Research - Station HYPO, Hawaii

Station HYPO, also known as Fleet Radio Unit Pacific (FRUPAC), was the U.S. Navy Intelligence Base at Pearl Harbour, Hawaii. It was one of two Allied Signal Intelligence Units (Fleet Radio Units), the other being Frumel in Melbourne, Australia.
It was under the control of OP-20-G (Office of Chief of Naval Operation/OPNAV, 20th Division of the Office of Naval Communications, G-Section/Communication), based in Washington and housed in the Old Administration Building at Pearl Harbour.
It was tasked with Cryptanalytic assignments relating to the Japanese along with a couple of other stations, namely CAST at Cavite and Corregidor in the Philippines.

The code they were most concerned with was called JN-25 which was the Japanese Naval Code.