bluetooth (or serial) digital compass

[kcchesnut]

i'm hoping for recommendations for a digital compass.
something that is bluetooth and developer friendly.
(a serial connection would work too)

basically i need to get what direction a person is facing into my application (including when they are standing still).

i know that all GPS devices can be used as a compass, as long as the person is moving.

but i really need something that will give a directional reading as a person is standing in place and just turning around.

an older GPS unit i had would just give the last direction you were heading as soon as you stopped. when you turned, that direction did not change until you kept moving again.

if some of the newer BT GPS units have a digital compass built in, to handle stationary direction changes, then that would be even better.

Thanks,
casey

[Sven Johannsen]

Don't know of anything that does that. Keep in mind that a digital compass will tell you which way north is on it's display. That means the unit would need to be glued to the PPC, it couldn't be seperate, either serial or BT. If that's confusing, think of a BT compass sitting on a table that has it's top pointed north. Face in that direction. Now turn around. The BT device is still pointed north and that is what it will say, but you are facing south. The only way it would know you turned around is if it was glued to you and turned with you...or to the PPC that you were viewing.

[ADBrown]

Have you tried using a GPS receiver? I've found that my GPS units usually follow stationary turns pretty well.

[kcchesnut]

yes, i would have the device on me. so it would be facing north as i faced north. as i turn, it will be facing the new direction. no, i will not be gluing it to my device :)

as my post said, i have tried an older GPS receiver and it only worked as a compass when i was moving. what GPS are you using that works well for stationary turns?

[Sven Johannsen]

Even if you do find a GPS that has a magnetic compass feature built in, like the eTrex Summit and others, there is no provision in the NMEA text string sent out of it for 'facing'. There is a heading, which implies movement, and a bearing which is the direction to a waypoint, and lat and long and all the other normal stuff.

Realize that a GPS has no inherent magnetic understanding. It only derives direction based on where you were and where you are now. By itself, if you don't move, it can't tell which way you are facing. If you get some direction while standing still, it is usually because of positional errors that make it look like you moved.

[ADBrown]

as my post said, i have tried an older GPS receiver and it only worked as a compass when i was moving. what GPS are you using that works well for stationary turns?

Oops, missed that part. Anyway, I've found that my Dell (DConnex) Bluetooth GPS seems to have a reasonably good idea what direction it's facing. Yes, it does pick it up from residual movement, but it registers changes as little as a few inches, so you don't exactly have to walk off with it for it to tell you the direction.

[kcchesnut]

i know that NMEA strings do not have bearing (i've written parsing code before). but that does not mean a GPS device with on board compass could not generate its own NMEA strings from the compass and feed them out to let me figure out bearing from the previous strings (even when standing still).

since no digital compasses have been recommended, i guess i will try the Dell Bluetooth GPS. a couple inches of movement to register direction might work.

Thanks,
casey

[kozak]

There's a new Bluetooth GPS out, it's only $109.99 and can track 16 satelites, as opposed to 12 on earlier models. It's shipping in a week t hough, but might be a better buy then the expensive dell gps. It's supposed to be very sensitive also. GPS Passion is doing a review on it currently, not sure when it will be posted.

I ordered mine here:
http://www.semsons.com/iblgpsre16ch.html

Hope this helps.