Bruno Latour, Aramis, or the Love of Technology, PDF - Dss-edit.com

OrdinateViewpoint of mobile unit/I--- XAbscissak--L------xViewpoint of sector control unitFigure 16.more often-every 20 milliseconds-so it allows much greater finesse. But asfor whether a given car is to be a target or not, it's the UGT that assigns therole, that makes the decision [Figure 16]."Doing this already entails quite a few problems, because the time neededfor realtime calculations with all these accelerations is not easy to manage,and in addition everything has to be coded, encrypted, to avoid errors; it's asif everything were being done twice, once openly and once in cryptic form,and then you hod to compare the two."If they match, you say, 'Okay, the order can be carried out.' If they don'tmatch, you send an alarm; you suspend the action and you check the calculations."In addition, there's a timer that ensures that the information is updated, tomake absolutely sure that the information is current and hasn't been lying aroundfor several milliseconds. But 011 that tokes time, space, personnel."Matra decided to do all that in 16 bits* to gain speed . At first they startedoff with 48 bits, but it was too slow. But with 16 bits, they can't possibly havesecurity. " [no. 16, p. 9]*The length of elementary messages. The shorter the message, the quicker thecalculation; hut since, to gain security, the information has to be encrypted in parallelform, half the bits are needed. If the message is longer, in order to allow security,the whole set of calculations is slower.ARAMIS AT THE CET STAGE