[Loadstone] approach announcement

Shawn Kirkpatrick shawn at odyssey.cm.nu
Thu Aug 9 02:45:09 BST 2007


It's working right. I'm not sure what our docs say about the max approach 
distance setting but it should probably say something like "do not change 
this, ever!" and it should probably say it with belles and whissles and 
flashing lights. The approach time setting is the one to change. The max 
approach distance is only used as a fall back if the approach time 
failes due to a very low speed that stops the unit from registering that 
you're moving. If you start setting the distance setting to a high value 
then it'll be larger than the time based calculations and won't work 
propperly.
The system works by calculating a radius around each checkpoint. That radius 
is calculated based on your current speed, the approach time in seconds, the 
current gps accuracy, and the accuracy at the time the point was saved.
When you enter the radius of a checkpoint then it's announced. If the points 
are close together or you have the approach time set high then these 
radiuses can overlap and you get multiple points being announced. The max 
approach distance is basically a minimum of what that calculation can be. 
Since accuracy is figured in to the calculation the results can change 
depending on drift and if you're receiver is having a bad day or if you're 
in an area where the receiver's accuracy is pour.

On Wed, 8 Aug 2007, Dave Mielke wrote:

> [quoted lines by Shawn Kirkpatrick on 2007/08/08 at 17:09 -0700]
>
>> This is pretty much what it does. The checkpoints just work on distance and
>> announce the closest one. If you have points close together then you might
>> bounce between them mainly because of gps drift or changes in approach
>> angle.
>
> I'm not sure it's working right, then. I tried (as an experiment) setting the
> Max Approach Distance really high and it started to try to announce a whole lot
> of points at once, some of which were much farther away than others.
>
> Perhaps the problem is that the software reacts too quickly when deciding that
> the current motion is away from the selected point. Perhaps waiting a couple of
> seconds to be sure would resolve it.
>
> Speaking of the Max Approach Distance setting, I've noticed something else.
> When I set it to 10 then it typically gives the announcement when the distance
> is around 40. When I set it to 45 then it announces when the distance is about
> 90. At least the announcement itself contains those higher numbers. I'm not
> sure, but I suspect I'm actually much closer to the point than the number in
> the announcement. I tried with all three distance units and the result was
> always the same.
>
> -- 
> Dave Mielke           | 2213 Fox Crescent | I believe that the Bible is the
> Phone: 1-613-726-0014 | Ottawa, Ontario   | Word of God. Please contact me
> EMail: dave at mielke.cc | Canada  K2A 1H7   | if you're concerned about Hell.
> http://FamilyRadio.com/                   | http://Mielke.cc/bible/
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