Which of the following HF digital modes uses variable-length character coding?
The correct answer is D: PSK31. Which of the following HF digital modes uses variable-length character coding is PSK31. PSK31 uses Varicode, which is a variable-length code. For amateur radio operators, this is important for understanding PSK31. Understanding this helps when operating PSK31.
Exam Tip
HF digital mode with variable-length coding = PSK31. Think 'P'SK31 = 'V'aricode (variable-length). PSK31 uses Varicode, which is a variable-length character code. Not RTTY, not PACTOR, not MT63 - just PSK31.
Memory Aid
"HF digital mode with variable-length coding = PSK31. Think 'P'SK31 = 'V'aricode. PSK31 uses Varicode, which is a variable-length character code. Important for understanding PSK31."
Real-World Application
PSK31 mode: It uses variable-length character coding (Varicode). Common characters like 'e' and space get short codes, less common characters get longer codes. This makes PSK31 efficient. RTTY, PACTOR, and MT63 use fixed-length coding. This is the mode - PSK31 uses variable-length character coding.
Key Concepts
Why Other Options Are Wrong
Option A (RTTY): Incorrect. RTTY uses fixed-length character coding (5 bits per character), not variable-length - PSK31 uses variable-length. RTTY isn't variable-length.
Option B (PACTOR): Incorrect. PACTOR doesn't use variable-length character coding - PSK31 uses variable-length. PACTOR isn't variable-length.
Option C (MT63): Incorrect. MT63 doesn't use variable-length character coding - PSK31 uses variable-length. MT63 isn't variable-length.
题目解析
The correct answer is D: PSK31. Which of the following HF digital modes uses variable-length character coding is PSK31. PSK31 uses Varicode, which is a variable-length code. For amateur radio operators, this is important for understanding PSK31. Understanding this helps when operating PSK31.
考试技巧
HF digital mode with variable-length coding = PSK31. Think 'P'SK31 = 'V'aricode (variable-length). PSK31 uses Varicode, which is a variable-length character code. Not RTTY, not PACTOR, not MT63 - just PSK31.
记忆口诀
HF digital mode with variable-length coding = PSK31. Think 'P'SK31 = 'V'aricode. PSK31 uses Varicode, which is a variable-length character code. Important for understanding PSK31.
实际应用示例
PSK31 mode: It uses variable-length character coding (Varicode). Common characters like 'e' and space get short codes, less common characters get longer codes. This makes PSK31 efficient. RTTY, PACTOR, and MT63 use fixed-length coding. This is the mode - PSK31 uses variable-length character coding.
错误选项分析
Option A (RTTY): Incorrect. RTTY uses fixed-length character coding (5 bits per character), not variable-length - PSK31 uses variable-length. RTTY isn't variable-length. Option B (PACTOR): Incorrect. PACTOR doesn't use variable-length character coding - PSK31 uses variable-length. PACTOR isn't variable-length. Option C (MT63): Incorrect. MT63 doesn't use variable-length character coding - PSK31 uses variable-length. MT63 isn't variable-length.
知识点
HF digital modes, Variable-length character coding, PSK31, Varicode
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.