Thu, 04 May 2000 17:39:08 -0400
Andy Talbot wrote:
> Unfortunately Magellan appear to be the odd ones out on GPS receivers. I
> have a Magellan Trailblazer, circa 1993-4 which is almost certainly similar
> to yours, and there is no trace of a 1 PPS signal inside the unit; I
> searched very hard for it ! In the end I gave up and bought a Garmin GPS25
> module from TAPR. That turned out to be a good move as the device is very
> very much better at locking up (1 minute fom cold instead of up to 20
> minutes) with more info available in the NMEA sentences - and of course the
> 1 PPS.
> Since SA was turned off, over the last two hours the mean position of my
> house has drifted just 2 metres RMS with an absolute worst case shift of
> 3.6m. I reckon that with a locking system like the Shera one and a good
> stable ovened VCXO, a frequency standard to rival Rubidium and verging on
> Caesium accuracy may now be possible. Getting a good enough VCXO will be
> the difficult part.
> Andy G4JNT
> -----Original Message-----
> From: Alberto di Bene <email@example.com>
> To: firstname.lastname@example.org <email@example.com>
> Date: 04 May 2000 16:53
> Subject: Re: LF: GPS Signals Accurate Now!!!
> >While we are discussing GPS, I have a question for all of you.
> >I bought a few months ago an OEM 5000 GPS board, made
> >circa 1993 by Magellan, because someone had told me that
> >on the interface there were available the 1 pps signal derived
> >from the received signals from the satellites, with the accuracy
> >and stability of their Cesium clocks, +/- the SA.
> >I was intending to homebrew something similar to the Shera
> >project appeared in a past issue of QST.
> >I have been unable to find that 1 pps signal, however. It just seems
> >not to be present on the interface. But there is a hope.
> >A few pins do not have signal on them, as seen on the 'scope,
> >but they have traces on the PCB leading somewhere. My last hope
> >is that the 1 pps signal must be enabled by some command to the
> >GPS unit.
> >Can anybody shed some light on this ? Anybody on this list that
> >has experience with the Magellan OM 5000 ? Thanks for any advice.
> >Alberto I2PHD