Abstract: Methods and apparatus for a structure function monitor provide for generation of parameters characterizing a refractive medium. In an embodiment, a structure function monitor acquires images of a pupil plane and an image plane and, from these images, retrieves the phase over an aperture, unwraps the retrieved phase, and analyzes the unwrapped retrieved phase. In an embodiment, analysis yields atmospheric parameters measured at spatial scales from zero to the diameter of a telescope used to collect light from a source.

Abstract: Briefly, in accordance with one embodiment of the invention, an access point may preemptively broadcast an alternate channel to switch to, along with an indication of the beacon timing for the alternate channel, prior to any catastrophic interference. The access point may switch to the alternate channel in the event of interference on the original channel without attempting to broadcast the alternate channel during the interference event. A mobile user may then know in advance of the interference event which alternate channel the access point switched to and may switch to the alternate channel.