Per https://www.topoquest.com/map.php?lat=40.02486&lon=-105.24468&datum=nad27&zoom=2&map=auto&coord=d&mode=zoomin&size=m the address in your signature is close to the 5250 ft (geoidal) contour.
Henry On Wed, Jun 8, 2016 at 3:18 PM, Henry Hallam <[email protected]> wrote: > Some of that is probably the difference between the geoid (what your > surveyed maps report height relative to) and the WGS84 ellipsoid (what > your GPS reports heights relative to). At Boulder that difference is > only about 15 meters, though. > > Generally with VDOP < 2 and a reasonably modern receiver the accuracy > of a GPS altitude measurement should be better than about 20 meters. > I'm not sure if the Thunderbolt counts as such. > > How flat is Boulder? Do you have a proper surveyed elevation of your > location? > > Henry > > On Wed, Jun 8, 2016 at 1:33 PM, Van Horn, David > <[email protected]> wrote: >> >> I have just installed a Thunderbolt here to get our time and frequency >> equipment all on the same page. >> As I was looking at the display on Lady Heather, I was noticing that the GPS >> altitude seems rather wrong. >> We are in Boulder CO, which is nominally 5430' and the antenna is about 20' >> off the ground. >> The display (near overdetermined position) reads 1589.72991 meters or 5216 >> and change in feet. >> Altitude is a big deal around here. :) >> >> I suppose 214' isn't that outrageous, but it does bring me to a question: >> >> How accurate is the altitude number really? >> >> Thanks. >> >> >> -- >> David VanHorn >> Lead Hardware Engineer >> >> Backcountry Access, Inc. >> 2820 Wilderness Pl, Unit H >> Boulder, CO 80301 USA >> phone: 303-417-1345 x110 >> email: >> [email protected]<mailto:[email protected]> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
