Question
How much change in signal strength is typically represented by one S unit?
Answer Options
- A) 6 dB
- B) 12 dB
- C) 15 dB
- D) 18 dB
Correct Answer: A
Explanation
While the S meter scale below S9 is often relative, the amateur radio industry standard (IARU Region 1 and others) defines a specific step size for one S unit. This standard dictates that an increase or decrease of one S unit (e.g., S6 to S7, or S4 to S3) is typically represented by a 6 \text{dB} change in signal strength.
This 6 \text{dB} step size means that to increase a received signal by one S unit, the transmitter would need to quadruple its output power (since 10 \log_{10}(4) \approx 6 \text{dB}). This standard is useful for estimating the magnitude of power changes needed to improve a signal’s readability.
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