XPost: sci.military.moderated   
   From: KevinWilloughby@acm.org.invalid.retro.com   
      
   In article , d.brevik@comcast.net   
   says...   
   > "Bob Martin"  wrote in message   
   > news:47365533.0404120935.3493c422@posting.google.com...   
   > > >     Read it again - the book specifically noted that they built (and   
   > > > later used) a backup catapult, [...]   
   > > Which book was this?  I've read Starship Troopers and I'm trying to   
   > > figure out which of his other ones would be good/similar to that one.   
   > "The Moon Is A Harsh Mistress"   
      
   That same book also contained a bit of stealth technology: the sentient   
   computer (Mike) claimed he could use a pair of radars in such a way that   
   the bad guys on earth would think there was only one radar half-way   
   between the two real radars.   
      
   When I first read this, I thought Heinlein was being silly. Years later   
   I discovered the audio-equivalent in my own living room: two   
   loudspeakers, fed identical signals and equidistant from the listener   
   (me!), sounded exactly like one speaker half-way between the real two.   
      
   Later yet, I learned of early airplane navigation systems where two   
   radio stations transmitted carefully chosen signals such that the pilot   
   would hear a continuous signal when and only when on-course. If the   
   pilot was off-course, the signal he heard would tell him how to get back   
   on-course.   
      
   These days, it is common to use multiple transmitters of carefully   
   chosen signals to determine location and direction. (keyword: GPS)   
   --   
   Kevin Willoughby         kevinwilloughby@acm.orgNoSpam.invalid   
      
   Imagine that, a FROG ON-OFF switch, hardly the work   
   for test pilots. -- Mike Collins   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)