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RE: Accuracy of GPS with respect to surveys
GPS precision can be greatly improved using several techniques, the most
common of which is differential correction. This technique relies on
receiving GPS information at a stationary, known location. In simple
terms, the difference between the known and measured readings at the
stationary location can be applied to the data from your moving GPS
either in real-time (often via radio link) or later. The US Coast Guard
operates many differential stations which transmit the corrections over
radio over most if not all of the US coast, as well as near the great
lakes and possibly other locations. Using equipment <$1000 we have been
able to achieve <10 m precision using US Coast Guard signals (which are
free to use), and with equipment <$10,000 we have been able to achieve
<2 m precision, all in real time. For another $10,000 or so you can set
up your own differential station anywhere.
------------------------------------------------------------
Christopher H. Clement
Scientific Specialist / Radiation Protection Program Manager
Low-Level Radioactive Waste Management Office
Atomic Energy of Canada Limited
clementc@aecl.ca
> ----------
> From: Pickett, Bruce D[SMTP:Bruce.Pickett@PSS.Boeing.com]
> Sent: April 30, 1998 5:55 PM
> To: Multiple recipients of list
> Subject: Accuracy of GPS with respect to surveys
>
> 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."
> > >
> > >
> >
>