€ [20] Survnet: SURVIVAL_ORIENTED TOPICS (9:2500/0) €€€€€€€€ SURVIVAL_ORIENTED €
 Msg  : 83 of 98 - 78 + 95                  Rcv                                 
 From : Jerry Ebert                         9:2400/900      Sat 06 Aug 94 03:07 
 To   : Larry Gowdy                                                             
 Subj : Infra Red Detectors                                                     
€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€

LG>         Does anyone have any info on how sensitive infra red detectors
LG>  are? Is there any difference between infra red and heat detectors?
LG>         Is it very difficult to shield yourself from being detected?
LG>  Depending on the sensitivity, I would imagine 2 layers of the metalic
LG>  backed space blankets should provide a fair degree of shielding, but
LG>  since I've never had the chance to try out any detectors, I'm not sure
LG>  how well they work. Approximately how many inches of earth would be
LG>  needed to shield human heat from the most senstitive detector?

Larry,
     I have an infra red motion detector that turns on my front porch
light.  Any heat source radiates infra red light.  The sensor I use
picks up a two degree temperature change and has a range of 30 feet.
There are much better units units, with a range of hundreds of feet,
available.  The unit I have has a sensor for the porch and a control
box that installs behind the light switch.  The kit, with instructions,
cost about $35.  These units can cost several thousand dollars for the
best detectors.

     A single sheet of metal coated mylar (a space blanket) will shield
you from most units.  A space blanket will shield you from a military
or high-tech sensor.  Imagine holding a gas lantern behind a spread out
blanket.  You would look like an eclipse of the sun.

     For security systems there are four basic sensors in use: infra
red, mass detectors, radar, and sonar.  Mass detectors have limited
range.  They are only reliable for a hundred or so feet.  Sonar (high
frequency sound) is good for two or three hundred yards.  Infra red and
radar are long to very long range (miles).  Space blankets show-up very
brightly on radar.  Three other systems are ammonia, seismic and laser
detectors.  Ammonia and seismic detectors are used by the military.
Laser is used by both the military and for traffic control.  Laser is
used like radar.  Seismic measures ground vibrations.  A good seismic
unit can "hear" the difference between dropping a penny or a dime in the
dirt.  All animals emit ammonia gas to the atmosphere.  The
characteristic pattern of human off-gassing can be "seen" from aircraft.

     The best defense against detection is to not be there.  It is
impossible to find someone who is not there.  The best equipment in the
world is the human brain.

Jerry


 * OLX 2.1 TD * Survival requires knowing when to duck.


--- WM v3.11/92-0508
 * Origin: THE BULLET BOX / SURV NET, So. Pasadena CA  (9:2400/900)

€ [20] Survnet: SURVIVAL_ORIENTED TOPICS (9:2500/0) €€€€€€€€ SURVIVAL_ORIENTED €
 Msg  : 95 of 99 - 83                       Rcv                                 
 From : Dean Varner                         9:2400/209      Sun 07 Aug 94 19:44 
 To   : Larry Gowdy                                                             
 Subj : Infra Red Detectors                                                     
€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€€

 -=> Quoting Larry Gowdy to All <=-

 LG> Does anyone have any info on how sensitive infra red
 LG> detectors are? Is there any difference between infra red and heat
 LG> detectors? Is it very difficult to shield yourself from being
 LG> detected? Depending on the sensitivity, I would imagine 2 layers of
 LG> the metalic backed space blankets should provide a fair degree of
 LG> shielding, but since I've never had the chance to try out any
 LG> detectors, I'm not sure how well they work. Approximately how many
 LG> inches of earth would be needed to shield human heat from the most
 LG> senstitive detector?

"Sneakers" is a good movie that has a lot on the subject of infra
red detectors.  After seeing it, I wanted to try it out, so I
took my cig into the store with me and blew smoke up towards one.
Unfortunately I didn't think it would work and ended up with a
"bumb" on my head! ;)   The trouble with earth alone, is that it
would see the earth as different from the surrounds that hadn't
been disturbed, unless it had been awhile, and everything had
grown back up. But, even septic tanks can be detected, so it
would have to be several feet. The "space blanket" aproach was
one of the things they considered in sneakers(a environment
suit), but hey opted for raising they temp in the room to body
temp.



... I'm a goat! Generalist of all trades.
___ Blue Wave/QWK v2.12


--- WM v3.10/92-0682
 * Origin: The Quiet Revolution, JOIN "U.S." 603-753-9716  (9:240  (9:2400/209)

