a tale of 2 <span class="highlight">gps</span>,s

Have you got them both set to the same datum, e.g. WGS84?

i'm hearing ya mate, and i was about to ask this very question.
i have a little Garmin Gecko 201 and the lat/long is S 32 06 214 E 115 50 787
the Garmin I-Que M4 is S 32 06 223 E 115 50 788

How come they are different when they are right next to each other?
Anybody know how to get the I-Que to talk to the pc through Ozi?

rick.

meow.

Have you got them set to the sames lat/long format

There are three formats:
(1) Degress. minutes, seconds
(2) Degrees, minutes, decimal minutes
(3) Decimal degrees

0.1876km long and .06649km lat I think

Next question LOL ;-)

Richard

Steeve,
The first unit is displaying deg.deg format while the second unit is displaying Deg.min
so converting the first to Deg.min = 38.03042 and 145.1647 which is very close.
Shouldn't get lost with two units :)
Peter

Do you live near a quarry or a creek, I make about 16.5k between points. barnray

Hello - yes I have an idea.. Nothing to do with Datum..that is ok.

One gps unit is set to display decimal degrees..(ie whole degrees with minutes and seconds as a decimal)

Lat 38.05070° long 145.27461°

and the other is set to display Decimal minutes (ie Whole degrees and whole minutes with seconds as a decimal) ..properly written as

lat 38° 03.05' long 145° 16.47'

Using my thoery they then plot 17m apart (could be better) instead of 9km apart. Datum issues are generally +/- ~200m.

Cheers
Greg

Don’t you only need 4 satellites for a Fix as 1 checks over the other 3 and the one that disagrees with the others is bumped off, LOL

Also if the Internal Clock in the GPS is out buy a 1/10th of a Microsecond or some BullS**t like that compared to the satellite clock then that apparently would make a difference in reading.

Steve
I get a distance of 9.9 klm apart

S38.03050 E145.16470 is near Pillars and Bowman Rd near Bangholme

S38.05070 E145.27461 On Cypress Cl

Doug

To add weight to my response, I am a degree qualified surveyor.

To do any comparison between units:
*You MUST have both units displaying results using the same datum. Usually WGS84
*You MUST have both units receiving the same number of satellites. You'll need at least four satellites for position and height. The more the merrier.
*The units MUST be "seeing" the same satellites. This means the same same space vehicle numbers (SVN).
*The units MUST be using the same SVN's in its calculation of your position. This can be checked by looking further into your units satellite info page for a VDOP, HDOP (vertical/horizontal dilution of precision) numberss. This is a factor which describes the "strength" of the positional calculation based on the geometry of the satellites used in the calculation of the position.

Whilst these units are getting increasingly user friendly, you can see there is still "magic" happening inside them that does require more in-depth knowledge for you to do the kind of comparison, and interpret the results meaninigfully, that you are trying to do.
I'm certainly not intending to belittle anybody, but hopefully sharing some knowledge. We're all experts at something.

Have complete faith in any GPS you use as long as the datum is the same as the paper map you are using. THIS IS A GOLDEN RULE. Have some understanding of degrees, minutes, seconds vs decimal degrees vs UTM eastings and northings.

To help you work out the difference between your two different readings, use the following:

1 minute of longitude = 1 nautical mile = 1.852 kms (exactly)
1 minute of longitude = 60 seconds
1 second of logitude = 1852m/60 = 30.87m

This conversion applies to latitude as well, at the equator, but changes as you get closer to the poles.

Cheers
Jayson