PSN-L Email List Message

Subject: Re: $200 microbarograph first light
From: "Arie Verveer" greensky@..............
Date: Thu, 12 Jan 2006 20:05:16 +0800

Hi, The Pressure sensor is a MKS Bartatron Type 223B
0.2 mmHg Full scale range. It's taut metal diaphragm
was placed parallel to the ground and I would guess
it's response to acceleration is quickly dampened, far
above the 10 Hz response. As my station was some 120km
 from our local seismic field direct (distant) measurement
 from a local quake was not possible. The infra-sound will
propagate up-wards and then refracts back to the detector
some 200 - 250 km away. I only detected events as the
atmosphere was displaced above the sensor.

Cheers Arie

On Thu, 12 Jan 2006 04:14:14 +0800, John Popelish  wrote:

> Arie Verveer wrote:
>> David,
>> A few year ago I ran an infra-sound detector and found
>> the air currents caused a great deal of problems.
>> Basically most of the signal. Only having a limited
>> space, I opted for a long length of thin wall silicon tube
>> coiled in a spiral. This tube was purchased from a medical
>> supplier. It acted a a large diaphragm reducing the air
>> currents at the detectors input. I managed to detect
>> the air pressure induced by the movement of a small local
>> quake (100 km away) that shook the ground under the detector.
>> A few observed meteors were detected plus some interesting
>> yearly changes in the background noise (ocean). I do think the
>> radial arm on porous tubes close to the ground would be
>> the best way forward assuming you have the space. My
>> detector operated 10 hz and lower.
> (snip)
> Do you have any idea what your pressure transducer's sensitivity to
> acceleration is?  Unless it is a balanced design that specifically
> cancels the effects of acceleration, you may have seen a signal that
> was a combination of pressure and sensor movement.
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