Keywords: Greeneville AVSDU.jpg The Analog-Video Signal Display Unit or AVSDU was a sonar repeater installed near the USS Greeneville's periscope platform On the day of the accident with Ehime Maru the AVSDU was not working U S Navy photo Source http //www ntsb gov/publictn/2005/MAB0501 htm PD-USGov USS Greeneville SSN-772 Submarine control rooms |