*Question T3C03:
What is a characteristic of VHF signals received via auroral backscatter?*  

*Correct Answer is  B: They are distorted and signal strength varies considerably*  

### AI Response: (may contain errors)  

VHF signals received via auroral backscatter exhibit unique characteristics due to the interaction of radio waves with the ionosphere during auroral events.

### Correct Answer: B - They are distorted and signal strength varies considerably

- **Explanation**: 
  - Auroral backscatter occurs when VHF signals reflect off ionized particles in the aurora borealis. This reflection can cause significant distortion in the signal, leading to variations in quality and strength. The irregularities in the ionosphere during these events can cause the signal to fluctuate, making it difficult to maintain a consistent reception.

### Why the Other Choices are Incorrect:

- **A: They are often received from 10,000 miles or more**  
  - While VHF signals can travel long distances under certain conditions, auroral backscatter typically affects signals over shorter ranges, often within a few hundred to a couple of thousand miles. The 10,000-mile range is more characteristic of other propagation modes, such as E-skip or F-layer propagation.

- **C: They occur only during winter nighttime hours**  
  - Auroral backscatter can occur at any time when auroral activity is present, not just during winter or nighttime. The phenomenon is related to solar activity and geomagnetic storms, which can happen at any time of the year.

- **D: They are generally strongest when your antenna is aimed west**  
  - The direction of the antenna does not guarantee stronger signals from auroral backscatter. The best direction depends on the location of the aurora and the specific propagation path. Signals can come from various angles, and aiming west is not a reliable rule for maximizing reception.

### Summary

In summary, VHF signals received via auroral backscatter are characterized by distortion and variable signal strength due to the nature of the ionosphere during auroral events. Understanding these characteristics helps in predicting and optimizing reception during such occurrences.