Just Bought My Gps - Help Me - Is This Performance Good?

[pluto2se]

Hi!

 

I just bought my first GPS - a bluetooth GPS module for my symbian phone, a xaiox 32channel instantfix, bought it on ebay from dealcat.de. It does not have EGNOS/WAAS support but has 32 channels and is advertised to do <5 M accuracy under open sky 90% of the time. That's why I choosed it over a EGNOS capable receiver since I've read all too much about EGNOS not making a noticable difference in europe.

 

I'm new to GPS and haven't got too much experience yet of the GPS system. My question is therefore, is the performance I'm getting good, or bad? or just average? I feel somewhat concerned about it.

 

I've done some geocaching, visited about 5-6 caches so I'm starting to get a feel for it and my gps device.

 

Under an open sky my GPS usually points me to a position within 2-7 meters of the cache spot. Not quite the "<5m 90% of the time" specified.

 

The real problems started when I went into the woods here. The device was pretty much completelly unable to sense my movement and give me a course. If I stood still for a long time it could sense my position but of course not give me a course. This was a real anticlimax, I don't know if I could have navigated out of the forest like this if I wouldn't know where I was, which I did thank god. The forest was pretty dense but not extremely dense. It got better when I got to an open spot within the woods but except for that place msot of the time it wouldn't sense my movement at all.

 

Another situation: A cache in the city, by the wall of an old castle (stone walls). Everything pointed fine until I got close to the walls, then things got bad, there was no real way of getting a direction and the gps only sensed my movement at certain spots. Perhaps the signal bounced on the stone walls, I don't know. Once again an anticlimax. I had a feeling for where the cache was, and I was right, butwithout that feeling I would probably have a search radius of at least 20-40 meters or so!

 

Finally I find the gps pretty "slow" on sensing my movement. Say I have a fix and start walking, it takes quite a few seconds before it senses my movement and gives a course and it takes even longer before the course is actually pretty correct. If I stop and walk the opposite direction it once again takes quite some time before it senses the change.

 

What do you think of this experience? Did I get a bad brand or model of my gps receiver or is this just "the way it is"? I'm quite a perfectionist perhaps but I expected abit more. Should I have bought a EGNOS capable receiver instead? (despite the fact I've heard alot of that it doesn't do a big difference in europe)

 

Please give me your reactions and experience on this! Can I get better results from another device?

 

regards,

Kristian Tigersjäl

[kb9nvh]

This type of reception under heavy tree cover is common in units a few years old. An older Magellan is supposed to be better.

 

The new Garmin 60csx and 76csx will give you what your looking for. It will not loose lock but under heavy tree cover you will loose some accuracy.

These are not bluetooth however.

 

Hi!

I just bought my first GPS - a bluetooth GPS module for my symbian phone, a xaiox 32channel instantfix, bought it on ebay from dealcat.de. It does not have EGNOS/WAAS support but has 32 channels and is advertised to do <5 M accuracy under open sky 90% of the time. That's why I choosed it over a EGNOS capable receiver since I've read all too much about EGNOS not making a noticable difference in europe.

regards,

Kristian Tigersjäl

Edited July 23, 2006 by kb9nvh

[+Robam]

60csx works under canopy and even indoors 20ft from windows. But you are looking at $400 as well. $600 with maps and nav kit and 1gig msd card. I love mine but look at it as an investment over say 4-5 years.

[arthurking83]

Looks to me, like you got BAMBOOZLED by the 32 channel receiver B$ advertising blurb!!

 

Th Garmin GPS's the others refer you to, will not work with your phone(almost certainly not, unless there is a USB connection and driver for it!)

 

Sounds to me like you need a SIRFIII chipset bluetooth GPS!

 

Forget the garbage advertising about 32 or 20 channel receivers...just concentrate on the chipset...ask the right questions and you're well armed!

 

You need a more "sensitive" receiver...and without EGNOS or WAAS you aint never going to see real accuracy less than about 10meters....regardless of what the manufacturers say!

 

SIRFIII bt GPS will solve your "forest problems"

[+Munin]

Kristian, most of your experiences sound very much like my own with my first GPSr (a Garmin Foretrex 201). Pretty decent out in the open, so-so under moderate tree cover, and sometimes erratic/poor/non-existant results in dense forests (tall dense stands of old pine were particularly problematic).

 

Tall buildings in a city, narrow canyons, cliffs on the sides of mountains, etc can all present problems for GPSrs. Signals from satellites close to the horizon can be blocked by the buildings/mountains, reducing the number of satellites available for calculating your position. Satellites high enough to clear the obstructions may find their signals bouncing around off the walls/cliffs/etc, sometimes resulting in the same signal arriving multiple times via multiple routes (direct, bouncing off building 'A', and again bouncing off building 'B'), making it harder for the GPSr to figure out which version of the signal is the "real" one.

 

Slow updates on your heading as you walk along may also be a sign of poor reception conditions (few visible satellites and/or multi-path). At least that seemed to correlate very well with my old Foretrex - the worse its accuracy got, the longer it tended to take to display the proper heading. (Possibly because if you only know someone's position +/- 15-20 meters, then they probably need to move a lot further before you're confident about their direction of travel compared to figuring this out when you know their position +/- 5 meters.)

 

While it's possible to go geocaching despite these problems (I did over 100 caches with my little old Foretrex ), you can probably get a better GPSr if you want - there's been incredible improvements in reception and signal processing over the last couple of years. My 76CS was a big improvement over my Foretrex, and my 76CSx continues to amaze me.

 

Since you're looking at a Bluetooth GPSr, you might want to take a look at the US GlobalSat BT338 receiver. (But shop around to see if you can get a better price than buying from USGlobalSat direct. ) I haven't used one of these myself, but a French colleague brought one along to a convention I attended back in November - it seemed to work nicely with his PPC PDA and he said he'd been pleased with its performance. The BT338 uses the same SiRF III chipset that the Garmin 60/76 C(S)x GPSrs use, so it should have similarly good performance under trees and even inside many buildings. (At the convention, my French friend was able to keep a lock walking around inside much of the convention center. The 76CS that I was using at that time just whimpered in frustration and gave up. Perhaps if he and I end up at the same spot this year I can try to keep up with him using my 76CSx, provided he hasn't picked up yet another newer/cooler toy in the meantime. )

[pluto2se]

Hi people and thanks for all replies and suggestions.

I've actually already from advices from others and my own thoughts, bought a globalsat bt-338 instead and it certainly does alot better than the "32 channel spook" Thanks everyone for the information. I am looking for a bluetooth solution pimarily as I it get's cheaper. thanks again.

 

Kristian