What could be wrong if you cannot decode an RTTY or other FSK signal even though it is apparently tuned in properly?
The correct answer is D: All these choices are correct. If you cannot decode an RTTY or other FSK signal even though it is apparently tuned in properly, the problem could be: the mark and space frequencies may be reversed, you may have selected the wrong baud rate, or you may be listening on the wrong sideband. All three are common causes of decoding problems. For amateur radio operators, checking all three helps troubleshoot FSK decoding issues. Understanding this helps when operating RTTY or other FSK modes.
Exam Tip
All three can cause FSK decoding problems: reversed frequencies, wrong baud rate, wrong sideband. When all listed causes can prevent FSK decoding, 'all of the above' is usually the answer. Check all three when troubleshooting.
Memory Aid
"All three can cause FSK decoding problems: Reversed frequencies, Wrong baud rate, Wrong sideband. Think 'A'll 'F'SK 'D'ecoding 'P'roblems. Check all three when troubleshooting RTTY or FSK signals."
Real-World Application
You can't decode an RTTY signal even though it's tuned in. Check: (1) Mark and space frequencies may be reversed - try reversing them, (2) Baud rate may be wrong - try different rates (45, 50, 75, 100 baud), (3) You may be on the wrong sideband - RTTY on HF typically uses LSB. All three can prevent decoding.
Key Concepts
Why Other Options Are Wrong
Option A: While correct, this is incomplete. Wrong baud rate and wrong sideband can also cause problems.
Option B: While correct, this is incomplete. Reversed frequencies and wrong sideband can also cause problems.
Option C: While correct, this is incomplete. Reversed frequencies and wrong baud rate can also cause problems.
题目解析
The correct answer is D: All these choices are correct. If you cannot decode an RTTY or other FSK signal even though it is apparently tuned in properly, the problem could be: the mark and space frequencies may be reversed, you may have selected the wrong baud rate, or you may be listening on the wrong sideband. All three are common causes of decoding problems. For amateur radio operators, checking all three helps troubleshoot FSK decoding issues. Understanding this helps when operating RTTY or other FSK modes.
考试技巧
All three can cause FSK decoding problems: reversed frequencies, wrong baud rate, wrong sideband. When all listed causes can prevent FSK decoding, 'all of the above' is usually the answer. Check all three when troubleshooting.
记忆口诀
All three can cause FSK decoding problems: Reversed frequencies, Wrong baud rate, Wrong sideband. Think 'A'll 'F'SK 'D'ecoding 'P'roblems. Check all three when troubleshooting RTTY or FSK signals.
实际应用示例
You can't decode an RTTY signal even though it's tuned in. Check: (1) Mark and space frequencies may be reversed - try reversing them, (2) Baud rate may be wrong - try different rates (45, 50, 75, 100 baud), (3) You may be on the wrong sideband - RTTY on HF typically uses LSB. All three can prevent decoding.
错误选项分析
Option A: While correct, this is incomplete. Wrong baud rate and wrong sideband can also cause problems. Option B: While correct, this is incomplete. Reversed frequencies and wrong sideband can also cause problems. Option C: While correct, this is incomplete. Reversed frequencies and wrong baud rate can also cause problems.
知识点
RTTY, FSK decoding, Troubleshooting, Digital modes
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.