I was once tasked with building some building sway monitoring systems. The People With the Bucks were rather tight lipped about why they wanted to monitor building sway, but I think this was closely related to the reason... and yes, tall buildings wobble like a weeble (but don't fall down) https://www.youtube.com/watch?v=dFzhjnjXc2o --------------- > Higher carrier frequencies make things like Doppler more important - some of the high rate point to point links actually have problems with tall buildings moving in the wind