Good quality sonar

We need to install a sonar to detect distance (4-8m) of a glass surface. Lidar doesn’t work well because of the tipology of surface (glass), we tought a sonar may work better. Anyone has a suggestion for a good sonar unit? Budget up to 300 USD.



The Sonar units I have tried have been junk but you probably know that. Over your budget by a bit but I wonder who has tried the Radar unit Ardupilot supports?

Even if it is over budget is no prob, as long as it works.
On what distance has the sonar been junk?

Maybe the Aerotenna US-D1 would be a good option. Anyone is using it with good results?