Re: Radar, sonar and more

The information I'm getting is helping ... especially
when it comes to the sonar question.

About the radar, I'm looking for some (potential)
natural occurring atmospheric disturbance that could
prevent the use of radar.

For instance, our intrepid explorers have just entered
an unknown atmosphere and discover that, for some
reason, their radar doesn't function properly. Is
there even the remote possibility that could happen?

--- Matthew Seidl <seidl@vex.cs.colorado.edu> wrote:
> On Thu, 24 Feb 2000 12:38:26 -0800 (PST), Cleats
> Balentine writes:
> >I'm working on a scenario inspired by a recent
> report
> >I heard on NPR about the ocean of Europa ... it's
> >still in the embryonic stages of development.
> >
> >Anyway, I need some help that I'm hoping some
> listers
> >might be able to provide:
> >
> >No. 1 Is there any naturally occurring element that
> >can block radar? Is there any elemnet hypothesized
> or
> >in hard sci-fi literature that can do this?
> >Essentially what I'm looking for is something that
> can
> >refract radar and prevent accurate readings.
> 
> Sure.  Lots of dirt.	Hills are good at blocking an
> amazing range of
> EM radiation.  Do you want something smaller?  steel
> blocks radar
> fairly well I seem to remember.  Mostly because it
> reflects it like
> crazy, so you get a good return on the steel, but
> not on anything
> behind it.  Really, radar penetrates things fairly
> poorly, so just
> about anything will block and reflect it. 
> 
> Now, if you want to absorb the radar so you get no
> returns, its a
> little harder.  I believe water absorbs radar pretty
> well, as do some
> new plastics and such.
> 
> >No. 2 Will an abnormally loud aquatic environment
> >prevent the effective use of sonar?
> 
> Maybe.  There are two general forms of sonar
> detection, active and
> passive.
> 
> Passive is just listening for sounds that sound
> unnatural.  If the
> background is loud and random, but there is still a
> repeating man made
> sound in there, you may well be able to find it, if
> the random
> sampling isn't so much higher amplitude that the man
> made sound is
> reduced to noise.
> 
> Active sonar is where you send out a loud "ping" and
> listen for the
> echos.  If the background is loud enough, it might
> be hard to hear the
> ping when it comes back, but in general you should
> be able to tune the
> frequency of the ping so that you can listen to a
> very tight frequency
> range and eliminate most of the noise.  
> 
> Does that help?
> 
> -=- Matthew L. Seidl		email: seidl@cs.colorado.edu 
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