A digital compass is more accurate than a conventional compass?

[jowook]

I just purchased Garmin 60 csx. As you guys know, this unit has a digital compass. I don't know the accuracy of this digital compass. Is it more accurate or as accurate as the conventional compass?

[geospatial_junkie]

That's a good question. For my money, nothing beats a conventional compass. I've been in too many situations where I've had to defer to my conventional compass because the GPS loses it's signal or has stopped working. I recommend to keep both on you.

[gallet]

I just calibrated and set to magnetic north and checked my HCx against a Silva compass and it was out by 5 degrees. The Siva is 20 years old so it may also be out.

 

Even if it was perfectly accurate, it still would not be useful for plotting a back bearing on a map. I'd always take a compass with me.

 

However for everyday use the fluxgate compass is accurate enough.

[+edmill]

Why don't you check your accuracy ?

Two solutions:

a) If you have a marine environment use a range marker bearing- it's verified by some pretty high-end hardware.

Lookup and try the bearing for 2 local benchmarks.

[twoclones]

I'm using the 60CSx daily for field work and the compass requires frequent calibration. I trust it for only a little while after calibration...

[Alphawolf]

I have a Vista HCx and I never even turn the compass on. I use my preferred compass...An old fashion, non-electronic Silva. It doesn't drain batteries and never, ever requires "calibration".

I imagine if you keep the electronic versions calibrated, they are just as accurate. But, no where near as reliable.

[Frabble]

The 60CSx manual states accuracy is +/- 5 degrees if calibrated properly. A conventional compass will always be more accurate.

[+Prime Suspect]

That's a good question. For my money, nothing beats a conventional compass. I've been in too many situations where I've had to defer to my conventional compass because the GPS loses it's signal or has stopped working. I recommend to keep both on you.

Huh? A GPS's digital compass doesn't rely on satellite signals. Like a conventional compass, it reacts to the earth's magnetic field lines.

 

My Suunto watch's electronic compass is accurate to within 2 degrees. I imagine a GPS's compass is at least as good.

Edited October 14, 2007 by Prime Suspect

[+tec_64]

Does the GPS's fluxgate compass automatically compensate for magnetic deviation in you region? That may cause the diff between the GPS flux compass and your "real" compass.

 

Be carefull when holding your compass. A "real" compass obviously works best when held level. (Your GPS compass may be a 3D compass).

 

I have a watch on my left wrist that has enough magnetism in it to throw off my compass by a few degrees if I hold it with that hand. When I'm shooting an az. I make sure nothing on me that has any magnetism in it is anywhere near my compass.

 

Just my 2 cents.

 

Wayne

[geospatial_junkie]

Prime Suspect, I wasn't talking about the digital compass option in the GPS unit itself. I was talking about the GPS unit itself. I can see how my above post could have been confusing. Sorry!

 

I know that you get what you pay for with conventional compasses. Some are more sensitive than others and some have defective needles, etc... My guess with a GPS unit is that this would be a secondary feature, thus cheaper parts would be used for the compass itself and all the attention would be focused on the GPS portion. Remember, there is no way to test the quality of the compass in a GPS compared to a conventional compass! Also, there is a reason some conventional compasses cost in the hundred's of dollars.

 

If your compass is 3-D, I am assuming it has a gyroscopic component to it (involves readings from the earth's tilt). This is something I would be very wary off as you are ow introducing another variable into calculating your position, thus potentially increasing the error of your reading.

 

If you heading anywhere with dense canopy cover and is fairly far from a road or trail, please take a conventional compass with you (and know how to use it!). I work as a GIS/Cartography professional and I regular hear from people coming back from field work that they had gotten lost because their GPS stopped functioning (got wet, ran out of batteries, GPS unit itself got lost, etc...) Should've taken a real compass and a map with them as well...

[gallet]

...GPS unit itself got lost, etc... Should've taken a real compass and a map with them as well...

 

Wouldn't it be easier to lose a real compass?

[+pengi]

There's another aspect of this...

 

A regular compass points to the magnetic north, and cant be calibrated to point to the true north of the earth. Almost all maps uses the true north as a reference, so the regular compass won't show the same direction as the map.

 

When using the compass in the GPS-unit, the gps is able to use the position information to compensate for the difference between the magnetic north and the true north. If I'm not mistaken, that difference can end up in a couple degrees...

 

But then, if setting up the gps-unit to point to the magnetic north, disabling it's electronic compass, and having the regular compass and the pointer at the gps screen aligned, it should show the right direction too...

[+Prime Suspect]

There's another aspect of this...

 

A regular compass points to the magnetic north, and cant be calibrated to point to the true north of the earth. Almost all maps uses the true north as a reference, so the regular compass won't show the same direction as the map.

Did you not know that better magnetic compasses will have declination adjustment mechanisms built into them?

Edited October 15, 2007 by Prime Suspect

[+tec_64]

I have a Brunton with a declination adj. You should be able to set it and leave it if you don't wander off (hundreds of miles) from the region where you normally use it. If you move to far (esp east or west) from your region, you will have to readjust it.

 

Your GPS will know where true north is after it sets up and you move. It also knows your location to apply a reverse declination if you select to use magnetic.

 

Where I'm at, the declination is currently 10.5 deg west. So if the GPS is set to true north and I don't have (or forgot about) the declination to compensate my "real" compass, I will end up with a 10 deg diff.

 

Wayne

[+Alan2]

My Suunto model M3D base plate compass and my 6 year old Vista GPS with on-board magnetic compass both seem to point in the same direction. I don't see any difference.

 

The other benefits of an on-board compass in a GPS is you can store the direction when you shoot a bearing. Just aim and press the button and the direction is stored. Or you can project waypoints something you can't do with a regular compass. And you don't have to worry about changing the declination when you travel - the GPS does it automatically. True it needs batteries - but that's what the regular compass is for-backup. And you should take extra batteries with you anyway.

 

Not to knock my Suunto. It's great as a backup and it's lots of fun when messing around with 24K quad topo maps. But it normally stays in my bag 98% of the time.