PSN-L Email List Message

Subject: Re: Instument Quality
From: "tchannel" tchannel@............
Date: Fri, 23 Oct 2009 08:28:18 -0600

I forgot to mention another variables, obvious, but may be not to newcomers. 
Each earthquake is unique.  Sometimes a 6m will be  clearly visible, and 
sometimes another 6m, same distance, same size will not be visible.
And of course your background noise at the time, is a major factor.
Lastly, the preliminary USGS event reports, can be modified, as more 
information becomes available, changing a 6.0m to a 5.7m etc.

----- Original Message ----- 
From: "Larry Conklin" 
Sent: Friday, October 23, 2009 7:52 AM
Subject: Re: Instument Quality

> 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.
> Larry
> 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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