@mmurray - The Orion carries 84 sonar buoys. The sonar buoys are dropped and release sophisticated underwater hydrophones that unreel on a 1000' (328M) long cable.
The buoy transmits any signal data discovered, back to the Orion for analysis, through a radio system in its surface unit.
The Orions have been re-configured to find the 37.5kHz signal and to contend with fluctuations in the 37.5kHz signal.