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This article is about Emergency Locator Transmitters (ELTs). For other uses of 'ELT', see ELT (disambiguation).
This article is about Personal Locator Beacons (PLBs). For other uses of 'PLB', see PLB (disambiguation).
Emergency position-indicating radio beacons
Emergency position-indicating radio beacons

In the field of Search and Rescue (SAR), distress radio beacons, also collectively known as distress beacons, emergency beacons, or simply, beacons, are tracking transmitters which aid in the detection and location of boats, aircraft, and/or persons in distress. For the TV series of this title see Search and Rescue (TV series. A Tracking transmitter broadcasts a Radio signal which can be detected by a Directional antenna (typically a Radio Direction Finder. A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it In the proper sense, the term refers specifically to the three types of radiobeacons (listed below) that interface with Cospas-Sarsat, the international satellite system for Search and Rescue. Electric beacons are a kind of Beacon used with direction finding equipment to find ones relative bearing to a known location (the Beacon Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada This article is about artificial satellites For natural satellites also known as moons see Natural satellite. When activated, such beacons send out a distress signal that, when detected by non-geostationary satellites, can be located by triangulation. A geostationary orbit (GEO is a Geosynchronous orbit directly above the Earth 's Equator (0° Latitude) with a period equal to the Earth's In Trigonometry and Geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either In the case of 406 MHz beacons which transmit digital signals, the beacons can be uniquely identified almost instantly (via GEOSAR), and furthermore, a GPS position can be encoded into the signal (thus providing both instantaneous identification and position. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth An encoder is a device used to change a signal (such as a Bitstream) or Data into a Code. ) Often using the initial position provided via the satellite system, the distress signals from the beacons can be homed by SAR aircraft and ground search parties who can in turn come to the aid of the concerned boat, aircraft, and/or persons. A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it

There are three types of distress radiobeacons compatible with the Cospas-Sarsat system:[1]

The basic purpose of distress radiobeacons is to get people rescued within the so-called "golden day"[2] (the first 24 hours following a traumatic event) when the majority of survivors can still be saved.

Since the inception of Cospas-Sarsat in 1982, distress radiobeacons have assisted in the rescue of over 20,531 persons in 5,752 distress situations. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada In 2005 distress radiobeacons aided in the rescue of 1,666 persons in 435 distress situations. [3] There are roughly 556,000 121. 5 MHz beacons and 429,000 406 MHz beacons. [4] As of 2002, there were roughly 82,000 registered (406 MHz) beacons, and over 500,000 of the older unregistered kind. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar.

Contents

General description

Most beacons are brightly colored and waterproof. EPIRBs and ELTs are larger, and would fit in a cube about 30 cm on a side, and weigh 2 to 5 kg (4 to 11 lb). PLBs vary in size from cigarette-packet to paperback book and weigh 200 g to 1 kg (½ to 2½ lb). They can be purchased from marine suppliers, aircraft refitters, and (in Australia and the United States) hiking supply stores. The units have a useful life of 10 years, operate across a range of conditions (−40°C/°F to +40°C/+104°F), and transmit for 24 to 48 hours. The Celsius Temperature scale was previously known as the centigrade scale. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724 [5] As of 2003 the cost varies from US$139 to US$3000, with varying performance (see below). Year 2003 ( MMIII) was a Common year starting on Wednesday of the Gregorian calendar.

By the 1st of February 2009 the 121. 5 MHz disress EPIRB will no longer be detected by satellites, you will need to purchase a new 406 MHz beacon. you can usually recycle your old EPIRB at a battery shop.

Classification nomenclature

The three distress radiobeacon types are further classified as follows:[6]

Beacon modes

The most important aspect of a beacon in classification is the mode of transmission. There are two valid transmission modes: digital and analog.

Digital Mode - 406 MHz beacons

406 MHz beacons transmit bursts of digital distress information to orbiting satellites, and may also contain a small integrated analog (121. 5 MHz) homing beacon. A homing beacon is a device that allows the user to track a ship an animal or another individual Advanced 406 MHz beacons are capable of transmitting a highly-accurate GPS location within their distress message, thus, the process of distress relief simply becomes "rescue" instead of "Search and Rescue. For the TV series of this title see Search and Rescue (TV series. "

The distress message transmitted by a 406 beacon contains the information such as:

The digital distress message generated by the beacon varies according to the above factors and is encoded in 30 hexadecimal characters. In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a The unique 15-character digital identity (the 15-hex ID) is hard-coded in the firmware of the beacon. SAR authorities refer to the distress messages and the identity transmitted by 406 beacons, variously, as "hex codes. "

406 Beacon Facts

Hex Codes

Example hex codes look like the following: [8]

SAR authorities and owners of beacons always refer to a beacon by its "15 Hex ID," which is printed or stamped on the outside of the beacon and is hard-coded into its firmware. In Computing, firmware is a computer program that is Embedded in a hardware device for example a Microcontroller. When the beacon transmits a distress signal, this 15-hex ID is digitally encoded within the beacon variable (15, 22, and) 30-hexadecimal-character distress messages (also called the transmitted hex code. ) The firmware 15-hex ID can only be reprogrammed by certified distress radiobeacon technicians.

