[Loadstone] I-Blue 737, RE: purchasing your first GPS receiver

R. Neill Hadder neill.hadder at gmail.com
Fri Apr 6 13:55:13 BST 2007


Hi all,

I agree that some way to post user reviews of receivers, perhaps by
archiving the loadstone list, would be very helpful.  As posted previously,
my first receiver was an I.Trek m6 using SIRF 3.2, and it was a lemon.  The
on/off button wasn't blind-friendly, there was no auto-on, and it was wildly
innacurate as well as insanely drifty.  Now I have the I-Blue 737 with the
MTK chip and I concur that it's much better than the SIRF for pedestrian
use.  I'm using it with a Nokia 6682, and here are some thoughts.  Your
mileage may vary.  I note some strengths and also some problems I'm having
with it.

* There is very little drift, and virtually no drift in compass orientation
while you're standing still.  No need to think about static threshhold.

* It is very slow to update, like five seconds or so, when you change
direction.  So it'll track you as going east for several seconds after you
turn north, then it'll catch up.

* Orientation seems to wabble between, say, 11:00 and 1:00, unless it's the
street changing direction, which I'm coming to doubt.

* I'm currently trying to pinpoint the accuracy of the unit.  My original
database was built using the I.Trek, so I'm not positive if the
forty-eight-yards-off points are all from that unit.  But I still seem
really to get a parallel tracking effect where it thinks I'm consistently 28
yards away from the same route taken earlier.  So, on my 1.5 mile walk to
work, I'll enter points and delete wrong ones; I'll come back home along the
same route and again mark points, which will often be 17-20 yards different.
This might be the real-world accuracy of the unit.  Once, it parallel
tracked me as 100 yards off of my actual location, and just gave crazy
results for the entire route until I turned the unit off and on again.
However, I've also known it to be right on target to a distance of 3 yards
or so.  So nothing conclusive to report about accuracy.  It's either
amazingly good or its not, and I can't tell which.

* the biggest problem is that it won't stay connected to my phone.  It goes
to sleep very readily, it seems, and loadstone disconnects.  I haven't been
able to determine if the behavior is random, battery-related, or
bluetooth-related.  I really would prefer if Loadstone could have a setting
to attempt hot-starting the gps when the clock seems to have stopped
ticking, rather than just disconnecting.  That would keep the gps from
suffering from narcolepsy or the appearance of it.  The GPS seems to still
have its satelite fix, since reconnecting brings up a fix instantly, but it
just keeps closing down the connection to the phone.Some days, it stays
connected just fine even while I'm sitting in a chair for an hour; other
days it goes out three times within a block of my house on a clear day with
12 satelites tracking and full battery charge while I'm going 4 miles an
hour.  So I have no idea.

* It's amazingly sensitive.  3 to 5 satelites in the middle floor of a big
campus building.  Easily 9 to 12 satelites during a walk.

* great design.  On/off slide switch, usb-powered (but no usb data
connectivity), and auto-on from Loadstone.  Battery can be used in the Nokia
6682, or at least I've done it without killing anything.  Your risk.



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