UK GMDSS _ Exam tips

Most important in UK GMDSS exam is ..


GK Paper---> for 25 min exam---> SOLAS is the scoring chapter for the descriptive part..and in objective part for 15 marks... the antenna, battery and some twisting quetions...


RT communication is easy ....but with the GREY box ....be cautious with the POSTION copying and time.....


OPT---- InmarSAT- C is the important.... As the Scenario model is implemented in OPT so the chance of scoring is easy ....but must have deep knowledge in SAT C and B .... 




there you can also expect random wise qns......

Model Qns,,, 2

1.         With respect to Distress communications the MAIN function of the On Scene Co-ordinator (OSC) is to

ANS:  maintain communication with all Search and Rescue (SAR) facilities

2.         Routine RT inter-ship VHF messages may be passed on

ANS: Ch.08 VHF is the only ship-to-ship channel listed in the options. Ch.16, Ch.13 and Ch.70 are used for other purposes.

3.         According to international regulations VHF Ch.06 may be used for

ANS: VHF Ch.06 has two functions. First it is the primary inter-ship RT (voice) channel. Secondly it is used for ship to aircraft communications during SAR operations

4.         n the terrestrial radio service, the category, message with the highest priority is a

ANS: weather observation

5.         The correct format for on-going on-board communications between sub station and bridge is

ANS: SEAQUEST CONTROL) this is SEAQUEST BRAVO is the correct format as per ITU radio regulations. It is used to avoid confusing with other vessels in crowded anchorages etc.

Model Qns,,,

·  After transmitting a MF DSC Safety Alert, the RT call should be transmitted on

You answered:	2182 kHz
Correct

·  The correct format for an RT Urgency Call to Clyde Coastguard is

You answered:	PAN PAN (x3) Clyde Coastguard (x3) this is Nonsuch (x3) GABC 232123456
Correct

·  Your vessel is in GMDSS Sea Area A1, drifting ashore and you require a tow. You should initially transmit by Ch. 70 DSC

You answered:	an All Stations Urgency Alert
Correct

·  After transmitting a VHF DSC Urgency Alert, the RT call and message is usually sent on

After transmitting a VHF DSC Urgency Alert, the RT call and message is sent on Ch. 16.

·  The correct format for an RT Safety Call to Clyde Coastguard is

You answered:	SECURITE (x3) Clyde Coastguard (x3) this is Nonsuch (x3) GABC 232123456

·  After receiving a DSC Distress Relay Alert from an MRCC on MF, you should

You answered:	listen for a MAYDAY RELAY message on 2182 kHz

·  To announce an unscheduled meteorological warning a coast station should transmit a DSC

You answered:	Safety Alert

·  You are in GMDSS Sea Area A2 and have received a DSC Distress Alert you should

You answered:	wait a short period, then acknowledge by RT on 2182 kHz

·  A DSC Distress Relay Alert should only be sent on the authority of

You answered:	person responsible for radio communications in an emergency

A DSC Distress Relay Alert should only be sent on the authority of the Master or person responsible for of the vessel.

·  You are in Sea Area A2 and require medical advice from Humber Coastguard. You should initially transmit by MF DSC on 2187.5 kHz

You answered:	an Urgency Alert addressed to Humber Coastguard’s MMSI
	...............................................

 FOLLOW for the Complete series........

Inmarsat Device

The standard Inmarsat C device on board consists of an Inmarsat terminal (this is the transmitter and receiver), a message terminal with disc drive and keyboard or another computer system, a printer, a power supply, an omnidirectional antenna, an antenna cable and, if not built-in, a GPS receiver.

Example of an Inmarsat C device.

The Inmarsat C device can be used for sending and receiving messages. These messages consist of data which is generated or decoded by the message terminal or computer connected to the Inmarsat C terminal. So it offers the possibility of sending and receiving various types of messages such as E-mail, Fax, TELEX, SMS etc.

Inmarsat Communication

The Inmarsat system is a satellite communication network. It is used by ships, and also by other users. This Inmarsat system supports the GMDSS system and for that reason it is used a lot on SOLAS ships as well as on non-SOLAS ships. Within the GMDSS system the Inmarsat system may be used for distress- alerting in sea area A3. Although areas A1 and A2 are not excluded from distress-alerting by Inmarsat, in these areas the GMDSS system offers better solutions for distress-alerting. It is also used for transmission of Maritime Safety Information (MSI) outside the coverage of a NAVTEX station. History The International Maritime Satellite Organization was founded on 16 July 1979. At this time Inmarsat took over the Marisat-network from the American company Comsat. From this moment on it was possible for ships at sea to communicate via satellite. In the beginning the system was only used by ships. Now Inmarsat is offering a wide range off products/services also for airplanes and other landmobile users. Apart from commercial activities, Inmarsat is committed to the IMO to ensure a 100% functioning communication network for Distress communication. Satellite Propagation The Inmarsat services will use 'direct wave' propagation (just like at the VHF 'Line of Sight'). There should always be a direct line of sight between the ship's Inmarsat antenna and the satellite used. For this reason the antennae should be fitted clear of the superstructure or other obstructions. Coverage for GMDSS purposes is considered reliable up to latitudes 70 degrees North and 70 degrees South (assuming not 'in shadow' of mountains, terrain or buildings), though service can often be accessed further North or South than the mentioned 70 degrees. The further you are from the equator, the lower the angle of sight from the antenna to the satellite, and the greater the possibility of losing sight of the satellite when near to land or other obstruction. Inmarsat satellites 36000 km above the earth The picture above shows the position of the four Inmarsat satellites. These geo-stationary orbiting satellites are situated in fixed positions above the equator

Last Radio Traffic from TITANIC

Distress Radio Traffic

Distress calls
The message "CQD" means a general call to all vessels, which indicates the vessel sending is in distress and requires immediate assistance.  At the time of the sinking, the Marconi company's "CQD" was still in common use, although it had been officially replaced by the well known "SOS" - which, by the way, does NOT mean "Save Our Souls" or anything so melodramatic - it was chosen specifically to be easily and instantly recognisable in morse - "dit dit dit, dah dah dah, dit dit dit".
Such was the dominance of Marconi over the infant marine radio industry that many ships still used CQD, rather than the official distress signal SOS.
This can be seen in the Titanic's initial and final distress calls - Jack Phillips stuck to the company CQD signal to the end....
 