Within its 30 hexadecimal character distress message, a 406 beacon will transmit a modified "15 Hex" code. These 15 hexadecimal characters will include both the encoded (physical/hard-coded) 15 hex ID of the beacon and, if GPS equipped, a rough (rounded) lat-long position. To determine a beacon's 15-hex ID from its transmitted 15-hex code, one can use the Cospas-Sarsat beacon decoder tool. When one enters the transmitted (i. e. GPS-location-included) 15-hex into the decoder, the unmodified 15-hex ID is printed at the bottom of the output of the Beacon Decoder page. This method can be used to confirm that a beacon is encoding the correct 15-hex ID (as printed on the side of the beacon) into its distress messages.

Analog Mode - all other beacons

Frequency

Distress beacons transmit distress signals on the following key frequencies; the frequency used distinguishes the capabilities of the beacon. A recognized beacon can operate on one of the three (currently) Cospas-Sarsat satellite-compatible frequencies. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada In the past, other frequencies were also used as a part of the search and rescue system. For the TV series of this title see Search and Rescue (TV series.

Cospas-Sarsat (satellite) compatible beacon frequencies

Compatible until 1 February 2009: *

Cospas-Sarsat incompatible beacon frequencies

Types

The type of a beacon is determined by the environment for which it was designed to be used:

Each type is sub-classified:

EPIRB sub-classification

EPIRBS are sub-classified as follows:[13]

Recognized Categories:

Unrecognized Classes:

ELT sub-classification

ELTs for aircraft may be classed as follows:[14]

Within these classes, an ELT may be either a digital 406 MHz beacon, or an analog beacon (see above). In the field of Search and Rescue (SAR distress radio beacons, also collectively known as distress beacons, emergency beacons, or simply beacons

PLB sub-classification

There are two kinds of PLB:

All PLBs transmit in digital mode on 406 MHz. Additional information about PLBs can be obtained from the Ultimate PLB FAQ at Equipped to Survive.

Activation methods

There are two ways to activate a beacon:

Automatic EPIRBs are water activated, while automatic ELTs are G-force (impact) activated. g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s Some EPIRBs also deploy; this means that they physically depart from their mounting bracket on the exterior of the vessel (usually by going into the water. )

For a marine EPIRB to begin transmitting a signal (or "activate") it first needs to come out of its bracket (or "deploy"). Deployment can happen either manually—where someone has to physically take it out of its bracket—or automatically—where water pressure will cause a hydrostatic release unit to release the EPIRB from its bracket. If it does not come out of the bracket it will not activate. There is a magnet in the bracket which operates a reed safety switch in the EPIRB. This is to prevent accidental activation when the unit gets wet from rain or shipped seas.

Once deployed, EPIRBs can be activated, depending on the circumstances, either manually (crewman flicks a switch) or automatically (as soon as water comes into contact with the unit's "sea-switch". ) All modern EPIRBs provide both methods of activation and deployment and thus are labelled "Manual and Automatic Deployment and Activation. "

