Station HYPO

The Last CDAA Site Built
Field Guide to Coronado History:
Top Secret Station, Codename “ITEM”

The shadowy world of radio intelligence, cryptology, and radio direction finding was for many years the primary activity of the Navy in Coronado Heights at the foot of the Silver Strand. Just like the National Security Agency today, almost all of this activity was highly classified.

The Navy first came to Coronado Heights in 1920 to establish Navy Radio Compass Station, Imperial Beach on land leased to them by the Coronado Beach Company. The site served ships at sea, helping them obtain accurate navigational fixes by reporting the bearings of ship radio signals back to the ship. If two stations were involved, the ship could obtain a cross fix of its location; if not, at least a “line of bearing” was possible.

As radio equipment became more sophisticated and sensitive by the end of the 1930s, shore stations could intercept and track high frequency signals for hundreds (in some cases, thousands) of miles. This specialty was called RDF, or Radio Direction Finding, and was used to locate and track a radio transmitter, like on an enemy ship.

With war looming and, with it, the need for greater intelligence gathering and tracking of radio intercepts, the Navy decided to formally take over Coronado Heights and expand their operations. The government canceled its existing land lease, condemned the property and paid about $55,000 for the beachfront. The new base was renamed Radio Direction Finder Station, Imperial Beach. At the same time, the Army built a large coastal fortification named Fort Emory also at Coronado Heights as part of a large coastal defense system. Units of the Coastal Artillery manned the Army batteries.

Beginning in December 1942, Navy radio equipment at Coronado Heights was significantly upgraded to transform the site from a purely RDF site to one that could intercept and code-break radio messages. A permanent Marine guard was also assigned reflecting a higher level of security.

Japanese diplomatic and naval messages were intercepted throughout World War II by listening posts throughout the Pacific and along the West Coast. Each of these intelligence-gathering stations was assigned a unique station identifier, a single letter or its phonetic alphabet letter. For instance, the radio intelligence station in Hawaii was named Station “H” (“Hypo”), and a station near Seattle was named Station “S” (“Sail”). The radio intelligence intercept cell at Imperial Beach was known as Station “I” or “ITEM”.

Part of Coronado Height’s wartime activities involved gathering secret radio intercepts and radio fingerprinting of Japanese transmitter characteristics with call-letter changes. Station ITEM’s location was particularly valuable because it was one of the flank stations of the Pacific net and could help guard the approaches to the West Coast.

The station also monitored U.S. naval frequencies within the Eleventh Naval District. Large numbers of Navy uniformed women volunteers (WAVES) were assigned to the station beginning in 1944. They were assigned clerical, communications, intelligence, and intercept operator roles. Of the three hundred radio personnel assigned to Imperial Beach in August 1944, 148 were women. These WAVES were originally billeted at the Coronado WAVES barracks on First Street. Later, as those accommodations filled, barracks were reserved at Coronado Heights itself for women.

Throughout the war, the communications activities at Station ITEM were hidden-in-plain-view from the public under a cover story (partially true) that the base was in use as the Landing Craft School of Naval Amphibious Base in Coronado. All orders cut for communications personnel were written in this manner, as were all public announcements. Part of the base was very open, with a Navy Exchange store, dispensary and a loading dock for trucks. Many referred to the site simply as Coronado Heights Annex.

Although all of Station ITEM’s activities were highly classified, there was the definite sense that Coronado Heights held a high standing in Navy priorities. Immediately following the war, when many other naval units disbanded and installations closed, Coronado Heights actually expanded.

By 1950 aerial views of Coronado Heights showed newly paved road grids and an explosion of new buildings including Navy residential units. Renamed the Naval Communications Training Center, Imperial Beach after the war, Coronado Heights had taken center stage as a primary naval training site for Navy radio intelligence and cryptologic specialties.

All in all … another tale of Times Past in Coronado, this one wrapped in secrecy and high level classification!

By Bruce Linder

A special thanks to CAPT Ivan Dunn, USN, ret for this post.