*Question E4A02:
Which of the following parameters does a spectrum analyzer display on the vertical and horizontal axes?*  

*Correct Answer is  B: Signal amplitude and frequency*  

### AI Response: (may contain errors)  

A spectrum analyzer is a tool used to visualize the frequency spectrum of a signal. It displays how the amplitude of a signal varies with frequency.

### Correct Answer: B: Signal amplitude and frequency

1. **Why the correct answer is correct:**
   - **Vertical Axis (Y-axis):** Represents signal amplitude, typically measured in decibels (dB). This shows the strength or power level of the signal at different frequencies.
   - **Horizontal Axis (X-axis):** Represents frequency, usually in hertz (Hz). This shows the range of frequencies present in the signal.

   A spectrum analyzer provides a visual representation of the signal's power distribution across different frequencies, which is essential for identifying and analyzing various signal components.

### Why the other choices are incorrect:

- **A: Signal amplitude and time**
  - This describes an oscilloscope, not a spectrum analyzer. An oscilloscope displays how a signal's amplitude changes over time.

- **C: SWR and frequency**
  - SWR (Standing Wave Ratio) is not directly displayed on a spectrum analyzer. SWR is typically measured with an SWR meter and relates to the efficiency of power transfer in a transmission line, not the frequency spectrum.

- **D: SWR and time**
  - Again, SWR is not displayed on a spectrum analyzer. This choice incorrectly combines SWR with time, which is not a function of a spectrum analyzer.

### Useful Concepts:

- **Spectrum Analysis:** Used to identify the frequency components of a signal, detect interference, and measure bandwidth.
- **Amplitude Measurement:** Helps in determining the power level of signals at specific frequencies, which is crucial for tuning and troubleshooting radio equipment.

Understanding how a spectrum analyzer works is vital for tasks like identifying unwanted signals, measuring bandwidth, and ensuring compliance with frequency regulations.