1. (Global Maritime Distress and Safety System)
Chapter 4
GMDSS
(Global Maritime Distress and Safety System)
PowerPoint slides by
Stf/C Harl Porter, SN
Marine Electronics
Rear Commander for Electro-Mechanical Systems is
R/C Gene Danko, SN

2. Overview History Carriage Requirements Digital Selective Calling (DSC)
Sea Areas
Maritime Mobile Service Identity (MMSI)
Emergency Position Indicating Radio Beacon (EPIRB)
Navigational Text Messages (NAVTEX)
Automatic Identification System (AIS)
Search and Rescue Transponder (SART)
Summary
Major sections in this chapter
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3. Good Reference
Good Reference Book written by USPS and published by McGraw-Hill
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4. History Analog VHF-FM dates back to post WWII
1978 SOLAS adopted digital standards
which became GMDSS
Adds digital calling and identification to marine radio
Scenario
GMDSS takes the “Search” out of Search and Rescue
SOLAS = Safety Of Life At Sea, an international treaty
Tell or read the scenario at the start of the chapter.
“Takes the ‘Search’ out of Search and Rescue” is a phrase coined by the federal authorities who manage GMDSS / SARSAT / NOAA.
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5. Carriage Requirements
GMDSS is mandatory, since 1999, for
Commercial vessels
Large vessels
Large private vessels on international voyages
Voluntary for
Recreational boaters
USCG
Vessels are GMDSS equipped (compliant)
CONUS VHF will be GMDSS compliant by 2009
Currently (early 2008) GMDSS is voluntary for recreational boaters
All USCG vessels are GMDSS / DSC equipped; however USCG shore stations are still being upgraded to monitor DSC Distress Calls on Channel 70. Coverage is being rolled out throughout the coastal U.S. and coverage of the contiguous (lower 48 states) US should be complete by Western rivers, Great Lakes, and Alaska will be completed after that date.
It only takes 5 seconds to make a DSC Distress Alert call. Start your MAYDAY call via DSC on channel 70, then immediately switch to channel 16 and make a voice MAYDAY call.
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6. GMDSS Basic Concept
Digital Selective Calling for MF, HF, VHF & INMARSAT Radios
Illustration from pamphlet “GMDSS for Recreational Boaters”
Shows a vessel in distress in Sea Area A1 (lightest blue)
It has done two things
1) Made VHF-FM DSC Distress Alert on Channel 70 (which is heard by both other boaters and USCG ashore)
2) Activated their EPIRB Emergency Beacon which is picked up by either a COSPAS or SARSAT satellite, then relayed to shore.
Both devices have unique registration numbers and are interconnected with GPS receivers.
Both the MMSI data base and EPIRB database contain information on Captain, Vessel and Emergency Points of Contact
Digital Maritime Mobile Service Identity (MMSI) is embedded in radio transmissions
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7. Digital Selective Calling
DSC and GMDSS
Why DSC Distress Calling
Classes of DSC radios
GMDSS Distress Call Elements
Nature of Distress Options
Distress DSC Calling
Routine DSC Calling
Topics covered in this section
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8. DSC and GMDSS Digital Selective Calling is a key feature
Combined with VHF, MF and HF radios
Combined with INMARSAT satellite radios
New radios, since 1999, must have DSC
VHF-FM/DSC uses Channel 70
Automatic transmission of distress call
By pressing
Automatically resent until acknowledged
DSC is built into newer MF, HF and VHF Marine Radios.
VHF DSC frequency is Channel 70 ( MHz).
To transmit a DSC Distress Call:
Open spring loaded protective cover
Hold down the DISTRESS button for 5 seconds
The rest is automatic
Will keep sending DSC Distress call until acknowledged.
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9. VHF-FM/DSC Radio All normal VHF-FM functions plus DSC
Automatic distress calling
Individual and group DSC calling
ICOM IM-602 radio costs around $600
It, and newer M-604, are DSC Class “D” radios with two receivers. One receiver is dedicated to DSC Channel 70.
