[Loadstone] Loadstone seizing up

Shawn Kirkpatrick shawn at odyssey.cm.nu
Sat Mar 17 05:56:48 GMT 2007


The accuracy field is a byte so it can contain from 0 to 255. At 0 the 
accuracy defaults to 50 but above the actual value is used. So, if you're 
sure the accuracy of your points is good try setting this to 1. Lower values 
mean better accuracy.
30 metres of drift is quite a bit. A more normal range would be around 15 to 
20. Some receivers are better for this than others thoe. If your receiver 
can get a waas/egnos signal then the drift can be around 1 or 2 metres.

On Sat, 17 Mar 2007, Cearbhall O Meadhra wrote:

> 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,
>
>
> Cearbhall
>
> "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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>>
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