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Can anyone confirm that the EGNOS satellite is now transmitting data that is acceptable to Garmin GPSr's ? I seem to remember someone saying that it would be on-line and transmitting valid data as from today.

 

John

 

Age and treachery will always triumph over youth and ability.

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Switch on the WAAS feature on your Legend (if I remember correctly?) and see what accuracy you get. The EGNOS signal is still a test signal until roughly 2004/5 I believe. All that's happened is that the ESTB have changed the signal slightly so that WAAS enabled units can receive it. I'm off out to play now and see what sort of accuracy I get! icon_biggrin.gif

 

Neutiquam erro.

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quote:
Originally posted by Pharisee:

Can anyone confirm that the EGNOS satellite is now transmitting data that is acceptable to Garmin GPSr's ? I seem to remember someone saying that it would be on-line and transmitting valid data as from today.

 

John

 

Age and treachery will always triumph over youth and ability.


 

John,

 

I've done a bit of playing last night and today...

 

without WAAS enabled on my Vista, I have been consistently getting '16 feet' accuracy with a good view of the sky, dropping to '23 feet' or more as the conditions worsen.

 

Last night I put the Vista on the bedroom windowsill (faces East, so sat No. 44 is possible, No.33 obscured by the house) and after giving it chance to acquire data, had the Vista reporting '9 feet' accuracy.

 

I went out this morning, on foot, and didn't seem to be able to 'see' #44, but could get a reasonable signal from #33. without WAAS, the performance was 17 feet, as normal. With WAAS enabled, reported accuracy deteriorated around to 30 or 40 feet until data was acquired, whereupon the reported accuracy was '14 feet'. Whilst this is better than I have ever seen without WAAS, it's not exactly an earth-shattering improvement.

 

I'll need to try it whilst staionary for a period of time to see if it improves over time, and will try to get out to a place not far from here where both #33 and #44 are visible so that i can see if there's any difference in performance.

 

I realise thet this test has been neither exhaustive, nor scientific, but at least it shows that some improvement is to be had with Garmins fitted with WAAS.

 

I'll post more when I've had a chance to collect more data.

 

Cheers,

 

G.

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Did some playing with my Garmin GPS V tonight. Enabled WAAS, and sats. 33 and 44 appeared, but was only getting a signal from 33, 44 being obscured by the horizon. upto 8 other sats visable, gave an initial 19ft EPE which is normal, after about 7 or 8 minutes, as the unit collected data one by one the sats started to show D, and the unit reported 3D Diferential accuracy, which fluctuated between 6-8ft once all the sats were dialled in.

 

Mark

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quote:
Originally posted by conedxf & family:

Did some playing with my Garmin GPS V tonight. Enabled WAAS, and sats. 33 and 44 appeared, but was only getting a signal from 33, 44 being obscured by the horizon. upto 8 other sats visable, gave an initial 19ft EPE which is normal, after about 7 or 8 minutes, as the unit collected data one by one the sats started to show D, and the unit reported 3D Diferential accuracy, which fluctuated between 6-8ft once all the sats were dialled in.

 

Mark


 

That sounds promising, then. I didn't get a chance to play last night (new PC arrived !!) but I'll have a go tonight.

 

John

 

Age and treachery will always triumph over youth and ability.

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So which sats are the EGNOS sats? Is it only #33 & #44? And how long does one have to wait to see the magical 'D'?

 

I ran around my back garden yesterday with my Venture and got no indication of EGNOS at all. I didn't run around for long though, the neigbours were watching icon_eek.gif

 

There are 10 types of people in the world - those who understand binary, and those who don't.

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There's a lot of 'easy to understand' stuff HERE. I'm not too 'up' on it but I believe that you have to lock onto one of the EGNOS satellites and then wait until it has downloaded the 'Almanac'. I think that when this has been achieved, you get a 'D' indication on the signal strength bars for the orbiting satellites. If I've got it wrong, then somebody will soon point it out. They're like that round here icon_wink.gif

 

John

 

Age and treachery will always triumph over youth and ability.

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quote:
Originally posted by wing-co:

So which sats are the EGNOS sats? Is it only #33 & #44? And how long does one have to wait to see the magical 'D'?

 


Correct, from the UK, the sats 33 & 44 on Garmin receivers are the current EGNOS sats. 33 is the INMARSAT over the Atlantic, so roughly SW on the Sat display, and 44 is over the Med, so roughly SSE and nearer the horizon.

They will only display on your reciever if you have enabled WAAS in the settings.

