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
> 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
> 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
>> 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
>> 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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