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User Coordinate System Behavior with the 610
May 18, 2012
3:56 pm
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zee
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When I asked Magellan CS if the User Grid Lambert would ever be finished in the Triton, they were stumped, but asked for my model, and would pass on my question to higer ups. No reply, and none to my direct emails to Magellan, or from the special link in the Triton Forum.
The Garmin 60 series lets one setup a modified Trans Merc User Grid, but the Lat is locked in to the Equator. I tried a 62s, but the newer format has a place to put in your chosen Lat, but then I found out that it too, has the Lat locked to the Equator. I returned that unit as it also had a bad "sticky" problem that wouldn't update, if I was moving slow, among other problems. I read where the sticky problem has been "improved", but not fixed. And I don't remember being able to get the 62s to display in feet, only in meters.
Hard to beat the MM, and the older Maggies, for my User Grid use.

May 18, 2012
12:16 pm
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Justmapit
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Zee, thanks for the feedback. Yes, the eXplorist will truncate the unit conversion at the 6th decimal place. However, I'm not looking for survey-level accuracy here, just to get within 15' or so.

So far Magellan has been silent on this question. I sent them an email right after my original posting here. Lots of folks speak well of their tech support, but I've got to say that Magellan's biggest competitor was much more responsive when we put similar questions to them about one of their units we are evaluating.

May 18, 2012
5:08 am
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zee
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I don't have an Explorist, but use an original MobileMapper for State Plane in Utah, both Trans Merc and Lambert con.
On the Unit to Meters the MM will take the full 0.30480061,
but on a Triton it cut off the "1", which shows up as a foot difference when I compared them on the MM. From what I've read, the Exp also cuts off the 1. Big deal they say, but I usually only 2 to 4 ft off from truth, when I visit a nearby surveyed point, under ideal PDOP, ( good sat lineup ) and no sun spot problems.
I always check on what I have entered in the L/L of origin, to see if the unit has changed it on it's own. The Triton was bad about this, not very often with a SporTrac, or Meridian.
Also check that the time/date is correct.
The MM is rare in that one can view, and compare, the difference between WGS 84 and NAD 83 on the position page.
I usually let my units sit out in the open for about 20 minutes before I use them. This lets them download a fresh almanac, get a leap second update, and WAAS time to do it's thing. Also, when I put in 0.01000000 in the Unit to meters, for it to display grid centimeters, it takes about 20 min for the cm's to settle. The SporTrac and Meridian can be set to cm's also. ( along with decimeters and inches )
Fun using the older units, I hope that the Explorist can do the above, and maybe more.

May 14, 2012
6:31 pm
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Justmapit
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Good day all!

I will certainly shunt this question off to Magellan tech support, but wanted to see if anyone on this forum has run up against this issue.

I work for a large airport and our engineering staff uses a US foot-based local grid system that is well defined in terms of its relationship to UTM. We have all the false easting & northing values, scale factor, lat/long of the coordinate system center and use the standard unit-to meter definition of 0.3048006...

We have two legacy Magellan units, a GPS 315 and a Thales Mobile Mapper we used as test units to see if we could get them to return accurate local grid values. The tests with both units was successful - just punching in our known values gives us accuracies +/- 20 ft, well within the accuracy potential of these receivers.

Thinking we wanted to move up in terms of receiver capability we went out and bought an eXplorist 610. However, using the same known values that worked on the 315 and the Mobile Mapper returned wildly out-of tolerance values on the 610. Looking over the returned values it struck me - the receiver is expecting a scale factor calibrated for meters, not feet. Once I reset the scale factor the 610 started returning accurate coordinate values.

It appears as though the 610 is handling the unit-to-meter conversion factor differently than the 315 or the Mobile Mapper, or ignoring it all together. Has anyone run up against this before? Any lessons learned or best practices?

Thanks in advance!

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