rad0 <rad0@ATTBI.COM> wrote:
> Dave Tweed <pic@DTWEED.COM> wrote:
> > Russell McMahon <apptech@PARADISE.NET.NZ> wrote:
> > > Speed can be deduced from position variation with time BUT you have a
> > > speed signal already available based on phase shift of received
> > > signals. It would be trivial to use this for a speedometer function
> > > and you could add code to make an informed decision about whether
> > > something "intetresting" was happening.
> > >
> > > Given that it's so easy to try, why not try it and see how it works out.
> >
> > Trivial? Easy to try? What kind of receivers do you have access to that
> > provide phase information?
>
> pardon me, but doesn't the gps give velocity in knots?  Is this completely
> useless?

Of course it does, but it's computed from successive positions. You seemed
to be implying that you could do better "based on phase shift of received
signals." That's the aspect I was questioning.

The very high accuracy "kinematic" receivers used for precision surveying
do in fact measure carrier phase, but these units cost thousands of dollars
and are not the type of thing you'd use for a "GPS speedometer".

-- Dave Tweed

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body