the legs and above the knees, while the generator handle was turned. The distress signal, in Morse code, was produced automatically as the crank handle was turned. An NS2 unit was captured by the British in 1941, who produced a copy, the Dinghy Transmitter T-1333. Britain gave a second captured unit to the United States, which produced its own copy, the SCR-578. United States Army Air Forces
United States Army Air Forces
The United States Army Air Forces was the military aviation arm of the United States of America during and immediately after World War II, and the direct predecessor of the United States Air Force....
aircraft carried the SCR-578 on over-water operations. Named the Gibson Girl
Gibson Girl
The Gibson Girl was the personification of a feminine ideal as portrayed in the satirical pen-and-ink-illustrated stories created by illustrator Charles Dana Gibson during a 20-year period spanning the late nineteenth and early twentieth century in the United States.Some people argue that the...
because of its 'hour-glass' shape, it was supplied with a fold-up metal frame box kite
Box kite
A box kite is a high-performance kite, noted for developing relatively high lift; it is a type within the family of cellular kites. The typical design has four parallel struts. The box is made rigid with diagonal crossed struts. There are two sails, or ribbons, whose width is about a quarter of the...
, or a balloon with a small hydrogen generator, for which the flying line was the aerial wire. Power was provided by a hand cranked generator. The transmitter component was the BC-778. The frequency was 500 kHz at 4.8 watts, giving it a range of 200 mi (321.9 km; 173.8 nmi). Keying could be automatic SOS
SOS
SOS is the commonly used description for the international Morse code distress signal...
, or manual. Crystals were a scarce item for the U.S. during the war and the SCR-578 was not crystal-controlled.
A post-World War II version, the AN/CRT-3, which added a frequency in the 8 MHz range, was in use by ships and civil aircraft until the early 1970s.
VHF era
The use of aircraft for search and rescueSearch and rescue
Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...
in World War II brought line-of-sight VHF radios into use. The much shorter wavelengths of VHF allowed a simple dipole
Dipole antenna
A dipole antenna is a radio antenna that can be made of a simple wire, with a center-fed driven element. It consists of two metal conductors of rod or wire, oriented parallel and collinear with each other , with a small space between them. The radio frequency voltage is applied to the antenna at...
or whip antenna
Whip antenna
A whip antenna is an antenna consisting of a single straight flexible wire or rod, often mounted above some type of conducting surface called a ground plane. The bottom end of the whip is connected to the radio receiver or transmitter. They are designed to be flexible so that they won't break...
to be effective. Early devices included the British Walter, a compact single vacuum tube oscillator design operating at 177 MHz (1.7 meter wavelength), and the German Jäger (NS-4), a two-tube master oscillator power amplifier design at 58.5 and, later, 42 MHz. These were small enough to include in life rafts used on single-seat fighter aircraft.
Post-war designs included the British Search And Rescue And Homing beacon (SARAH) beacon, the U.S. AN/URC-4 and the Soviet R 855U. These operated on the aircraft emergency frequencies
Aircraft emergency frequency
The aircraft emergency frequency is a frequency used on the aircraft radio band reserved for emergency communications for aircraft in distress. The frequencies are 121.5 MHz for civilian, also known as International Air Distress and 243.0 MHz for military use, also known as Military Air...
of 121.5 and 243 MHz (2.5 and 1.2 meter wavelengths).
Automated beacon systems
After a light plane with two U.S. congressmenHale Boggs
Thomas Hale Boggs Sr. , was an American Democratic politician and a member of the U.S. House of Representatives from New Orleans, Louisiana...
on board went down in 1972 and could not be found, the U.S. began requiring all aircraft to carry an Emergency Locator Transmitter (ELT) that would turn on automatically in the event of a crash. Initially these units sent beacon
Electric beacon
Electric beacons are a kind of beacon used with direction finding equipment to find ones relative bearing to a known location .The term electric beacon includes radio, infrared and sonar beacons.- Radio beacons :...
signals on the 121.5 MHz aircraft emergency frequency. These are being phased out in favor of rescue beacons that use a 406.025 MHz signal, which can be picked up by the Cospas-Sarsat
Cospas-Sarsat
Cospas-Sarsat is an international satellite-based search and rescue distress alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. It is best known as the system that detects and locates emergency beacons...
international satellite system for search and rescue. Each 406 MHz beacon has a unique digital ID code. Users are required to register the code with the Cospas-Sarsat, allowing inquiries to be made when a distress signal is picked up. Some advanced models can transmit a location derived from an internal GPS or GLONASS
GLONASS
GLONASS , acronym for Globalnaya navigatsionnaya sputnikovaya sistema or Global Navigation Satellite System, is a radio-based satellite navigation system operated for the Russian government by the Russian Space Forces...
receiver.
Maritime practice has shifted from rescue radios on 500 kHz distress frequency (which is no longer officially monitored) to the Global Maritime Distress Safety System
Global Maritime Distress Safety System
The Global Maritime Distress and Safety System is an internationally agreed-upon set of safety procedures, types of equipment, and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft....
, which includes use of the Cospas-Sarsat
Cospas-Sarsat
Cospas-Sarsat is an international satellite-based search and rescue distress alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. It is best known as the system that detects and locates emergency beacons...
system and other measures, including radar transponders and hand-held marine VHF radio
Marine VHF radio
Marine VHF radio is installed on all large ships and most seagoing small craft. It is used for a wide variety of purposes, including summoning rescue services and communicating with harbours, locks, bridges and marinas, and operates in the VHF frequency range, between 156 to 174 MHz...
s.