The messages -

Titanic time	Message(s)
12-15 a.m	CQD (6 times) DE (this is) MGY (6 times) position 41.44 N. 50.24 W La Provence and Frankfurt receive Titanic's first distress signals.  Titanic sends position to Frankfurt. Frankfurt says "OK: stand by"
12-15 a.m	Mount Temple heard Titanic sending CQD Says require assistance. Gives position. Cannot hear me (sic). Advise my Captain (sic) his position at 41.46 N. 50.24 W.
12-15 a.m.	Cape Race coast station hears Titanic giving position on CQD 41.44 N. 50.24 W.
12-18 a.m.	Ypiranga hears CQD from Titanic.   Titanic gives CQD here (sic).  Position 41.44 N. 50.24 W. Require assistance (calls about 10 times).
12-25 a.m.	Carpathia calls Titanic and says "do you know that Cape Cod is sending a batch of messages for you ?"  Titanic says "Come at once. We have struck a berg. It's a CQD OM (it's a distress situation old man) Position 41.46 N. 50.14 W." Carpathia says "Shall I tell my Captain ?. Do you require assistance ?"  Titanic says "yes, come quick"
12-25 a.m.	Cape Race hears MGY (Titanic) give corrected position 41.46 N. 50.14 W. Calling him, no answer. (Titanic's 4th Officer Boxhall had just provided a corrected position to the radio room)
12-25 a.m.	MGY (Titanic) says CQD, Here (is my) corrected position 41.46 N. 50.14 W. Require immediate assistance. We have collision with iceberg. Sinking. Can hear nothing for noise of steam (engineers releasing excess steam pressure from boilers to minimise risk of explosion) Sent about 15 to 20 times to Ypiranga.
12-26 a.m.	DKF (Prinz Friedrich Wilhelm) calls MGY (Titanic) and gives position at 12 a.m. 39.47 N. 50.10 W. MGY (Titanic) says, "Are you coming to our ?" "We have collision with iceberg. Sinking. Please tell Captain to come." DKF says, "O.K. will tell"
12-27 a.m.	Titanic sends following: "I require assistance immediately. Struck by iceberg in 41.46 N. 50.14 W."
12-30 a.m.	Caronia sent CQ message (message addressed to all ships) to MBC Baltic and CQD (ie: a distress relay message): MGY (Titanic)  struck iceberg, require immediate assistance
12-30 a.m.	Mount Temple hears MGY (Titanic) still calling CQD. Our (sic) Captain reverses ship. We are about 50 miles off.
12-34 a.m.	Mount Temple hears Frankfurt give MGY (Titanic) his position 39.47 N. 52.10 W. Titanic says (to Frankfurt) " are you coming to our assistance ?" Frankfurt says : "what is the matter with you ?" Ttianic says "We have struck an iceberg and sinking. Please tell Captain to come" Frankfurt replies "O.K. Will tell the bridge right away" Titanic says "O.K., yes, quick."
12-45 a.m.	Titanic calls Olympic (Olympic is Titanic's sister ship - 500 miles away en route to England) SOS - (first use of "SOS" by Titanic- Bride jokingly suggests to Phillips that it may be his last chance to use the new distress call).
12-50 a.m.	Titanic calls CQD and says, "I require immediate assistance. Position 41.46 N. 50.14 W." Received by Celtic.
12-53 a.m.	Caronia to MBC (Baltic) and SOS,"MGY (Titanic) CQD in 41.46 N. 40.14 W. Wants immediate assistance."
1-0 a.m.	MGY gives distress signal. DDC (Cincinatti) replies. MGY's position 41.46 N. 50.14 W. Assistance from DDC (Cincinatti) not necessary as MKC (Olympic) shortly afterwards answers distress call.
1-0 a.m.	Titanic replies to Olympic and gives his position as 41.46 N. 50.14 W., and says, "We have struck an iceberg."
1-2 a.m.	Titanic calls Asian and said, "Want immediate assistance" Asian answered at once and received Titanic's position as 41.46 N. 50.14 W., which he immediately takes to the bridge. Captain instructs operator to have Titanic's position repeated.
1-2 a.m.	Virginian calls Titanic but gets no response. Cape Race tells Virginian to report to his Captain the Titanic has struck iceberg and requires immediate assistance.
1-10 a.m.	Titanic to MKC (Olympic), "We are in collision with berg. Sinking Head down. 41.46 N. 50.14 W. Come soon as possible."
1-10 a.m.	Titanic to MKC (Olympic), Captain says, "Get your boats ready. What is your position?"
1-15 a.m.	Baltic to Caronia, "Please tell Titanic we are making towards her."
1-20 a.m	Virginian hears MCE (Cape Race) inform MGY (Titanic) "that we are going to his assistance. Our position 170 miles N. of Titanic."
1-25 a.m.	Caronia tells Titanic, "Baltic coming to your assistance"
1-25 a.m	Olympic sends position to Titanic 4-24 a.m. G.M.T. 40.52 N. 61.18 W, and asks "Are you steering southerly to meet us?" Titanic replies, "We are putting the women off in the boats."
1-27 a.m	Titanic says, "We are putting the women off in the boats."
1-30 a.m	Titanic tells Olympic, "We are putting passengers off in small boats." "Women and Children in boats, can not last much longer"
1-35 a.m.	Olympic asks Titanic what weather he had. Titanic replies, "Clear and calm."
1-35 a.m	Baltic hears Titanic say "Engine room getting flooded." (Captain Smith had just visited the Titanic's radio room and advised this to Phillips and Bride)
1-35 a.m.	Mount Temple hears DFT (Frankfurt) ask "are there any boats around you already?" No reply
1-37 a.m.	Baltic tells Titanic, "We are rushing to you."
1-40 a.m.	Olympic to Titanic "Am lighting up all possible boilers as fast as (we) can."
1-40 a.m.	Cape Race says to Virginia: "Please tell your Captain this: "The Olympic is making all speed for Titanic, but his (Olympic's) position is 40.32 N. 61.18 W. You are much nearer to Titanic. The Titanic is already putting women off in the boats, and he says the weather there is calm and clear. The Olympic is the only ship we have heard say, "Going to the assistance of Titanic.  The others must be a long way from Titanic
1-45 a.m.	Last signals heard from Titanic by Carpathia, "Come as quickly as possible old man: the engine-room is filling up to the boilers"
1-45 a.m.	Mount Temple hears Frankfurt calling Titanic. No reply.
1-47 a.m.	Caronia hears Titanic though signals unreadable still
	Virginia hears Titanic calling very faintly, his power being greatly reduced. (At 2-05 a.m. the Captain visits the wireless room for the last time and says: "Men, you have done your full duty. You can do no more. Abandon your cabin. Now it's every man for himself" Phillips looks up for a second, and then bends over the equipment once more. Captain Smith tries again "You look out for yourselves. I release you." A pause, then he adds softly "That's the way of it at this kind of time....every man for himself" He then leaves the wireless room. Phillips continues sending)
1-48 a.m.	Asian heard Titanic call SOS Asian answers Titanic but receives no answer. DFT (Frankfurt) calls Titanic and says, "What is the matter with u ?"
1-50 a.m.	Titanic says to Frankfurt "You fool, stdbi and keep out" Caronia hears Frankfurt working to Titanic.  Frankfurt according to position 172 miles from MGY (Titanic) at time first SOS sent out.
1-55 a.m.	Cape Race says to Virginian "we have not heard Titanic  for about half an hour. His power may be gone."
	During this period Phillips and Bride are struggling with a stoker who entered the wireless room and tried to steal Phillips life jacket. Bride holds the stoker, while Phillips punches him. The stoker is (presumably) knocked unconscious.
2-10 a.m.	Virginian hears 2 v's signalled faintly in spark similar to Titanic's (Most probably Phillips was transmitting a test signal whilst Bride adjusted the main transmitter motor-generator field regulators to compensate for the dying power supply from the engine room).
2-17 a.m.	Virginian hears Titanic call CQ (call to all ships) , but unable to read him. Titanic's signals end very abruptly as (if) power suddenly switched off. His spark rather blurred or ragged... (Phillips had actually intended to send "CQD DE MGY", however at this point there is a loss of all power to the radio room - water can be heard flooding the wheelhouse - Phillips says to Bride "Come on, let's clear out". Bride climbs to the roof of the officer's quarters and assists with launching collapsible lifeboat B - Phillips disappears aft.)
2-17 a.m.	Virginian Called Titanic and suggested he should try emergency set, but heard no response
2-20 a.m.	Virginian to Olympic,"have you heard anything about Titanic"   Olympic says, "No. Keeping strict watch, but hear nothing more from Titanic. No reply from him"
about 2-20 a.m.	This was the official time the ship foundered in 41.46 N. 50.14 W. as given by the Carpathia in message to the Olympic.
2-35 a.m.	Mount Temple hears MPA (Carpathia) send, "If you are there we are firing rockets."
2-40 a.m.	MPA (Carpathia) calling MGY (Titanic).
2-58 a.m.	SBA (Birma) thinks he hears Titanic so sends, "Steaming full speed for you. Shall arrive you 6-0 in morning. Hope you are safe. We are only 50 miles now."
3-0 a.m.	MPA (Carpathia) calling MGY (Titanic)
3-28 a.m.	La Provence to Celtic, "Nobody has heard the Titanic for about 2 hours."
4-24 a.m.	SBA (Birma) says "we are 30 miles S.W. off Titanic".
6-40 a.m.	Parisian hears weak signals from MPA (Carpathia) or some station saying Titanic struck iceberg. Carpathia has passengers from lifeboats
6-40 a.m.	Asian, with German oil tank in tow for Halifax asked what news of MGY (Titanic). Sends service (message) later saying heard MGY (Titanic) v. faint working. C. Race up to 10.0 p.m., local time. Finished calling SOS midnight.
7-40 a.m.	6-45 a.m. Mount Temple hears MPA (Carpathia) report rescued 20 boat loads.
8-07 a.m.	Baltic sends following to Carpathia: "Can I be of any assistance to you as regards taking some of the passengers from you? Will be in position about 4-30. Let me know if you alter your position."
8-10 a.m.	Baltic in communication with MPA. (Carpathia). Exchanged traffic re passengers, and get instructions to proceed to Liverpool
8-15 a.m.	Baltic turns round for Liverpool, having steamed 134 miles W. towards Titanic
8-40 a.m.	Mount Temple hears MPA (Carpathia) call CQ and say, no need to std. Bi (stand by) him. Advise my Captain (sic), who has been cruising round the icefield with no result. Ship reversed.
8-45 a.m.	Olympic sent MSG (message) to Owners, New York via Sable Island saying, "Have not communicated with Titanic since midnight."
8-55 a.m.	Carpathia replies to Baltic, "Am proceeding to Halifax or New York full speed. You had better proceed to Liverpool. Have about 800 passengers on board."
9-0 a.m.	Carpathia to Virginian: "We are leaving here with all on board about 800 passengers. Please return to your Northern course."

