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windyn Occasional Visitor
Joined: Nov 13, 2008 Posts: 3
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Posted: Thu Nov 13, 2008 7:58 pm Post subject: Should I use OSGB or BNG |
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Hi All
Newbie here - I am wondering which setting to use for GPS on the Active 10.
I have a copy of Discovery Walking Guides Lake District (North and South) and in their GPS setup advice they say:
"check that your gps is set to the OSGB datum and BNG 'location/position format'"
On the Active 10 there it seems you can set to either OSGB or BNG.
Please could someone advise what setup I should use?
Thanks |
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lightshipman Occasional Visitor
Joined: Nov 11, 2008 Posts: 8
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Posted: Thu Nov 13, 2008 9:13 pm Post subject: |
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You should set your Satmap to OSGB, you get the same result with BNG (British National Grid), the co-ordinates are the same but with an extra prefix which just confuses the matter. OSGB is also the commonly used format. I used to carry out a lot of Marine Hydrographic surveys in my previous employment, and know all about positioning, so keep it simple. I asssume that the OSGB on the Satmap is OSGB36 datum, which dates back to 1936.
Nowadays most GPS systems work on WGS 84 which is the latest International standard, so you will find that your Lat Long positions may not be exact, but it is only 0.08 S 0.03 E out so not really a great deal for our puposes. OSGB mapping is in OSGB36 Datum, so stick to that datum on yor Satmap. |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Thu Nov 13, 2008 9:49 pm Post subject: |
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Welcome to the forum, have a look at page 17 of the full manual which can be downloaded as a pdf from Here What is really needed is a way of going straight from the CD contents that the guide books also have available straight to the SatMap - sadly without quite a bit of messing around this isn't too easy, the slight error described by lightshipman is worth noting though for some of the more difficult walks - Mike |
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windyn Occasional Visitor
Joined: Nov 13, 2008 Posts: 3
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Posted: Thu Nov 13, 2008 10:49 pm Post subject: |
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Hi, thanks for the replies and advice.
I have downloaded the full manual, which IMO is a poor document, but I guess hard to cover all bases.
I have done some looking around about converting routes and am comfortable about conversions etc.. I haven't got the CD's but am looking to use a PC to upload routes to satmap.
Completely different subject, but struggling to find Linux software for this.
The thins that seems to be at odds is the use of a mixture of OSGB and BNG in the walking guides.
Thanks again. |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Thu Nov 13, 2008 11:07 pm Post subject: |
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I doubt you will find Linux based software for the active10 - AFAIK they don't even support Mac.
The coordinates used in the book are a little strange as they do appear to be using OSGB for part of it and Eastings/ Northings for the numbers, the main GPS related book they have in the series appears somewhat outdated and geared to the early Garmin devices - I do have a number of the books which are excellent but the coordinate format lets them down if you are trying to get the best out of a PDA or SatMap device - Mike |
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windyn Occasional Visitor
Joined: Nov 13, 2008 Posts: 3
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Posted: Fri Nov 14, 2008 7:42 am Post subject: |
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Thanks Mike
Not looking for Linux software for satmap, (although) that would be nice), but something to create waypoint routes. Have googled and quite a bit of freeware for Windoze which I am looking at.
Cheers |
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philpugh Lifetime Member
Joined: Dec 28, 2005 Posts: 2003 Location: Antrobus, Cheshire
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Posted: Fri Nov 14, 2008 12:22 pm Post subject: |
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lightshipman wrote: | You should set your Satmap to OSGB, you get the same result with BNG (British National Grid), the co-ordinates are the same but with an extra prefix which just confuses the matter. OSGB is also the commonly used format. I used to carry out a lot of Marine Hydrographic surveys in my previous employment, and know all about positioning, so keep it simple. I asssume that the OSGB on the Satmap is OSGB36 datum, which dates back to 1936.
Nowadays most GPS systems work on WGS 84 which is the latest International standard, so you will find that your Lat Long positions may not be exact, but it is only 0.08 S 0.03 E out so not really a great deal for our puposes. OSGB mapping is in OSGB36 Datum, so stick to that datum on yor Satmap. |
The Ordnance Survey refer to the normal (i.e. AA eeeee nnnnn) co-ord display as the National Grid and most GPS manufacturers call this the British National Grid (BNG) to give it a unique name. The other grid system you describe is actually more logical and consistent in that it does away with the letter changes every 100Kms. Had they (OSGB) adopted the all numeric system then the maths would have been simpler also!!
As to the errors by getting the wrong map datum. Whilst they are minimal (tens of metres around me) they vary across the country as the OSGB grid and the WGS84 grid are not aligned. Whilst you could get by (at a push) it is far better to use the correct datum and co-ord system for the map you are using. The error is sufficient to place you on a different track on some walks - which is potentially dangerous. _________________ Phil |
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mikealder Pocket GPS Moderator
Joined: Jan 14, 2005 Posts: 19638 Location: Blackpool , Lancs
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Posted: Sat Nov 15, 2008 12:27 pm Post subject: |
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I have written some software to convert the Discovery Walking Guides into files that the SatMap SatSync application can use, as I have taken the raw Lat/ Long data which is available on the CD it gets rid of any potential errors due to the coordinate system being slightly out when on the device.
Next is to contact the people who distribute the CD and see if they will add this data format to their disk, they can have it for free. It is a shame they have chosen to list coordinates in a format that was probably compatible with the older Garmin devices (it looks like the book they produce on GPS is specific to Garmin and/ or Magellan and the units shown are a good few years old) - Mike |
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