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AM Spectrum XT: FFT Chart

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FFT Chart
Shows overall level of energy in the band whether its transmitted by WiFi or non-WiFi interfering sources

FFT stands for Fast Fourier Transform.  FFT is essentially a mathematical algorithm that correlates the value of RF power as a function of a radio frequency. It shows the relative power levels in dBm across the frequency range from the selected band.  

The x-axis shows frequency range and the y-axis shows the detected power readings in dBm.  This graph can phase four different types of color-coded spectrum data.


  • Yellow = Max Hold:  Indicates the highest power readings that have been recorded since the session began
  • Red = Max: Indicates the maximum power in the RF spectrum of a single channel sweep.  A sweep consists of 256 samples within a 64-millisecond sampling period.
  • Green = Average:  Indicates the average historical power readings recorded since the beginning of the session.
  • Blue = Current:  Indicates the last sample power in the RF spectrum of a single Channel sweep.   (Disabled by default).

Mousing over any frequency will display a Tool Tip that contains Max-Hold, Max, and Average information for that frequency.






Chart Configuration Options:

Display Settings:


  • Show Area Fill:  Enables a view preference to view the graph with or without fill. This option can be fairly CPU intensive; there may be improved application performance if this option is set to the default setting of No.
  • Line Options: Enables control over which lines are displayed in the graph.
    • Average
    • Current
    • DFS
    • Duty Cycle
    • Max-Hold
    • Maximum
  • Marker Settings:
    • Enable Marker:  enables the clicking of a point of interest in the FFT graph.  If this is enabled a blue dot will appear at the click point on the graph. 
      • Marker Type: 
        • Single:  displays a single marker which can be dragged to any point of interest on the FFT graph.
        • Delta:  displays two markers; one fixed at a particular location, and the other which can be dragged across the FFT plot for comparison.
  • Misc:  Enable Tooltip refers to whether to show a pop up as you mouse over the graph. 
  • Span Settings:
    • Minimum Power: Refers to the power level on the y-axis.  By default, it is set to -120 dBm, but it can be set as low as -140 dBm. 
    • Peak Power: Enables changing the maximum power level on the y-axis.  By default, it is set to -120 dBm, but it can be set to any value less than 0 dBm. 
    • Start Frequency:  Enables setting/changing of the start point of the frequency.
    • Stop Frequency:  Enables setting/changing of the end point of the frequency range.