power and control pulses for the IC, timed and actuated the dropping mechanism fer th. underwater detector, and recorded receipt of test Signals ona series of mechanical remsters that could be read from a small boat alongside the coracle. The ICB’s contain their own power supply, are packaged in vaporproof Plexiglass cases 1uty, by 14!, by 12 inches high, and weigh about 15 pounds. The ICB’s receive the minus-5- minute, minus-l-minute, and minus-5-second signals and are designed for a closed-contact signal of not less than 1.-second duration. The units have a reset button, which disarms all latched components and returns all timing devices to their zero poSition. A cross-reference time mark is obtained by blanking the timing pulses on both the Standard and the underwater GITR tapes upon receipt of a minus-1l-minute Signal and by reinstating these timing pulses upon receipt of a minus-5-second Signal. By this means, the IC and all GITR records could be correlated intime. This time-blanking circuit had a backup feature that restored the tim- ing pulses automatically after 60 seconds in the event of failure of the minus-5-second signal. Although the ICB register system worked as designed, it could be used only if there were regularly scheduled timing signal runs. The fact that EG&G sent many hand signals on demand between the scheduled timing runs rendered the register system entirely useless. After the accidental radio signal before Shot Wahoo, the project cannibalized the control box register and installed a dead-safe switch arrangement with its own batteries and arming light in the old register housing. This switch completely deactivated the entire coracle system, regardless of any signals received by the EG&G radio trigger. The coracle was armed by pulling a lanyar connected to this switch. This modification gave the project partial protection against accidental firing of the coracle stations; however, if a signal was on the EG&G radio or if any of the EG&G relays had been closed by jarring, the coracle would fire when the dead-safe switch was thrown. Three such accidental firings did occur on the final arming run for Umbrella. 2.2.8 GITR Tape Readout. The GITR tape readout (GITOUT) was an electronic readout device developed at NRDL for converting radiation pulses (Appendix F) on the recorded tapes into dose rate information (Figure 2.10). The GITOUT employed digital techniques with a digital- to-analog conversion near the end of the system to give an x-y presentation of time versus data on graph paper. The system (Figure 2.11) was composed of commercially available component So that no electronic development was required. The instrument is more fully described in Ref erence 66. Tapes are placed inthe tape transport and are played at a speed depending upon the field resolving-time desired. The information from the timing channel and from oneof the radiation channels is read off the tape and shaped into square-wave pulses. The timing pulses are sent to a time counter, where they are accumulated and converted by an associated printer to an analog voltage which, in turn, drives the x axis of the plotter. Radiation pulses are sampled by the other counter at a rate determined by the timing pulses. This counter either accumulates the pulses or resets itself after each time increment, depending upon whether total dose or dose rate is required. The data counter controls a second printer, which also converts the radiation pulse count into an analog voltage to drive the y axis of the plotter. Log converters can be inserted between the printers and the x-y plotter to give a log-log or semilog presen.ation of the data versus time. A digital record of the information can also be obtained directly from the printers. .2.3 SPECIAL OPERATIONS Although only a support activity, the maintenance of fixed coracle stations in deep water represented a major Operational problem. Since the installation of deep moors on the steep slopes of coral atolls may be again required, a brief description of the specially adapted moor employed by the project is given here. Deep-anchoring techniques, developed at SIO (Reference 67), had been used on a Small scale during Operations Ivy and Wigwam but were first used extensively during Operation Redwing where 13 deep-anchored positions were maintained in depth. 65