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How many satellites?

 

There are 32 satellites orbiting the Earth. My NUVI40 satellite view has room to show inputs from 12 of them.

Something I read recently suggests that it uses at least 4 to determine location. (Three are minimal to pinpoint locations)

Is the Garmin using all of the satellites it can see?

And, what is that red dot on my satellite screen?

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NUVI40 Kingsport TN

Red Dot

David King wrote:

There are 32 satellites orbiting the Earth. My NUVI40 satellite view has room to show inputs from 12 of them.

Something I read recently suggests that it uses at least 4 to determine location. (Three are minimal to pinpoint locations)

Is the Garmin using all of the satellites it can see?

And, what is that red dot on my satellite screen?

from Garmin

Quote:

Question: What does the red circle indicate on the satellite page of my automotive unit?

Answer:
When the Map View is shown in North Up, the red circle indicates your direction of travel. When the Map View is set to Track Up or 3-D, the red circle will indicate North.

What if...

jgermann wrote:

When the Map View is shown in North Up, the red circle indicates your direction of travel. When the Map View is set to Track Up or 3-D, the red circle will indicate North.

What if I'm standing still? The last direction of travel when I was moving?

--
NUVI40 Kingsport TN

Don't know..

David King wrote:
jgermann wrote:

When the Map View is shown in North Up, the red circle indicates your direction of travel. When the Map View is set to Track Up or 3-D, the red circle will indicate North.

What if I'm standing still? The last direction of travel when I was moving?

I was interested in what the red dot was, so looked up what Garmin said.

Maybe someone else can chime in.

Try it

David King wrote:

What if I'm standing still? The last direction of travel when I was moving?

Try it and find out. Let us know.

--
Garmin Nuvi 2450

Yes

jfossy wrote:
David King wrote:

What if I'm standing still? The last direction of travel when I was moving?

Try it and find out. Let us know.

Just did. It appears so. The red dot is at the northeast, and, according to my Navigation screen, my vehicle is pointing NE.

--
NUVI40 Kingsport TN

Satellite Info Screen

--
Nüvi 255W born on 602117815/nüMaps Lifetime North America

Accuracy comes into the play

David King wrote:
jfossy wrote:
David King wrote:

What if I'm standing still? The last direction of travel when I was moving?

Try it and find out. Let us know.

Just did. It appears so. The red dot is at the northeast, and, according to my Navigation screen, my vehicle is pointing NE.

When you look at the satellite info, you will see how many feet of accuracy. That indicates what the maximum error would be. Of course, it is almost impossible to see 0 foot accuracy because this not military grade equipment.

When you are standing still, and turn on your GPS, there is no last movement direction. Then the accuracy comes into the play, you will see the direction of travel keeps moving around ever few minutes, and you will also see speed of movement. Because the error in GPS thinks your are moving to that direction.

GPS Accuracy

When driving for a certain period of time on a frontage road located parallel to an interstate highway, the consumer GPS won't know which one your driving on even though it states 12 feet accuracy.

Here's an interesting article concerning the snap to road feature.

http://www.gpsreview.net/snap-to-roads/

--
Nüvi 255W born on 602117815/nüMaps Lifetime North America

Interesting

Thanks for the link.

Snap to road

I used my gps while mowing my sister's yard. I knew that the trip log feature would not give me the track I wanted. So I used the "Raw Logging" feature found on most Garmins. The link to a pic gives a pretty good idea of the accuracy of the unit.
http://i139.photobucket.com/albums/q297/spokybob/nancylawn-1...
I don't know how to share the MapSource file I created.

--
1490LMT 1450LMT 295w

Snap-To

canuk wrote:

When driving for a certain period of time on a frontage road located parallel to an interstate highway, the consumer GPS won't know which one your driving on even though it states 12 feet accuracy.

Here's an interesting article concerning the snap to road feature.

http://www.gpsreview.net/snap-to-roads/

My '40 does this, if I use the 'Where To' mode.

It recommends that I go on the major road to my route, but sometimes I use the parallel frontage road (about 20 meters away). It thinks I am on the major road, and gives me directions as such.

But, if I use the 'Navigation' mode, it correctly tells me that I am on the frontage road.

--
NUVI40 Kingsport TN

WAAS/EGNOS

Hopefully not taking this thread too much off topic...

Do the Nuvis, specifically the Nuvi 1390, use WAAS data? My old Quest and it's manual talked quite a bit about WAAS improving accuracy, but I find almost nothing recently about WAAS.

If so, can you turn WAAS on and off on the Nuvis? On the satellite screen are any specific satellite numbers actually WAAS data?

--
-Quest, Nuvi 1390T

Tis OK.

ddeerrff wrote:

Hopefully not taking this thread too much off topic...?

Don't worry about that. Where ever y'all want it to go.

