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[Archive] [WLA] FAQ on Radar detection - Process and actions taken by the AP



Article ID: KB25044 KB Last Updated: 10 Oct 2020Version: 3.0

This article describes the following:

  • How is radar detected?
  • Is the AP continually searching for radar?
  • How does the AP notify clients of the presence of radar?

Q1. How is radar detected?

A1. Each radar pulse detected by the AP is given a timestamp. The AP software keeps a history of pulse timestamps. Periodically (every 50 ms), the pulse history is analyzed to see if it matches the criteria of a known radar signal. If the pulse history matches a known radar pattern, then the AP indicates that it has detected radar.

Q2. Is the AP continually searching for radar?

A2. Yes. The radar detection algorithm runs continuously on the current channel. Specifically, it runs during the initial channel check, during normal operation, and during the 30 minute quiet period.

Q3. How does the AP notify clients of the presence of radar?

A3. The AP sends an 802.,11h Action Management Message containing a basic measurement report. The AP broadcasts this message on each SSID configured on the AP's 11a radio.
Modification History:
2020-10-10: Archived article.
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