[Loadstone] Loadstone seizing up

Cearbhall O Meadhra cearbhall.omeadhra at idd.ie
Sat Mar 17 01:30:25 GMT 2007

Thanks, Sean,

You raise some very interesting points.  

Firstly, I think we can discard any thoughts of inaccurate data as we
checked the co-ordinates in the points file with the co-ordinates displayed
under an aerial picture of the location. They matched perfectly. The
co-ordinates are available to us in ten decimal places but we are only
taking seven because that seems to be the max. that Loadstone will take.

I am interested in the drift idea. I have been complaining to Aedan and
Ronan since we began this work that my front door swings up to 30m away and
comes back again whilst I stand still. This is, I understand, more likely to
happen when standing near a vertical wall such as the front of a house.
However, it also happens when I stand on the Bray seafront where there are
no buildings for 100m around!

I had not understood the importance of the accuracy setting. I keep this to
zero in our points file. You point out that a zero setting will limit
Loadstone to an accuracy of 50m. That alone could explain the problem. What
is the highest value that the accuracy setting can have? I think we should
et our accuracy to that figure and see what happens.

I have not changed the default settings for anything except the max range
which I now keep down to 10k. I also carry the Holux receiver on my shoulder
tucked into the collar of my jacket so heavy
Clothing is not an issue.

I shall try out the points which you have highlighted and report back. Let's
hope I come back with full enlightenment and a face-splitting smile!

All the best,
"Good design enables - Bad design disables"
Tel: 01-2864623 Mob: 08333 23487 Em: secretary at idd.ie

-----Original Message-----
From: loadstone-bounces at loadstone-gps.com
[mailto:loadstone-bounces at loadstone-gps.com] On Behalf Of Shawn Kirkpatrick
Sent: 17 March 2007 00:10
To: General discussion pertaining to the Loadstone GPS program
Subject: Re: [Loadstone] Loadstone seizing up

You could be dealing with a few things here. The first is the accuracy of
the data. If you save a point using loadstone then the latitude and
longitude values are saved with 7 decimal places of accuracy. If you're
getting data from other sources then it may not be that accurate. Sometimes
the source will say what the accuracy is but not always. If that's the case
then the accuracy column for those points is set to 0. When that happens the
accuracy is defaulted to 50 meters when doing calculations for the
checkpoint announcements. Add all this to normal gps drift and things can
start to go wrong. This will also depend on what you have the approach time
and distence settings set to. If you change the defaults, especially the
approach distance, then things tend not to work right. The best way to
change the approach alarm is to use the approach time setting.
This also could be your gps receiver. Every time we've gotten reports of gps
receiver trouble it's been a holux. One way to test the drift of the
receiver would be to stand somewhere and make sure you have a good signal. 
Then save that position as a point and then press the select key to see how
far you drift from your actual position. You might get better results
depending on how you carry the receiver. If it's in a lower pocket or
covered by heavy clothing etc. it might effect its accuracy. You'd have to
experiment with this.

On Fri, 16 Mar 2007, Cearbhall O Meadhra wrote:

> Thanks, Monty,
> I completely agree that if we do start anything we should work closely 
> with your team in order to reinforce the quality of the work.
> I am struggling with a new problem now.
> I have found that the Loadstone is announcing what it seems to think 
> are current locations but that are actually around 100m away from me. 
> I have checked the long. And lat. that have been input to the database 
> and these are definitely correct when matched with aerial photographs 
> for the same co-ordinates.
> This suggests that the  problem must lie in the Loadstone program or 
> in the Holux GPS receiver.
> Could there be any setting in the Loadstone program that would cause 
> this error?
> Have you any idea how I might check the calibration of the Holux 
> receiver in case that is the cause?
> All the best,
> Cearbhall
> "Good design enables - Bad design disables"
> Tel: 01-2864623 Mob: 08333 23487 Em: secretary at idd.ie
> -----Original Message-----
> From: monty at loadstone-gps.com [mailto:monty at loadstone-gps.com]
> Sent: 16 March 2007 10:35
> To: Cearbhall O Meadhra
> Subject: RE: Loadstone seizing up
> HiCearbhall,
> It looks like something screwed up when I attempted to reply to 
> another message and it may have accidently gone to you by mistake.  
> Sorry about that!
> Anyway, the project is open-source so you and the rest of the world 
> are certainly welcome to download the code and may use it under the 
> terms of the GPL.  Not that anyone has done it yet, but we would also 
> welcome patches or improvements.  Let us know if you are doing any 
> development so we can work together!
> Check out the download page on the web site to grab the code.
> Best regards,
>   Monty
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> Loadstone at loadstone-gps.com
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