Free GMDSS Navigation and Communication Questions and Answers — Questions and Answers
Question 1: Equipment for radiotelephony use in survival craft stations under GMDSS must have what characteristic(s)?
- Operation on Ch-16
- Permanently-affixed antenna
- Watertight
- All of these (Correct answer)
Correct answer: All of these
Explanation: <br> Equipment for radiotelephony use in survival craft stations under GMDSS must have several characteristics to ensure effective communication during distress situations. These characteristics typically include the ability to operate on Channel 16 (the international distress and calling frequency), having a permanently fixed antenna for reliable transmission, and being watertight to withstand harsh maritime conditions. Therefore, all the characteristics listed must be met by equipment used in survival craft stations under GMDSS regulations.
Question 2: How are paired NBDP frequencies normally used?
- These are normally used only for distress communications to limit channel interference.
- These are normally used for ARQ communications with coast radio stations. (Correct answer)
- These are normally used for FEC communications with coast radio stations.
- These are normally used for DSC communications with coast radio stations.
Correct answer: These are normally used for ARQ communications with coast radio stations.
Explanation: <br> Paired NBDP (Narrow-Band Direct Printing) frequencies are typically used for ARQ (Automatic Repeat reQuest) communications with coast radio stations. ARQ is a data transmission protocol used to ensure the reliable delivery of messages over a radio link. In ARQ communications, data packets are sent from one station to another, and the receiving station acknowledges the receipt of each packet. If a packet is not received correctly, it is automatically retransmitted until it is successfully received. Therefore, paired NBDP frequencies are used for ARQ communications to facilitate reliable data exchange between ships and coast radio stations.
Question 3: To set up the MF/HF Transceiver for a voice call to a coast station, the operator must:
- Select J3E mode for proper voice operations. (Correct answer)
- Select J3E mode for proper Sitor operations.
- Select F1B mode or J2B mode, depending on the equipment manufacturer.
- Select F1B/J2B modes or J3E mode, depending on whether FEC or ARQ is preferred.
Correct answer: Select J3E mode for proper voice operations.
Explanation: <br> To set up the MF/HF Transceiver for a voice call to a coast station, the operator must select J3E mode. J3E mode is the appropriate mode for voice communications in the High-Frequency (HF) band. It is commonly used for transmitting voice signals over long distances with good audio quality and efficiency. Therefore, selecting J3E mode ensures proper voice operations during the call.
Question 4: Which statement is NOT true regarding the COSPAS-SARSAT system?
- Doppler shift is used to locate the beacons.
- May be used to transmit public correspondence. (Correct answer)
- EPIRBs are used as satellite beacons aboard lifeboats as alerting devices.
- Locates distress beacons transmitting on 406 MHz.
Correct answer: May be used to transmit public correspondence.
Explanation: <br> The COSPAS-SARSAT system is primarily designed for search and rescue operations, specifically to locate and assist distressed vessels, aircraft, and individuals. While it utilizes Doppler shift to locate distress beacons transmitting on 406 MHz and EPIRBs are used as satellite beacons aboard lifeboats as alerting devices, it is not intended for transmitting public correspondence. The system's main function is to detect and relay distress signals to search and rescue authorities for prompt action, rather than facilitating general communication. Therefore, the statement that COSPAS-SARSAT may be used to transmit public correspondence is not true.
Question 5: Equipment for radiotelephony use in survival craft stations under GMDSS must have what capability?
- Operation on 457.525 MHz
- Operation on Ch-16 (Correct answer)
- Operation on 121.5 MHz
- Any one of these
Correct answer: Operation on Ch-16
Explanation: <br> Equipment for radiotelephony use in survival craft stations under GMDSS (Global Maritime Distress and Safety System) must have the capability to operate on Channel 16. Channel 16 is the international distress and calling frequency designated for maritime communication. It is monitored continuously by maritime authorities and other vessels to coordinate distress, safety, and emergency communications. Therefore, operation on Channel 16 is a crucial requirement for survival craft stations to ensure effective communication during distress situations.
Question 6: If the vessel is experiencing atmospheric interference with NAVTEX broadcasts, especially in the tropics, the GMDSS operator should:
- Select one of the 6 HF MSI frequencies and set up the transceiver in ARQ telex mode.
- Select the MF MSI frequency dedicated to tropical MSI and set up the transceiver in FEC telex mode.
- Select one of the 6 MF MSI frequencies and set up the transceiver in FEC telex mode.
- Select one of the 8 HF MSI frequencies and set up the transceiver in FEC telex mode. (Correct answer)
Correct answer: Select one of the 8 HF MSI frequencies and set up the transceiver in FEC telex mode.
Explanation: <br> In areas experiencing atmospheric interference with NAVTEX broadcasts, especially in the tropics, the GMDSS operator should select one of the 8 HF (High-Frequency) MSI (Maritime Safety Information) frequencies and set up the transceiver in FEC (Forward Error Correction) telex mode. FEC is a method used to detect and correct errors in transmitted data without the need for retransmission, which is beneficial in environments where atmospheric interference may corrupt the received signal. By using FEC telex mode on the HF MSI frequencies, the operator can improve the reliability of receiving NAVTEX broadcasts despite atmospheric interference.
