Currently I do some research about SODAR and at this paper, the author wrote (p. 1502f):
A site should be relatively clear of obstacles that could act as potential fixed-echo reflectors. If that is not possible, then it is therefore important to construct an obstacle vista diagram prior to sodar installation which identifies the direction and height of potential reflectors in relation to the sodar (Baxter, 1994, 1996). This diagram can be used after some data have been collected to assess whether or not reflections are of concern at some sodar height ranges.
Unfortunately, I can't find any access to the referenced literature and google wasn't helpful either. So, what is an obstacle vista diagram and how to construct it?