Stephen,

Sounds like an interesting project.  My first suggestion would be to
join the PSN mailing list so there can be a full discussion.  See:
http://psn.quake.net/maillist.html to subscribe.

Some needed details of your project include:
purpose
time available to complete
rough budget limit
size of field
what other activity is going on in the field at the same time

Cheers,
John

At 09:23 PM 5/25/00 , Larry Cochrane wrote:
>Stephen,
>
>Sounds like an interesting project. Unfortunately I can't help you much. I
>would think three geophone would do the job if the sensors can pick up the
>impact offer the local ground noise.
>
>I'm CC'ing this message to the Public Seismic Network mailing list. Maybe
>someone on the list can help you.
>
>PSN'ers please send any info directly to Stephen Hertig at
>shertig@........... and CC the list, since he is not on this mailing list.
>
>Regards,
>Larry Cochrane
>Redwood City, PSN
>
>At 10:02 AM 5/25/00 -0500, Stephen Hertig wrote:
> >
> >Dear Mr. Cochrane
> >
> >I am researching how to calculate low-mass (like baseballs), impact surface
> >locations on a grass field (2D only, X & Y's) in a relatively small area
>(100 x
> >300 m)  using vibration sensors or geophones and PC-based, real-time data
> >recording.
> >
> >The software and programming is very much in the public domain and I'm
>assuming
> >it can be worked out, but it's the general hardware parameters that have me
> >perplexed (out of my field) at this stage.
> >
> >I'm not sure how many geophones I'll need or what fequency response would
>best
> >be suited for these measurements.  As the area is small the low-mass,
>hense low
> >energy impacts may not be a problem, but the signal to noise ratio is a
>concern.
> >However, I've got no feel if this is assumption is close to reality or
> >equivalent to the energy (db) distance ratios of earthquakes, but that 
> is the
> >current analog I'm using to try to build a prototype system to record
>these xy,
> >impact locations.  Although I suspect as all I need are s-wave, first
>arrivals I
> >may be able to detect and calculate the "epicenter" (+/- about 1/m???)
>from at
> >least 3 senors and hopefully be well above any noise. If more than 3
>senors are
> >needed to record the events in this area (e.g., sensor has to be closer to
>the
> >impact than about 100 yds to see signal above noise) then I suspect things
>get
> >really complicated/expensive in terms of the A/D device and new modified
> >multi-channel (3+) software needed.
> >
> >Do you think this can be done with only 3 sensors (i.e. Channels)?
> >
> >If so what type/parameters of senors would you suggest? (i.e. geophone
>frequency
> >response, vertical or horizontal spring orientations. Is horizontal better
>for
> >just s waves?)
> >
> >If not any comments on a alternate system setup? or others to ask these
> >questions?
> >
> >
> >You can blame your great web page(s) for this request, and thank you very
>much
> >for taking time
> >for any consideration or comments.
> >
> >Sincerely,
> >Steve Hertig, geologist
> >shertig@..........
> >
> >
> >
> >
> >
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>
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John C. Lahr
1925 Foothills Road
Golden, CO 80402
(303) 215-9913
http://lahr.org/john-jan/science.html
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