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Back in December I asked this question of IGN as to how the Long/Lat ties up. This is the question and answer I had. Good luck! In the U.K. it's a doddle, just go to the units via Main menu, etc. as below and select Ord Srvy GB for the map datum and British Grid for the position format and you are there, where ever that is?

>I am sorry that this question is in English, but I just moved to France
>and I am learning to speak French and the writing will come later.
>I am tyring to find out how to use my GPS with the 1:25000 Série Bleue
>Intinéraires de Randonnée. Can you tell me what setting I have to use for
>the ''Position format'' and the ''Map datum''. The GPS is a Garmin Etrex
>Vista.
>Thank you,
>John

Hello

we are trying to answer your question and we hope the explanation in french
will be agreable to you

Il faut parametrer votre GPS Carmin comme ceci : UTM ZONE et WGS 84.
Sur la carte TOP 25 ou serie bleue compatible GPS le quadrillage
correspondant aux coordonnees WGS 84 est dessine en bleu.
Kind regards - Cartotheque CLB    ?

I think it means that in the Main menu, Setup options, Units, Map datum take the WGS84 option, but not tooo sure on that yet 'cause I ain't had chance to try it properly.

John.

 

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I had the same question and got the answer via a GPS user group bulletin board.

The IGN maps work on WGS84 like most others and you set it to UTM using the Units Screen in the Setup page of the Main Menu

The Position Format is set to UTM UPS on the Vista and the Map Datum to WGS 84.

In the UK it is set to British Grid and Ord Srvy GB respectively exactly as John says.

I have used it in France and it is so much easier using the settings above as the IGN grid square (shown on the maps in blue as indicated in the reply to John's e mail to Cartotheque) is a kilometre (if I remember correctly) whilst the latitude and longitude lines are much more widely spaced so harder to measure by eye.

It is incredible how many map datums there are!

And, no, the Vista does not actually make tea, but if you know the location of a tea shop it can help you find it!!! Good news is that it does not actually drink the tea although it eats batteries.

I have been working out some walking routes this evening and plotting them on the IGN maps. Then saved them and did the editing - re-naming etc so you can tell which route is which and then I downloaded them into the GPS so when I next go I will have it ready to use. Can't wait to get back to the Var - only 8 weeks now!

You can save the routes on your PC - they are quite a small file size - so that you can share them with others. I will not do that until I have actually walked them though. If anyone with a Garmin GPS would like copies of walks around Collobrieres (83610) let me know and when I have checked them out I will make them available. I will also eventually put together some for the Verdon Gorge but that is a long term project.

Andy

 

 

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Many thanks to Andy and John. When I received my Vista this morning I was slightly worried as to the usefulness of Lat and Long. Now that I know how to put in the grid reference I am reassured. I stood by the window and searched. The grid reference indicated that I was in my own house. I looked up and there was my daughter - so it was right! Phew, and to think that without this valuable aid I could have been in someone else's house by mistake!

But seriously this is going to be very useful, and if, like all my other electronic gizmos, I can only remember 10% of what it does , never mind. At least it will settle those arguments I have with my wife." How long was that walk?" "Er, about 5 miles." "What! it was at least 10!" I'll just have to remember to switch it off half way round.

Thanks once again.

Patrick

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Hi Patrick,

This posting is a breath of fresh air compaired to some that are floating around at the moment (hot air rises?). If the distance is questionable there are always those trees?! If you get lost in the Aude just e-mail me I might just be able to provide an aliby (?) . Your Vista didn't take long to arrive!!!

Our new house is on the edge of some serious garrigue and we will be walking the legs off of our chocolate labrador. My Vista, it is going to earn it's living. We get the keys in 3 weeks from today, less 12 hours (who's counting?)

Good luck and safe walking, but remember it's only accurate to within about 5 metrik yards so if you are on a sharp ridge back in fog? (definition --- 1 meter = 1 yard +10% inflation!)

Take care and keep in touch,

John.

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John I could not have said it better myself. I almost dropped out of this bulletin board due to the predisposition of some to back biting etc but glad I persevered. After all we all (?) went into this to share info and our love of France rather than to score points.

