Hi One of our standing jokes when we lived by the shore was that we actually lived underwater. The GPS routinely put is 30 to 50’ below sea level ….
Bob > On May 20, 2015, at 3:36 AM, Björn Gabrielsson <[email protected]> wrote: > > Hi Bob, > > You are confusing the readers here. > > 1) zero altitude relative the WGS84/GPS ellipsoid are often tens of > meters over or below sea level, depending on your location. > > 2) zero altitude relative to a geoid (EGM96 or something else) is very > close to sea level. > > Then if you think of the ellipsoid as a second order model of the geoid... > we can start comfusing people again. > > -- > > Björn > >> Hi >> >> The gotcha is that the GPS numbers are related to a geoid model and not to >> sea level. >> You can indeed find points that are âunderwaterâ based on the geoid, >> but quite dry in >> real life (and vice-versa). >> >> Bob >>> On May 19, 2015, at 12:26 PM, Demian Martin <[email protected]> >>> wrote: >>> >>> I would buy that (Google Maps being off) except that I'm less than 2 >>> miles from the SF bay and -5M would have me underwater. That may well >>> happen but not for a few years at least. Also the Arbiter does match >>> Google maps pretty closely. It doesn't really matter a lot, just a >>> curiosity. >>> Demian >>> >>>> Date: Mon, 18 May 2015 18:12:58 -0400 >>>> From: Bob Camp <[email protected]> >>>> To: Discussion of precise time and frequency measurement >>> <[email protected]> >>>> Subject: Re: [time-nuts] Thunderbolt Height Error >>>> Message-ID: <[email protected]> >>>> Content-Type: text/plain; charset=us-ascii >>> >>>> Hi >>> >>>> The simple answer is that Google maps may or may not be correct. There >>>> are a lot >>>> of examples of them being off by 10M or more. That said, my *guess* >>>> would be that the >>>> Thunderbolt is closer to the truth. >>> >>>> Bob >>> >>>> On May 18, 2015, at 2:34 AM, Demian Martin <[email protected]> >>>> wrote: >>>> >>>> I have 2 GPSDO's. A Thunderbolt and an Arbiter 1083A. The Arbiter is >>>> old but >>>> it works fine (and has a Wenzel 5 MHz streamline oscillator in it). It >>>> has >>>> the 1995 firmware issue, and I could get new firmware for it ($$) but >>>> I'm >>>> not using it as a clock, just a frequency source. >>>> >>>> >>>> >>>> I just moved and have re-setup both. They share an antenna. I got both >>>> to do >>>> a self survey. The Arbiter was really close to what Google maps >>>> indicate is >>>> my location. The Thunderbolt was about the same except it has me >>>> underground. The arbiter has the height as +30M. The Thunderbolt as >>>> -6M. >>>> What setting do I have wrong in the Thunderbolt? Would it affect the >>>> operation as a frequency standard in any way? >>>> >>>> >>>> >>>> >>>> >>>> Demian Martin >>>> >>>> San Leandro, CA 94577 >>> >>> _______________________________________________ >>> 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. >> > > > _______________________________________________ > 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.
