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Subelement C
Equipment Operations
Section 15
MF-HF Equipment Controls
Which modes could be selected to receive vessel traffic lists from high seas shore stations?
  • AM and VHF-FM.
  • ARQ and FEC.
  • VHF-FM and SSB.
  • Correct Answer
    SSB and FEC.

Which modes could be selected to receive vessel traffic lists from high seas shore stations?

(D). SSB and FEC.

SSB: Single Side Band
FEC: Forward Error Correction

For AM frequencies there is a "carrier" which is like a steady hum, and this carrier is disturbed by broadcasted sound, which results in the Upper Side Band and Lower Side Band (mirror waves of each other)

The disturbance is what you hear as meaningful sound. SSB mode eliminates the carrier frequency and usually the Lower Side Band. So, you hear only Upper Side Band, known as SSB. The SSB mode has far greater radiation propagation.

More on SSB

Forward Error Correction is a technique of sending additional data that is used to verify accuracy of transmission and detect errors.

More on FEC

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Why must all MF-HF Distress, Urgency and Safety communications take place solely on the 6 assigned frequencies and in the simplex operating mode?
  • For non-GMDSS ships, to maximize the chances for other vessels to receive those communications.
  • Correct Answer
    Answers a) and c) are both correct.
  • For GMDSS or DSC-equipped ships, to maximize the chances for other vessels to receive those communications following the transmission of a DSC call of the correct priority.
  • To enable an RCC or Coast station to only hear communications from the vessel actually in distress.

Why must all MF-HF Distress, Urgency and Safety communications take place solely on the 6 assigned frequencies and in the simplex operating mode?

B. Answers a) and c) are both correct.

A. For non-GMDSS ships, to maximize the chances for other vessels to receive those communications.

C. For GMDSS or DSC-equipped ships, to maximize the chances for other vessels to receive those communications following the transmission of a DSC call of the correct priority.

For a fantastic comprehensive understanding in this area and other related areas, please look at:

Principles of Maritime Mobil Service

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To set-up the MF/HF transceiver for a voice call to a coast station, the operator must:
  • Select J3E mode for proper SITOR operations.
  • Select F1B mode or J2B mode, depending on the equipment manufacturer.
  • Correct Answer
    Select J3E mode for proper voice operations.
  • Select F1B/J2B modes or J3E mode, depending on whether FEC or ARQ is preferred.

To set-up the MF/HF transceiver for a voice call to a coast station, the operator must:

(C). Select J3E mode for proper voice operations.

Code of Federal Regulations, Title 47 Chapter I Subchapter
D Part 80 - STATIONS IN THE MARITIME SERVICES

§ 80.880 Vessel radio equipment.

47 CFR 80.880(b) Vessels operated solely within one hundred nautical miles of shore must be equipped with a medium frequency transmitter capable of transmitting J3E emission and a receiver capable of reception of J3E emission within the band 1710 to 2850 kHz, in addition to the VHF radiotelephone installation required by paragraph (a) of this section, and must maintain a continuous watch on 2182 kHz. Additionally, such vessels must be equipped with either:

§ 80.905 Vessel radio equipment.

47 CFR 80.905(a)(1) Vessels operated solely within 20 nautical miles of land must be equipped with a VHF-DSC radiotelephone installation meeting the requirements of § 80.1101(c)(2), except that a VHF radiotelephone installation without DSC capability is permitted until one year after the Coast Guard notifies the Commission that shore-based sea area A1 coverage is established. Vessels in this category must not operate more than 20 nautical miles from land.

47 CFR 80.905(a)(2) Vessels operated beyond the 20 nautical mile limitation specified in paragraph (a)(1) of this section, but not more than 100 nautical miles from the nearest land, must be equipped with a MF-DSC frequency transmitter meeting the requirements of § 80.1101(c)(3) and capable of transmitting J3E emission and a receiver capable of reception of J3E emission within the band 1710 to 2850 kHz, in addition to the VHF-DSC radiotelephone installation required by paragraph (a)(1) of this section, except that a MF radiotelephone installation without DSC capability is permitted until one year after the Coast Guard notifies the Commission that shore-based sea area A2 coverage is established. The MF or MF-DSC transmitter and receiver must be capable of operation on 2670 kHz.


§ 80.67 General facilities requirements for coast stations.

47 CFR 80.67(a) All coast stations licensed to transmit in the band 156-162 MHz must be able to transmit and receive on 156.800 MHz and at least one working frequency in the band.

47 CFR 80.67(b) All coast stations that operate telephony on frequencies in the 1605-3500 kHz band must be able to transmit and receive using J3E emission on the frequency 2182 kHz and at least one working frequency in the band.


J3E (SSB) mode for voice operations

Please see Wikipedia's article on Types of radio emissions

J3E is Single Side Band Mode, which is appropriate for voice, but SITOR (Simplex Teletype Over Radio) is another digital mode, which eliminates choice A.

F1B and J2B are both digital modes, and not appropriate for a voice call, which eliminates choices B and D.

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MF/HF transceiver power levels should be set:
  • Correct Answer
    To the lowest level necessary for effective communications.
  • To the level necessary to maximize the propagation radius.
  • To the highest level possible so as to ensure other stations cannot “break-in” on the channel during use.
  • Both a) and c) are correct.

MF/HF transceiver power levels should be set:

(A). To the lowest level necessary for effective communications.

FCC requires that only the minimum amount of power needed for effective radio communication should be used.

This is to reduce the chance of unintended interference with other stations, especially as HF and MF are both long range.

It also allows other stations to "break-in‚" if necessary, such as in distress situations.

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To set-up the MF/HF transceiver for a TELEX call to a coast station, the operator must:
  • Select J3E mode for proper SITOR operations.
  • Correct Answer
    Select F1B mode or J2B mode, depending on the equipment manufacturer.
  • Select F1B/J2B modes or J3E mode, depending on whether ARQ or FEC is preferred.
  • None of the above.

To set-up the MF/HF transceiver for a TELEX call to a coast station, the operator must:

(B). Select F1B mode or J2B mode, depending on the equipment manufacturer.

TELEX is text messaging on teleprinters.

-  F1B is Frequency Shift Keying (FSK) like RTTY (radio teletype)
  -  J2B is Phase Shift Keying like PSK31.

Both of these data modes lend themselves to teleprinter communications.

Please see Wikipedia's article on Types of radio emissions

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What is the purpose of the Receiver Incremental Tuning (RIT) or “Clarifier” control?
  • Correct Answer
    It acts as a “fine-tune” control on the receive frequency.
  • It acts as a “fine-tune” control on the transmitted frequency.
  • It acts as a “fine-tune” control on both the receive and transmitted frequencies.
  • None of the above.

What is the purpose of the Receiver Incremental Tuning (RIT) or “Clarifier” control?

(A). It acts as a “fine-tune” control on the receive frequency.

When you are tuning to a radio station but still get noise, you change the frequency a little to get a clear sound. This is the incremental frequency tuning. Works same on all transreceivers.

For more info on RIT, please see eHam.net's You Are OFF Frequency

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