Good luck with your house move.

We only have a holiday home at present but look forward to the day when we can spend more time in France. A few more years work will do the trick. In the meantime we spend as much time as we can there and I have even been able to negotiate a week at the end of June purely devoted to hiking and biking so I will be recording as many routes as I can and, if they are interested, I will pass them on to the village Tourist Office.

Patrick, good luck with the hiking - where are you by the way?

As John says, don't rely on accuracy when approaching cliffs in fog! Actually accuracy will improve dramatically when EGNOS/WAAS comes on line properly - it is overdue already so surely not much longer.

If I am ever in the Aude I will give you a call John

Andy

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Hi Andy, John,

I absolutely agree with both your comments. You have both been incredibly helpful. I think this forum is brilliant, despite the occasional back-biting. I have received so much helpful advice on a variety of different subjects. It restores your faith in human nature. Given half a chance I think that most people like to be helpful and supportive to their fellow man. Ooooh, I think I might be sliding into philosophy here - a long way from gps!

Yes the Vista did arrive quickly. Ordered at 15.30 on Thursday, arrived at 09.00 Friday. I took it for its first outing yesterday - great fun, even if I'd only mastered the odometer bit. But you know what's coming - yes, another question! When it loses satellite contact, because of trees or whatever, does it "catch up" when it regains contact? What I mean is can you assume the distance walked to be accurate? I found it interesting that although we ascended a total of 1000feet, we only came back down 800 feet. So, apparently, we're still 200 feet in the air somewhere!

In answer to your question, our place is in 58. A holiday home at present, although I spend about 4 months a year there currently. But in a couple of years if all goes well it will be our permanent home.

My very best wishes to you both.

Patrick

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Patrick, I am not 100% sure but I think that it does measure the distance between the points at which the signal was lost and regained. However it might be a direct line between the 2 points rather than completely accurate since it has no way of knowing whether you diverted from a straight track. If you find out for certain what happens let me know!

When you download the 'breadcrumb trail' onto your PC to compare where you actually walked with where you planned to walk - i.e. trail as against track - it just joins up any missing parts (or so I am told as I have not actually done that myself yet).

I also believe that if you are out of signal for a long time the unit can get confused to the extent that you have to turn it off and on again. That is what our instructor said anyway, although it has not yet happened to me.

Hope that helps

Andy

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Very interesting thread. The one thing I would add though, is that (IMO) a GPS is no substitute for being able to read a map.

I have a Garmin Emap which is about 4 years old and I have ordered the CD Rom from IGN to cover my area around Puy de Dome to help plan a few more routes.

However, if I am honest, I do find that the GPS is more of a toy than a necessary tool, and I find myself using the map most of the time as I usually get asked questions like "what is the name of that peak over there?", something I couldn't answer by just using the Garmin.

Still, I look forward to receiving the CD and plotting some routes on my laptop. One thing I would like to know, is whether there is a better (newer) unit I should use or if my old Garmin Emap will be able to cope with downloading the CD information. I understand that I can only get waypoints and routes but is it worth upgrading to something else? Any ideas?

 

 

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I was a scout leader for a few years and my passion was TRYING to teach young scouts to read maps. They can give you so much information on an area. I found that map reading to them was totally Greek most of the time, as was trying to teach them to tie knots and splice ropes .

OS maps are far better than the IGN, in fact they are the best in the world on sale to the general public. Never the less IGN has done a great job and without them getting around would be a lot more difficult. I've never yet found that the batteries go flat either .

I collect maps and when we moved over here we had a fairly large box full, so I can only agree with you Wizzer.

Wizzer if you have a look at the web sites I posted earlier in the thread I think (!) one of them has a system of part ex-ing. If not there it's on one of the links on here, brain fade I'm afraid?

John.

P.S. Wots (IMO)?

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Wizzer I agree wholeheartedly with you re maps. The most important thing taught on the courses is that the GPS supplements the map - on its own it is misleading and possibly dangerous since if it fails when you are in mist on the mountain you are b-------.

