What is the bandwidth of an FT8 signal?
The correct answer is B: 50 Hz. The bandwidth of an FT8 signal is 50 Hz. FT8 is a very narrow-band digital mode designed for weak-signal work, and it occupies only 50 Hz of bandwidth.
FT8 uses 8-FSK (8-tone frequency shift keying) modulation with a symbol rate of 6.25 baud. The narrow 50 Hz bandwidth allows many FT8 signals to operate in a small frequency range (typically 200 Hz wide segments) without interfering with each other. This narrow bandwidth, combined with forward error correction, makes FT8 very effective for weak-signal communications. FT8's 50 Hz bandwidth is one of its key characteristics that makes it popular for DX and weak-signal work.
Exam Tip
FT8 bandwidth = 50 Hz. Remember: FT8 signals occupy 50 Hz bandwidth. This narrow bandwidth allows many FT8 signals to operate in a small frequency range.
Memory Aid
"**F**T8 **B**andwidth = **5**0 **H**z (think 'FB = 50Hz')"
Real-World Application
You're operating FT8 on 20 meters. Your FT8 signal occupies only 50 Hz of bandwidth. This narrow bandwidth, combined with FT8's error correction, allows you to make contacts even with very weak signals. Many FT8 signals can operate in a 200 Hz segment without interfering with each other because each only uses 50 Hz.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. 10 Hz is too narrow for FT8. FT8 uses 8 tones and needs 50 Hz bandwidth.
Option C: Incorrect. 600 Hz would be way too wide for FT8. FT8 is designed to be very narrow-band (50 Hz).
Option D: Incorrect. 2.4 kHz is much too wide. That's more typical of SSB voice bandwidth, not FT8.
题目解析
The correct answer is B: 50 Hz. The bandwidth of an FT8 signal is 50 Hz. FT8 is a very narrow-band digital mode designed for weak-signal work, and it occupies only 50 Hz of bandwidth. FT8 uses 8-FSK (8-tone frequency shift keying) modulation with a symbol rate of 6.25 baud. The narrow 50 Hz bandwidth allows many FT8 signals to operate in a small frequency range (typically 200 Hz wide segments) without interfering with each other. This narrow bandwidth, combined with forward error correction, makes FT8 very effective for weak-signal communications. FT8's 50 Hz bandwidth is one of its key characteristics that makes it popular for DX and weak-signal work.
考试技巧
FT8 bandwidth = 50 Hz. Remember: FT8 signals occupy 50 Hz bandwidth. This narrow bandwidth allows many FT8 signals to operate in a small frequency range.
记忆口诀
**F**T8 **B**andwidth = **5**0 **H**z (think 'FB = 50Hz')
实际应用示例
You're operating FT8 on 20 meters. Your FT8 signal occupies only 50 Hz of bandwidth. This narrow bandwidth, combined with FT8's error correction, allows you to make contacts even with very weak signals. Many FT8 signals can operate in a 200 Hz segment without interfering with each other because each only uses 50 Hz.
错误选项分析
Option A: Incorrect. 10 Hz is too narrow for FT8. FT8 uses 8 tones and needs 50 Hz bandwidth. Option C: Incorrect. 600 Hz would be way too wide for FT8. FT8 is designed to be very narrow-band (50 Hz). Option D: Incorrect. 2.4 kHz is much too wide. That's more typical of SSB voice bandwidth, not FT8.
知识点
FT8, Bandwidth, 50 Hz, Narrow-band digital
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.