On Sat, 1 Nov 2003, Mighty Chimp in USMA:27391 wrote: > I understand the GPS system is not metric and that the Europeans > are working on a new system for civil use that will be metric. > Any one aware of this?
Hello Euric, I'm aware of GPS and Galileo, but am not aware of any meaningful sense in which "the GPS system is not metric." As Joe Reid correctly pointed out recently [USMA:27210], GPS is operationally unit-neutral, at least as far as users are concerned. That is, it's up to the individual GPS receiver to process the incoming satellite signals and compute location/velocity/etc., and as part of this (considerable!) processing, that information can be transformed with respect to whatever coordinate system, datum, and distance units are desired. And I've never seen or heard of a GPS receiver that didn't speak metric, in that sense. (As for any unit-specific data used *internally* by the system [say, the orbital parameters from which the receivers compute their (pseudo)ranges from the satellites], I'd be very surprised if any such units were non-metric, but I don't have solid information to know for sure. I can think of 'non-meaningful' ways in which GPS might be 'not metric' -- for example, I'd believe it if someone me that some of the satellite parts were machined to inch sizes -- but I doubt that's what you mean here!) If you have any information that suggests that GPS isn't metric-friendly, or that Galileo will be more so, I'd be interested to hear about it. > Info I found online: > > Galileo is intended to complement (or is the correct word compete with? - > Euric) the existing satellite navigation system, which relies entirely on > GPS, the American Global Positioning System. Good point you insert there! Probably "complement" and "compete with" both apply: One hopes that both systems will always be available to everyone, and that their parallel operation will provide even more reliable and accurate positioning data than we have now. But no small impetus behind the Galileo system is a reluctance to base all that civil infrastructure on a system ultimately controlled by the US (military), US assurances of perpetual availability notwithstanding. Bruce H.