I have no idea about compatibility, but you should be able to find out on the Garmin web site.

Alternatively try gpstraining - details in previous post - as I am sure they will know, or at least how to find out.

John, have you yet figured out how to create a track from waypoints or how to estend a track by adding new stretches with the IGN software? I have no problem in producing the initial track or altering it by dragging waypoints to different positions but I have yet to work out how to qickly convert a string of waypoints to a track. I think you should be able tostart to do it by ticking the required waypoints in the Bibliotheque but not sure what to do after that.

When I go to Collo next I will get my French pal to have a play with it as maybe I am missing something in the Help screens. (or should that be screams)

Andy

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Hi Wizzer.

I've just found the site for the possible part ex if you are interested.   http://www.gpstraining.co.uk/ . I subscribed to their newsletter, which has just popped up on my e-mail and there it was!

Andy I haven't got round to doing anything about the IGN digi maps yet. I had a look at the web site and had a 'bad French day'!!! We live in 11, near Carcassonne, how do I go about finding out what digi maps are available for this area? Single sylibals, English or French pleese. We are 2 and a bit weeks away from signing for our new, to us, house and we are suffering from total brain cell failure!!??

John

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Hi John and Wizzer

GPSTraining are the people I trained with and I gave their web site in an earlier post. They are excellent. They do trade ins but I think that they will only be interested in reasonably up to date models as they tend to use the traded in units for their training days. However they can do good prices.

I have also just asked them the question about distance measured when the GPS is out of signal and will let you know if the answer differs from the guess I gave in the previous post.

As regards a map for your area, John, you can find these on the IGN website. The exact location for your area is http://www.ign.fr/affiche_rubrique.asp?rbr_id=1312&lng_id=FR&GRA_ID=BAY11 I have copied and pasted that from the opened page and it worked OK when I tried it.

Aude Ouest covers Carcassonne but you will probably want Aude Est too - postage is the same whether you order one or two.

We have plans for a long weekend in Carcassonne some time so when we do I will be in touch to see if we can maybe meet for a glass or two. Hope the move goes well.

Andy

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I have just received my Carto Exploreur 3 for Puy-de-Dome (63 Sud) in the post from IGN. I will try and load it on to my PC tonight and report back.....

It will be interesting to see how much I will be able to download on to my Garmin. Being of the old school and having navigated in rally cars for years using maps, I'm sure even if it is successful, I will carry my maps with me at all times anyway!

BTW, IMO means in my opinion!

 

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Re GPS Errors here is some info that I received from Peter Judd at GPS Training which gives an insight. It just goes to emphasise that you should never rely on GPS alone - like any technology it really needs the application of common sense to assess if the results it give are valid!

Andy

Multipath Errors

Why does my GPS tell me I’m doing 600mph?

 

Multipath results when the direct path to your receiver is blocked (by your body, your house, roof, trees, mountains, buildings, etc) and some object REFLECTS the signal from the satellite.  The reflecting surface could be, buildings, mountains, the ground, or any object that happens to be a radio reflector


Multipath are radio signals, which have travelled FURTHER to get to your receiver than they should have.  This can result in your GPS miscalculating its position because the signals may have travelled from feet to miles further to get to you than a direct line of sight signal path would have been.


Multipath can cause longer-term "stable" errors or it can cause your position to wander at varying rates (even thousands of miles per hour if your GPS could follow such speeds).  Sometimes GPS wanderings caused by multipath can cause your GPS to "jump" from one position to another as the multipath signal "comes and goes" and causes your GPS to jump from using one group of erroneous signals to another.

Knowing your exact physical situation wherein you had the "large spikes" in position or speed is of course impossible, because the satellites are constantly in motion and are in different configurations in the sky from moment to moment.


If your GPS does not have a clear sky view** then multipath errors are possible, even likely.  These multipath errors can often cause both position and speed "spikes" on any consumer GPS receiver.  EVEN IF you have a clear sky view, multipath is possible, but the possibility of multipath errors are at least minimized with a clear sky view since it is probable that the GPS will have more than the minimum 4 satellites in view and can perhaps throw out the "bad" measurements.  NOTHING here should be construed to suggest that a "clear sky view" would always eliminate multipath or position or speed excursions under all circumstances.  These multipath errors are just the nature of the technology at this point.