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10. Why DSC Distress Calling
Increased reliability
Distress call is repeated until acknowledged
Automatic transmission of vessel’s location
When interfaced to a GPS receiver
Information on captain and vessel
From the MMSI database
Reduced incidences of hoax distress calls
From MMSI they know who you are
False distress alert is a felony offense
Fines of up to $5,000
Plus cost incurred by SAR forces
Reason for DSC was to reduce hoax calls.
How is digital MMSI (unique identification) imbedded into every Channel 70 DSC call? The operator loads it when installing the radio.
Before DSC, the USCG and FCC did not know the identity of suspected hoax callers and actual locations.
With DSC and MMSI they know:
Location of radio
What vessel it is on
Name of Captain (radio’s owner)
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11. Classes of DSC Radios Class D is for VHF radios carried by:
Recreational boaters
Commercial fishing vessels
Other non-SOLAS regulated vessels
Internally, it has two receivers
One dedicated to DSC Channel 70
Other for general voice communications
Class SC101 is discouraged
Other classes are described in “The Boatowner’s Guide to GMDSS and Marine Radio”
If you are going with DSC, USPS strongly recommends the class D radio.
Cheaper Class SC101 radios
- have DSC, have MMSI and GPS interface
- but have only one receiver that scans selected voice frequencies and Channel 70. It may miss a DSC Channel 70 Distress Alert while listening to a voice channel.
- work to relaxed standards and may not be fully compatible with other DSC components in the GMDSS system.
Other classes of DSC radios are for large commercial vessels.
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12. DSC Distress Signal Basic Elements
MMSI
Nature of distress
Operator selected
Default is “Undesignated”
Vessel’s position (fix)
If interfaced with GPS receiver
If entered manually
Time of fix
Interface DSC radio with GPS receiver!
NMEA 0183
Default Nature of Distress is “Undesignated”
Undesignated is the highest level of Distress Alert
If you have time and conditions warrant, manually select Nature of Distress from list (next slide).
Vessel Position and time of fix are best if obtained from the GPS interface. It is possible, if you don’t have an interfaced GPS, to manually input these numbers (but that takes time and is error prone).
Therefore if you have a DSC radio, interface it with you GPS and obtain and input you MMSI into the radio.
Interface between DSC radio and GPS receiver is NMEA 0183.
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13. Nature of Distress Flooding Abandoning Grounding Adrift Listing
Capsizing
Collision
Disabled
Explosion
Fire
Flooding
Grounding
Listing
MOB (Man Overboard)
Piracy
Sinking
Undesignated
Options for Distress Alert
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14. DSC Distress Calling - 1 Press & hold “DISTRESS” button for 5 sec
Then switch to channel 16 and initiate voice MAYDAY call
Say “Mayday” three times, followed by “this is” and the boat’s name
Give MMSI (only once)
Say “over”
DSC automatically continues to send channel 70 DSC distress call until acknowledged
Initially 5 times
Then repeated every 3 to 4 min until acknowledged
When you press and hold the “DISTRESS” button for 5 seconds, the radio automatically switches and sends the DSC Distress Alert. The alert is repeated until acknowledged (normally by USCG).
After broadcasting the DSC (channel 70) digital MAYDAY call, the radio should automatically switch to channel 16; make voice MAYDAY call on channel 16.
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15. DSC Demo #1 Distress call without GPS
Distress call with interfaced GPS
Use the DSC simulator
1st make Distress call with GPS off
2nd make Distress call with GPS on
Link to DSC Simulator
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16. DSC Distress Calling - 2 Remember DSC distress alert includes MMSI
Nature of distress
“Undesignated” suggests most dire emergency
If time – select nature of distress from list
Vessel’s position
Time of fix
From the MMSI, the Rescue Coordination Center retrieves information about the captain and vessel
Basically only USCG can acknowledge a DSC distress call.
Class D and SC 101 radios cannot; Class A radios can (carried by commercial vessels)
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17. Accidental Distress Alert
Immediately turn off DSC transceiver
Then, turn the radio back on
Make a voice broadcast on channel 16:
“All Stations” giving the vessel’s name, call sign and MMSI
Cancel the distress alert verbally, giving date and time
False distress alert is a felony offense
Fines of up to $5,000
Plus cost incurred by SAR forces
It is hard to make an “Accidental” Distress Alert – this requires the protective cover to be raised and the DISTRESS button to be held down for at least 5 seconds.
