A search and rescue transponder (SART) is a self-contained, waterproof

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...

intended for emergency use at sea. These devices may be either a radar-SART, or a GPS-based

AIS-SART An AIS-SART is a self-contained radio device used to locate a survival craft or distressed vessel by sending updated position reports using a standard Automatic Identification System (AIS) class-A position report. The position and time synchroniz ...

(

automatic identification system The automatic identification system (AIS) is an automatic tracking system that uses transceivers on ships and is used by vessel traffic services (VTS). When satellites are used to receive AIS signatures, the term ''Satellite-AIS'' (S-AIS) is ...

SART). The radar-SART is used to locate a survival craft or distressed vessel by creating a series of dots on a rescuing ship's

radar display A radar display is an electronic device that presents radar data to the operator. The radar system transmits pulses or continuous waves of electromagnetic radiation, a small portion of which backscatter off targets (intended or otherwise) and re ...

. A SART will only respond to a 9 GHz

X-band The X band is the designation for a band of frequency, frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is set at approximately 7.0� ...

(3 cm

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

)

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

. It will not be seen on

S-band The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the convention ...

(10 cm) or other radar. Shipboard Global Maritime Distress Safety System (GMDSS) include one or more search and rescue locating devices. The radar-SART may be triggered by any X-band radar within a range of approximately . Each radar pulse received causes the SART to transmit a response which is swept repetitively across the complete radar

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

band. When interrogated, it first sweeps rapidly (0.4

microsecond A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10−6 or ) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available. A microsecond is to one second, ...

) through the band before beginning a relatively slow sweep (7.5 microseconds) through the band back to the starting frequency. This process is repeated for a total of twelve complete cycles. At some point in each sweep, the radar-SART frequency will match that of the interrogating radar and be within the

passband A passband is the range of frequency, frequencies or wavelengths that can pass through a Filter (signal processing), filter. For example, a radio receiver contains a bandpass filter to select the frequency of the desired radio signal out of all t ...

of the radar receiver. If the radar-SART is within range, the frequency match during each of the 12 slow sweeps will produce a response on the radar display, thus a line of 12 dots equally spaced by about will be shown. When the range to the radar-SART is reduced to about , the radar display may show also the 12 responses generated during the fast sweeps. These additional dot responses, which also are equally spaced by , will be interspersed with the original line of 12 dots. They will appear stronger and larger the closer the interrogating radar gets, slowly becoming arcs at first until the SART is within 1NM, the arcs will become full circles indicating the active SART is in the general area. SARTs are typically cylindrical, about the size of a person's forearm, and brightly coloured.

Sources

* IMO Sub-Committee on Safety of Navigation, ''Operation of Marine Radar for SART Detection''
SN/Circ. 197

External links

* SART Test equipment �

SART user guide example
{{DEFAULTSORT:Search And Rescue Transponder Maritime communication Emergency communication Rescue equipment Radar

See also

Sources

External links