OpenStreetMap

New GPS iBlue 747

Posted by amillar on 21 June 2008 in English (English)

I got a new GPS receiver, the iBlue 747 (apparently also known as a BT747). It is a small receiver and logger with no display. It can record to memory, and also has both USB and Bluetooth interfaces.

It is much more accurate than my previous GPS, the Magellan GPS Companion on a Palm V. The old one takes several minutes to get a signal lock (up to 5 or 10 minutes when moving), can't receive a signal inside a house or most buildings, and has large variations (like 10 to 20 meters) in repeated readings of the same location. In the car, it needed to be on the dashboard with the best possible view of the sky to get any decent readings.

The 747 is much quicker and more accurate. It always has a lock within 30 to 45 seconds, even when moving. It has good reception indoors, and is much more consistent from one reading to the next. In the car, it gets just as good readings as the old GPS when it is in my pants pocket, and on the dashboard it is very accurate. It looks like it is a little better in the downtown "urban canyons" too.

I've been using it mostly as a stand-alone logger, and downloading the tracks by USB. I definitely missed the sattelite display at first, to know if I was getting good reception. I quickly came to find that I didn't need it with the 747 like I needed it on the Magellan; the 747 "just works" without lots of adjustment and positioning.

I have tried a few Java apps on my S-E Z525 bluetooth cellphone, but I haven't liked any yet. The biggest problem is the phone has a short battery life running Java and bluetooth, and I can't stop the screen dimmer. GpsMid looks nice, but it doesn't recognize my GPS over the bluetooth. TrekBuddy works fine, but I find that with the 747's built-in logging, I just don't need an interface much.

I'm thinking about getting a Nokia 770 on ebay. I want something that can give me some choices in GPS software, and wifi web browsing would be nice also. I looked at the Palm Tx, but I like the Linux software choices more, and the Tx is selling for more than the 770 on ebay, so the 770 looks like the better choice for me. Next I shall consult my good friend Esnipe for a deal.

Comment from James Derrick on 22 June 2008 at 17:24

If you can live without a keyboard (useful for direct entry of street names when surveying), a N800 or 770 works well. If you can stretch to the N800, the additional CPU runs [[Maemo mapper]] very smoothly, and give a good mapping workflow (see http://wiki.openstreetmap.org/index.php/Creating_a_track_with_Maemo-mapper for details).

From general comments, although the N810 has a GPS built in, an external BT device will give much better performance. For the best accuracy, try attaching your BT GPS to the shoulder strap of a backpack using rubber bands. This works well with a hydration pack for longer trips.

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Comment from sumpfralle on 23 June 2008 at 02:49

Personally I would not recommend the N770 due to its poor performance (small RAM) and some resulting stability issues.
Additionally I did not manage to use my BT757 device with recent Hacker's Editions (new firmware versions).
The N800 should be a better choice for you, I guess.

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Comment from le_top on 22 June 2009 at 21:17

The iBlue 747 was mistakingly called BT747 in a french forum once which leaded to the opensource SW being called BT747 (http://bt747.free.fr).

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