Subelement B: MF-HF-DSC-SITOR (NBDP) Equip. & Operations— Topic :
Question 21B3
Element 9 (GMDSS Maintainer)Selective FEC communications (SFEC) are employed when:
Explanation
Selective Forward Error Correction (SFEC) is a digital communication mode designed for highly reliable, one-way messaging to a specific station. The "Forward Error Correction" (FEC) capability allows the receiving station to detect and correct errors in the received data without needing the transmitting station to resend information. This is particularly valuable in situations where the target station might be unable or unwilling to transmit.
Therefore, SFEC is employed when an individual station must receive critical communications, such as distress alerts or safety information, but needs to maintain radio silence or is physically unable to transmit an acknowledgment. Options B and D are incorrect because FEC is a receive-side error correction technique and does not involve the receiving station transmitting for "phasing." Option A is less accurate as SFEC is "selective" for an individual station, rather than for multiple stations without a specific group call.
Related Questions
21B1 If a vessel is within range of NAVTEX broadcasts and both the Inmarsat-C and the NAVTEX receiver are inoperative the GMDSS operator should:21B2 The sequence ARQ, FEC, SFEC best corresponds to which of the following sequences?21B4 Which of the following is true of SITOR (NBDP) Mode B (FEC), in the presence of static crashes.21B5 If the vessel is beyond range of NAVTEX broadcasts and the Sat-C system fails, the GMDSS operator must:21B6 If the vessel is experiencing atmospheric interference with NAVTEX broadcasts, especially in the tropics, the GMDSS operator should: