G8C15 - What does an FT8 signal report of +3 mean?

Question

What does an FT8 signal report of +3 mean?

Answer Options

  • A) The signal is 3 times the noise level of an equivalent SSB signal
  • B) The signal is S3 (weak signals)
  • C) The signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth
  • D) The signal is 3 dB over S9

Correct Answer: C


Explanation

Signal reports in the FT8 digital mode are based strictly on the Signal-to-Noise Ratio (SNR) as calculated by the decoding software, unlike the subjective S-meter readings. The report is given in decibels (\text{dB}).

An FT8 signal report of +3 means the signal-to-noise ratio is equivalent to $+3 \text{ dB in a 2.5 \text{ kHz} bandwidth (the standard reference bandwidth for SSB). Since FT8 can decode signals well below the noise floor, reports often range from as low as -25 \text{ dB} up to +10 \text{ dB} or higher for very strong signals.


This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!