What test instrument is used to locate and measure interfering narrowband RF signals in an IEEE 802.11 WLAN, among other things?

• A. Oscilloscope
• B. Network analyzer
• C. Spectrum analyzer
• D. Spectrum monitor.

Answer: (C)

Locating interfering RF signals is all about seeing the signal's content in the frequency domain. A spectrum analyzer displays how much power exists at each frequency, so you can spot a sharp, narrowband peak, identify its exact frequency, and measure its power and bandwidth. That lets you determine which channel the interference is affecting in the IEEE 802.11 WLAN and how strong it is, which is essential for choosing a cleaner channel or applying mitigation.

An oscilloscope shows time-domain waveforms, which isn’t as helpful for pinpointing a signal’s carrier frequency across a wide spectrum. A network analyzer focuses on how a device under test responds (S-parameters) rather than locating external interference sources. A spectrum monitor can continuously watch a broad band, but for precise identification and measurement of a specific interfering signal, the spectrum analyzer is the go-to tool.