Hello Bob Hancock;

This all makes common sense.
What types of sensors were used ?
Piezo, Magnetic, Something we never heard of before ?

Who manufactured these devices ?

Could they sense seismic events as well as human disturbances ?

Maybe someone could show us a readout that an
operator/technician might see ??

US Sonobuoys were only monitored for spectrum content
then threats were determined through identifying
the various components of a given spectrum
with whatever. Such a database was the calassified
part of the works and thats not what I am looking for
here. Just want a new idea to get first time of arrivals
for P waves.

It seems to me that in the military calibration and intelligence
was more impoirtant to them then hardware alone.
They gave meanings to things that if I were to say the
same thing to a civilian that civilian would call me crazy
and lock me away.

We need details about their hardware.
Especially the sensors.

Like some sonar elements are what you
call magnetostrictive which is simply
a block of nickle surrounded in a coil of
wire and when you put that metal in a
magnetic field it will change in dimension.
I have never heard of magnetostrictive devices
being used in seismology ???

Are there sensors suitable for seismology that
us amateures have never heard of before ??

Michealson interferometers, electron microscopes ???

Magnetic Levatation ??

Any knowledge there beyond us amateures ?

Regards;
geoff

----- Original Message ----- 
From: "Bob Hancock" 
To: 
Sent: Saturday, September 23, 2006 1:47 PM
Subject: RE: Border Patrol Use Of Seismic Sensors


> The use of seismic sensors to find intruders dates back to the Vietnam War.
> They were placed along the Ho Chi Min trail, a network of paths from North
> Vietnam to South Vietnam that also crossed into Laos and Cambodia.  The
> sensors were modified US Navy sonobuoys, and about 20,000 were dropped along
> the trail.  There were two versions, one stuck into the ground like a lawn
> dart, and the other was dropped by parachute, and could remain above ground.
> The signals were picked up by nearby airplanes and relayed to ground
> stations.
> 
> Bob Hancock
> Three Points, AZ  

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