Radio callsigns
Radio call signs for the ships and shore stations involved are listed below.
In 1912, ships were issued with 3 letter call signs (this later changed to 4, as more ships were fitted with wireless).

Wireless shore stations:
Cape Race Newfoundland MCE
Sable Island Nova Scotia MSD
Sea Gate New York MSE
Sagaponack New York MSK
Siasconset Massachusetts MSC
Cape Sable Nova Scotia MSB

Vessels name and radio callsign (with the Captain's name listed where known):
Antillian Capt. Japha MJL
Amerika Capt. Knuth DDR
Asian Capt. Wood MKL
Baltic MBC
Blucher DDB
Birma SBA
Californian Capt. S.Lord MWL
Caronia Capt. Barr MSF
Carpathia Capt. A.H.Rostron MPA
Celtic MLC Cedric MDC
USS Chester Capt. S.G. Decker NDG
Franconia Capt. Smith MEA
Frankfurt DFT
Empress of Britain MPB
La Touraine Capt. Coussin MLT 
Titanic Capt. Smith MGY
Mount Temple MLQ
Mesaba Capt. Clark MMU
Minnehaha MMA
Minnewaska Capt. Gates MMW
Noordam Capt. Krol MRA
Olympic Capt. Haddock MKC
Parisian MZN
Prinz Friedrich Wilhelm DKF
Virginian Capt. Gambell MGN

