The passive sonar system differs from the active system in many regards. Passive sonar system. Hydrophone array . These are the sensitive elements which detect the acoustic energy emitted from the target. Again, they are arranged into an array to improve the beamwidth.
Common configurations are cylindrical or spherical.
The cylindrical array operates at a fixed vertical angle, usually downward. Since the submarine may be below what it is tracking, the array must be able to look upwards to some extent. The large downward angles are only used for bottom bounce detection. Spherical array showing multiple vertical beams. Beamforming processor .