Advanced Qualification · A-005 Transmitters, modulation and processing · A-005-008-006
What error-correction system is used in AMTOR FEC (Mode B)?
- A Mode
- B The receiving station automatically requests repeats when needed
- C The receiving station checks the frame check sequence (FCS) against the transmitted FCS
- D Each character is sent twice
Correct answer: D — Each character is sent twice. From the official ISED question bank, verified word for word.
Why
In AMTOR Mode B, the system corrects errors by sending every single character twice in a row, allowing the receiver to compare the two copies and fix any mistakes caused by static. The full explanation — and one for every question — is in Pro.
Practise this section
Transmitters, modulation and processing: AM, FM, SSB, keying, speech processing, and the numbers behind occupied bandwidth.