 

Distress, Urgency and safety calls - Tx + Dx

Transmitting, Receiving and Relaying Distress, Urgency and Safety Calls

Reception of a Distress Alert

A vessel receiving a DSC distress alert should not normally acknowledge the alert by DSC, but should do so by voice or telex on the emergency frequency indicated in the alert. A DSC acknowledgement is usually done only by a Coast Station, because acknowledging the alert by DSC will stop the transmitting station from sending further alerts. Generally, it is much better for all concerned if a Coast Station hears and acknowledges the alert, and then assumes control of the operation. Another vessel should only acknowledge the alert by DSC if it is being transmitted on VHF or MF, and if it seems that no Coast Station has received the call and the transmission of the distress alert is continuing. In this situation, the receiving vessel may acknowledge the call by DSC to terminate the transmissions. But the receiving vessel is then required to contact the nearest Coast Station by any practical means and inform them of the situation. A DSC distress alert on HF should never be acknowledged by DSC by another vessel, because by the nature of HF propagation the two vessels are likely to be many hundreds of miles apart. Transmission of a DSC acknowledgement will stop the transmission of further alerts, and it would be better for the distressed vessel to continue sending alerts in the hope that a Coast Station will receive the call directly and take control of the situation. A vessel receiving an alert on HF should relay the alert to a Coast Station.

Reception of a DSC DISTRESS ALERT on VHF or MF

If a DSC distress alert is received on VHF or MF, the normal procedure to follow is: (a) Watch the DSC control unit for reception of a DSC acknowledgement from a Coast Station. Such an acknowledgement will stop further transmissions of the distress alert. (b) Tune the radio to the frequency and mode indicated in the DSC alert. (c) Acknowledge the receipt of the distress alert on the frequency indicated, either by voice or by telex as indicated in the DSC alert. The message acknowledging the distress alert should be as follows: Mayday - The word Mayday indicates that it is a distress message. Identity of Distressed vessel - This will be their MMSI, repeated three times - neither the name nor the call sign of the distressed vessel will be indicated on the DSC alert. This is......... - Your identity - your MMSI and/or name and call sign, repeated three times. Received Mayday. Over. If there is a Coast Station, or Rescue Co-ordination Centre controlling the operation and they want you to help, they will call you back. If no Coast Station nor RCC has taken control, the distressed vessel should hear your acknowledgement and may call you back to ask for your assistance if it is needed. If no Coast Station nor RCC has taken control and you do not hear any response to your acknowledgement by the distressed vessel, then you should send a distress alert relay.

Reception of a DISTRESS ALERT on HF

Vessels operating in Areas A3 and A4 are expected to monitor at least two of the DSC HF emergency frequencies. Normally 8414.5 kHz is designated as one and the other is chosen according to conditions - a lower frequency by night or a higher one by day. Many DSC watch-keeping receivers will in fact scan through all the DSC emergency frequencies; which are: 4207.5 kHz 6312 kHz 8414.5 kHz 12577 kHz 16804.5 kHz If you receive a DSC distress alert on HF from another ship you must not acknowledge it by DSC. Because of the likely propagation of the HF signal it is probable that the other vessel is several hundreds, or possibly thousands of miles away. If the distress alert was acknowledged by DSC then no further distress alerts would be transmitted by the distressed station, and this could well reduce the chances of it being heard by a shore station who could co-ordinate rescue attempts. If you do receive an HF DSC distress alert then the correct procedure is: a. Note on which band or bands the DSC alert was received. b. Note the position of the distressed vessel, and compare to your own. Unless the HF signal was received on ground wave, it is likely to be many hundreds of miles from your own position. c. Tune the HF radio to the mode and frequency indicated in the alert, or if no frequency and mode was specified then to the emergency frequency in the band on which the DSC alert was received. The HF emergency frequencies are: Voice emergency frequencies: 4125 kHz 6215 kHz 8291 kHz 12290 kHz 16420 kHz Telex emergency frequencies: 4177.5 kHz 6268 kHz 8376.5 kHz 12520 kHz 16695 kHz If telex was specified in the alert then the telex frequency should be monitored, but if it is possible to monitor the voice frequency on the same band as well then this should be done. If the DSC alert was received on several frequencies then monitor the most likely band, probably 8 MHz if the alert was received on this band. d. If no distress traffic is heard on the frequency to which you tuned within two minutes, then switch to the emergency frequency on another band on which the DSC alert was received or another of the emergency frequencies that might be appropriate, considering the position of the other vessel in relation to you and the likely propagation. e. If distress working is heard, then the situation should be monitored until it is obvious that the Coast Station has the situation under control. If no distress working is heard and no DSC acknowledgement has been transmitted by a Coast Station, then transmit a DSC distress alert relay to inform the nearest Rescue Co-ordination Centre or Coast Station by any means possible.

Transmission of a Distress Alert Relay

A vessel should transmit a distress alert relay if: (a) the distressed vessel herself is not able to transmit a distress alert. (b) the master of the relaying ship considers that more assistance is required. (c) a distress alert has been received but no contact with the distressed vessel has been possible and no Coast Station has responded to the alert. The distress alert relay could be sent to 'all stations', to vessels in a particular area or to a specific Coast Station or RCC. On VHF or MF an 'all stations' call might be considered appropriate to alert vessels in the vicinity as well as any Coast Stations within range. Usually, in the case of an HF DSC alert relay, it will be better to send it to a specific Coast Station or Rescue Co-ordination Centre, and let them co-ordinate the rescue. Do not do an 'all stations' call. There is no point in alerting vessels, for example, in the Indian Ocean for a vessel in distress in the North Atlantic. A DSC distress alert relay is sent as follows. a. Tune the radio to the DSC emergency frequency of the most suitable band. b. Select 'distress relay' on the DSC control unit. c. Address the call as 'all stations', or to the MMSI of a specific Coast Station or RCC. d. Key in the MMSI of the distressed vessel, if known. e. Select the nature of the distress, if known. f. Key in position of distressed vessel. g. Key in UTC time that the position was valid. h. Indicate frequency and mode for subsequent traffic. i. Transmit the DSC distress alert relay. j. Watch on the DSC control unit for a DSC acknowledgement. Tune the radio to the stipulated frequency and mode, and transmit the distress relay message. The distress relay message should take the format: Mayday relay - Mayday indicates that there is a distress situation, but by adding the word 'relay' it indicates at once that it is not you in distress. This is......... - Your MMSI, name of vessel, and call sign. Text of message - Indicating identity and position of distressed vessel, nature of distress, assistance needed and number of persons on board if known.