Based on my experience last night, it takes a while for the reciever to acumalate enough data to start applying corrections (several minutes) and then it seems to apply the correction 1 sat. at a time, so a D appears on one Sat. then another and so on.

 

Good luck

 

Mark

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I was out this evening with my GPS V and it took a long time to get enough data from the geostationary EGNOS sats 33 & 44. Once the data had been collected I got a D on each GPS sat and the accuracy improved to between 8-10 feet (best readings).

 

Andy.

 

----------------------------------------

All our science, measured against reality, is primitive and childlike-and yet it is the most precious thing we have - Albert Einstein

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Thanks for the info.

 

My own experience (lunchtime, 'one foot in the downs') is that it does take a few minutes to spot #33 & #44 and they're both 'low' (so easy to lose). But if you can see them for a while (long enough for an almanac download) you will see better accuracy. I regularly saw 4m on my Venture. I also regularly saw 20m - but that's nothing new.

 

I guess you have to remember that the purpose of EGNOS is not to improve the accuracy of GPS, but to provide a 'proof' that the signal you are receiving is valid and therefore OK to fly your 'plane with.

 

There are 10 types of people in the world - those who understand binary, and those who don't.

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As I arrived early for the cache bash I got a chance to take a look at the WAAS/EGNOS stuff on my Vista. I've previously managed to get the 'D's on my display in the UK, however the accuracy always got worse whenever they appeared.

 

However they certainly seem to have done something to the signal recently as I got an accuracy of 2m after sitting with the GPS for a couple of minutes, and a full house of 'D's after waiting for 5 minutes to get all the corections. The best I have ever got, even in North America is 4m.

 

Richard

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Worth mentioning:

 

EGNOS/WAAS does not transmit positional data only corrections due to atmosphere etc. It will not guarantee better accuracy but will improve your Garmin's estimate of error. So with WAAS enabled, if your Garmin says 10 ft accuracy it is probably within 10 ft.

 

The signal is still a test signal, so if they feel like it they can turn it off or deliberately introduce inaccuracies. I think it's unlikely that they will though.

 

-------

jeremyp

The second ten million caches were the worst too.

http://www.jeremyp.net/geocaching

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OK, chaps. Have now messed with the Vista for a week or so and have noted that once the almanac data is acquired from Sats 33 and/or 44 then a reported accuracy of 6 feet is common, even when travelling at speed. reported accuracy is definitely lower than without WAAS/EGNOS whilst acquiring data, and it doesn't seem to make any difference whether 33, 44, or 33 & 44 are visible.

 

Now I guess that the question is - how long is the almanac data valid for? It appears that the 'D' markers stay visible for a few minutes after loss of the WAAS/EGNOS signal, and are quick to restore when the sats come into view again provided that the signal isn't lost for very long.

 

I'll have to have a dig arouond to see if I can find out more...

 

Regards,

 

G.

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quote:
Originally posted by Pooter:

Is there any limit to how far south you have to be to get a signal because my Vista sat out on a post in the garden (near Glasgow) for half an hour with not a trace of 33 or 44 making an appearance.


 

Pooter, The WAAS/EGNOS sats are in geostationary orbit, so you shouldn't have a problem 'seeing' them, provided that you have good, low-elevation view to the south and east. You should be able to see the symbols for the sats , even if you can't receive the signal.

Don't forget that you have to have WAAS enabled from the setup menu... you should then see (on the sat page) up to (only) 10 'normal' sats, and the 2 WAAS/EGNOS sats - 33 is almost due S, 44 is out to the ESE, closer to the horizon.

 

Give it another go, and remember that to initially acquire the data might take 15 or 20 mins - you should be able to see the'grey bars' whilst this is happening, though.

 

G.

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At the weekend I was getting a reported error of 6 feet on the Legend with a medium/good signal strength from '33' and a D in all the other usable signal strength bars. This was by far the best I've ever seen. I've yet to obtain a signal from '44' though.

Just to confuse things a bit, this lunchtime I had my Legend and my GPS III side by side. The GPS III is not WAAS enabled and was reporting an error of 16 feet (pretty normal for this machine). The Legend, with a good lock on 33 and usable signals on 5 orbiting satellites (with D's) was reporting an accuracy of 30 feet. Both, however, were showing the same lat/long position plus or minus one on the least significant digit.

 

John

 

Age and treachery will always triumph over youth and ability.

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quote:
Originally posted by jeremyp:

Worth mentioning:

 

EGNOS/WAAS does not transmit positional data only corrections due to atmosphere etc. It will not guarantee better accuracy but will improve your Garmin's estimate of error. So with WAAS enabled, if your Garmin says 10 ft accuracy it is probably within 10 ft.

