Re: Accuracy of GPS with respect to surveys

["Phil V. Egidi" <7pe@ornl.gov>]

Bruce,

Differential GPS is much better, it will get you within 3 or 4 meters, and
survey quality GPS will get you to within centimeters (at a 95%
probability).

Phil Egidi
ORNL/GJ
7pe@ornl.gov



Pickett, Bruce D wrote:

> GPS's accuracy for non-military applications is limited to 100 meters.
> How do you account for this in your surveys?
>
> Bruce Pickett
> bruce.d.pickett@boeing.com
>
> > ----------
> > From:         Clement, Christopher[SMTP:clementc@aecl.ca]
> > Sent:         Thursday, April 30, 1998 2:37 PM
> > To:   Multiple recipients of list
> > Subject:      RE: A hunting we will go!
> >
> > Our office does the same sort of surface survey as described below
> > except that we throw in a computer and a GPS, and often use multiple
> > probes.  This allows us to gather much more data than using the manual
> > method for the same amount of survey time.  We can then apply very
> > sensitive statistical analysis algorithms to detect levels of
> > contamination which would almost certainly have been missed with a
> > "visual" analysis.  I've got a few papers on this subject.  Anyone
> > interested in more information can respond directly to me.
> >
> > ------------------------------------------------------------
> > Christopher H. Clement
> > Scientific Specialist / Radiation Protection Program Manager
> > Low-Level Radioactive Waste Management Office
> > Atomic Energy of Canada Limited
> > clementc@aecl.ca
> >
> >
> >
> > > ----------
> > > From:       Joel Baumbaugh[SMTP:baumbaug@nosc.mil]
> > > Sent:       April 30, 1998 3:49 PM
> > > To:         Multiple recipients of list
> > > Subject:    Re: A hunting we will go!
> > >
> > >     David,
> > >
> > >     Having done similar "hunts" in the past - the first thing you
> > > need to do (in my humble opinion) is find the stuff!  Get a high
> > > energy scintillation probe (like a Ludlum 44-2), grid your area and
> > > start walking back and forth "till you find it.  A high energy probe
> > > because the low energy photons won't reach your probe if they
> > > originate at any depth and you have enough mid-high energy photons
> > > being generated with Th-232 and its progeny. I often let the probe
> > > sort of "dangle" (a scientific term if I ever heard one) near the
> > > ground and slowly swing it back and forth as I slowly walk my grid.
> > > In a grid area (if I have a companion) I will call out the CPM
> > > readings so as not to forget where my highest readings are/were.
> > >
> > >     Regarding the pyrophoric part - time for the asbestos under-ware
> > > (grin).
> > >
> > >     Good Luck,
> > >
> > >     Joel
> > >
> > > ..
> > >
> > > At 12:24 PM 4/30/98 -0500, you wrote:
> > > >     Folks,
> > > >
> > > >     For the sake of an excavation/remediation project, we are
> > > assuming
> > > >     that there are 360 pounds of Th-232 buried in a waste pit full
> > > of
> > > >     other contaminants.  We don't know exactly where in the pit
> > this
> > >
> > > >     material is or quite how deep.  What we do know is that it may
> > > be
> > > >     pyrophoric and, we suspect, it is concentrated in one
> > location.
> > > >
> > > >     We would like to find this material before it finds us.  We're
> >
> > > >     thinking of using gamma spectroscopy to search for the Ac-228
> > > .991 MeV
> > > >     gammas.
> > > >
> > > >     Any advice?  Thanks in advance!
> > > >
> > > >     David Levy
> > > >     Health Physicist
> > > >     david.levy@fernald.gov
> > > >     (513) 648-3816
> > > >
> > > >
> > > >
> > >
> > > Joel T. Baumbaugh, MPH, MHP
> > > baumbaug@nosc.mil
> > > Radiation Safety Officer
> > > SSC San Diego, CA
> > >
> > >
> > >     NOTE:   The contents of this message have not been reviewed, nor
> > > approved by
> > > the Federal Government, the U.S. Navy, my bosses or my wife...
> > >
> > >     How times change - how everthing remains the same:
> > >
> > > 2000 B.C.     "Eat this root."
> > > 1000 A.D.     "That root is heathen.  Say this prayer."
> > > 1850 A.D.     "That prayer isn't medicine.  Drink this potion."
> > > 1940 A.D.     "That potion is snake oil.  Swallow this pill."
> > > 1985 A.D.     "That pill is ineffective.  Take this antibiotic."
> > > 2000 A.D.     "That anibiotic is ineffective.  Eat this root."
> > >
> > >
> >