Advantages and disadvantages of the various beacons

Analog (121. 5 MHz) Beacons 406 MHz (Digital) Beacons
SAR response delay SAR response delay
  • SAR response to anonymous beacons can be delayed 4-6 hours, and as much as 12 hours[15]
  • Resolution or response to registered beacons is very swift. SAR response can be activated within approximately 10 minutes of beacon activation (and GEOSAR detection) if distress is evident.
  • Unregistered beacons can usually be responded to after only 1 LEOSAR satellite pass; after two passes, response is immediate
False alerts False alerts
  • 98. 5% of 'alerts' detected are false alerts (2006[16])
  • Fewer than 2 in 1000 alerts and 2 in 100 composite alerts are actual distress. [17]
  • The Cospas-Sarsat system has no way of distinguishing between analog beacons and interference (from set top boxes, etc. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada A set-top box (STB or set-top unit (STU is a device that connects to a Television and an external source of signal, turning the signal into )
  • False alerts may result in a long and fruitless search by costly SAR assets, although rescue co-ordination centres typically analyse the circumstances, considering location, movement of the source and confirmatory reports before launching an operation
    • Searches for interference signals and false alerts inhibit SAR assets from being available for real searches
  • All alerts (100%) come from beacons (analog interference is ignored)
  • Approximately 7 out of 10 of all 406 false alerts are resolved by a phone or radio call, therefore,
    • SAR resources are not wasted
    • SAR assets are more available for actual distress
    • Persons responsible for causing false alerts can more likely avoid having to pay fines and/or paying the costs of operating SAR assets
    • Follow-up to false activations allows continuous reductions in the number of false alerts
  • 97. 1% of all alerts are false alerts (2006[18])
Information transmitted by the beacon Information transmitted by the beacon
Anonymous siren tone
  • A unique 15, 22, or 30 digit serial number called a Hex Code is transmitted
  • The Hex Code can contain a plethora of information, such as:[19]
    • the Country of beacon registration
    • the identification of the vessel or aircraft in distress, and
      • Identification for aircraft ELTs can be in the form of the aircraft's callsign or its ICAO 24-bit address (from its Mode-S transponder)
    • optionally, position data from onboard navigation equipment (GPS)
Beacon registration information Beacon registration information
Anonymous beacons cannot be registered
  • There is no charge to register 406 beacons (see below). In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a In Broadcasting and Radio communications a call sign (also known as a callsign or call letters, or abbreviated as a call, or otherwise A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation In the field of Search and Rescue (SAR distress radio beacons, also collectively known as distress beacons, emergency beacons, or simply beacons [20]
    • Unless otherwise advised, personal information is used exclusively for SAR distress alert resolution purposes
  • Hex Code registration is mandatory in most countries of the world
  • Beacons are registered with MCCs who have 24-hour access to registry data, such as:
    • Name of the owner of the beacon
    • Name or callsign of the ship, aircraft, or other vehicle the beacon is associated with
    • Cellular, MMSI, and/or pager numbers, and/or other contact information
Transmission power Transmission power
0. In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a A Maritime Mobile Service Identity (MMSI is a series of nine digits which are sent in digital form over a Radio frequency channel in order to uniquely identify ship stations 1 W continuous - weak signal cannot usually penetrate debris or trees 5 W pulse mode - strong pulse reaches the satellites
Potential to be seen by a satellite Potential to be seen by a satellite
  • To hear and process an analogue signal, both a LEOSAR and a LEOLUT must be within sight of each other continuously for a sufficient duration (several minutes). Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada The LEOLUT does signal analysis via a dotplot of the signals heard, and the computer looks for a Doppler shift in the signal to triangulate a position.
  • LEOSAR satellites can be spaced by up to 90-100 minutes
  • Second detection is necessary due to false alerts and to resolve position—takes an additional 45-100 minutes before SAR assets can be called
  • GEOSAR provides nearly-instantaneous coverage 70 degrees north and south of the equator
  • Worldwide coverage via LEOSAR — 6 satellites
    • For 406 signals, LEOSARs do not have to be in sight of a LUT to relay a distress message to Cospas-Sarsat. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada Once a 406 signal is detected by a satellite, the satellite will "dump" this data towards Earth (thus to all LUTs) for 24 hours.
  • Future use of GNSS satellites will allow worldwide real-time coverage (MEOSAR)
Location detection Location detection
  • Two (roughly) "50% chance" mirror-positions (called the "A-side" for the most likely and the "B-side" for the least likely to be accurate) are generated by Doppler triangulation after the first pass of a LEOSAR
    • Due to false alerts, no reaction can occur based on first pass alert
  • A second pass resolves the ambiguity and resolves the search location to a radius of 20 km[21]
  • Moving targets (usually false alerts) produce interfering anomalies; calculated positions are inaccurate
  • LEOSAR uses same technique as for analog beacons, but, since beacons are uniquely identified as beacons and have improved frequency stability, response can occur based on first-pass information[22]
  • Doppler-only accuracy is within 5 km (3. Global Navigation Satellite System (GNSS is the standard generic term for satellite navigation systems that provide autonomous geo-spatial positioning with global coverage Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada 1 statute miles or 2. A mile is a unit of Length, usually used to measure Distance, in a number of different systems including Imperial units United States 6 nautical miles)— that is, the position is sufficiently accurate for SAR purposes even after only one pass. A nautical mile or sea mile is a unit of Length. It corresponds approximately to one minute of Latitude along any meridian. What's more, the "A-position" (the most likely of the two 'mirror' positions) can be determined valid with 98. 5% accuracy after only one satellite pass.
    • This accuracy can be increased to 99. 3% using so-called "combined Leo-Geo processing,"[23] and this technique also enables accurate positions to be generated with as little as two or three bursts from the beacon (i. e. less than 4 minutes of transmission) and thus greatly increases the chances of being found even if the beacon is ultimately consumed by fire or is otherwise destroyed
  • GPS Position can be encoded into the Hex Code and can be updated real-time via GEOSAR
    • Encoded GPS position accuracy is about 15 m (45 ft)[24]
  • These increases in accuracy are a paradigm shift from analog beacons - going from two possible positions, each within a 20km radius, to 15m accuracy at one position could be considered an over 2500 times improvement in accuracy
    • The improvements in accuracy are largely responsible for the advent of the phrase "taking the 'search' out of Search and Rescue"
  • LEOSAR Doppler triangulation is less affected by beacon movement due to improved frequency stability
  • In the future, near-instantaneous detection & position triangulation via MEOSAR
Age of technology Age of technology
121. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada 5 MHz beacons were developed in the late 1960s, when car phones weighed roughly 20 lb[25] (the first ELT TSO C91 was written in 1971. The 1960s decade refers to the years from the beginning of 1960 to the end of 1969 A Technical Standard Order ( TSO) is a minimum performance standard issued by the United States Federal Aviation Administration for specified materials [26]) 406 MHz beacons use proven, modern technologies reminiscent of those found in modern cell phones.