Reception of a Distress Alert Relay

See a typical Mayday Relay transmitted via Inmarsat-A by JRCC PIRAEUS. When a Coast Station, RCC, or indeed another vessel, has received, and acknowledged a DSC distress alert it may elect to transmit a distress alert relay to other vessels. It can do this to all stations, a group of vessels, vessels in a particular geographic area, or to one specific vessel. Vessels receiving such a DSC alert should not acknowledge it by DSC, but instead should tune to the indicated frequency and mode and acknowledge it on the appropriate frequency on the same band as it was received. The procedure is: - a. Do not acknowledge by DSC. Tune the radio to the appropriate frequency and mode indicated in the relay call. b. Acknowledge the alert relay by voice or telex as appropriate. The format of the acknowledgement message is: Mayday - The word Mayday indicates that it is a distress message. Identity of Distressed vessel - This will be their MMSI, repeated three times. (Neither the name nor the call sign of the distressed vessel will have been indicated on the DSC alert. This is......... - Your identity, including your MMSI and/or name and call sign, repeated three times. Received Mayday. Over. If there is a Coast Station or Rescue Go-ordination Centre controlling the operation and they want you to help, they will call you back. Continue to monitor the frequency after you have transmitted the acknowledgement. If a DSC distress alert relay is received from another ship who has perhaps done an 'all stations' distress alert relay, the procedure is exactly the same. Do not acknowledge by DSC, instead acknowledge by voice or telex as appropriate, in exactly the same way as above.

Urgency Calls

An urgency call is for serious situations but not one where the ship or a person is in 'grave and imminent' danger. An example of an urgency call might be a vessel which has lost her engines and may be swept ashore in the next hour or so. The danger is grave, but not yet imminent, so the correct call is an urgency call rather than a distress call. A serious medical problem may warrant an urgency call for assistance or evacuation. An urgency call must not be broadcast to the world in general, it must be addressed to somebody, even if it is to 'all stations.'

Transmission of an Urgency Alert

DSC is used to alert other stations that an urgency message is about to be transmitted on a nominated frequency. The message itself is then transmitted on an appropriate frequency in the normal way. The procedure is: a Select 'urgency call' on the DSC control unit. b. Select on which band you want to transmit the DSC alert. c. Tune the radio to the DSC frequency of the chosen band. The DSC control unit may do this for you. d. Address the call to 'all stations' or to the MMSI of a particular Coast Station or vessel, or group of vessels. e. Key in the mode and frequency on which the urgency message will be transmitted. f. Transmit the DSC urgency alert.

Transmission of an Urgency Message

The radio can now be tuned to the emergency frequency of the band on which the DSC alert was sent for transmission of the urgency message. The format of an urgency message is: Pan Pan - The words Pan Pan indicate that the message is an urgency message, and as such, it should have priority over all but distress traffic. In the case of a request for medical assistance, the signal is Pan Pan Medico. Note that this is for medical assistance. A request for medical advice is not a Pan Pan. Address - All messages except distress must be addressed to somebody. A general call, perhaps for a tow, would be addressed to 'all stations'. A Pan Pan Medico is more likely to be addressed to a specific Coast Station, but under some circumstances that too could be addressed to 'all stations'. Identity - You must identify yourself in all transmissions. Any station that has received your urgency call on DSC has received your MMSI number as part of the call, so your identity should include the MMSI number as well as the name and call-sign of your vessel. Position - This may have been included in the DSC call, but it should be repeated here. If somebody is to help you, they need to know where you are. As in the distress message, your position as a distance and bearing from a prominent landmark may mean more to the receiving station than a latitude and longitude. Assistance - State what assistance is needed. Over - Terminate the message with Pan Pan, name of your vessel and call-sign, and the word 'over', so the other stations know you have finished, and they can respond. Once communications have been established with a suitable station, the subsequent traffic will normally transfer off the emergency frequency onto a working channel. If the communication is on VHF and the traffic is inter-ship, then channel 6 could be used. If the communication is with the Coastguard, then they will probably transfer operations to channel 67 in the UK or 22A in the USA. A Coast Station will move communications to one of their working channels.

Reception of an Urgency Alert

Vessels receiving a DSC urgency alert should not acknowledge by DSC but should switch to the indicated channel, normally the emergency frequency for the band where the DSC alert was received, and listen for the urgency message.

Safety Calls

A safety call is to warn other vessels of a particular danger. It may be some danger to navigation, such as a drifting derelict or it could be an urgent weather warning. Again, the call and the message must be addressed to somebody even if it is to 'all stations'. The DSC safety alert can be addressed to 'all stations', a particular Coast Station, a group of vessels, vessels in a specified geographic area, or an individual vessel. Safety messages if they are short (less than a minute in duration), and if they are primarily intended for vessels in the immediate vicinity can be transmitted on the emergency frequency, but any longer messages should be transmitted on a working channel. If the message is addressed to 'all stations' and is primarily intended for reception by other vessels in the vicinity, then VHF will be used both for the DSC alert and the subsequent traffic and the message itself could be transmitted on channel 6, the inter-ship safety channel, or channel 13, the bridge-to-bridge navigational safety channel. For example, if you were entering a narrow channel in thick fog and you wanted to warn other vessels of your location, you would do this on channel 13.

Transmission of a Safety Alert

As with the urgency call, DSC is used to alert a station or stations that there is a safety message about to be transmitted and advises them of the frequency and mode. To send a DSC safety alert: a. Tune the radio to the DSC frequency of the band on which it is desired to transmit the alert. b. Select 'safety call' on the DSC control unit. c. Address the call to 'all stations' or to the MMSI of a particular Coast Station or vessel or group of vessels. d. Key in the channel on which the urgency message will be transmitted. For most safety messages a working channel (such as VHF channel 13 or 6) is selected, rather than the emergency channel. e. Transmit the DSC safety alert.

