User guide

AirMagnet Spectrum XT User Guide
Chapter 5: Auto Pattern Detection and Custom Device Classification 53
To create a custom signature of a pattern:
1) From the Settings drop-down menu, select Show Auto Detected Patterns.
2) Click the desired pattern from the pattern list on the left side of the window.
3) Replace New Signature with a custom name for the signature.
4) You may also assign the signature to a group using Group Name. All signatures assigned
to the same group will show up as children of that group in the Device Signature List that
is part of the Custom Device Classification Manager.
Note: Both Pattern Start and Stop fields will be auto-filled with the frequency range.
5) Add any description comments, if desired.
6) Click Add Custom Signature to save the signature.
Once a signature is created it may be viewed and edited using the Device Classification
Manager.
Note: Custom signatures may be imported and exported using the Custom Device Classification
Manager.
Best Practices
How Auto-Detect Works:
The Auto Detect FFT Pattern feature in Spectrum XT looks for repeating patterns in the
incoming FFT data. It does this by performing the following steps:
1) Performs a 7 point weighted average of the signal, to smooth out small changes in the FFT
data.
2) Looks for points in the line that exit/enter the noise floor, producing FFT shape start/stop
points.
3) These FFT shape start/stop points are categorized based on their start/stop frequency.
They are compared against patterns seen in previous iterations of the algorithm. When the
mean delta between patterns with the same start/stop frequencies is less than 5 dB, the
pattern is said to have been observed again.
4) When the observation count for a particular pattern reaches 6, the pattern is said to have
been Auto Detected and is now available for inspection in the UI.
5) Patterns which are not seen again within a 1 minute duration are recycled (thrown away).
Thus, the user may observe the Auto Detected FFT Pattern count increase and decrease
over time.