PSN-L Email List Message

Subject: Re: those strange jumps
From: Bob Smith bobsmith5@........
Date: Tue, 25 Jul 2000 17:11:15 -0400

John --

One additional thought, The time that a radio station "signs
off" does not necessarily coincide with the time that they
drop carrier (shut down the transmitter), same on start up
in the morning.  These periods just after and just before
the broadcast day are often used for tranmitter adjustments
and testing.  I suggest a portable A.M. radio to listen for
carrier outage while you are monitoring.  A strong,
unmodulated carrier will have a marked "quieting" effect on
what you hear.

	Best wishes, Bob Smith

John Tacinelli wrote:
> HI again,
> I am overwhelmed with good ideas! Thank you all so much.  I will try do deal with each.  First of all the line voltage.  I ha
ve not checked this, however since the UPS showed the same problem, I don't think it is the line voltage.  I called the utility
 company and they said there were no shifts related to capacitors at that time.  They said there was a shift in usage around th
at time but they couldn't be very specific.  I'm pretty sure its not a joke, our students are not that bright....  I thought ab
out streetlights but each is on its own photo cell and so they come on irregularly.  I did not have the seismograph running dur
ing the time change so I don't know if it tracks.  We are decidedly not in the desert here in Minnesota so I doubt it is the bu
ilding heating and cooling, besides, this is too regular for something like that.
> I like the idea put forward by Charles and Bob about AM radio interference.  I called around and there are two radio stations
 that have restricted licences.  One goes off the air at 8:45 and back on at 5:45.  Very interesting.  The other station change
s power level from 5000 to 1000 watts at about that time.  They couldn't be more specific.  The station that goes off air says 
that I could shield the coil with grounded aluminum foil.  So I took the box that I use as an air cover and taped aluminum foil
 all over it.  I attached a wire to it with electrical tape and modified a regular AC 3-prong plug so that only the ground plug
 was there.  I attached the wire and plugged it into the  power strip for the computer.  The trace that had been going more or 
less down the middle, shifted to the left side of the screen.  So it seems to be doing something.  Tonight I will watch the thi
ng again, this time with the shield in place and two radios going.  If it happens again I'll see if it
> coincides with the radio sign-off ( or signal decrease).  Also , the radio station changes its on-off times monthly so I can 
also see if it changes at the end of the month.  I am hopeful and will keep you all informed.  Thanks again for the help.
> John Tacinelli
> Earth Science Instructor
> Rochester Community and Technical College
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---------  Avoid computer viruses  --  Practice safe hex 
 * * Specializing in small, cost effective embedded control
systems * *
Robert L. (Bob) Smith			Smith Machine Works, Inc.
internet   bobsmith5@.............. Lumlay Road
landline   804/745-1065	                Richmond, Virginia

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