Subelement N: N – Marine— Topic 86: MF-HF, SSB-SITOR
Question 3-86N4
Element 3 (GROL)Which of the following statements concerning SITOR communications is true?
Explanation
SITOR (SImplex Teletype Over Radio) in ARQ (Automatic Repeat reQuest) mode is an interactive, error-correcting digital communication method. When operating in ARQ, data is transmitted in specific blocks. These blocks are indeed three characters long, consisting of two information characters and one service character. The service character facilitates error detection and acknowledgment. If a block is not correctly received, the transmitting station will automatically retransmit it, ensuring reliable data delivery.
Option B is incorrect because ARQ relies on acknowledgments for each block or small group of blocks, not solely at the end of the message, to enable real-time error correction. Option C is incorrect; SITOR ARQ's primary error correction mechanism is retransmission, not time diversity. Option D is incorrect as Forward Error Correction (FEC) is a non-interactive, simplex mode, where the receiver corrects errors without requesting retransmissions, making it unsuitable for interactive communication.
Related Questions
3-86N2 What might contribute to apparent low voltage on marine SSB transmitting?3-86N3 What type of wire connects an SSB automatic tuner to an insulated backstay?3-86N5 The sequence ARQ, FEC, SFEC best corresponds to which of the following sequences?3-86N6 Which of the following statements concerning SITOR communications is true?3-87N1 What causes the SART to begin a transmission?