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Subel. F
6 questions
Subelement F

Survival Craft Equip & S.A.R.:

Section 40

SART - Radar Display - SAR - AIS SART

How does the searching vessel's radar interrogate a survival craft SART?

  • Activate the IFF interrogation system.
  • Correct Answer
    The SART responds automatically and transmits the 12-blip signal when it detects the search craft or other vessels' X-Band radar signal.
  • Maintains watch on VHF-FM Ch-70 for the SART's unique identifier.
  • The SART responds automatically when it detects the search craft or other vessel's 10-CM radar signal.

How does the searching vessel's radar interrogate a survival craft SART?

(B). The SART responds automatically and transmits the 12-blip signal when it detects the search craft or other vessels' X-Band radar signal.

SART transponder emits 12 beeps on 9 GHz frequency. These 12 signals are called "Homing Signals."

See SART info and radar display illustration on eGMDSS.com site The Basis of SART

See active SART display on radar screen SART code on the indicator of radar for ship

See great overall SART info on Casual navigation site at What Is A SART?

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What radar display changes indicate the correct approach to a SART and what care should be taken in a SAR situation?

  • The line of dots indicate the SART's position, the dots become increasing arcs as the distance to the SART lessens, rescuing vessels should increase speed to reach Distress more quickly.
  • A line of dots on a radar screen rotates to indicate the SART's position along its line of bearing; rescuing vessels should steer for the center of the line of dots.
  • Correct Answer
    The line of dots indicate the SART's position, the dots become increasing arcs as the distance to the SART lessens, rescuing vessels should reduce speed as the arcs get greater in degree.
  • The line of dots indicate the SART's position, the dots become decreasing arcs as the distance to the SART lessens, rescuing vessels should reduce speed as the arcs lessen in degree.

What radar display changes indicate the correct approach to a SART and what care should be taken in a SAR situation?

(C). The line of dots indicate the SART's position, the dots become increasing arcs as the distance to the SART lessens, rescuing vessels should reduce speed as the arcs get greater in degree.

SART transponder emits 12 beeps on 9 GHz frequency. These 12 signals are called "Homing Signals."

Depending on how far the transponder is, the beeps first appear as dots. Then, as the transponder gets closer, they appear as arcs, which get larger is the transponder gets even closer.

Finally, the arcs become 12 complete circles as the transponder is very close and that means that the SAR, search and rescue team, is now in the close position to the transponder.

For more info and illustrations, see BlueSeas site on SART - Search and Rescue Transponder

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How can rescue personnel detect that a SART is transmitting in the immediate vicinity?

  • The DSC unit will react to the SART's signal and respond with the two-tone auto alarm.
  • The SART can provide an approximate location to within a two nautical mile radius, per IMO standards.
  • The SART signal appears as a target which comes and goes; the effect of heavy swells on a SART.
  • Correct Answer
    The SART's dots on the PPI will become arcs and then eventually become concentric circles.

How can rescue personnel detect that a SART is transmitting in the immediate vicinity?

(D). The SART's dots on the PPI will become arcs and then eventually become concentric circles.

SART transponder emits 12 beeps on 9 GHz frequency. These 12 signals are called "Homing Signals."

Depending on how far the transponder is, the beeps first appear as dots. Then, as the transponder gets closer, they appear as arcs, which get larger is the transponder gets even closer.

Finally, the arcs become 12 complete circles as the transponder is very close and that means that the SAR, search and rescue team, is now in the close position to the transponder.

For more info and illustrations, see BlueSeas site on SART - Search and Rescue Transponder

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What signal is detected as originating from an AIS SART and how is the signal displayed?

  • Correct Answer
    An AIS SART signal is shown on any AIS receiver as a special 970 MMSI coded symbol.
  • The 3-CM radar reflections are converted to AIS signals and displayed on ECDIS/ARPA screens.
  • An AIS SART transmits on AIS frequencies and the signals are converted to 3-CM radar targets for display on 3-CM radars.
  • An AIS SART transmits on 9 GHz so that a 3-CM radar can display the signals.

What signal is detected as originating from an AIS SART and how is the signal displayed?

(A). An AIS SART signal is shown on any AIS receiver as a special MMSI-like coded symbol.