** A clear sky view means that the GPS can see in roughly a hemisphere of clear sky.  That is:  Your GPS antenna is unobstructed in ALL directions.  For these reasons, an amplified external GPS antenna accessory may be desirable in a particular situation.

Joe Mehaffey

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Guys,

If any of you are interested in more details on how GPS works ,Trimble - one of the major developers - have some readable (i.e not reliant on jargon) stuff on this site - http://www.trimble.com/gps/. It is a bit dated but the basics are still good.

There is also some decent explanations on Garmin's web site http://www.garmin.com/aboutGPS/ but that is a bit more sales orientated (i.e tends to gloss over some of the shortfalls of GPS).

Then there is  a "real anorak" site in French and English at http://www.gpspassion.com/fr/Default.asp.

If any of you have any specific questions on the satellites and how the network works I would be happy to see if I can answer them for you.

rgds

Hagar

 

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Hi Hagar,

I'm going to be careful about any sites you post in future. I've just spent about an hour on the Trimble site. As you say, simple, but it has taught me a few things. Especially surprising was the satalite orbit height! I wouls still like to know how they sync the GPS clock in the first place, someone with an egg timer perhapse ?

John.

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I previously asked a question about whether the GPS receiver can make up lost distance when it loses satellite contact for a while. My experience today may clarify this [or possibly not!]

I went for a wander up to the shops. I took my Garmin with me on the basis that having lived here for only 25 years I might lose myself. I noted the distance to the shops and walked back using exactly the same route. At one point the Garmin lost contact and when it regained contact it "jumped" to make up the distance on the odometer. When I got back home I noted that the distance out and back was identical. So it would seem that, as you pointed out Andy, it simply assumes a straight line where data is missing. Or does anyone know anything different?

Now where's my Garmin, I need to go out to the shed.

Patrick

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I have downloaded my Carto Exploreur 3 on to my computer, which was all fairly easy, as was plotting and moving waypoints. What I can't do is convert these waypoints into routes - did anyone find out how to do it?

As a computerised map it is very interesting (particularly the altitude tool) but I don't know how accurate it is - when I move the cursor to Puy de Sancy, which is marked as 1885m on the map, the altitude tool shows 1860m. Also if I click on a contour and follow it, the height changes! Still it is good fun to play with. Boys with toys eh?!

 

 

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[quote]Hi Hagar, I'm going to be careful about any sites you post in future. I've just spent about an hour on the Trimble site. As you say, simple, but it has taught me a few things. Especially surprising w...[/quote]

My Apologies Jon - but it is quite fascinating isn't it.

The satellites themselves have atomic clocks on board - these are regulated from land based control stations. These are the most accurate timepieces available.

The GPS receiver obviously doesn't have such an accurate clock so they use a very clever trick to synchronise the recievers with the satellites. The whole system is based on the time it takes for a signal to reach the receiver from the satellite. Taking signals from three satellites gives you a unique position on the globe.  If you then take a signal from a fourth satellite it should simply confirm the original position. If however the receiver and the satellites are not using exactly the same clock time then the fourth signal will not match the position from the first three. With some clever trigonometry and a bit of algebra we use the "error" from the fourth signal to work out the actual error in the reciever's on board clock.  The receiver's software then applies the correction to its clock and recalculates the position using the correct time. Simple No !.

This is why you need signals from 4 satellites to generate a 3d position when simple trigonometry suggests you only need 3.

Interesting when you think that the greatest breakthrough in navigation was John Harrison's invention of the marine chronometer in the late 18th century.

Here is another site for you http://news.bbc.co.uk/1/hi/sci/tech/1864737.stm

"Even today Harrison's legacy remains very much alive. "What H4 was doing is still current today because in GPS, for example, accurate time standards are required for navigation," said Jonathan Betts. "You'd be surprised how clocks rule our modern lives." "

I going to take my anorak off now.!

rgds

Hagar

 

 

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Wizzer - I finally figured it out last night.

