1. Scuds and Patriots CSE 200

2. History 1 st Gulf war 1991 Iraq attacking US troops using Scud missiles US defense: Patriot missiles

3. Binary Forms Decimal ~ binary 2 ~ 10 3 ~ 11 8 ~ 1000 9 ~ 1001 0.5 ~ 0.1 0.1 ~ 0*1/2 + 0*1/4 + 0* 1/8 + 1*1/16 + 1 *1/32 + 0*1/64 + 0*1/128 + 1*1/256... = 0.00011001...

4. Patriot Clock Start: 0 secs Elapsed time: how many 1/10 secs 1/10 sec: approximatd by 24 digit binary Off by 25 th binary digit

5. Patriot Tracking 1. Object detection (Position + velocity) 2. Position prediction after 1sec 3. Based on ballistic trajectory 4. Object at predicted position? -- Fire

6. The Scud Desaster Patriot System up for 100 hrs Timing off by 0.3 secs Scud position missed by 500+ m Patriot not fired

7. More… http://sydney.edu.au/engineering/it/~alum/p atriot_bug.html