Question 3-84M3

GMDSS-DSC (Global Maritime Distress and Safety System - Digital Selective Calling) transmissions utilize a specific Forward Error Correction (FEC) scheme to ensure reliability in challenging marine radio environments. Each character transmitted by DSC is a 10-bit code. This 10-bit character is composed of 7 bits of actual data (information) and 3 additional bits dedicated to error correction. These 3 error-correcting bits are derived from the 7 data bits, allowing the receiving station to detect and correct single-bit errors within each 10-bit character. * **Option A** correctly describes this structure: a 10-bit error correcting code, where 7 bits are data and 3 bits are for error correction. * **Option B** is incorrect because the data bits come first conceptually, and the error-correcting bits are calculated from them, not the other way around. * **Option C** is incorrect as DSC uses a 10-bit character, not an 8-bit one, and employs error *correction* (multiple parity bits) rather than just a single parity bit for detection. * **Option D** is incorrect because while repetition can aid error correction, the fundamental DSC character is 10 bits, not 7, and it uses a more sophisticated FEC code rather than simple retransmission for error correction within each character.