But, if accidentally done, you must cancel it promptly with a call on channel 16. Make sure that USCG acknowledges the canceled DSC distress alert.
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18. Routine DSC Calling First, enter MMSI of vessel to be called
Next enter a desired working frequency
Then press “SEND” or “ENTER” key
Digital hail transmitted on Channel 70
Target radio sounds incoming call alert
To answer, press “SEND” or “ENTER” key
Radios automatically switch to working freq
Both parties talk on working frequency
If called radio does not answered
Logs incoming call (like an answering machine)
You must know the other boat’s MMSI to call them. DSC radio can store many MMSIs, just like a cell phone can store many phone numbers. You will need the boat name and MMSI from your boating friends, just like you know their name and cell phone number.
Either select MMSI from radio’s list or enter manually.
If you miss a DSC call, you can press a button on you radio and it will automatically call the other party back, and if answered then automatically switch to the suggested working frequency.
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19. DSC Demo #2 DSC hail, followed by voice on working channel
Position request
Use DSC Simulator
1st make DSC hail followed by voice on working channel
2nd make DSC position request
Link to DSC Simulator
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20. Sea Areas A1 - Shore out to 20 nm
A2 - From 20 out to 100 nm from shore
A3 - Over 100 nm from shore 70º N to 70º S
A4 - Polar regions above 70º
The four Sea Areas are defined by radio range
Sea Area A1 is VHF-FM radio coverage from USCG shore based radio towers. Range has not been determined as “Rescue 21” upgrade of USCG VHF radios is still underway, but should be 20 miles.
Sea Area A2 is past Sea Area A1 to end of assured MF radio coverage. It is usually at least 100 nm and may be out to 150 nm, but in some instances has been reported to be only 40 nm.
Sea Area A3 is INMARSAT radio coverage past Sea Area A2 from 70 degrees North to 70 degrees South (coverage from the four geostationary satellites).
Sea Area A4 is above INMARSAT coverage. GMDSS says use HF. Given a choice, using a satellite in a polar orbit like Iridium would provide better communications. EPIRBs are reliable here, but are transmit-only devices.
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21. Sea Area A1
Within range of USCG shore-based VHF DSC radios – typically out to at least 20 nm
Channel 70 for DSC calling and distress
Channel 16 for voice calling and distress
Area 1 is VHF-FM radio coverage from USCG shore based radio towers.
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22. Sea Area A2
Within range of USCG shore-based MF DSC radios – typically out to 100 nm
Excludes Sea Area A1
KHz for DSC calling and distress
KHz for voice calling and distress
Sea Area A2 is past Sea Area A1 to the end of assured MF radio coverage. It is nominally 100 nm and may be out to 150 nm.
The chart shows extent of assured (guaranteed) USCG MF coverage out to approx 100 nm; most probably good coverage is out to 150 nm. Dotted “line” shows extent of intermittent coverage (probably 150 nm). Actual intermittent coverage is probably father out.
Note SE (eight o’clock) area off Puerto Rico – assured coverage is only 40 nm there.
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23. Sea Area A3 Within INMARSAT satellite coverage Between 70º N to 70º S
Excludes Sea Areas A1 and A2
Sea Area A3 is the INMARSAT radio coverage zone past Sea Area A2, from 70 degrees North to 70 degrees South (coverage from the four geostationary satellites).
INMARSAT, and other satellite communications systems, are covered in chapter 5. Coverage is for data-only Mini-C satellite terminals, or bigger voice terminals. Mini-M, the low cost voice coverage system, is not this good (see coverage chart in chapter 7).
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24. Sea Area A4 Polar Regions (above 70º) Excludes Sea Areas A1, A2 and A3
No assured communications
Use High Frequency SSB voice (6216 / 8291 KHz)
FYI - Arctic / Antarctic circles are at 66º 34’
Sea Area A4 is above INMARSAT coverage. GMDSS says use HF. Given a choice, using a satellite in a polar orbit (like Iridium) would provide better communications.
