Subelement C: Satellite Systems— Topic :
Question 30C4
Element 9 (GMDSS Maintainer)What condition can indicate a communication failure between the second receiver (RX2) and the Antenna Control Unit (ACU) in an Inmarsat Fleet 77 terminal?
Explanation
Modern satellite terminals, like the Inmarsat Fleet 77, incorporate sophisticated internal diagnostic capabilities. When a critical internal communication path, such as between the second receiver (RX2) and the Antenna Control Unit (ACU), fails, the terminal's operating system is designed to detect this anomaly. It then presents a clear, user-friendly error message on the display to alert the operator. Therefore, an explicit message like "RX2 Comm error" or "ACU Comm error" is the direct indication of such a communication breakdown.
Options A and B describe successful states (locking onto a signal or receiving a valid frame), which are the opposite of a communication failure. Option D, concerning DCE/DTE communication protocol configuration, typically refers to external interface settings (e.g., connecting a computer to the terminal) and is not usually relevant to the internal, hard-coded communication between the RX2 and ACU modules within the terminal itself.
Related Questions
30C2 How can a LES/RCC (Rescue Coordination Centre) determine if an Inmarsat-C Distress Alert is a TEST transmission?30C3 What is the meaning of the “ACB” Inmarsat-C Non-Delivery Notification (NDN) failure code?30C5 Which of the following devices can cause interference to Fleet 77/55 systems?30C6 What error message may be displayed if a connection to the Inmarsat Mobile Packet Data Service (MPDS) network fails?31C1 An Inmarsat-C terminal shows a “No Receive Signal” alarm. There is no voltage on the antenna center pin. What is the most likely cause?