See also Cospas-Sarsat - Advantages of 406 Beacons and Canada's National Search and Rescue Secretariat—Advantages of 406 Beacons

Although modern systems are significantly superior to older ones, even the oldest systems provide an immense improvement in safety, compared to not having any beacon whatsoever.

Phase-out of 121. 5 & 243 beacons

Beginning 1 February 2009, only 406 MHz beacons will be detected by the international Cospas-Sarsat SAR satellite system. Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen This article is about the year For the film see 2009 Lost Memories. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada This affects all maritime beacons (EPIRBs), all aviation beacons (ELTs) and all personal beacons (PLBs). In other words, Cospas-Sarsat will cease satellite processing of 121. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada 5/243 MHz beacons 1 February 2009. Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen This article is about the year For the film see 2009 Lost Memories.

According to Cospas-Sarsat (often abbreviated C-S), the international organization responsible for the Search and Rescue (SAR) satellite system, all beacon owners and users should begin taking steps to replace their 121. 5/243 MHz beacons with 406 MHz beacons as soon as possible. [29] C-S recommends that beacon owners should consider purchasing a 406 MHz beacon when the battery on an older 121. 5 MHz beacon needs replacing. Typically, batteries need replacing about every five years. The sooner a beacon owner upgrades, the better the service that the Cospas-Sarsat System can provide in case the beacon is activated in a distress event.

More information about the switch to 406 is available on Cospas-Sarsat's 121.5/243 Phase-Out page.

Despite the switch to 406, pilots and ground stations are encouraged to continue to monitor for transmissions on the emergency frequencies, as many 406 beacons are also equipped with 121. 5 'homers. ' Furthermore, the 121. 5 MHz frequency continues to be used as a voice distress frequency (especially in aviation. )

SAR response to various beacons

Emergency beacons operating on 406 MHz transmit a unique 15, 22, or 30 character serial number called a Hex Code. When the beacon is purchased the Hex Code should be registered with the relevant national (or international) authority. Registration provides Search and Rescue agencies with crucial information such as:

Registration information allows SAR agencies to start a rescue more quickly. For example, if a shipboard telephone number listed in the registration is unreachable, it could be assumed that a real distress event is occurring. Conversely, the information provides a quick and easy way for the SAR agencies to check and eliminate false alarms (potentially sparing the owner of the beacon thousands of dollars in negligent false alert fines. )

An unregistered 406 beacon still carries some information, such as the manufacturer and serial number of the beacon, and in some cases, an MMSI or aircraft tail number / ICAO 24-bit address. A Maritime Mobile Service Identity (MMSI is a series of nine digits which are sent in digital form over a Radio frequency channel in order to uniquely identify ship stations An aircraft registration is a unique Alphanumeric string that identifies an Aircraft, in similar fashion to a licence plate on an automobile A transponder is an electronic device that produces a response when it receives a radio-frequency interrogation Despite the clear benefits of registration, an unregistered 406 beacon is very substantially better than a 121. 5/243. 0 beacon; this is because the Hex Code received from a 406 beacon confirms the authenticity of the signal as a real SAR alert.

Beacons operating on 121. 5 and/or 243. 0 MHz simply transmit an anonymous siren tone, and thus carry no information to SAR agencies. Such beacons implicitly rely on the doppler location detection system. SAR authorities have no way of knowing whether a 121. 5/243. 0 MHz signal is actually a SAR signal until they physically deploy to the location and home in on the source (and sound) of the transmission. Direction finding (DF refers to the establishment of the direction from which a received signal was transmitted Since SAR resources are scarce (and expensive), most countries do not deploy the most useful SAR homing assets (aircraft) until ambiguity has been resolved (see doppler).

Responsible agencies

In the U. S. , offshore beacons are investigated and victims rescued by the Coast Guard. On-shore beacons are investigated by local search and rescue services in Alaska. The Air Force Rescue Coordination Center is charged with land-based emergency signals, usually dispatching volunteer members from The United States Air Force Auxiliary Civil Air Patrol. The Civil Air Patrol ( CAP) is the civilian auxiliary of the United States Air Force (USAF In the U. S. there are no published notification systems for other locations.

Statutory requirements

In the U. S. (as in most jurisdictions) no special license is required to operate an EPIRB. The following paragraphs define other requirements relating to EPIRBs, ELTs, and PLBs.

Registration

There is no charge to register 406 MHz beacons. IT MAY SAVE YOUR LIFE. [30]

All distress alerting beacons operating on 406 MHz should be registered; all vessels and aircraft operating under SOLAS and ICAO regulations must register their beacons. The International Civil Aviation Organization ( ICAO) an agency of the United Nations, codifies the principles and techniques of international air navigation Some national administrations (including the United States, Canada, Australia, and the UK) also require registration of 406 MHz beacons.

The Cospas-Sarsat Handbook of Beacon Regulations provides the status of 406 MHz beacon regulations in specific countries and extracts of some international regulations pertaining to 406 MHz beacons.

The following list shows the agencies accepting 406 beacon registrations by country:

Environment-specific requirements

Aviation (ELTs)

Most general aviation aircraft in the U. S. are required to carry an ELT, depending upon the type or location of operation, while scheduled flights by scheduled air carriers are not. However, in commercial aircraft, a cockpit voice recorder or flight data recorder must contain an underwater detection beacon. A Cockpit Voice Recorder (CVR is a Flight recorder used to record the audio environment in the flightdeck of an aircraft for the purpose of investigation of accidents and incidents The flight data recorder ( FDR) or Black Box is a Flight recorder used to record specific Aircraft performance parameters

As per 14 CFR 91.207.a.1, ELTs built according to TSO-C91 (of the type described below as "Traditional ELT, unregistered") have not been permitted for new installations since June 21, 1995; the replacing standard was TSO-C91a. Furthermore, TSO-C91/91a ELTs are scheduled to phased out February 1, 2009 to be replaced by the 406 MHz [31] ELT, a far superior unit. [32]

Though monitoring of 121. 5 and 243 MHz (Class B) distress signals by satellite is scheduled to cease in 2009, there is currently no upgrade of older ELT units mandated by the FAA for aircraft in the United States.

Marine (EPIRBs)

EPIRBs are a component of the Global Maritime Distress Safety System (GMDSS). The Global Maritime Distress Safety System ( GMDSS) is an internationally agreed-upon set of Safety procedures types of equipment and communication protocols used Most commercial off-shore working vessels with passengers are required to carry a self-deploying EPIRB, while most in-shore and fresh-water craft are not.

As part of the United States efforts to prepare beacon users for the end of 121. 5 MHz frequency processing by satellites, the FCC has prohibited the use of 121. 5 MHz EPIRBs as of January 1, 2007 (47 CFR 80. New Year See also New Year The Ancient Romans began their consular year on January 1st since 153 BC Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. 1051). See the United States Coast Guard (USCG) brief on the 121.5/243 Phase-out.

The most current and comprehensive information about EPIRBs is provided by the Equipped To Survive Foundation. See also the 406 beacon performance review.

Personal locator beacons (PLBs)

Personal locator beacons operating on 406 MHz must be registered. PLBs should not be used in cases where normal emergency response exists (i. e. 911. )

The most current and comprehensive information about PLBs is provided by the Equipped To Survive Foundation. See also the 406 beacon performance review.

Detailed type descriptions

Current types

EPIRBs (marine)

Current marine EPIRBs are generally divided into three classes; Category I, Category II, and Class B (or Category B).

ELTs (aircraft)

ELTs used in aircraft are of the following types:

Types Being Phased Out:

PLBs

All PLBs must have a Hex Code on the body. Persons must register this Hex Code with their national SAR agency. See below for types of PLBs no longer used.

Obsolete types

Obsolete EPIRBs

There are also several older types of EPIRB devices which are no longer recommended for use.

Furthermore, the U. S. Coast Guard recommend that no EPIRB of any type manufactured before 1989 be used.

Obsolete ELTs

Obsolete PLBs

How they work

All the systems work something like this: A beacon is activated by a crash, a sinking, or manually by survivors. The beacon's transmission is picked up by one or more satellites. The satellite transmits the beacon's signal to its ground control station. The satellite's ground station processes the signals and forwards the data, including approximate location, to a national authority. The national authority forwards the data to a rescuing authority. The rescuing authority uses its own receiving equipment to locate the beacon and makes the rescue or recovery. Once the satellite data is in, it takes less than a minute to forward the data to any signatory nation.