Transmission of a Safety Message

The radio can now be tuned to the appropriate channel and the message transmitted. The message should be in the format: Securite - The word securite - pronounced securitay - indicates that this is a safety message. Address - The message must be addressed to somebody, very often in this case to 'all stations'. Identity - Give your MMSI, which will have been given in the DSC call, and the name of your vessel and/or call-sign. All transmissions must be identified, even if you are not expecting a reply. Message - The text of the safety message. Out- Terminate the transmission with the name/call-sign of the vessel, and the word 'out', which signifies the end of the transmission and that you are not expecting a reply. 'Over' signifies the end of that part of the transmission and that you are standing by for a reply. Although one hears it every day, it is incorrect to say 'over and out' - the two together are contradictory.

Reception of a Safety Alert

Another vessel may want to issue a safety message to warn of a danger to navigation, or perhaps a Coast Station has an urgent gale warning or navigational warning to transmit. The DSC alert may be addressed to 'All Stations', a group of vessels, vessels in a particular area, or it may be addressed to you specifically. If the DSC control unit recognises that the safety call concerns you, you will be alerted. a. Do not acknowledge by DSC, unless the alert is addressed only to your vessel. b. Tune the radio to the frequency and mode indicated in the call c. Listen for the transmitted message. Non-DSC equipped vessels should make distress, urgency, or safety calls on the emergency frequency of a suitable band prior to transmitting the message. The call is Mayday, repeated three times, for a distress call; Pan Pan repeated three times for an urgent call; or Securite repeated three times for a safety call. This should be followed by your vessel's name and/or call sign again repeated three times. Then the message should be transmitted in exactly the same way as if a DSC alert had been sent, e.g., MIPDANIO for distress. Under the GMDSS regulations there is no obligation for anybody to monitor any of the emergency frequencies other than the DSC frequencies, although hopefully somebody will hear you.

UTC Time - Converter

UTC TIME Converter

MF radio communication

In the High Frequency range and partly in the MF range (actually from about 1 MHz to 30 MHz), sky-wave propagation is most affected by ionospheric reflection, and as the density of atmospheric ionization fluctuates, so must the frequency, a higher frequency corresponding to higher density of ionization. Variations in propagation length occur according to such factors as time of day, year, sunspots as well as other ionospheric conditions.

During the day, the reflection of the wave back from the ionosphere occurs lower (layer E), so more waves are necessary for longer propagation and therefore, a higher frequency must be used. At night, the wave reflections are from the higher layer F2, so a lower frequency generally suffices.
The data about the height of ionosphere is provided daily by several observatories. The most known European observatory is the National Observatory of Athens in Greece, which publishes data for the whole world (www.iono.noa.gr). Here an operator can find the current status of layer height ( h ) and density (f0).
The angle of reflection (alpha) depends on both the layer height and distance (d) across land or sea of the point of reflection and may be calculated by the formula:
alpha = arc tg ((d/2)/h)
Where only one reflection occurs during propagation, this is called 'single hop' propagation. The more hops, the greater the distance of propagation, but the lesser the quality of transmission and the more energy required. Whenever possible single hop is used.
To reach a certain station (ship, RCC, etc.) with a single hop the communication may be done only within the limits from LUF (Lowest Usable Frequency) and MUF (Maximum Usable Frequency). The optimum communication is called OTF (Optimum Traffic Frequency), which is around 85% of MUF. As the radio operator may not choose just any frequency, but only those designated for maritime traffic, the operator should use the nearest available frequency. MUF and OTF are calculated by the formula:
MUF=f₀/cos (alpha)
OTF=MUF * 0.85
LUF depends upon transmitter power, sensitivity and tuning of the receiver
The distance the signal travels before reaching the earth again is called the skip distance. It will also be found that there is often an area between the limit of the ground wave coverage and the reflection zone (where the skywave returns to earth) where no signal can be received. This area is called the dead zone or skip zone. To communicate within the skip zone, the frequency must be lowered.
In general:

• day MUF is higher than night MUF
• summer MUF is greater than winter MUF
• if sun activity arises, MUF and OTF increases, skip distance decreases
• if sun activity decreases, MUF and OTF decrease, skip distance increases

The ground wave propagates at all times, day and night. The day time service area of a MF station is determined by the characteristics of the ground wave's mode of propagation. This is affected by the carrier wave frequency and the effective conductivity of the ground. On the sea the conductivity is higher than on earth. The distance significantly depends on the power of the transmitting station. All registered ship stations should have enough power to reach shore stations within 150 nautical miles (the minimum requirement for Sea area A2).

During the night a signal is propagated as a sky wave via the ionosphere as well as a ground wave, so the distance of possible communication is greater. The reflection from the ionosphere causes what is called a skip distance, but within MF propagation, this distance is covered by the ground wave so there is no skip zone.

Normally the ship is using DSC to establish the connection with other stations. For priority communications (distress, urgent, safety) the DSC frequency 2187.5 kHz should be used. But for the ship's routine calls (all non-priority) the simplex frequency 2177 kHz is used for ship to ship calls, while for ship to shore call the duplex frequency 2189.5 kHz (ship transmit)/2177 kHz (ship receive) must be used.

When the connection is established, the radio operator should move to working frequency. For priority communications (distress, urgent, safety) by radiotelephony frequency 2182 kHz should be used. For routine communications, the operator should consider the frequency list for a particular MF region (see appendix). Ship to ship communications are possible on frequencies 2045 kHz or 2048 kHz in region 1, while for regions 2 and 3, the frequencies are 2635 kHz or 2638 kHz. For ship to shore communications, the shore station provides the ship working frequencies.

VHF radio communication

The wavelength of frequencies within the VHF band is approximately 2 m. Practically, this means that the length of a VHF antenna (dipole antenna) for a VHF radio need not be longer than about half this length, about 1 m., which makes VHF radio communications ideally suitable for all vessels: from large passenger ships down to the smallest fishing boat or yacht.