Note that most of this area is ice, not water.
Stf/C Harl Porter, Marine Electronics, would chose Iridium satellite phone over HF in this area. But area is too cold to for him to go there in a small vessel under 65 feet.
EPIRB emergency beacons will work in Sea Area A4 as they are picked up by COSPAS-SARSAT satellites in polar orbits.
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25. MMSI Maritime Mobile Service Number (MMSI) Structure Obtaining
Duration
Programming
Topics in this section
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26. MMSI Structure Maritime Mobile Service Identity (MMSI)
Unique to each vessel
EPIRB emergency beacons use a different registration number
Obtained from NOAA
See chapter 8
Nine digit number
Country prefix (MID) of 3 digits
Station identifier of 6 digits
Ends in “0” if boating internationally
Ends in 1 to 9 if boating only domestically
MMSIs only work if registered!
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27. Obtaining a MMSI International boaters:
Includes to Canada, Mexico and Bahamas
Electronically at:
Or mail FCC Form 605 Schedule B to FCC
Domestic boaters, normally electronically at:
BoatUs:
Sea Tow:
USPS at:
Note that USPS can furnish the MMSI number if you are a domestic boater. Domestic normally means not in Sea Area A3 and not going all the way across either ocean.
Form 605 Schedule B is discussed on the next two slides.
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28. FCC Form 605 Schedule B Page 1
There is no charge to get or update a MMSI.
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29. FCC Form 605 Schedule B Page 2
Keep Search and Rescue information current! Don’t wait for the reminder to update information every two years.
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30. Duration of MMSI Valid for 10 years if issued by FCC
Renew within 60 days of expiration
No limit if issued by Registered Agent
Will be contacted every 3 years to see if information is still current
KEEP IT CURRENT!
Search and Rescue information
One MMSI is required per vessel. You use the same MMSI if you have multiple radios on a vessel.
If you sell a radio, USPS recommends that you remove your MMSI before it is delivered to the new owner. If you get new radio, program your MMSI in it immediately.
If you sell your boat and its radios, get a new one for new boat and require the new owner to obtain his/her own MMSI info to reflect ownership and other contact info.
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31. Programming MMSI Register one MMSI per entire vessel
Consult your users guide & follow instructions
Test calls with another DSC radio
DO NOT TEST “Distress Alerts”
(DO NOT PRESS “Distress” button)
It is not easy -- follow the directions carefully.
The best test is, give your MMSI number to a friend and have them hail your boat by the MMSI you gave them. This way you can see if you programmed your radios correctly with your MMSI.
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32. EPIRB Emergency Position Indicating Radio Beacon
Cat I – 406 / MHz beacon
Float free
Automatically activated
Cat II – 406 / MHz beacon
Removed from storage bracket
Manually activated
Cat I or II with GPS
Improved position reporting
Some include a strobe light
Read or tell the scenario found in the student text.
Note differences between Cat I and Cat II EPIRBs.
Either Cat I or Cat II EPIRBs may be equipped with an internal GPS receiver, at higher cost.
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33. SARSAT System Search And Rescue Satellite Aided Tracking
Same as figure 8-3 in Student Text.
The next slide will illustrate the different elements.
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34. SARSAT Elements At the upper left is a collection of EPIRBs.
Upper right are COSPAS and SARSAT satellites. Actually, SARSAT is a package on NOAA weather satellites. The 3 Russian COSPAS and 5 SARSAT satellites are in low earth polar orbits. Doppler shift is used to calculate approximate position of a beacon if it does not have an internal GPS. Not shown is the geostationary GEOSAT satellite; there are 4.
Lower right is Ground Station for COSPAS-SARSAT satellites, called the Local User Terminal. The U.S. has 7 fixed LUTs.
Lower left is the U.S. Mission Control Center in Suitland, MD. It is operated by NOAA.
Not shown is a USCG Rescue Coordination Center.
Center are USCG SAR assets responding to the EPIRB alert.
