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510 won't save waypoint coords correctly
April 11, 2012
2:27 pm
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robertkeehn
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The coordinates do now always change when entering them, I believe this is a rounding bug in the software. The difference between .001 is only about 6 feet, actually less than the accuracy of the GPS unit itself. If you look at the secondary coordinates for the same latitude you will see that it saves it as 40.99607'N and 60x.99607 is actually 59.7642. But if you enter into the secondary coordinate system .99607, it will convert primary to 59.765.

here is a chart of how the GPS does the rounding from decimal degrees to degrees/min

Entered GPS Converted Mathmatically Rounded should be

40.99608 >> 40 59.765 >> 40 59.7648 >> 40 59.765
40.99607 >> 40 59.765 >> 40 59.7642 >> 40 59.764
40.99606 >> 40 59.763 >> 40 59.7636 >> 40 59.764
40.99605 >> 40 59.763 >> 40 59.7630 >> 40 59.763

Now if we convert the other way:

Entered GPS Converted Mathmatically Should be
40 59.762 >> 40.99603 >> 40.99603333
40 59.763 >> 40.99605 >> 40.99605
40 59.764 >> 40.99607 >> 40.99606666
40 59.765 >> 40.99608 >> 40.9960833

So it appears to be rounding correctly when converting from deg/min to decimal degrees. But when converting from Decimal degrees to deg/min something funny is going on.

Try This:

Enter 40'59.764
Click back and you will see it changed to 40'59.763
Now Look at secondary coordinate it is 40.99607'
Now click on secondary coordinate, and then the back button without changing it
And you will now see that the primary coordinate has changed to 40'59.765
Now click on the primary coordinate, and then the back button without changing it.
And you will now see that the secondary coordinate has changed to 40.99608
Now clicking back and forth it does not change anymore

March 20, 2012
3:56 pm
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phild31
Nashua, New Hampshire USA
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Most companies now have programers all over the world doing their codes in bits and pieces, this bug may be considered minor and they haven't given it a high priority.

I have no idea about writing code but I suspect that any coordinates input to the unit are translated to a format like MGRS and then re-translated back to lat/long when you save the waypoint.
I haven't done any extensive tests but it seems to go up one digit when the last digit inputted by a user is 5 or higher.
In other words it's averaging up when it converts lat/long to MGRS & back to lat/long during a coordinate input.
That's just a guess on my part.

In the real world it doesn't make enough of a difference to worry about.
But it is a minor annoyance. :dry:

When in trouble or in doubt, run in circles, scream and shout

March 20, 2012
2:39 pm
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Team Hildy
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Thanks for the reply. I was wondering how much of a difference that digit made. I'm so used to MGRS that I have a hard time interpreting the lat / long stuff.

I wonder why they don't just fix their code if it's a known bug.

March 20, 2012
5:54 am
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phild31
Nashua, New Hampshire USA
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Yes it's a known bug.
One digit off is only about six feet, not enough to cause a real problem because the best accuracy of the units is about 16 feet anyway.

When in trouble or in doubt, run in circles, scream and shout

March 20, 2012
4:52 am
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Team Hildy
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Today was the first time I've had to enter the coordinates for a waypoint manually (usually just download them from geocaching.com).

I made new waypoints three times with no problems. On the fourth try, the Explorist kept changing my coordinates on me. I would type in a 6 for the last digit of my coordinates, XX degrees XX.XX6. Then, when I pressed the back button the coordinates would read XX degrees XX.XX7. It did this every time. I deleted the waypoint, started over, and it did the same thing.

Is this a known bug?

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