The On-Top Position Indicator (OTPI) system is used in conjunction with the UHF radio direction finder to provide the capability for the detection and location of sonobuoys. The OTPI system consists of a VHF radio receiver and RF amplifier, located in the electronic compartment, and a control panel located on the upper section of the sensor station. Indications are displayed in the No.1 pointer of the three BDHIs, and the system utilizes the UHF/DF antenna for reception of sonobuoy signals.

The OTPI system is protected by one AC circuit-breaker, marked “OTPI”, located on the AC circuit-breaker panel, and one DC circuit-breaker, marked “OTPI”, located on the overhead circuitbreaker panel. The system receives DC power from the primary bus and AC power from the No.1 generator.