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35. USCG for Maritime Alerts
RCCs and their AORs
USCG for Maritime Alerts
AKRCC ELMENDORF
USAF for Inland Alerts
RCC
CLEVELAND
RCC
TRENTON
RCC
JUNEAU
RCC
VICTORIA
RCC
HALIFAX
RCC
SEATTLE
RCC
BOSTON
RCC = Rescue Coordination Center
AOR = Area Of Responsibility
This slide shows the nine USCG RCCs, their locations and areas of responsibility.
The USAF is responsible for inland (land based) alerts. They have two RCCs, one for entire mainland U.S. and one for Alaska.
AFRCC
LANGLEY
RCC
HONOLULU
(CG / PACOM)
RCC
NORFOLK
RCC
ALAMEDA
RCC
MIAMI
RCC
NEW ORLEANS
RSC
SAN JUAN
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36. EPIRB with GPS 406 MHZ search area approx 2.6 nm wide
406 MHz with GPS search area 100 meters wide
406 MHz-only Search Area 2 to 3 hours Search Time
406 MHz with GPS Search Area Minimal Search Time
This slide illustrates the advantage of a smaller search area, of an EPIRB with internal GPS receiver.
As a point of interest, if the EPIRB is picked up only by a geostationary GEOSAT satellite, the system cannot perform Doppler analysis to determine an approximate location. It only provides an alert that an EPIRB has been activated.
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37. EPIRB Registration Must be done immediately after purchase
$10,000 fine if unregistered EPIRB activated
Can be done online at:
www. beaconregisteration.noaa.gov
Required information
15 digit EPIRB ID number
Type of EPIRB
Owners name, address, and contact info
Vessel info (name, color, size, homeport, etc.)
Primary and alternate 24-hour emergency contact phone numbers
406 MHz EPIRBs, among other things, were designed to reduce the number of false alerts from older 243/121.5 MHZ beacons. This is accomplished by assigning each EPIRB a unique transmitted ID number.
Registration is required for the system to be used. Hence it is mandatory and free. It can easily be done online.
Information required is as shown. The next slide shows the actual registration form.
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38. Registration Form
EPIRB registration form that can be filled in online.
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39. EPIRB Utilization EPIRBs with internal GPS are best
Register with NOAA after purchase
Cat I is float free; automatically activates
Cat II have to be released and manually activated (turned on)
Once turned on, leave it on!
Until rescued
Will operate for minimum of 48 hours
Take with you if you abandon the vessel
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40. EPIRB Technical – 1 Actual frequency of 406.028 MHz 121.5 MHz
Beacon and data picked up by satellite
Hex character is a digitally encoded signal
5 watts for at least 48 hours
121.5 MHz
Used for homing by SAR
50 to 100 milliwatts for at least 48 hours
Uses lithium battery
Shelf life of 5 years
Replace (by dealer) before expiration date
Note that 406 EPIRBS actually transmit on MHz +/- 6 kHz
121.5 accuracy is +/- 6 kHz
If equipped with a 406 direction finder, the SAR unit can also home on the 5 watt 406 signal which is stronger than the 50 to 100 milliwatt MHz signal
The MHz beacon is used by the SAR unit with their direction finder to actually locate the EPIRB in the search area, determined by Doppler signal processing at the LUT. If the EPIRB is equipped with an internal GPS receiver, the MHz beacon is not as important.
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41. EPIRB Technical - 2 EPIRB digital transmission gives:
Country of beacon registration
ID of vessel or airplane
If internal GPS, position information
Store and forward LEO satellite
LUT, using Doppler, calculates search area
MCC retrieves and forwards registration info to the RCC
Note the information contained in the 406 MHz signal. The ID number is used to obtain registration details from the national registration data base of EPIRBs maintained by NOAA.
Only the LEO (low earth orbit) polar satellites are store-and-forward. The advantage of store and forward is that all EPIRB signals received by a satellite are transmitted to a ground station.
The ground station of the LUT (local user terminal) calculates an approximate EPIRB position by using the Doppler shift of the 406 signal as received by the satellite.
The MCC (Master Coordination Center) automatically retrieves EPIRB registration data from its database and forwards both the alert and this information to the appropriate RCC (Rescue Coordination Center). This is an automatic process.
