Sw A& (9 (lo (11) (12) land Eac(. Parry Eniwetols Photo Tower at Aomon (13) Photo Tower at Runit (14) Photo Tower Aniyaanii (15) Photo Tower Coral Head The requirements for the Radiological Net were determined by 6 November 1947. The plan was to employ approximately twelve (12) radiological safety (RADSAFE) parties after the shot, operating from boats in conjunction with the scientific teams who would be returning to the Zero Island to gather their records and data. It was decided that each RADSAFE party would be equipped with an SCR-300 “Walkie-Talkie,” enabling them to communicate with their respective boats. There, messages would be relayed from the boats by Navy TCS (high frequency, voice) radio sets to the Radiological Safety Centers on the AGC-7 and CVE-115. Two (2) special SCR-608 circuits were to he provided between the Radiological Safety Centers. In addition, circuits were planned for communication between the Radiological Safety Centers, helicopters and aircraft to be used in the initial radiological survey immediately following the shot. On 4 November 1947, a requirement developed for a frequency band of 150 to 160 megacycles to be used by six (6) blast telemetering equipments. Later, discussion arose concerning the possibilityy of employing six (6) channels in the vicinity of 80 megacycles for the same purposes, It was decided in the end that a band of 156 to 180 megacycles would be satisfactory with the understanding that a concentration would be effected in the high end of the band to avoid possible interference with the 100 to 156 aircraft VHF band. On 16 December 1947, a requirement developed for two (2) SCR-300 nets termed “Blast Nets” to aid in the installation and testing of blast measuring equipment. One net was to have eight (8) SCR-300’S and the other, th~teen (13). An additional requirement for a Voice Time Signal Broadcast had arisen by 1 November 1947. The purpose of this broadcast was to inform all land stations, ships and aircraft of the time of the test. The original plan was to transmit the signals from the AGC-7 after they had been relayed from the Control Station on Parry Island over the radio-telephone system. This was later changed in the interest of reliability to a direct broadcast from the Control Station. It was decided on 15 January 1948 that AVR air-sea rescue boats would be employed to evacuate the ilnal personqel from the Zero Island before each shot. A communication circuit was therefore required for use between the AVR’S, the Control Station and the AGC-7 (Command Ship). This circuit was to employ Navy TCS equiment and would share one of the frequencies of the Radiological Net since radiological safety personnel intended to use the AVR’S after each shot. It was planned to provide communications to the final personnel on the Zero Island by connecting telephones at the Tower Top, Tower Base and Timing Station in parallel to an unattended AN/TRC-l system working into the Eniwetok telephone switchboard. The communications equipment left on the island was to be expended at the time of the shot. The communications requirements of the Radio Chemistry Group (LAJ-2) were 107