Electro-magnetic waves of such a relatively small wavelength tend to travel or propagate in an almost straight line between Tx and Rx and extend only as far as the visible horizon (line of sight). These space waves, as they are referred to, will not pass through objects such as hills or large buildings, but may be reflected by such structures. For these reasons, it is best to site the VHF antenna at the highest point of the vessel in order to obtain the greatest communication range (in Tx and Rx).

The range of VHF radio communications (distance from antenna to the visible horizon) is calculated by the following formula (the symbol √ stands for square root):
Range [NM] = 2.25 x √height of antenna [m]
When calculating the range between two antennas, the range of both antennas have to be taken into consideration. The formula is:
Range between two antennas [NM] = 2.25 x (√height of antenna I [m] + √height of antenna II [m])
Example: the range between vessel antenna (30 m above sea level) and CRS antenna (62 m above sea level) is 2.25 x (√30 + √62) = 30.04 NM

The range of VHF radio communications at sea may vary greatly between different types of vessel and between different types of vessel and CRS. This is due to the varying heights of antennas ( h ) in use, and is dependent on the size of vessels and locations of CRS. Under normal radio conditions the expected radio communication range at VHF will normally be expected to be between 20 to 30 NM.

The marine frequency band for VHF radio communication, extending between 156 MHz and 174 MHz, contains 57 individual VHF CH (channels) numbered consecutively from VHF CH 1 to VHF CH 28 and from VHF CH 60 to VHF CH 88.

DSC - Detailed notes

The GMDSS enables Maritime Rescue Centres and radio stations to keep automatic watch on the
distress channels. A ship equipped with a DSC apparatus can make a distress call by simply
pressing a button, which results in an automatic alarm signal at the maritime rescue centre nearest
to the vessel.
DSC can be used for all kinds of radio calls between ship-ship and ship-shore–ship. DSC calls are
made on channel 70, which means that any voice communication on this channel is not allowed.
The DSC call includes and shows the following information:
- Format or Type of Call
- Receiver or Party ID
- Call Category or Priority
- Telecommand
(follow-up radio communication)
- Working Channel
1. FORMAT OR TYPE OF CALL
One of the following are chosen on the DSC apparatus:
- distress alert / distress call in a distress
- all ships a call to all stations
- selective/individual a call to one station
(e.g. in routine calls)
- group a group of stations
- area / geographical call to stations in a
particular area

2. PARTY/RECEIVER ID (IDENTIFICATION)
The receiver of the call (Party ID) you can click either the Maritime Mobile Service Identity (MMSI)
number of the recediving station, a group call number or area call number. The MMSI always
contains nine digits.
Example of MMSI Number system:
MMSI Vessel Explanation
230252000 230 country code (Finland)
always three digits
252000 (ship’s number)
MMSI Coast Station Explanation
002301000 00 means coast station in general
230 country code (Finland)
number of particular coast station
1000 (Turku Maritime Rescue Coordination Centre)
3. CALL CATEGORY OR PRIORITY
- distress
- urgency
- safety
Routine Communication can be of two kinds:
- routine
- ship’s business
4. TELECOMMAND
This gives information on what kind of follow-up radio communication the sender wishes to have. It
also gives information on what kind of message the sender is giving. The most common
telecommand choices include:
- telephony G3E/F3E simplex
o voice communication on VHF
- distress acknowledgement
o request for acknowledgement of distress call
- distress relay alert
o request for relay of distress
- ship’s position
o request for a vessel’s position to be shown on DSC (routine call)
5. WORKING CHANNEL
The one who sends a DSC call can suggest a working channel for continued voice radio
communication.
NOTE: When a vessel is calling a coast station it does not suggest a working channel. The coast
station announces which radio channel to continue on.

ROUTINE COMMUNICATION WITH DSC CALL
EXAMPLE 1

A RADIO MESSAGE FOR SUOMENLINNA COAST GUARD STATION
COMPARE THE FOLLOWING TO THE EXAMPLES SENT WITHOUT DSC:
A Russian yacht Marlene is approaching the Finnish coast on its way to spend a holiday partly in
Helsinki and partly by sailing in the Finnish archipelago. According to European union laws a
foreign pleasure boat must report for passport control when she has entered the territorial waters
of one of the member states. The Marlene is a luxury yacht and is linked to GMDSS and has DSC.
It is 12.30 at Suomenlinna Coast Guard Station on a fine summer day.
The DSC at Suomenlinna starts signalling and shows the following message:
Format: SELECTIVE
Party ID: 002300005
Category ROUTINE
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70
NOTE: Marlene does not suggest a working channel. In communication between ship and coast
station, it is always the coast station that determines the choice of working channel.
SELECTIVE directed to a specific station only
PARTY ID 002300005 the MMSI number of Suomenlinna Coast Guard Station

The Coast Guard station sends the following acknowledgement:
Format: SELECTIVE
Party ID: 273678951
Category: ROUTINE
Telecom 1: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel: 74
Transmitted: Ch 70
Party ID 273678951 = the MMSI number of Marlene
Format SELECTIVE = directed towards one station
The Coast Guard Station suggests:
Work channel 74
After this Marlene CONTINUES BY VOICE COMMUNICATION on channel 74:
Calling Finnish Coast Guard Suomenlinna, Finnish Coast Guard Suomenlinna,
This is Russian vessel Marlene, JAAA,
Russian vessel Marlene JAAA,
On VHF channel 74.
Over.

Russian Vessel Marlene JAAA,
This is Finnish Coast Guard Station
Suomenlinna,
Over.

Finnish Coast Guard station,
This is Russian yacht Marlene,
My position is: Latitude: 59° 56.9´ N Longitude : 024° 56.3´ E
I am in the approach channel passing Helsinki Lighthouse. I am proceeding to the Coast Guard
Station for passport control. REQUEST: Please give instructions to reach Suomenlinna Coast
Guard Station. Over.
Marlene,
This is Finnish Coast Guard.
INSTRUCTIONS: Proceed along the fairway. Pass Harmaja Lighthouse and proceed along the fairway
distance 1.6 miles. Take fairway depth 9.6, course 328°.
Proceed distance 0.8 miles. You can see the information on your starboard side.
I repeat: Proceed along the fairway. Pass Harmaja
Lighthouse and proceed along the fairway distance 1.6 miles. Take fairway depth 9.6, course 328°. Proceed
distance 0.8 miles. You can see the information on your starboard side. Over.
Finnish Coast Guard ,
This is Marlene.

