Deep Dive: G8C15
The correct answer is C: The signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth. What an FT8 signal report of +3 means is that the signal-to-noise ratio is equivalent to +3dB in a 2.5 kHz bandwidth. FT8 reports are in dB relative to noise in a 2.5 kHz bandwidth. For amateur radio operators, this is how FT8 signal reports work. Understanding this helps when operating FT8.
Why Other Answers Are Wrong
Option A: Incorrect. +3 doesn't mean 3 times noise level - FT8 reports are in dB, not multiples. 3× noise would be about +4.8 dB, not +3 dB. Option B: Incorrect. +3 doesn't mean S3 - FT8 reports are in dB relative to noise, not S-meter readings. S3 is different. Option D: Incorrect. +3 doesn't mean 3 dB over S9 - FT8 reports are relative to noise, not S-meter. S9+3 dB is different.
Exam Tip
FT8 report +3 = signal-to-noise ratio equivalent to +3dB in 2.5 kHz bandwidth. Think 'F'T8 'R'eport = 'F'requency 'T'one '8' = 'R'eport in 'd'B relative to noise. FT8 reports are in dB relative to noise in 2.5 kHz bandwidth. Not 3× noise, not S3, not S9+3 - just +3dB SNR in 2.5 kHz.
Memory Aid
FT8 report +3 = signal-to-noise ratio equivalent to +3dB in 2.5 kHz bandwidth. Think 'F'T8 'R'eport = 'd'B relative to noise. FT8 reports are in dB relative to noise in 2.5 kHz bandwidth. Standard FT8 reporting format.
Real-World Example
An FT8 signal report of +3: The signal-to-noise ratio is equivalent to +3 dB in a 2.5 kHz bandwidth. This means the signal is 3 dB above the noise floor in that bandwidth. FT8 reports are standardized - they're always relative to noise in a 2.5 kHz bandwidth. This is how FT8 signal reports work.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G8C
Reference: 2023-2027 Question Pool · G8 - Signals and Emissions
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G8C topic.