GPS Forums


Reply
Thread Tools Display Modes

Differential GPS (Yes this is recreational)

 
 
Dave Fawthrop
Guest
Posts: n/a
 
      05-22-2005, 02:54 AM
I hope to survey the position of cup and ring stones on Rombald's/Ilkley
moor and other places in the West Riding to an accuracy of 1m. There are
a couple of web sites which list this sort of thing, and I would wish They
have already been surveyed to 10m and have an 8 figure National Grid
Reference (10m) published in Prehistoric Rock Art of the West Riding
http://www.alkelda.f9.co.uk/wybook1.htm giving details of some 600 of these
stones, of which I have a copy on order.

They are however stones, some less than 1m dia. and 1m high, in the middle
of a featureless heather moor, and the heather is normally knee high, and
if it has not been burned recently to provide food for grouse, can be thigh
high. Searching a 10m square area is a bit of a pain, though much less
of a pain than searching a 100m square.

As my ordinary Garmin Etrex often gives a positional accuracy of 4m, and
other GPS receivers are probably just as accurate. If others have a 10
figure (1m) National Grid Reference and a receiver giving 4m accuracy they
should in theory only have to search a 5m square.

I have got myself a username on http://www.gps.gov.uk/ and am ploughing
through the information there.

Has anyone any experience of differential GPS?

--
Dave Fawthrop <dave hyphenologist co uk>
Beware of anyone posting X-No-Archive yes,
they must have something to hide or something to be ashamed of.
Your task, should you wish to accept it, is to determine *what*.

 
Reply With Quote
 
 
 
 
Dave Fawthrop
Guest
Posts: n/a
 
      05-22-2005, 12:10 PM
On Sun, 22 May 2005 09:51:56 +0100, Dominic Sexton
<{da-sep03}@dscs.demon.co.uk> wrote:

| In message <(E-Mail Removed)>, Dave Fawthrop
| <(E-Mail Removed)> writes
| >I hope to survey the position of cup and ring stones on Rombald's/Ilkley
| >moor and other places in the West Riding to an accuracy of 1m. There are
| >a couple of web sites which list this sort of thing, and I would wish They
| >have already been surveyed to 10m and have an 8 figure National Grid
| >Reference (10m) published in Prehistoric Rock Art of the West Riding
| >http://www.alkelda.f9.co.uk/wybook1.htm giving details of some 600 of these
| >stones, of which I have a copy on order.
| >
| >They are however stones, some less than 1m dia. and 1m high, in the middle
| >of a featureless heather moor, and the heather is normally knee high, and
| >if it has not been burned recently to provide food for grouse, can be thigh
| >high. Searching a 10m square area is a bit of a pain, though much less
| >of a pain than searching a 100m square.
| >
| >As my ordinary Garmin Etrex often gives a positional accuracy of 4m
|
| That is a guesstimate of the accuracy based on the satellite signals
| used by the receiver. It cannot be relied upon. The only way to really
| know the accuracy at a given point and time is to compare the
| co-ordinates reported to accurate co-ordinates for the point.

The OS give have many stations surveyed to a ridiculous accuracy on
http://www.gps.gov.uk/viewpassiverec...umber=C1SE0945
Registration required. This is the one I will use, being a few km from
where I will be working.

ETRS89 Cartesian ETRS89 Geodetic
X: 3764259.283 m Latitude: 53 54' 9.3367'' N
Y: -121892.621 m Longitude: 1 51' 16.8450'' W
Z: 5130708.688 m Ellipsoid height: 426.877 m

National Grid (converted by OSTN02/OSGM02)
Eastings: 409646.018 m
Northings: 445166.928 m
Height: 376.472 m (Orthometric height above MSL, Newlyn Datum)

| >, and
| >other GPS receivers are probably just as accurate. If others have a 10
| >figure (1m) National Grid Reference and a receiver giving 4m accuracy they
| >should in theory only have to search a 5m square.
| >
| >I have got myself a username on http://www.gps.gov.uk/ and am ploughing
| >through the information there.
| >
| >Has anyone any experience of differential GPS?
| >
|
| If you have access to a laptop or PSION 5 you can log the raw data from
| the eTrex and post process it against the data available from
| gps.gov.uk. With 2 to 5 minutes collecting data at each point of
| interest you are likely to be close to 1m accuracy. The longer you
| collect data for the more accurate the end result will be.
|
| See
| http://artico.lma.fi.upm.es/numerico...antonio/async/
|
| and
|
| http://mywebpages.comcast.net/dmilbert/softs/index.html

Thanks Those will take some study.

--
Dave Fawthrop <dave hyphenologist co uk>
Beware of anyone posting X-No-Archive yes,
they must have something to hide or something to be ashamed of.
Your task, should you wish to accept it, is to determine *what*.
 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Buidling A GPS Receiver with Built-in Differential GPS Reception x.anon Global Navigation Satellite Systems 10 09-29-2011 08:31 PM
U.S. DOT Considers Future of National Differential GPS Sam Wormley General GPS Discussion 0 08-04-2007 07:06 AM
Buidling A GPS Receiver with Built-in Differential GPS Reception Stephen Brown Global Navigation Satellite Systems 0 04-26-2006 07:50 AM
Differential GPS data adding noise. Kenneth McManus General GPS Discussion 0 06-03-2005 02:02 PM
Any info regarding Canadian Differential GPS Fred F. General GPS Discussion 1 10-23-2004 04:33 PM


All times are GMT. The time now is 12:42 PM.