Overview diagram of EPIRB/COSPAS-SARSAT communication system
Overview diagram of EPIRB/COSPAS-SARSAT communication system

There are several systems in use, with beacons of varying expense, different types of satellites and varying performance. Note that even the oldest systems provide an immense improvement in safety, compared to not having a beacon.

GPS-based, registered

The most modern 406 MHz beacons with GPS (US$ 1200-$3000 in 2002) locate a beacon with a precision of 100 meters, anywhere in the world, and send a serial number so the government authority can look up phone numbers to notify next-of-kin in four minutes, with rescue commencing shortly afterward. Basic concept of GPS operation A GPS receiver calculates its position by carefully timing the signals sent by the constellation of GPS Satellites high above the Earth The GPS system permits stationary, wide-view geosynchronous communications satellites to enhance the doppler position received by low Earth orbit satellites. A Low Earth Orbit (LEO is generally defined as an Orbit within the locus extending from the Earth’s surface up to an altitude of 2000 km EPIRB beacons with built-in GPS are usually called GPIRBs, for GPS Position-Indicating Radio Beacon or Global Position-Indicating Radio Beacon.

High-precision registered

An intermediate technology 406 MHz beacon (US$ 500-900) has world-wide coverage, locates within 2 km (12. 5 km² search area), notifies kin and rescuers in 2 hours maximum (46 min average), and has a serial number to look up phone numbers, etc. This can take up to two hours because it has to use moving weather satellites to locate the beacon. To help locate the beacon, the beacon's frequency is controlled to 2 parts per billion, and its power is a hefty five watts.

Both of the above types of beacons usually include an auxiliary 25 milliwatt beacon at 121.5 MHz to guide rescue aircraft.

Traditional ELT, unregistered

The oldest, cheapest (US$ 139) beacons send an anonymous warble at 121. 5 MHz. They can be detected by satellite over only 60% of the earth, require up to 6 hours for notification, locate within 20 km (search area of 1200 km²) and are anonymous. Coverage is partial because the satellite has to be in view of both the beacon and a ground station at the same time—the satellites do not store and forward the beacon's position. Coverage in polar and south-hemisphere areas is poor. The frequency is the standard aviation emergency frequency, and there is interference from other electronic and electrical systems, so false alarms are common. To reduce false alarms, a beacon is confirmed by a second satellite pass, which can easily slow confirmation of a 'case' of distress to up to about 4 hours (although in rare circumstances the satellites could be position such that immediate detection becomes possible. ) Also, the beacons can't be located as well because their frequency is only accurate to 50 parts per million, and they send only 75-100 milliwatts of power.

These ELTs will not be monitored by Cospas-Sarsat after February 1, 2009. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen This article is about the year For the film see 2009 Lost Memories.

Location by Doppler (without GPS)

When the beacon has no GPS receiver, the system locates the beacon from its Doppler shift as received by the quickly-moving satellites. The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for Using the same techniques as radar, basically, the frequency received varies depending on the speed of the beacon relative to the satellite. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships The amount of shift is proportional to the range and bearing to the satellite. The instant the beacon's Doppler shift changes from high to low indicates the time when the bearing from the beacon to the satellite's ground track is 90 degrees. The side of the satellite track is determined because the rate of change of the Doppler shift is faster when the Earth is turning towards the satellite track.

One key to an effective Doppler position triangulation is excellent frequency stability. If the signal is not monotone (stable), then the results of the triangulation will vary. This is why 406 MHz beacons can be triangulated to within 5km and the b-side (unlikely mirror position) can be ruled out with 98. 5% accuracy, whereas the old technology of analog beacons is only accurate to within a 20 km radius per mirror image, each of which is roughly equally likely to be the correct position.

In order to handle multiple simultaneous beacons, modern 406 MHz beacons transmit in bursts, and remain silent for a few seconds. This also conserves transmitter power.

Russia developed the original system, and its success drove the desire to develop the improved 406 MHz system. Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending The original system is a brilliant adaptation to the low quality beacons, originally designed to aid air searches. It uses just a simple, lightweight transponder on the satellite, with no digital recorders or other complexities. Ground stations listen to each satellite as long as it is above the horizon. Doppler shift is used to locate the beacon(s). Multiple beacons are separated when a computer program performs a Fourier transform on the signal. This article specifically discusses Fourier transformation of functions on the Real line; for other kinds of Fourier transformation see Fourier analysis and Also, two satellite passes per beacon are used. This eliminates false alarms by using two measurements to verify the beacon's location from two different bearings. This prevents false alarms from VHF channels that affect a single satellite. Regrettably, the second satellite pass almost doubles the average time before notification of the rescuing authority. However, the notification time is much less than a day.

