[Lowfer] LF interference - slightly off topic...

[Howell, Laurence (Shanghai/Singapore)]

 Thanks to all - yes I searched Google images under geophones and there
was a Chinese manufacture, as they
More than resemble those in situ and causing more than the normal trip
hazards.

Well done Mike and others - They guys are sitting in a small dome tent,
with a bowl and water jug so probably living in there -  
that tent is small doesn't appear to be "mains connected" but they maybe
over a manhole. They appear to be gradually working their way thru the
city and
Dressed up in very elegant red coveralls.

I note that this is a seismic active area or they are looking for
something else. 

The reason I started this was pulsing noises in the low KHz range around
9kHz which were very strong, with harmonics at 137kHz -  and were
Coming from my antennae "array" (the baby bottle) and not internal to
house (that's why I mentioned it here)

I've still not determined this intermittent sources location but instead
Of hammering the ground is often done I wonder if they are using another
higher freq sounder/transducer?

Anyway its not there late this evening but there again they don't appear
to work at night.

The golf course is covered with them here too - arrays are 24 phones in
a 6 meter separated grid where they have
Room.

I should have known what I was looking at as I'm in that industry :-)

Laurence

-----Original Message-----
From: lowfer-bounces at mailman.qth.net
[mailto:lowfer-bounces at mailman.qth.net] On Behalf Of mikea
Sent: Tuesday, March 03, 2009 2:23 PM
To: Discussion of the Lowfer (US, European, &UK) and MedFer bands
Subject: Re: [Lowfer] LF interference - slightly off topic...

On Tue, Mar 03, 2009 at 10:46:22AM +0000, Dave Pick wrote:
> Laurence
> 
> What are they cabled to? Control box, mains...?
> 
> Dave 'YXM
> 
> 2
I think those are geophones. I'm used to seeing them out in the wild,
used
by oil surveyors to detect echoes from rock layers and structures after
a
blast or a thump from a thumper truck. They're a rather common sight in 
Texas and Oklahoma, but I've never seen them pounded into a sidewalk 
before. 

Interesting ... .

-- 
Mike A
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