horizontal beam separationUp to Waves
horizontal beam separationPosted by pukha lenee-bluhm at September 07. 2011
"Spatial aliasing prevents resolving the direction of waves with wavelengths shorter than two times the smallest horizontal separation between two array elements. For the AWAC, the two closest array positions are the center AST and one of the velocity measurements. The horizontal separation is depth dependent (d * sin 25 deg) and leads to an upper frequency limit for wave directions." (Nortek Technical Note TN-024)
Re: horizontal beam separationPosted by Jonas Røstad at September 08. 2011
You are right, the Technical Note is wrong. The horizontal distance is given by d * tan 25 deg.
The consequence however is not large since the hypotenuse is not much greater than the adjacent cathetus for small angles.