Operational testing

According to the FAA, ground testing of type A, B and S ELTs is to be done within the first 5 minutes of each hour. The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of Testing is restricted to 3 audio sweeps. [2] Type I and II devices (those transmitting at 406 MHz) have a self test function and must not be activated except in an actual emergency.

The Coast Guard web page for EPIRBs states: "You may be fined for false activation of an unregistered EPIRB. The U. S. Coast Guard routinely refers cases involving the non-distress activation of an EPIRB (e. g. , as a hoax, through gross negligence, carelessness or improper storage and handling) to the Federal Communications Commission. The FCC will prosecute cases based upon evidence provided by the Coast Guard, and will issue warning letters or notices of apparent liability for fines up to $10,000. " [3]

Satellites used

Receivers are auxiliary systems mounted on several types of satellites. This substantially reduces the program's cost.

The weather satellites that carry the SARSAT receivers are in "ball of yarn" orbits, inclined at 99 degrees. The longest period that all satellites can be out of line-of-sight of a beacon is about two hours.

The first satellite constellation was launched in the early 1970s by the Soviet Union, Canada, France and the USA. The Union of Soviet Socialist Republics (USSR was a constitutionally Socialist state that existed in Eurasia from 1922 to 1991 Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page This article is about the country For a topic outline on this subject see List of basic France topics. The United States of America —commonly referred to as the

Some geosynchronous satellites have beacon receivers. Since end of 2003 there are four such geostationary satellites (GEOSAR) that cover more than 80% of the surface of the earth. As with all geosynchronous satellites, they are located above the equator. The GEOSAR satellites do not cover the polar caps.

Since they see the Earth as a whole, they see the beacon immediately, but have no motion, and thus no doppler frequency shift to locate it. However, if the beacon transmits GPS data, the geosynchronous satellites give nearly instantaneous response.

History

The original impetus for the program in the U. S. was the loss of Congressmen Hale Boggs (D-LA) and Nick Begich (D-AK) in the Alaskan wilderness on October 16, 1972. The United States House of Representatives is one of the two chambers of the United States Congress; the other is the Senate. Thomas Hale Boggs Sr ( February 15, 1914 &ndash Undetermined presumably October 16, 1972) was an American Democratic Nicholas Joseph "Nick" Begich Sr ( April 6, 1932 – Undetermined presumably October 16, 1972) was a Democratic Party Alaska ( Аляска Alyaska) is a state in the United States of America, in the northwest of the North American continent Events 456 - Magister militum Ricimer defeats the Emperor Avitus at Piacenza and becomes master of the western Year 1972 ( MCMLXXII) was a Leap year starting on Saturday (link will display full calendar of the Gregorian calendar. A massive search effort failed to locate them. The result was a U. S. law mandating that all aircraft carry an emergency locator transmitter. Technical and organizational improvements followed.

Cospas-Sarsat is an international organization that has been a model of international cooperation, even during the Cold War. Cospas-Sarsat is an international satellite-based Search and rescue (SAR Distress alert detection and information distribution system established by Canada Cold War is the state of conflict tension and competition that existed between the United States and the Soviet Union (USSR and their respective allies from the SARSAT means Search And Rescue SATellite. COSPAS is a Russian acronym with the same meaning. A consortium of Russia, the U. S. , Canada and France formed the organization in 1982. Since then 29 others have joined.

Cospas-Sarsat defines standards for beacons, auxiliary equipment to be mounted on conforming weather and communication satellites, ground stations, and communications methods. The satellites communicate the beacon data to their ground stations, which forward it to main control centers of each nation that can initiate a rescue effort.

The U. S. Coast Guard once promoted an emergency beacon on maritime VHF emergency channels. Marine VHF radio is installed on all large ships and most motorized small craft It now promotes the superior Cospas-Sarsat system, and no longer services emergency beacons on maritime VHF frequencies.