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42. EPIRB Rental From Boat US Cat II EPIRB They do the registration
Details on their web site at:
EPIRBs are expensive, starting at about $900 for a Cat II EPIRB only (no internal GPS receiver).
EPIRBs can be rented from Boat US. As of February 2010, the cost is $40 for three days, plus shipping. Additional details are on their web site.
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43. Personal Locator Beacons
406 / EPIRB with internal GPS
Must be registered as an EPIRB
Size and weight of a cellular phone
Can also be used on land when: hiking, skiing, camping, hunting, etc.
Not for use in cities or cars
Severe penalties for deliberate misuse
Personal Locators Beacons are EPIRBs for individuals. They also must be registered.
They can be used either on a boat or also on land when hiking, skiing, camping, hunting, etc. They are not for use in cities or with cars on a road.
There are severe penalties for their misuse!
- fines up to $250,000
- imprisonment up to 6 years
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44. All messages are in English
NAVTEX
Navigation warnings, weather forecasts and warnings, search and rescue notices, and Notices to Mariners
Part of GMDSS at 518 kHz
Daytime range of about 400 nm
Nighttime range of up to 600 nm
Note first line on display “ZCZC HE05”
“H” (1st character) give country of transmitter
“H” transmitter is located in Sweden
“E” (2nd character) indicates a Meteorological forecast
Partial list of subject identifiers on next slide, all in text
All broadcasts on 518 kHz are in English, even if originating from non-English speaking countries.
All messages are in English
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45. USCG NAVTEX Sites Canadian coverage of much of Great Lakes Kodiak, Ala
Guam (not shown)
Honolulu, HI
Astoria, OR
Pt. Reyes, CA
Cambria, CA
Chesapeake, VA
Savannah, GA
Miami, FL
Cape Cod, Mass
New Orleans, LA
San Juan, PR
Other countries also have NAVTEX transmitters
Transmission on 518 kHz always in English
Canadian coverage of much of Great Lakes
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46. NAVTEX Messages Modulation 170 Hz FSK at 100 baud
Four character header
1st character identifies the transmitting station
2nd character identifies the subject
A = Navigational warning
B = Meteorological warning
D = Search & Rescue information
E = Meteorological forecasts
3rd & 4th characters are the message number
Header is transmitted twice per message
Modulation 170 Hz FSK at 100 baud
Some countries also broadcast NAVTEX, in their local language, on 490 kHz
USCG transmitter IDs are given in text.
Partial List of Subject Identifiers
Complete list in text
A, B & D cannot be rejected, others are selectively enabled
Modulation is same as Amateur Radio service (AMTOR) – frequency shift keying at 100 baud (characters per second).
Some non-English countries have two NAVTEX transmitters
518 kHz in English
490 kHz in local language
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47. Automatic Identification System
AIS shares positions & intentions
Collision avoidance
In Vessel Traffic Service (VTS) Sea Area A1
Text fig 4-5
AIS was designed for collision avoidance in Vessel Traffic Service areas. In addition to transmitting vessel position and intentions data to shore, it also exchanges position and movement data between vessels. The display is similar to Radar and is shown on a later slide.
Components
Shore-based Master Station
Class A (commercial) and Class B (recreational) terminals
AIS (relay) Stations
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48. Near collision warning
AIS Displays
Similar to Radar
With info tag provided by other vessel
Check out
On left is a standalone AIS display made by Si-Tex.
AIS info can also be displayed on a chart plotter or on a radar screen.
On the right is a color AIS (only) display of AIS-equipped ships in the immediate area. The purpose of AIS is collision avoidance. Displays can calculate the Closest Point of Approach (CPA) and Time to Closest Point of Approach (TCPA) for all nearby tracks. Shown on this display, circled in red, is a “Near Collision” alert. These two vessels, if they maintain their current speeds and directions, will in 57 seconds pass within 0.15 nm of each other. This same information can be determined for Radar using its MARPA functions which has to be manually activated; AIS automatically calculates CPA and TCPA for any nearby vessels.
