782| Spectrum Analysis AOS-W 6.5.3.x| User Guide
Real-Time FFT
The Real-time FFT chart displays the instantaneous Fast Fourier Transform (FFT) signature of the RF signal seen
by the radio. The Fast Fourier Transform (FFT) converts an RF signal from time domain to frequency domain.
The frequency domain representation divides RF signals into discrete frequency bins; small frequency ranges
whose width depends on the resolution bandwidth of the spectrum monitor (that is, how many Hz are
represented by a single signal strength value). Each frequency bin has a corresponding signal strength value.
Because there may be a large number of FFT signatures received by the radio every second, an algorithm
selects one FFT sample to display in the Real-time FFT chart every second.
A hybrid AP on a 20 MHz channel will see 40 MHz Wi-Fi data as non-Wi-Fi data.
This chart can show an average for all samples taken over the last second, the maximum FFT power measured
for all samples taken over ten channel sweeps, and the greatest FFT power recorded since the chart was last
reset. When you hover your mouse over any line, a tooltip shows the power level and channel or frequency
level represented by that point in the graph. When you hover your mouse over a frequency level (within the
blue brackets on the graph), a tooltip shows the types of devices seen on that frequency, and each device’s
BSSID, power level, channels affected and the time the device was last seen by the spectrum monitor.
Figure 132 Real-TIme FFT
This chart shows the maximum power level recorded for any device on all channels or frequencies monitored
by the spectrum monitor radio by default.
Table 176 describes the other parameters you can use to customize the Real-time FFT chart. Click the down
arrow in the upper right corner of this chart, then click the Options menu to access these configuration
settings. Once you have configured the desired parameters, click OK at the bottom of the Options menu to
save your settings and return to the spectrum dashboards.
To Next Page
Loading...