How to read garmin nuvi signal strength screen?

The 4th satellite is time, the 4th dimension.

Mio

I think the 4th satellite may have something to do with time. You need 3 to get your position on earth but 4 to determine elevation---your position above sea level. That might be measured by the time it takes for the signal to reach you from the transmitter, but I'm not sure. Anyway, 4 are needed for elevation. I think 3 are sufficient to navigate.

I don't have the satellite picture on the nuvi 200, but I used to have it on an aviation Garmin. It showed the satellites I was receiving, their ident numbers, their locations in relation to me in the center. I didn't have a red dot, so don't know what that is.

You are in the center and the red dot is the direction you were last headed.

You can identify a location in a single plane with 3 satellites, but you need a fourth once altitude is introduced. The intersection of 2 spheres is a circle. Add a third and you reduce the possible locations to 2 points on that circle. The fourth defines which it is.

The WAAS requires the 4th satellite.

In order to enable WAAS, the GPSr needs to receive signal from one or more special satellites. There are only a handful WAAS birds in North America. Those birds basically provide error corrections.

One can get signals from 12 birds. If one of those is not a WAAS satellite. WAAS is not enabled in your GPSr. The Garmin auto GPSrs don't seem to tell you which is a WAAS bird. The mapping GPSr I have do.

That is so cool - thank you for explaining the red dot to me. I've verified your statement as true... I've been wondering about that since I've had my nuvi. Thank You.

Thanks for all who replied... Out of all it's options, that was one of the few I was uncertain about.

About the longitudinal coordinates... the number after the degree symbol is...?

Say 33 degrees 49.972' ?

Is the 49.972' feet, decimal of another degree, something else?

This is all new to me - thanks all for all the good info.

--Rob

Coordinates can be expressed in several different formats.

They are most commonly Degrees Minutes Seconds (DDD MM SS), Decimal Degrees (DDD.DDDD), or Degrees Decimal Minutes (DDD MM.MMM).

The last format is the most common in current GPS models. The second one is the one we use in Custom POI files.

Here are some examples of the same coordinates expressed in different formats.

Degrees, Minutes and Seconds
DDD° MM' SS.S"
N 32° 18' 23.1" W 122° 36' 52.5"

Decimal Degrees
DDD.DDDDD°
N 32.30642° W 122.61458°

Degrees and Decimal Minutes
DDD° MM.MMM'
N 32° 18.385' W 122° 36.875'

Be sure you don't substitute one for the other. They aren't interchangeable.

.
In your example, 33 49.972, the 49 is Minutes and the .972 is a fraction of a Minute.

How many feet in a degree is a different discussion.

That's 49.972 seconds.

I'm not sure about in this case. But in most cases you can adjust the coordinates to read in a different format like dd.dddd. Look under Coordinates>Format.

P.S. Not only is MM faster and more complete, she also has the advantage of being correct.

At the top of my Nuvi 360 it says "15 Metre Accuracy" as I am inside now, but right below it has a number that is constantly changing. Ranging from -12m to 55m, what is this telling me because it tells me acculracy in the green bar at the top?

Thanks.

I read a long time ago that the GPS system actually has the ability to be far more accurate than our units are, but civilian receivers, such as ours, are restricted by law (In the US at least). Only military GPS units can use the GPS system to its fullest potential.