 

-------

jeremyp


 

So you lose a couple of channels (which could be tracking more birds) so that you get more confidence in your EPE. An interesting trade-off...

 

I think most of the time I'd rather have extra sats.

 

Black holes are where God divided by zero.

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As an aside, I was using my map 176c on my boat with Bluechart the other day and it was showing my position to within 10 feet. After going up on deck with it and getting a lock on sat 33, it displayed 4 feet accuracy.

 

This would not actually be relevent if not for the fact that on the Bluechart chart it actually shows the finger pontoon on the chart and on overzoom I could clearly see that my boat was exactly alongside the correct pontoon. With EGNOS off I could never get it to show my boat that acurately.

 

As for channels being taken up by WAAS/EGNOS, I don't ever remember a time when I have had more than ten locks on sats, even in the middle of the sea with clear horizons.

 

I woke this morning and my boat was not rocking...for one horrid moment I thought I lived in a house!

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I am not sure my GPSrs are WAAS comaptible. Can anybody ocnfirm if an eMAp or a Summit are? I think not.

 

Thanks

 

Chris

 

LASSITUDE- (noun) Tiredness and apathy: a state of weariness accompanied by listlessness or apathy[15th century. Via French from Latin lassitudo , from lassus 'weary'.]

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quote:
Originally posted by wing-co:

quote:
Originally posted by jeremyp:

EGNOS/WAAS does not transmit positional data only corrections due to atmosphere etc.


So you lose a couple of channels (which could be tracking more birds) so that you get more confidence in your EPE. An interesting trade-off...

 

I think most of the time I'd rather have extra sats.


I thought the corrections transmitted by EGNOS meant that position is much more accurate. So while the exact distance to the EGNOS sats can't be determined by the GPS, the signals they transmit allow the GPS to more accurately determine the distance to the other sats it's tracking, and hence improve both positional accuracy, and confidence in the EPE.

 

'Course, my trusty old GPS12MAP doesn't do WAAS, so it's all wishful thinking for me icon_frown.gif

 

GeocacheUK - resources for the UK Geocaching community.

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quote:
Originally posted by Lassitude:

I am not sure my GPSrs are WAAS comaptible. Can anybody ocnfirm if an eMAp or a Summit are? I think not.

 

Thanks

 

Chris

 

LASSITUDE- (noun) Tiredness and apathy: a state of weariness accompanied by listlessness or apathy[15th century. Via French from Latin lassitudo , from lassus 'weary'.]


 

No I am afraid that neither of those units are EGNOS/WAAS Chris but hey, what's a few feet between friends icon_smile.gif

 

I woke this morning and my boat was not rocking...for one horrid moment I thought I lived in a house!

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quote:
Originally posted by Iwuzere:

Doesn't the increased accuracy make the game too easy though?


 

No it bl**dy well doesn't... icon_biggrin.gificon_biggrin.gif

The EGNOS satellite is quite low on the southern(ish) horizon and it doesn't take much to block the signal. The GPSr still doesn't work too well under tree cover and most caches were hidden without the aid of EGNOS anyway so the quoted co-ordinates can only be approximate. You could be searching 'accurately' for a box that was hiden 'un-accurately' if you see what I mean. On top of that.... you've got some really devious people out there hiding the boxes.

 

John

 

Age and treachery will always triumph over youth and ability.

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quote:
Originally posted by Pharisee:

quote:
Originally posted by Iwuzere:

Doesn't the increased accuracy make the game too easy though?


 

... most caches were hidden without the aid of EGNOS anyway so the quoted co-ordinates can only be approximate. You could be searching 'accurately' for a box that was hiden 'un-accurately' if you see what I mean. On top of that.... you've got some really devious people out there hiding the boxes.

 


 

Suppose that the game grows enormously in the next few years. The majority of players have WAAS/EGNOS and most caches end up with accurate coordinates.. even the most devious hides are going to be pretty obvious when you're only 1 metre away!

 

Not trolling, but seriously and objectively just wondering if the game will end up with a limited lifespan and technology will make it obsolete? (not meant to be heresy, LOL)

 

I admit that I'd still be interested even if a GPSr took me straight to it. It still gets you out of the house and into the Real World!

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quote:
Originally posted by Ann_and_Brian:

Of course it is always possible that some people ... might deliberately offset the co-ord by a few metres icon_biggrin.gificon_biggrin.gif to increase the difficulty.


 

Now who on earth would do a rotten thing like that? icon_wink.gif

 

"Woof" quoth he. Oh, and "Grrr" also.

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