465
Scientists Use WiFi to See Through People's Walls
(www.popularmechanics.com)
This is a most excellent place for technology news and articles.
Oh I wonder if that's how the Pic was taken that trump tweeted out of that rocket launch site, people didn't think it was physically possible for a satellite to have that resolution
It all comes down to the size of the mirror/lense—the bigger, the better. Up to a point. The biggest problem is air currents and different air densities refracting light and distorting the image. That's what these laser beams are for on photos taken of astronomical observatories—they give reference light spot that can be used to calibrate adaptive optics to current atmospheric conditions reducing distortion.