Question
What parameter evaluates distortion of an AFSK signal caused by excessive input audio levels?
Answer Options
- A) Signal-to-noise ratio
- B) Baud error rate
- C) Repeat Request Rate (RRR)
- D) Intermodulation Distortion (IMD)
Correct Answer: D
Explanation
Excessive input audio levels into an AFSK/SSB transmitter cause the \text{SSB} final amplifier to become non-linear, clipping the signal peaks. This non-linearity generates spurious signals outside the desired channel, resulting in splatter and poor signal quality. A specific parameter is used to quantify this distortion.
The parameter that evaluates distortion of an \text{AFSK} signal caused by excessive input audio levels is Intermodulation Distortion (\text{IMD}). This is measured using a two-tone test (the two \text{AFSK} tones act as the test signal) and checking the level of the spurious third-order products (\text{IMD}3) relative to the main signal tones. A higher \text{IMD} level means more signal clipping and splatter.
This topic was automatically created to facilitate community discussion about this exam question. Feel free to share study tips, memory tricks, or additional explanations!