The voltage input-frequency output characteristic of the high-frequency converter was determined by static measurements, using a direct current voltage source, a precise ¥ voltmeter, and a counter. desired can be deduced characteristic output cy The complete current input-frequen 2.13. Figure in shown is from the data then available. It 2.4.3 Detector 3 (Lil). The procedure was the same as for Detector 2 Channel. The data is shown in Figure 2.14. 2.4.4 Detector 4 (KBr). The procedure here was to introduce measured currents, from a high-voltage, high-resistance source, to the proper detector lead, and then to measure the associated converter frequencies with a counter. The data is shown in Figure 2.15. ; In addition to the preflight calibration discussed above, provisions were made to simulate signal inputs to the data encoder at minus 2 minutes. This was done with a condenser-thyratron single-tube pulser fired by command from the ground. This sys~ tem provided pulses to all data channels and initiated the timing sequence, so that any deviation from the preflight condition could be detected. 2.5 COMMAND AND PROGRAMMING SYSTEM The in-flight operation of the canister depended on five commands. The first four conaisted of relay closures in the Project 1.10 equipment, initiated by the command transmitter in the ground station. The fifth was the arrival of the gamma-ray pulse at the canister. 2.8.1 Minus 7 Minutes. This command signal supplied internal battery power to all equipment in canisters, producing “ready” condition. The tape~recorder was recording, playing back, and erasing continuously. This provided a preliminary check on the operation of the equipment, since the free-running rate of the converters was being transmitted to the ground atation. 2.5.2 Minus 2 Minutes. This command signal initiated the in-flight calibration se- quence and provided the arming voltage required to hold the tape recorder in the playback mode. This command was maintained for 45 seconds, the period required to play back all eight channels on the tape. Its release restored the system to the “ready” condition. 2.5.3 Minus 10 Seconds. Up to this time, the system was reversible and could be reset by turning off the minus-7-minute command. However, the minus-10-second command produced some irreversible changes, which were required to reduce power drain during the playback period and to protect the system from shock-induced relay closures. 2.5.4 Minus 2 Seconds. voltage to tape recover. This signal fired displacement rocket and supplied arming 2.5.5 Gamma-Ray Pulse. Initiated timing sequence in tape recorder, causing the 30