Question
Which of the following narrow-band digital modes can receive signals with very low signal-to-noise ratios?
Answer Options
- A) MSK144
- B) FT8
- C) AMTOR
- D) MFSK32
Correct Answer: B
Explanation
FT8 is a digital mode specifically designed by Joe Taylor, K1JT, for weak-signal work, where the signal is often buried below the noise floor. Its key to success is its very narrow bandwidth, low symbol rate, and the use of sophisticated Forward Error Correction (FEC) and averaging over its 15-second transmission period.
FT8 can successfully decode signals with Signal-to-Noise Ratios (SNR) as low as -20 \text{ dB}, making it one of the most sensitive narrow-band modes available to amateurs. This allows it to reliably complete contacts when traditional modes like SSB or CW would be impossible.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!