Exam 300-110 Topic 1 Question 73 Discussion

In a Layer 1 passive wireless site survey using a channel analyzer tool (such as Metageek Chanalyzer or Cisco Spectrum Expert) in the 2.4 GHz spectrum, the chart that indicates the ratio of interference present during the capture duration is the Duty Cycle chart. The duty cycle chart displays the percentage of time that detected energy - including both Wi-Fi and non-Wi-Fi signals - is present on each channel. A high duty cycle on a channel indicates that the channel is occupied by transmissions for a significant portion of time, reducing available airtime for Wi-Fi clients. This chart directly communicates the ratio of interference because it shows what fraction of the observation period had detectable RF energy above the noise floor. Signal strength charts show amplitude (how strong), while duty cycle charts show temporal occupancy (how often) - the latter is the correct metric for quantifying interference ratio. Reference: WLSD Study Guide - Layer 1 Spectrum Analysis, Duty Cycle Chart Interpretation, Spectrum Analyzer Methodology.