U.S. Military survival radios
Military organizations still issue pilots and other combat personnel individual survival radios, which have become increasingly sophisticated, with built-in Distance Measuring EquipmentDistance Measuring Equipment
Distance measuring equipment is a transponder-based radio navigation technology that measures distance by timing the propagation delay of VHF or UHF radio signals....
(DME), Global Positioning Satellite receivers, and satellite communication. United States military survival radios include:
- AN/CRC-7 - World War II era set, 140.58 MHz
- AN/PRC-17
- AN/PRC-32 - Navy rescue sets, 243 MHz.
- AN/PRC-49
- AN/PRC-63 - Smallest set built.
- AN/URC-64 - (Air Force), 4 frequency rescue sets. Four crystal controlled channels (225-285MHz)
- AN/URC-68 - (Army), 4 frequency rescue sets.
- AN/PRC-90 - Vietnam War era airman rescue set. AN/PRC-90-1 and AN/PRC-90-2 are improved, repairable versions. Operates on 121.5, 243 and 282.8 MHz AM. The PRC-90 also included a beacon mode, and a tone generator to allow the sending of Morse Code.
- AN/PRC-103 - (Air Force) Rescue Swimmer Radio.
- AN/PRC-112 - Offers Synthesized radio in the VHF and UHF aircraft bands. A PRC-112 and a hand held GPS were used by Capt. Scott O'GradyScott O'GradyScott Francis O'Grady is a former USAF Captain and former United States Air Force fighter pilot who gained prominence after the June 2, 1995 Mrkonjić Grad incident, in which he ejected over Bosnia when his F-16C was shot down by a Bosnian Serb SA-6 while he was patrolling the no-fly zone...
when he was rescued after being shot down over Bosnia. The AN/PRC-112B, initially known as the Hook 112, is a PRC-112 modified to include a GPSGlobal Positioning SystemThe Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
receiver, allowing encrypted position information to be sent. Also has Cospas-SarsatCospas-SarsatCospas-Sarsat is an international satellite-based search and rescue distress alert detection and information distribution system, established by Canada, France, the United States, and the former Soviet Union in 1979. It is best known as the system that detects and locates emergency beacons...
beacon. The latest model PRC-112G, built by General DynamicsGeneral DynamicsGeneral Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...
can communicate with satellites as well. Over 31,000 radios in the PRC-112 family have been produced. - AN/PRC-125 (Navy) Rescue Swimmer Radio.
- AN/PRC-149 Rescue Radio, replaces the PRC-90, PRC-112 and PRC-125 for non-combat use.http://www.olive-drab.com/od_electronics_anprc149.php Includes GPS and Cospas-Sarsat beacon. Operates on 121.5 MHz, 243.0 MHz, and 282.8 MHz and 406.025 MHz. Built by TadiranTadiranTadiran refers to a former Israeli conglomerate, which was founded in 1962 by the merger of two companies, Tadir and Ran...
, the PRC-149 uses standard D cellD batteryA D battery is a size of dry cell. A D cell is cylindrical with electrical contacts at each end; the positive end having a nub or bump...
batteries, unlike other units that took special batteries. - AN/PRQ-7 Combat Survivor/Evader Locator (CSEL) combines selective availability GPS, UHF line of sight and UHF satellite communications along with a Sarsat beacon. It can send predefined messages digitally along with the user's location. As of 2008, the PYQ-7 cost $7000 each, "batteries not included." A rechargeable lithium-ion battery pack cost $1600, while a non-rechargeable lithium-manganese dioxide unit cost $1520. BoeingBoeingThe Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
had delivered 20,000 PYQ-7s, with 15,000 more on order. - AN/URC-4 - 121.5 and 243 MHz
- AN/URC-11 - (243 MHz), "A" versions replaced one audio tube with transistors.
- AN/URC-10 - The RT-10 are subminiaturized, completely transistorized UHF radio sets. They consist of a crystal-controlled receiver-transmitter, a 16-v dry battery, and a power cable assembly. The unit operates on one channel in the 240-260 mc band, usually 243 MHz. RT-60 and RT-60B1 were two frequency versions of the RT-10
- AN/URC-14 - (121.5 MHz)
See also
- Distress radiobeacon
- Distress signalDistress signalA distress signal is an internationally recognized means for obtaining help. Distress signals take the form of or are commonly made by using radio signals, displaying a visually detected item or illumination, or making an audible sound, from a distance....
- Global Maritime Distress Safety SystemGlobal Maritime Distress Safety SystemThe Global Maritime Distress and Safety System is an internationally agreed-upon set of safety procedures, types of equipment, and communication protocols used to increase safety and make it easier to rescue distressed ships, boats and aircraft....
- Search and Rescue Transponder
- Joint Electronics Type Designation SystemJoint Electronics Type Designation SystemThe Joint Electronics Type Designation System , which was previously known as the Joint Army-Navy Nomenclature System and the Joint Communications-Electronics Nomenclature System, is a method developed by the U.S. War Department during World War II for assigning an unclassified designator to...
- List of military electronics of the United States