UNDERSTOOD. I will proceed along the fairway and pass Harmaja Lighthouse. I will take fairway
depth 9.6, steering course 328°. I will proceed along the fairway distance 0.8 miles ahead. I can
see information sign on starboard side. THANK YOU AND OUT.
AS YOU NOTICED THE DSC CALL REPLACES THE INITIAL VOICE COMMUNICATION CALL
AND ANSWER ON CHANNEL 16. CHANGING TO A WORK CHANNEL ALSO HAPPENED VIA
DSC.
THUS A TRADITIONAL VOICE TRANSMISSION ON CHANNEL 16 DIFFERS SLIGHTLY IN THE INITIAL STAGE BUT RADIO PROCEDURE IS OTHERWISE THE SAME.
DSC DISTRESS COMMUNICATION

DSC DISTRESS INFORMATION:
A distress alert by Digital selective call should include the following information:
·  the nature of call is DISTRESS
·  MMSI number of vessel in distress
·  position of vessel in distress in coordinates
·  position at TIME
·  nature of distress
·  suggestion for follow up communication ( voice or text)
NOTE:
·  A distress call is always addressed at all stations.
·  Voice communication always takes place on channel 16.
NATURE OF DISTRESS
The DSC apparatus has a menu including the following choices for nature of distress:
·  fire, explosion
·  flooding
·  collision
·  grounding
·  listing in danger of capsizing
·  sinking
·  disabled and adrift
·  undesignated distress
·  abandoning ship
·  piracy/armed robbery attack
·  man overboard
·  EPIRB

EXAMPLE - DISTRESS CALL DSC
Area A1 on VHF
The DSC shows the following information:
Format: DISTRESS
Distress ID 230136780 (MMSI number of vessel)
Postion: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Transmitted: Ch 70
EXAMPLE - DISTRESS ACKNOWLEDGEMENT DSC
Area A1 on VHF
The Distress call is acknowledged by MRCC Turku:
The acknowledgement repeats the information in the Distress Call.
It is directed to and seen on the DSC apparatus by all ships in the vicinity.
Format: ALL SHIPS
From: 002301000
Category: DISTRESS
Telecom 1: DISTRESS ACKNOWLEDGEMENT
Distress ID: 230136780
Position: 59 23 N 020 36 E
Pos.UTC: 1345 UTC
Nature of distress: LISTING IN DANGER OF CAPSIZING
Telecom: TELEPHONY (F3E/G3E SINPLEX)
Transmitted: Ch 70
AFTER THIS FOLLOWS VOICE COMMUNICATION ON CHANNEL 16
DISTRESS MESSAGE
MAYDAY
This is 230136780
VERA
CALL SIGN JULIETT ALFA BRAVO CHARLIE
POSITION: 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
DISTRESS ACKNOWLEDGEMENT
MAYDAY
VERA VERA VERA
Call sign Juliett Alfa Bravo Charlie
This is RESCUE CENTRE TURKU RESCUE CENTRE TURKU
RESCUE CENTRE TURKU
RECEIVED MAYDAY
Over
FOLLOWED BY A MAYDAY RELAY FROM THE RESCUE
CENTRE ON CHANNEL 16...
MAYDAY RELAY MAYDAY RELAY MAYDAY RELAY

ALL STATIONS ALL STATIONS ALL STATIONS
This is 002301000
Rescue Centre Turku Rescue Centre Turku Rescue Centre Turku
Following received from Vera Juliett Alfa Bravo Charlie at 1200 UTC on VHF channel 16 :
Begins
Mayday
This is Vera
Juliett Alfa Bravo Charlie
In position 59º 23´ NORTH 020º 36´ EAST
Heavy leaking, danger of capsizing. Sea is rough.
Three men on board, five men in dinghy.
REQUEST: I require immediate assistance.
Ends
Ships in area report to Rescue centre Turku
Over
DSC SAFETY COMMUNICATION
The following is an example of the MESSAGE STRUCTURE of a Safety Call with DSC by Turku
Radio. This call is seen by vessels in the area.
Format: All ships
From: MMSI NUMBER (002300230)
Category SAFETY
Telecom: TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted: Ch 70
It is followed by a safety call by voice communication sent by Turku Radio on VHF channel 16, so
that every vessel, even smaller ones without DSC will receive the warning. The safety message is
then read on the traffic channel:
SAFETY CALL ON CHANNEL 16:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING
PLEASE SWITCH TO TRAFFIC CHANNELS
SAFETY MESSAGE ON TRAFFIC CHANNEL:
SECURITÉ SECURITÉ SECURITÉ
ALL STATIONS ALL STATIONS ALL STATIONS
THIS IS: MMSI NUMBER
NAME OF STATION 1 X:
NAVIGATIONAL WARNING ….

DSC URGENCY COMMUNICATION
A vessel or a coast station can send an urgency call (Pan-Pan call) by DSC. The DSC call contains
information on which channel the voice communication will be read (Channel 16). The call can be
directed to all stations or directly to the nearest Maritime Rescue Centre.
A Pan-Pan message may be sent in, for example, the following situations:
·  a person has fallen overboard and the ship needs help with search and rescue
·  signals have been observed that might be distress signals
·  when reporting on missing vessels
·  if a person on board a vessel needs immediate medical assistance
·  red rockets have been observed
EXAMPLE
The following is an example of an Urgency call to all stations by DSC:
A
Format ALL SHIPS
Category URGENCY
Telecom 1 TELEPHONY (F3E/G3E SIMPLEX)
Work Channel 16
Transmitted 70
A vessel can send an urgency call directly to the nearest Maritime Rescue Centre. Example of a
call sent to MRCC Turku:
B
Format SELECTIVE
Party ID 002301000
Category URGENCY
Telecom 1 TELEPHONY F3E/G3E SIMPLEX)
Work channel NONE
Transmitted CH 70

NOTE: when sending a DSC call to a Rescue Centre or Coast Station a vessel does not suggest
the working channel. This is done by the Coast Station or Rescue Centre.