--
NUVI40 Kingsport TN

WAAS

ddeerrff wrote:

Hopefully not taking this thread too much off topic...

Do the Nuvis, specifically the Nuvi 1390, use WAAS data? My old Quest and it's manual talked quite a bit about WAAS improving accuracy, but I find almost nothing recently about WAAS.

If so, can you turn WAAS on and off on the Nuvis? On the satellite screen are any specific satellite numbers actually WAAS data?

I think that most (all?) nuvis now do not use WAAS. Correct me if I'm wrong, folks.

But remember that with City Navigator maps, the nuvi uses "snap to" so that when traveling down a street or highway, rather than seeing your vehicle where the GPS lat/long actually places it, it'll snap your vehicle to the nearest roadway.

StreetPilot uses WAAS

ddeerrff wrote:

Hopefully not taking this thread too much off topic...

Do the Nuvis, specifically the Nuvi 1390, use WAAS data? My old Quest and it's manual talked quite a bit about WAAS improving accuracy, but I find almost nothing recently about WAAS.

If so, can you turn WAAS on and off on the Nuvis? On the satellite screen are any specific satellite numbers actually WAAS data?

My old c340 uses WAAS, very accurate. The other day I was sitting on our porch swing rocking back and forth, watching the map flip at the same time as the GPS adjusted accordingly. I was rather impressed by that.

--
Streetpilot C340 Nuvi 2595 LMT

WAAS

ddeerrff wrote:

Do the Nuvis, specifically the Nuvi 1390, use WAAS data?

Look at the user manual and then scroll through the different modes to see if your unit has it. I don't think that any of the newer models have it.

ddeerrff wrote:

If so, can you turn WAAS on and off on the Nuvis?

Yes, as an example, look at the user manual for the nüvi350 on page 45
https://buy.garmin.com/shop/shop.do?cID=164&pID=31655

Garmins explanation of WAAS http://www8.garmin.com/aboutGPS/waas.html

Cheers

--
Nüvi 255W born on 602117815/nüMaps Lifetime North America

No mention in manual

canuk wrote:

Yes, as an example, look at the user manual for the nüvi350 on page 45

Yeah, no mention of WAAS in the manual for my model (Nuvi 1390T)

--
-Quest, Nuvi 1390T

WAAS above 32

ddeerrff wrote:

On the satellite screen are any specific satellite numbers actually WAAS data?

The WAAS birds are geostationery, so over time if you are not moving very far, you can notice them to stay at the same azimuth and elevation from your position, unlike the others.

The "real" GPS birds get numbers from 1 through 32 on the Garmin display, while the WAAS birds get numbers above that range.

As a geeky note, the number displayed by Garmin for WAAS birds is the actual PRN minus 87, which gives the NMEA designation.

I've never seen a WAAS bird on my nuvis (855 and 3790LMT) and don't think it is mentioned in the manuals. On my eTrex Vista HCx, which is WAAS-capable, turning the WAAS function on or off is an option on the system configuration menu.

--
personal GPS user since 1992

Garmin says

Quote:

Is my Garmin nuvi compatible with WAAS/EGNOS?
Answer:
If you have a Garmin nuvi 300 or 600 series device you will have the option to enable WAAS/EGNOS. Enabling WAAS/EGNOS on your nuvi 300 or 600 series unit may improve the accuracy to less than three meters on average.

To enable WAAS/EGNOS on your nuvi:
1. Power the nuvi on
2. Touch on the Spanner/Wrench icon from the main menu screen
3. Touch System
4. Touch Off next to WAAS/EGNOS
5. Touch On
6. Touch OK
WAAS/EGNOS will now be enabled on your device.
Note: Only the nuvi 300 and 600 series have the WAAS feature. All other nuvi models contain a high-sensitive GPS receiver that does not require the WAAS feature.

Last modified on: 12/17/2010

You are

CraigW wrote:

I think that most (all?) nuvis now do not use WAAS. Correct me if I'm wrong, folks.

You are correct. Some of the original Nuvi models used WAAS but it's been a number of years now since a Nuvi used it. My understanding was that even with the models that did use it, finding a WAAS bird was tricky depending on where in the country you were and overall made little difference in the strength of the sat. signal or the units accuracy.

--
Nuvi 350, 760, 1695LM, 3790LMT, 2460LMT, 3597LMTHD and TomTom XXL540s

I had an iQUE (Palm with

I had an iQUE (Palm with Garmin). It used WAAS. It improved accuracy, my memory is to 10-12 feet. You had to turn the feature off if you were running off the internal battery off batter, and wanted any battery time. The unit didn't really lock on the satellites (in the car) very well. I mounted an external antenna on the roof.

I suspect current GPS units get adequate results without the added expense of including WAAS. Garmin deleted mp3 playback, presumably to save a small licensing fee.

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