[Loadstone] Loadstone and GPS query

David Tanner david-tanner at peoplepc.com
Wed Aug 16 05:01:27 BST 2006

Based on what you are saying here, if you were trying to identify and find several stores in a strip mall would a person be able to identify each store if they were within 15FT to 20FT of each other?

----- Original Message ----- 
From: "Monty Lilburn" <monty at loadstone-gps.com>
To: "General discussion pertaining to the Loadstone GPS program" <loadstone at loadstone-gps.com>
Sent: Tuesday, August 15, 2006 9:51 AM
Subject: Re: [Loadstone] Loadstone and GPS query

: Hello Brett,
: OK, you have a few things going on here that probably aren't helping much.
: First off, are you running the latest version of Loadstone (V0.62).  It's 
: best to always be running the latest version as that is normally what any 
: support will be for.
: The first problem it would seam you are running into is your value in the 
: Max Search Radius setting.  I suspect you have it set to the old default 
: of 20000 KM which effectively is the entire world.
: From the documentation:
: Nax search radius = When you use a function that requires Loadstone GPS to 
: determine the location of a Point, it searches for the nearest point using
: a vectored search pattern. It begins searching with a rather narrow radius 
: and progressively widens the search field until it finds a point. The 
: maximum search radius value determines how far (in kilometres) Loadstone GPS
: will  search until it stops. At the moment there is not a method of stopping 
: the  search while in progress so it is advised to keep the value as small as
: possible  without compromising usefulness.
: What is likely happening here is you you only have a couple of points in 
: your database and if you search in a direction where there aren't anymore 
: points it will keep searching until it rounds the globe and approaches 
: your other point from the other side.  To help this you should use a much 
: smaller value in the Max Search Radius setting.  If you only have a couple 
: of points you could even set it as low as 10KM or something like that and 
: it will be quite quick.  I have lots of points and find that 200KM meets 
: my needs very well.
: Another thing to note in the test you performed is that the points you 
: created are very close together.  Most GPS receivers have a best accuracy 
: of 3-5 metres  so it's quite possible that even though you walked 5 metres 
: down the platform that both of your created points  could be much closer 
: together (even right on top of each other in theory)!  Remember when you 
: create a point the actual physical coordinates of that point could be 
: anywhere in the accuracy radius (3-5 metres) in any direction.
: I suspect the other thing that might have happened is that the Last 
: Position recorded  by Loadstone prior to disconnecting the GPS will not be 
: identical to the second point you created.  This is because All SiRF3 GPS 
: receivers have a bit of drift when standing still.
: In general what you should expect from GPS technology when thinking in 
: terms of train platforms is that if you are lucky and created a well 
: positioned point you should be able to know what platform  you come in on 
: the next time you enter the station and if you create multiple points you 
: should perhaps be able to identify the top and the bottom of the platform 
: but probably nothing like being able  to identify each train car or 
: anything like that!
: Please let me know if you require further clarification and keep us posted 
: on your progress!
: Best Regards,
:   Monty
:  On Tue, 15 Aug 2006, 
: Brett wrote:
: > Hi all,
: >
: > I don't yet have a bluetooth GPS receiver, but am intending to get one.
: >
: > Anyway, I met up with a friend of mine at the train station on the way
: > home from work, he has a bluetooth receiver, which he uses with
: > StreetTalk. I wanted to give it a quick try with Loadstone, I got it
: > connected with out any hassle and marked a POI, I then walked about 5
: > meters down the platform and marked another point. I disconnected my
: > friends GPS receiver as his train arrived.
: >
: > I started playing with the exploration mode, and while trying to find my
: > closest point and the direction I would have to travel to get to it.
: > Anyway, both of the points I marked are moving around in a clockwise
: > circle. I have no GPS receiver connected and would have expected that
: > Loadstone would remember my last position and looking around, I would
: > have been able to find the other point and that it's direction would be
: > static. However, Loadstone seems to think I am somewhere in the middle
: > of these two points and both are gradually moving clockwise. It takes
: > about a minute and a half for one point to move from north, all the way
: > around back to north.
: >
: > Is this suppose to happen? If so, how can you reliably determine the
: > direction you should be travelling in, when the direction of the point
: > keeps changing according to loadstone. If this isn't the way these
: > things are suppose to work, do you have any ideas what the problem could
: > be?
: >
: > The bluetooth receiver is a Globalsat BT338 which is a SiRF3 one, if
: > that makes a difference.
: >
: > Hope this message makes some sense and thanks for any advice,
: > Brett.
: >
: > Pretty cool that the world can spin with out me even having a drink,
: > Smile.
: >
: >
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: > Loadstone at loadstone-gps.com
: > http://www.loadstone-gps.com/mailman/listinfo/loadstone
: >
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