You enter your waypoints individually and then create a new route in Bibliotheque. Then there is a button to add waypoints to the route. You need to have named them as you have to enter them in the right order. It appears that you can add any of the waypoints you have previously created on other routes so, for example, I will set up a waypoint outside my front door and call it, for example, France Home and then use that as the start for all local walks. In other words a waypoint is entirely discrete and does not only exist as part of a particular route.

I have only done it the once and that as a trial exercise and there may well be quicker ways to do it.

Andy

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I'm with you up to where you add the waypoints Andy, but I can't see which button adds them to the new route in bibliotheque de routes... Which button is it?

Hmmm, well I have now worked out how to add the waypoints to the route but I want it to follow the marked paths, rather than draw a straight line - I'll have to play around a bit more I think...

 

 

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Wizzer I am at work at present so  don't have the mapping in front of me, but once you have clicked for a new route in biblio de routes there is a button in that box to add waypoints. I will have another crack at it tonight if I have time and post again then

 

Andy

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Re last response here is how to do it.

CREATING ROUTES FROM WAYPOINTS WITH IGN CARTO 3

 

  1. Place your waypoints on the map and name them (Right Click on Waypoint, open Proprietes and then name it) I suggest that you initially name them with a number in order of the route you want)
  2. Open Bibliotheque de Routes (BdR)
  3. Right Click in the BdR screen and click on Nouvelle Route – Name it.
  4. Right Click on the new Route created. Click on Details to open the Details de la Route screen.
  5. Close BdR
  6. Open Bibliotheque de Waypoints (BdW)
  7. Drag the waypoints you want (Left click and hold down whilst dragging) into Details de la Route in the correct order. New Waypoints can be inserted anywhere in the list. If you put a Waypoint in the wrong place in the list you can move it up or down using the up and down arrows in the Toolbar – next to the red cross.
  8. You now have your route!
  9. When deleting a route take care not to delete waypoints which also form part of another route

Hope this helps. I am sure it is in the Help pages if your French is good enough to translate them, but mine is not so it is trial and error mostly.

 

Andy

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Hi all,

I'm glad the stroppies ain't found this thread! Thank's for the gen on the routes. My Carto Ex. 3 arrived yesterday, both 1/2s of the Aude. As has been said, just the same as the paper jobbies. I haven't worked it out yet, but if you were to buy all the paper maps to cover the digi type you wouldn't be too far short of the same price. Quite a surprise...

I have copied you instructions for the routes. My French is not up to sorting things like that yet in the help pages, but we wll get there?! Once you have a route, if it is for road navigation, how do you get it to follow the roads, or does it do that anyway. I have not had chance to see if it does that yet and it may well have to wait for a while to try it, because Frances, my better 3/4, insists that our impending house move takes priority! No sense of humour? One thing about walking around here is that if you walk alongside the Canal du Midi even I don't get lost, very often...

Lunch calls,

John.

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Hi John

Once the stroppies arrive I'm outa here as they say; I can't be bothered to give pettiness room to develop.

On to more important matters!

Have you noticed how the digital map sheets change colour at the borders between the paper versions. Must be because they have digitised varying paper editions in which the colours of the originals differed. Weird but I have got used to it. This is an area where IGN are way behind Ordnance Survey.

I have never used this unit for road navigation so I cannot reply authoritatively on that. Hopefully someone else knows the answer.

My guess would be that, provided the unit can 'see' the sky, or has one of those fancy aerials (which I have not - can anyone tell me where to get them and how much they are?) then the direction arrow will point you the right way at each waypoint. However, on my course it was recommended that in fact you set the waypoint a little before the turn so you know before you reach it to start looking for the track going off ahead. In a car at speed I expect that advice is even more appropriate.

I think that in practice there are much better units for navigating when driving - the Vista is really designed for hiking and biking.

Good luck with the move - let us know how it goes.

Andy

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