Question 7: If the vessel is beyond the range of NAVTEX broadcasts and the Sat-C system fails, the GMDSS operator must:
- Select an HF MSI frequency and FEC telex mode to receive MSI. (Correct answer)
- Select 518 kHz ARQ telex on the MF/HF console to receive MSI.
- Request repairs of the Sat-C system and wait until within range of NAVTEX.
- Select 518 kHz FEC telex on the MF/HF console to receive MSI.
Correct answer: Select an HF MSI frequency and FEC telex mode to receive MSI.
Explanation: <br> When the vessel is beyond the range of NAVTEX broadcasts and the Sat-C system fails, the GMDSS operator can rely on High-Frequency (HF) MSI (Maritime Safety Information) broadcasts. In this situation, the operator should select an HF MSI frequency and set up the transceiver in FEC (Forward Error Correction) telex mode to receive MSI. FEC telex mode helps to ensure reliable data transmission over HF radio links, even in challenging conditions or over long distances. Therefore, selecting an HF MSI frequency and FEC telex mode is the appropriate action for receiving MSI when NAVTEX and the Sat-C system are unavailable.
Question 8: FEC NBDP transmissions are normally used to?
- Receive Coast station traffic lists, NAVTEX, and VHF MSI broadcasts.
- Receive weather messages, Coast Station traffic lists, and company messages.
- Receive HF MSI and NAVTEX. (Correct answer)
- None of the above.
Correct answer: Receive HF MSI and NAVTEX.
Explanation: <br> FEC NBDP transmissions are indeed used to receive HF MSI (High-Frequency Maritime Safety Information) and NAVTEX (Navigational Telex) broadcasts. These transmissions are vital for receiving important safety-related information such as navigational warnings, weather forecasts, and other maritime safety messages.
Question 9: Selective FEC communications (SFEC) are employed when:
- An individual station must receive communications without using any transmitters (Radio Silence). (Correct answer)
- An individual station must receive communications by using its transmitter to achieve phasing and block other stations from breaking in.
- Multiple stations without a group selcall must receive communications without using their transmitters (Radio Silence).
- Multiple stations must receive communications by using their transmitters to achieve phasing.
Correct answer: An individual station must receive communications without using any transmitters (Radio Silence).
Explanation: <br> SFEC is utilized when a station needs to receive communications while refraining from transmitting, such as during radio silence periods. SFEC allows the station to receive messages reliably without the need for its transmitter to be active. This is particularly important in situations where maintaining radio silence is crucial, such as during certain military operations or emergency scenarios.
Question 10: Which is the key part of the search and rescue system under GMDSS?
- NASA satellites
- AMSAT satellites
- US Space Agency satellites
- COSPAS/SARSAT satellites (Correct answer)
Correct answer: COSPAS/SARSAT satellites
Explanation: <br> COSPAS/SARSAT (Cosmicheskaya Sistyema Poiska Avariynich Sudov/Search and Rescue Satellite-Aided Tracking) satellites are the key component of the search and rescue system under GMDSS. These satellites are part of an international satellite system designed to detect and locate distress signals from emergency beacons (EPIRBs, ELTs, and PLBs) transmitted by ships, aircraft, and individuals in distress. When a distress signal is received, COSPAS/SARSAT satellites relay the signal to ground stations, which then coordinate search and rescue efforts to assist the distressed party. Therefore, COSPAS/SARSAT satellites play a crucial role in saving lives at sea and in remote areas around the world.
Question 11: Which would indicate proper operation of an SSB transmitter rated at 60-watt PEP output in J3E mode?
- In SITOR communications, the power meter can be seen fluctuating regularly from zero to the 60-watt relative output reading.
- In SSB (J3E) voice mode, with the transmitter keyed but without speaking into the microphone, no power output is indicated. (Correct answer)
- In SSB (J3E) mode, speaking into the microphone causes the power meter to fluctuate well above the 60-watt reading.
- A steady indication of transmitted energy on an RF power meter with no fluctuations when speaking into the microphone.
Correct answer: In SSB (J3E) voice mode, with the transmitter keyed but without speaking into the microphone, no power output is indicated.
Explanation: <br> In Single Sideband (SSB) voice mode (J3E), the transmitter should not produce any power output when keyed but without speaking into the microphone. This is because SSB transmitters are designed to only transmit audio frequencies, and if there is no audio input (i.e., no speaking into the microphone), there should be no power output. This behavior indicates proper operation of the SSB transmitter, ensuring that it does not transmit unintended signals or interference when not in use.
Free GMDSS Navigation and Communication Questions and Answers
Equipment for radiotelephony use in survival craft stations under GMDSS must have what characteristic(s)?