Permissive Changes against Full Retest after a Firmware Update
Firmware updates altering output power, channels, or DFS logic trigger mandatory permissive change filings or retests before distribution.
Dfs Threshold
Meaning
Regulatory radar detection limits in the 5 GHz spectrum mandate that unlicensed wireless devices vacate operational channels upon detecting radar emissions above a specified power level. The dfs threshold establishes the precise RF signal strength, measured in dBm over a defined bandwidth, at which an access point or client device must initiate channel switching. Operating below this threshold allows continuous transmission, whereas signals exceeding it force immediate channel evacuation to prevent interference with primary radar installations.
Radar Pulse Signal
Radar pulses operating across military, meteorological, and aviation frequency bands represent high-priority transmissions. A master device evaluates incoming signals against the dfs threshold during both initial channel availability checks and in-service monitoring. Receiver sensitivity and antenna gain figures must be factored into the internal calculation to ensure weak radar pulses trigger the compliance logic.
Detection Response Timing
Triggering the dfs threshold initiates a mandatory channel availability check or channel switch announcement.
Channel Evacuation Boundary
Channel clearing limits enforce a hard boundary where transmissions must cease within a strict window, typically ten seconds. A system failing to respond when receiving signals at or above the dfs threshold loses regulatory certification and cannot legally operate in shared spectrum bands.