*Question G8C14:
Which of the following describes a waterfall display?*  

*Correct Answer is  C: Frequency is horizontal, signal strength is intensity, time is vertical*  

### AI Response: (may contain errors)  

A waterfall display is a visual representation used in radio and signal analysis to show how signals change over time. Here's how it works:

1. **Correct Answer: C**  
   - **Frequency is horizontal**: The x-axis represents frequency. As you move left to right, you see different frequencies.
   - **Signal strength is intensity**: The brightness or color intensity of the display indicates the strength of the signal. Brighter or more intense colors represent stronger signals.
   - **Time is vertical**: The y-axis represents time. As you move from top to bottom, you see how the signal changes over time.

2. **Why the other choices are incorrect:**
   - **Choice A**: Incorrect because it states that signal strength is vertical and time is intensity, which does not match the typical waterfall display format.
   - **Choice B**: Incorrect because it states that frequency is vertical and time is horizontal, which is the opposite of the standard waterfall display orientation.
   - **Choice D**: Incorrect because it states that frequency is vertical and signal strength is horizontal, which does not align with how waterfall displays are typically structured.

3. **Useful Information:**
   - Waterfall displays are commonly used in software-defined radios (SDRs) and other digital signal processing tools to provide a real-time view of the radio spectrum.
   - They help operators quickly identify signals of interest by visualizing how signal strength varies across different frequencies and over time.

Understanding the layout of a waterfall display is crucial for interpreting the data it presents, which is why knowing the correct orientation is important for the exam.