Ham Amateur Radio Technician Practice Exam

What happens to HF signals during high atmospheric noise levels?

1. They propagate further

2. They become distorted

3. They are amplified

4. They are generally weaker

The correct answer is: They are generally weaker

During high atmospheric noise levels, HF signals are generally weaker. This is because atmospheric noise, which can come from natural phenomena like lightning strikes and other electrical activity in the atmosphere, can introduce a significant amount of interference on the HF bands. When this noise level increases, it can mask or obscure the desired signal, making it harder to hear and distinguish from the background noise. This phenomenon can lead to reduced signal-to-noise ratios, where the strength of the signal is comparatively low against the noise floor. Operators may find that even strong signals appear weaker due to the increased noise, affecting communication quality over HF frequencies. In contrast, while HF signals do have a tendency to propagate effectively under good conditions, high atmospheric noise can diminish this propagation quality. The other options, such as distortion or amplification, do not accurately describe the typical effect of atmospheric noise on HF signals during periods of heavy interference.