Re: Air and Water pressure measurements

linnix wrote:
Rich Grise wrote:


But, I'm also thinking; isn't there differential GPS, that can get
within centimeters? How hard would it be to get Z axis information from
their signals?


DGPS can get millimeter precision within small areas. Horizontal, at
least. I know that GPS favors horizontal accuracy over vertical, but I
don't really know how much it can be corrected. You could make use of
it by using two GPS receivers and calibrating them at a reference
location, then moving one around to make your measurements. That's how
public DGPS works.

Using a Garmin C320 and sampling hundred points (while eliminating some
points) , I can position horizontal locations within a meter. So,
given enough samplings, horizontal positioning is not a problem. In
theory, vertical positioning is at best 10% of horizontal. I don't
even bother to find out how to get that from my C320.

But if vertical DGPS is comparable to horizontal DGPS, you can get
sub-meter precision at least. Maybe even millimeter precision. Does
anyone here have enough knowledge to say?

By the way, you
have to poll the GPS from a PC. Their great software is supposed to
hide that detail from the user.


So get a couple of handhelds that you can read directly :-).

John Perry
.

Relevant Pages

  • Re: Air and Water pressure measurements
    ... DGPS can get millimeter precision within small areas. ... I know that GPS favors horizontal accuracy over vertical, ... Some handheld GPS devices are cheating - if they think you're not moving, ...
    (sci.electronics.design)
  • Re: GBR21
    ... The GPS 120 is NOT a WAAS enabled GPS, ... You may not be able to tell the difference in accuracy between the GPS 120 with the GBR21 attached and working compared to the GPSMAP76CS when WAAS is in use. ... If you don't have a WAAS capable GPS, then the answer is that a DGPS equipped receiver will produce a smaller error that one no so equipped. ...
    (sci.geo.satellite-nav)
  • Re: New and Better GPS Satellite Launched - Good News, or Bad ?
    ... Spoofing can easily be done right now by generating false GPS signals. ... that the Global Positioning System is Vulnerable to Spoofing" by ... Let's say that Toronto customs folks use a sniffer dog on air passengers ...
    (alt.privacy)
  • Re: Shades of J Orwell
    ... They all come with a GPS sender now... ... Mobile logons can be pin-pointed fairly accurately by triangulating mast signal strengths, but it has nothing to do with global positioning satellites. ... It just means they don't automatically pass on positioning data to 911 centers and potential text message advertisers, which happens by default in most cases. ...
    (soc.culture.irish)
  • Re: PRN01? Still usable?
    ... AVAILABLE FOR FUTURE SATELLITE SERVICE. ... I'm still using it for positioning. ... MILITARY - GPS OPERATIONS CENTER at HTTP://GPS.AFSPC.AF.MIL/GPSOC, ... 2SOPS will typically set the bird unhealthy *before* issuing the NANU. ...
    (sci.geo.satellite-nav)