PSN-L Email List Message

Subject: Re: Instument Quality
From: Larry Conklin lconklin@............
Date: Fri, 23 Oct 2009 09:52:21 -0400

Hi Ted,

I have an Excel spreadsheet that I use to record the events I've seen 
with my SG system.  The sheet includes a magnitude vs distance scatter 
plot, with each point color coded (A - D) to represent my (very) 
subjective assessment of the quality of the detection.  I have a 
database of over 800 events.

My system is far from an optimal construction and my location is pretty 
noisy, but I think overall my results are reasonably typical of a fair 
to middlen amateur system.

If you or anyone else would like a copy of the sheet and data to examine 
for comparison to your own results, I'd be happy to send it to you. 
I've included a few other features, and I use it to manage all of my 
event files.


tchannel wrote:
> I have a follow up question, only somewhat related.   When the sensor is 
> completed, one of the first questions a novice might ask is "What can I 
> expect to see"?     I know this would depend, not only the sensor, but 
> many other things, like the location, and the other components of the 
> station.
> We all try to build the best one we can, using the ideas and materials 
> we have.   This site is the best tool I have in my workshop.
> The most common statement I have seen is,  "My sensor can see >7.0M 
> anywhere in the world"   I have never complete a sensor which could not 
> do this.
> I view USGS sites, and find equipment costing thousands of dollars, pick 
> up more and small events, then mine, but not not by much.
> I also know, several of my ideas are not as sensitive as they could be, 
> and some of the ideas simply don't work.   I learn a lot from both 
> failures and successes.
> Could someone state, as best as you can "What should I expect to see"?
> Something like:
>  >6.8m anywhere in the world.
>  >6.m within 90 degrees
>  >5.m within 30 degrees  
> All who have been doing this for a while, know what our equipment will 
> see.   If someone, with really nice homebuilt sensors, would share these 
> numbers, it would act, for me, as a benchmark.
> Thanks, Ted
>     ----- Original Message -----
>     *From:* Randy Pratt 
>     *To:* psn-l@.............. 
>     *Sent:* Friday, October 23, 2009 12:29 AM
>     *Subject:* Re: Instument Quality
>     Chris,
>     I apologize for misreading your tone and intent.  It's an
>     unfortunate attribute of email that it loses personality.  I agree
>     that a school purchasing an instrument for instruction should have a
>     high quality but I don't see that our schools are at that point or
>     that caveman is recommending this as a school solution. 
>     Let me try to explain my sensitivity.  My son's middle school
>     dropped earth science to meet state mandates for an increase in
>     physical education hours.  We moved shortly after that to another
>     state.  Here I became involved with the science fair and to my shock
>     the largest middle school in the region did not participate.  When I
>     inquired I found no contract for extra work outside the classroom
>     hours so no science projects.  One high school science teacher
>     explained to me that there is no time to fit any extra topics in
>     order to meet federal and state curriculum guidelines.  The one
>     teacher that did let me demonstrate a seismograph left the area
>     and her job was cut.  A German exchange student I am hosting is near
>     the top of the English class and shows better understanding than
>     most others according to her teacher.  She has only been in the
>     US since August so what does that tell you.  Our political mandates
>     are dumbing down the best students.  It really is approved and
>     budgeted science only and that leaves only individual interest.
>     An old magazine article from 1960 something about a smoked drum
>     seismograph stuck in my mind until I started to research in 1995 and
>     build my first.  The Lehman article has been the basis for many on
>     this list but few of us are using pipe fittings on a board anymore. 
>     Maybe something simple like the caveman web page will spark other
>     individual interest.  How well it functions doesn't matter
>     if thinking is set in motion and the steps to reach something better
>     follow.  That's where learning starts.  Think about what percent of
>     aeronautical engineers started with paper airplanes looping into the
>     ground and being refolded? 
>     Randy

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