Current events

In a Safety Recommendation released 4 September 2007,[33] the NTSB once again recommended that the FAA require all aircraft have 406 MHz ELTs. Events 476 - Romulus Augustus, last emperor of the Western Roman Empire, is deposed when Odoacer proclaims himself Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. The National Transportation Safety Board (NTSB is an independent U The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of They first recommended this back in 2000 and after vigorous opposition by AOPA, the FAA declined to do so. The Aircraft Owners and Pilots Association (AOPA is a non-profit Political organization whose membership consists mainly of General aviation The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of This recommendation is apparently a reaction to the looming cessation of 121. 5 MHz satellite processing. Citing two recent accidents, one with a 121. 5 MHz ELT and one with a 406 MHz ELT, the NTSB concludes that switching all ELTs to 406 MHz by 1 February 2009 is a necessary goal to work towards. The National Transportation Safety Board (NTSB is an independent U Events 1327 - Teenaged Edward III is crowned King of England, but the country is ruled by his mother Queen This article is about the year For the film see 2009 Lost Memories. [34]

See also

References

  1. ^ Microsoft Word - G3Oct30.98D.­
  2. ^ Community Emergency Response Team Participant Handbook
  3. ^ System Saves
  4. ^ http://www.cospas-sarsat.org/DocumentsSystemDataDocument/SD32-DEC06.pdf
  5. ^ http://www.cospas-sarsat.com/DocumentsTSeries/T1Nov05.pdf
  6. ^ Microsoft Word - G3Oct30.98D.­
  7. ^ NASA Search and Rescue Mission Office : Distress Alerting Satellite System (DASS)
  8. ^ Example of 406 MHz Beacon Coding
  9. ^ Microsoft Word - G3Oct30.98D.­
  10. ^ RSS-187, Emergency Position Indicating Radio Beacons, Emergency Locator Transmitters, Personal Locator Beacons, and Maritime Survivor Locator Devices
  11. ^ KANNAD 406 AS
  12. ^ RSS-187, Emergency Position Indicating Radio Beacons, Emergency Locator Transmitters, Personal Locator Beacons, and Maritime Survivor Locator Devices
  13. ^ Emergency Position Indicating Radiobeacon (EPIRB) - USCG Navigation Center
  14. ^ RSS-187, Emergency Position Indicating Radio Beacons, Emergency Locator Transmitters, Personal Locator Beacons, and Maritime Survivor Locator Devices
  15. ^ 406 MHz BEACONS
  16. ^ http://www.icao.int/icaoimojwg/meetings/jwg14/docs/JWG_SAR14wp13.pdf
  17. ^ U.S. Legal Personal Locator Beacons (PLBs)
  18. ^ http://www.icao.int/icaoimojwg/meetings/jwg14/docs/JWG_SAR14wp13.pdf
  19. ^ 406 MHz Beacons
  20. ^ Emergency Position Indicating Radiobeacon (EPIRB) - USCG Navigation Center
  21. ^ 121.5 Phase-Out
  22. ^ 121.5 Phase-Out
  23. ^ [1] - Cospas-Sarsat - Summary Report of the 406 MHz Geostationary System Demonstration and Evaluation - "3. The aircraft emergency frequency (also known as guard) is a Frequency used on the Aircraft Radio band reserved for emergency communications The Civil Air Patrol ( CAP) is the civilian auxiliary of the United States Air Force (USAF The Global Maritime Distress Safety System ( GMDSS) is an internationally agreed-upon set of Safety procedures types of equipment and communication protocols used Shipboard Global Maritime Distress Safety System (GMDSS installations include one or more search and rescue locating devices The Global Maritime Distress Safety System ( GMDSS) is an internationally agreed-upon set of Safety procedures types of equipment and communication protocols used Electric beacons are a kind of Beacon used with direction finding equipment to find ones relative bearing to a known location (the Beacon The Sumburgh disaster was the crash of a Boeing 234LR Chinook Helicopter on 6 November 1986 with a loss of 43 passengers and two crew members Varig Flight 254 was a Boeing 737 -241 c/n 21006/398 registration PP-VMK on a scheduled passenger flight from São Paulo, São Paulo The 1996 New Hampshire Learjet crash involved a Learjet 35A which disappeared on Christmas Eve 1996 near Dorchester New Hampshire. 10 Combined LEOSAR/GEOSAR Operations (T-10)"
  24. ^ Wikipedia - GPS - Accuracy
  25. ^ History of mobile phones
  26. ^ http://www.avionicswest.com/articles/eltupdate.htm
  27. ^ BoatUS.com: Government Affairs
  28. ^ A-07-51
  29. ^ 121.5 Phase-Out
  30. ^ Emergency Position Indicating Radiobeacon (EPIRB) - USCG Navigation Center
  31. ^ http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgTSO.nsf/0/0F451B230D34559F86256DAC0068F32A?OpenDocument TSO-126
  32. ^ http://www.avionicswest.com/articles/eltupdate.htm
  33. ^ A-07-51
  34. ^ NTSB to FAA: Require 406 MHz ELTs | Doug Ritter’s Equipped.org Blog

External links

The Global Maritime Distress Safety System ( GMDSS) is an internationally agreed-upon set of Safety procedures types of equipment and communication protocols used Events 81 - Domitian becomes Emperor of the Roman Empire upon the death of his brother Titus. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century.
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