AIS, or the automatic identification system, tracks ships' signals, consisting of unique ID and position among other data, and shows it on the ECDIS, electronic chart display and information system, using VHF with GPS, or GNSS.

For more info, please see Wikipedia site on Automatic identification system

MMSI is the Maritime Mobile Service Identity system sends 9 digits to identify the vessels, coast stations, and other maritime locations. The signal, then, allows communication with ships by telex or telephone.

For more info, please see Wikipedia site on Maritime Mobile Service Identity

The AIS-SART sends current location data in the form of the standard Automatic Identification System (AIS) class-A position report. Since AIS-SART includes a a GNSS, it can send its current position on 161.975 MHz and four signals on 162.025 MHz, so that there is a greater chance of being received.

For more information, see Wikipedia article on AIS-SART

GNSS is the global navigation satellite system, sending position and time by using the he International Multi-Constellation Satellite System, employing satellites such as GPS, Galileo, GLONASS, Baidu, and others.

For more info, see Wikipedia's site on GNSS software-defined receiver

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How can vessel personnel detect the operation of a SART in its vicinity?

  • A unique two-tone "warbling" signal heard on VHF-FM Ch-70.
  • It will activate an AIS new signal alarm on the AIS receiver.
  • The SART signal appears as a target that comes and goes--due to the effect of heavy swells on a SART.
  • Correct Answer
    A unique 3-CM signal consisting of a 12-dot pattern radiating outward from a SART's position along its line of bearing.

How can vessel personnel detect the operation of a SART in its vicinity?

(D). A unique 3-cm signal consisting of a 12-dot pattern radiating outward from a SART's position along its line of bearing.

SART transponder emits 12 beeps on 9 GHz frequency, of 3 cm wavelength. These 12 signals are called "Homing Signals."

Depending on how far the transponder is, the beeps first appear as dots. Then, as the transponder gets closer, they appear as arcs, which get larger is the transponder gets even closer.

Finally, the arcs become 12 complete circles as the transponder is very close and that means that the SAR, search and rescue team, is now in the close position to the transponder.

For more info and illustrations, see BlueSeas site on SART - Search and Rescue Transponder

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What is not an advantage of an AIS SART signal when compared to a radar-based SART signal?

  • Correct Answer
    The AIS SART can be detected much farther away than radar SART models.
  • Not every AIS transmission needs to be received to achieve an accurate presentation of the location.
  • The AIS SART position has GPS accuracy and transmits on AIS VHF frequencies.
  • AIS SART units may be easier to find in poor radar target conditions.

What is NOT an advantage of an AIS SART signal when compared to a radar-based SART signal?

(A). The AIS SART can be detected much farther away than radar SART models.

Seems counter intuitive. Perhaps, smaller detection range better pinpoints the location? Just memorize this. Below is the info in this area. Good to know stuff.

The range of SART depends on the mounting height. Higher location extends the range. The 12 blip signals are on the 9 GHz frequency, which is the 3 cm wavelength, displaying on the X Band radar. The signal is in the SHF, super high frequency, range. Because of the small wavelength, no ionosphere or ground bounce, the 3 cm wave can only communicate by the line of sight, or about 30 to 40 miles.

See great overall SART info on Casual navigation site at What Is A SART?

The AIS-SART sends current location data in the form of the standard Automatic Identification System (AIS) class-A position report. Since AIS-SART includes a a GNSS, it can send its current position on 161.975 MHz and four signals on 162.025 MHz, so that there is a greater chance of being received. These frequencies are in the VHF band with wavelengths of 1 meter to 10 meters.

Because of the longer wavelength than SART of 3 cm, the propagation does extend due to ground bounce, though still line of sight.

Every time wave bounces from ground, it loses some of its energy (attenuation), but the propagation range is well extended when the bounce is over salt water. Generally, the range is at least 100 miles.

For more information, see Wikipedia article on AIS-SART

Sometimes, the E layer of the ionosphere helps, especially at F2 layer during the height of the 11-year sunspot cycle. Warm and cold air inversion (ducting) will help, as do passing meteors (meteor scatter) or even airplanes.
See more on Wikipedia article Radio propagation

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