Guest jimjann Posted September 3, 2001 Share Posted September 3, 2001 I hope this question is not too repetitive. My Map 330, with WAAS and several minutes of averaging, never seems to settle on one position reading. We did a check today with the 330 and our eTrex Summit. We let the 330 average while we took several readings with the Summit. Between each reading we turned the unit off, walked about 200 feet away from the starting point, and turned the unit on. Then we walked to the starting point and took a reading. The range of latitude varied from .491 to .497 and longitude varied from .693 to .702. During about a 45 minute period the 330 showed .494/.695, .497/695, and .501/.695. I realize these variances are not great but what number comes closest to representing the best reading? Why? Thanks. Quote Link to comment
Guest tedoca Posted September 4, 2001 Share Posted September 4, 2001 I'm far from an expert but from my limited experience and what I have read here in the forums this is how I would approach it... Your lat readings range from a low of .491 to a high of .501. If you throw out the high and the low and average the remaining readings (.494, .497, .497) I'd say you'd come up with a figure of .496 for your final reading. Your lon readings were: .693, .695, .695, .695, so I would use .695 as my final reading. There's really no high and low to throw out here but even if you did throw out the .693 and one of the .695's you would end up with .695 I'm sure someone else can explain it better but that's how I would do it. Tedoca ------------------ Always remember to burp your tupperware! Quote Link to comment
Guest Markwell Posted September 4, 2001 Share Posted September 4, 2001 Pretty succinct. Can't beat that. Jeremy likes to use a shotgun graph to determine the best coords. It's a pretty neat idea. Here's a graph that would represent this information above, including a purple dot for tedoca's averaged point. I think you're in pretty good territory for the right spot using that set of coords. Quote Link to comment
Guest tedoca Posted September 4, 2001 Share Posted September 4, 2001 Hey Markwell, That chart really is neat, what a great idea! I'm thinking I might just make up a few of those, blank (as in without the numbers), maybe laminate them and use an erasable marker, to plot my coords out on when hiding a cache. Then I'll have a visual representation to look at that just may give me a different perspective than simply looking at the numbers alone. Thanks, Tedoca Quote Link to comment
Guest Markwell Posted September 4, 2001 Share Posted September 4, 2001 Just threw together a good old XY scatter graph in Excel Tough part was getting it to show every increment of 0.001 - but that only took an extra 30 second for this geek. Never thought of taking an empty one into the forest. I'd suggest going out and buying some graph paper. (They do still sell that stuff don't they?) Quote Link to comment
Guest Markwell Posted September 4, 2001 Share Posted September 4, 2001 Just threw together a good old XY scatter graph in Excel Tough part was getting it to show every increment of 0.001 - but that only took an extra 30 second for this geek. Never thought of taking an empty one into the forest. I'd suggest going out and buying some graph paper. (They do still sell that stuff don't they?) Quote Link to comment
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