D Grab
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Oh good grief! Does it really matter? We go up, we go down. Though by my calculations it is a 20.7% grade for approximately .01th of a mile along the left side past the bend of the second corner from the start line. But I could be off in my measurements...
Jake Bigham <jak-@gorge.net> wrote:
GPS devices are notoriously inaccurate with regard to elevation. Even
if the GPS reads a EPE (estimated possible error) as low as 12 or 16
feet that is an indication of "plan" or map view error. Usually most of
the satellite signal is coming from units more overhead than at or near
the horizon, hence vertical triangulation is more prone to error. You
can see this for yourself - all you need to do is hold still and watch
the altitude reading on your GPS fluctuate or go to a spot with a known
altitude and see what the GPS says. Even with good coverage
(5-7satellites)
it will fluctuate as much as 60 feet.
An air pressure altimeter that has been calibrated to a known
altitude within a couple of hours is far more accurate, and if you are
just
looking for a change in altitude and not an absolute number the
altimeter doesn't even need to be calibrated at all
On Wednesday, June 11, 2003, at 09:37 AM, Clark Ritchie wrote:
I borrowed a Garmin Geko 201 GPS unit and zero'd it
out by the gate at the lower reservoir. I put it in
my jersey pocket and soft pedaled the course. That's
what the GPS read when I was done with the loop.
YMMV. ...CDR
=====
Clark Ritchie
=====
--- __o
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MRRR
jake bigham
jak-@gorge.net
home/ 503 228 1338
gorge/ 541 298 1999
cell/ 503 784 1026
Jake Bigham
2774 SW Summit Dr.
Portland, OR 97201
h/ 503 228 1338
c/ 503 784 1026
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<DIV>Oh good grief! Does it really matter? We go up, we go down. Though by my calculations it is a 20.7% grade for approximately .01th of a mile along the left side past the bend of the second corner from the start line. But I could be off in my measurements...<BR><BR><B><I>Jake Bigham <jak-@gorge.net></I></B> wrote:
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid"><BR>GPS devices are notoriously inaccurate with regard to elevation. Even<BR>if the GPS reads a EPE (estimated possible error) as low as 12 or 16<BR>feet that is an indication of "plan" or map view error. Usually most of<BR>the satellite signal is coming from units more overhead than at or near<BR>the horizon, hence vertical triangulation is more prone to error. You<BR>can see this for yourself - all you need to do is hold still and watch<BR>the altitude reading on your GPS fluctuate or go to a spot with a known<BR>altitude and see what the GPS says. Even with good coverage <BR>(5-7satellites)<BR>it will fluctuate as much as 60 feet.<BR>An air pressure altimeter that has been calibrated to a known<BR>altitude within a couple of hours is far more accurate, and if you are <BR>just<BR>looking for a change in altitude and not an absolute number the<BR>altimeter doesn't even need to be calibrated at
all<BR><BR>On Wednesday, June 11, 2003, at 09:37 AM, Clark Ritchie wrote:<BR><BR>> I borrowed a Garmin Geko 201 GPS unit and zero'd it<BR>> out by the gate at the lower reservoir. I put it in<BR>> my jersey pocket and soft pedaled the course. That's<BR>> what the GPS read when I was done with the loop.<BR>> YMMV. ...CDR<BR>><BR>> =====<BR>><BR>> Clark Ritchie<BR>><BR>> =====<BR> --- __o<BR> -- -- _ \ \_~<BR> (_)/ (_)<BR>MRRR<BR>jake bigham<BR>jak-@gorge.net<BR>home/ 503 228 1338<BR>gorge/ 541 298 1999<BR>cell/ 503 784 1026<BR><BR><BR>Jake Bigham<BR>2774 SW Summit Dr.<BR>Portland, OR 97201<BR>h/ 503 228 1338<BR>c/ 503 784 1026<BR><BR>To respond to the whole group send to ob-@topica.com.<BR>To respond to the list manager send to ob-@teleport.com<BR>To unsubscribe send to
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