Users Guide

Parameter Description
NOTE: This parameter is not configurable for graphs created by hybrid APs.
Center Frequency If you selected Frequency in the X-Axis parameter, enter the frequency, in MHz,
that you want to appear in the center of the x-axis of this chart.
Span If you selected Frequency in the X-Axis parameter, specify the size of the range of
frequencies around the selected center frequency. If you set a frequency span of
100 MHz, for example, the chart shows the FFT duty cycle for a range of frequencies
from 50MHz lower to 50 MHz higher than the selected center.
Show Select a checkbox to display that information on the FFT Duty Cycle chart.
l Duty Cycle: The percentage of duty cycle the channel or frequency was
actively used.
l Max Hold: The maximum recorded percentage of active duty cycles for the
channel frequency since the chart was last reset. To clear this setting, click the
down arrow at the end of the title bar for this graph and select Reset
MaxHold.
l Max of last sweeps: This chart shows the maximum percentage of active duty
cycles for the channel of frequency recorded during the last 10 sweeps, by
default. To change the number of sweeps used to determine this value, enter a
number from 2 to 20, inclusive. To clear this setting, click the down arrow at the
end of the title bar for this graph and select Reset MaxNSweep.
Interference Power
The Interference Power chart displays various power levels of interest, including the Wi-Fi AP with maximum
signal strength, noise, and interferer types with maximum signal strength. The ACI displayed in the Interference
Power Chart is the ACI power level based on the signal strength(s) of the Wi-Fi APs on adjacent channels. A
higher ACI value in Interference Power Chart does not necessarily mean higher interference, because the AP
that is contributing to the maximum ACI may or may not be very actively transmitting data to other clients at
all times. The ACI power levels are derived from the signal strength of the beacons.
This chart displays the noise floor of each selected channel in dBm. The noise floor of a channel depends on
the noise figure of the RF components used in the radio, temperature, presence of certain types of interferers
or noise, and the width of the channel. For example, in a clean RF environment, a 20 MHz channel has a noise
floor around -95 dBm and a 40 MHz channel has a noise floor around -92 dBm. Certain types of fixed-
frequency continuous transmitters such as video bridges, fixed-frequency phones, and wireless cameras
typically elevate the noise floor seen by the spectrum monitor. Other interferers such as frequency-hopping
phones, Bluetooth, and Xbox may not affect the noise floor of the radio. A Wi-Fi radio can only reliably decode
Wi-Fi signals that are a certain dB above the noise floor. Therefore estimating and understanding the actual
noise floor of the radio is critical to understanding the reliability of the RF environment.
The chart also includes information about the AP on each channel with the highest power level. You can hover
your mouse over an AP on the chart to view the AP’s name, SSID, and current power level. The example below
shows that the AP with the maximum power on channel 157 has the SSID qa-ss, and a power level of -55dBm.
Dell Networking W-Series ArubaOS 6.5.x | User Guide Spectrum Analysis |
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