A radio frequency (RF) source detector detects and analyzes RF signals in order to determine the source of interference. The source detector is useful for installing and troubleshooting a wireless local area network (WLAN) or similar communication devices. The detector includes a receiver to receive RF signals from unknown RF sources, a processor for determining the level and characteristics of the RF signals and for determining the identities of unknown RF sources, and a display on which the processor displays the identities of the RF sources.