Our Vessel
Near collision warning
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49. AIS Data From ship’s GPS and other sensors Data transmitted:
Vessel identification
Speed
Heading
Other information for Class A vessels
Time sensitive data every 2 to 10 seconds
Other data every 6 minutes
AIS gets vessel position and movement information from an interfaced GPS receiver.
The table at the bottom shows other data that are transmitted by Class A commercial vessels.
Time sensitive data include:
Vessel Position, Time (in UTC), Navigational Status, True Course over Ground, Speed over Ground, True Heading and Rate of Turn.
Class B (recreational AIS terminals) don’t transmit Navigational Status, Rate of Turn or Voyage Related data.
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50. AIS Additional Info Class A for commercial vessels
Required since 31 Dec 2004
Class B for recreational boats
FCC type accepted in 2008
Not required by Dept of Homeland Security
Receive-only AIS installations
Master (shore) station
Also identifies buoys and other NavAids
Can create virtual NavAids
Currently AIS is not required for Recreational Vessels. This may change.
Raymarine, Shine Micro, and probably others make receive-only and/or Class B AIS systems that displays AIS info on either a chart plotter or radar display.
The Master (shore based) AIS station for the area can add data tags on buoys and other aids to navigation (ATONs). They also have the capability to create virtual ATONs that only show up on an AIS display.
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51. AIS Technical Information
Uses VHF Channels 87B & 88B at 12.5 watts
2,250 self-organizing slots per data ring (2)
Similar to cellular phone technology
Channel 87B is MHz
Channel 88B is MHz
Time Division Multiple Access
2,250 slots per ring
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52. Radar with SART replies
Search And Rescue Transponder (SART)
Radar with SART replies
SART units
Like EPIRBs, SART is another element of GMDSS.
Like the MHz portion of an EPIRB, it is designed to assist in locating a life raft.
On the left are SARTs. The yellow one is manufactured by ACR and costs about $800.
On right is a x-band radar display showing the 12 dots or arcs from an activated SART. Text fig 4-6
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53. SART In life raft Responds to X-band radars (9.2 to 9.5 GHz)
Mount as high as possible
Secure and turn on
Responds to X-band radars (9.2 to 9.5 GHz)
Helps locate life raft
Displayed on radar as 12 inline dots or arcs
Uses Lithium batteries
5-year life
Standby for 96 hours
Reply to X-band radars for over 8 hours
Like VHF and higher frequency radios, SART range is primarily a function of height. Therefore you want the SART mounted as high as possible in the life raft.
Radar display was shown on previous slide.
Once in the life raft, secure and activate the SART, and then DO NOT turn it off until rescued. Hopefully you activated your EPIRB before abandoning your vessel. In addition to a SART, a well equipped life raft should have a VHF radio and its own EPIRB or Personal Locator Beacon.
Upon receiving an X-band radar pulse it immediately replies with a series of 12 same-frequency pulses.
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54. Other Components MF and HF radios covered in Chapter 7a
INMARSAT covered in Chapter 7b
These components of GMDSS are covered in other chapter, as shown.
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55. Summary - 1 DSC (VHF channel 70) Distress calling Routine calling
Takes the “Search” out of Search & Rescue
Distress calling
Press the red button for 5 seconds
transmits the nature of the distress
location and time
MMSI ID
Retransmits until acknowledged
Routine calling
Takes the place of channel 16 voice hail
Automatically switches radio to working freq
If not answered, like an answering machine
No notes
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56. Summary - 2 Sea Areas EPIRB A1 VHF-FM to 20 nm off shore
A2 MF/HF 20 to 100 nm off shore
A3 INMARSAT over 100 nm 70º N to 70º S
A4 HF beyond 70º N or 70º S
EPIRB
Cat I and II digital ID on MHz
121.5 MHz beacon for SAR homing
Leave on until rescued
will last at least 48 hours
Can be rented from Boat US
No notes
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57. Summary - 3 NAVTEX AIS SART Text messaging system at 518 kHz
Worldwide system; all messages in English
AIS
Data exchange between vessels
used for collision avoidance
USCG ashore can insert virtual ATONs
Not required for recreational boaters
SART
Life raft X-band radar transponder
No notes
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