In SITOR (NBDP) communications, what is true about FEC transmissions?

In SITOR (Ship to Ship Telex Over Radio), which is a form of NBDP (Narrowband Direct Printing) communication, FEC (Forward Error Correction) transmissions are designed to enhance reliability in data being communicated over radio waves, which can often be subject to various types of interference that may corrupt data.

The correct choice regarding FEC in SITOR communications is centered on the technique used to reduce errors during transmission. When employing FEC, each character is transmitted twice. This means that if the receiving station encounters potential interference or loss of data for one of those characters, the second transmission serves as a fallback to ensure that the correct information can still be received accurately. This redundancy is a critical feature since it allows the communication system to self-correct to an extent without needing immediate confirmation from the receiving end, thereby improving the robustness of the communication.

The other options describe characteristics that do not accurately represent FEC in the context of SITOR communications, focusing instead on other processes or methodologies used in data communication that are less relevant to the specific function and mechanisms of FEC. For instance, the mention of three-character data groups pertains to structure rather than error correction. Phasing or handshaking processes typically relate to establishing a connection rather