drishaq <drishaqazhar@gmail.com> wrote in news:944b1c6d-4369-4f85-82a4-
3609cfec756c@b30g2000prf.googlegroups.com:
> For some people there is a debate over which to choose a Bluetooth gps
> receiver or a compact flash gps receiver.
> http://gadgetupdates.googlepages.com...oth_gps_cf_gps
>
GPS receiver is always better because of the nature of GPS.....
GPS antennas must ALWAYS, regardless of the cellphone nonsense, have a
clear view of the sky to it can receive the really miniscule, near-
noise-level UHF signals from up to 12 satellites in very high orbits,
compared, for instance, to INMARSAT phone satellites just on the very
edge of the thin atmosphere. You can see their current positions about
halfway between the near earth orbit cluster where the shuttle, Hubble
and ISS orbit, hardly out of the air, and the stationary satellite ring
of birds orbiting at the same speed the earth turns so they appear to be
stationary from earth. A JAVA applet fed with NORAD data is here:
http://science.nasa.gov/Realtime/jtr.../JTrack3d.html
It is continuously updated. If you watch it over time, the birds are
all moving in their orbits. Click on a point and the track and
satellite info appear on the applet.
Around 16,000 miles from your massive iPhone antenna, you can imagine
the immense power level available to your receiver, which in the daytime
barely overcomes the noise from the hot tarmac of the parking lot and
the sun which radiates billions of watts on all frequencies of noise.
(It's that bright object it hurts to look at.)
So, here we set, perhaps in an airplane with our little sellphone GPS or
as the OP states a compact flash GPS stuck in the side of the
laptop.....
GPS signals are RADIO and do not pass through anything conductive, like
the metal roof over your office, all those floors full of junk over
your floor in a big building, thru the roof of your car or the skin of
Flight 77 heading out to sea to be scuttled with all aboard. So, it is
a fantastic advantage of the Bluetooth GPS receiver that it can be
positioned SEPARATELY from where the laptop or sellphone or internet
tablet is being used...under the above obstructions. The little BT GPS
receiver can be placed in the window of the airplane so it has a clear
RF view of even a few of the birds available, if only in one hemisphere
of one that is outside. Placing the GPS in the window, allows you to
run the BT connected computer or other device in a more convenient
position that is NOT GPS signal friendly up to 30' away.
For this reason, alone, a BT GPS is always better than one mounted on
your laptop or inside your.....er, ah.......iPhone.
I'm using the fantastically sensitive Nokia LD-3W 20 channel, WAAS
compensated, sellphone battery powered, rechargeable, GPS receiver. It
is so sensitive, it can most times get a lock INSIDE the windows of a
restaurant, but to get a good fix you must not be running off signals
reflected off objects in this manner. GPS will ONLY give you an
accurate fix, especially a 3D fix, if it can see a minimum of THREE
birds DIRECTLY. Signals bouncing off objects screw up GPS's analog
timing and make your position fix appear in a different place, moving
around the correct location by up to 100 ft in all directions. Sitting
with a good view, say on the dash of your car under its windscreen, the
LD-3W will place its position on a mapping program within 2-3 feet of
perfect. Nokia has a newer, smaller model than this huge 3x2x1/2" box
that weighs 65 grams:
http://www.nokiahowto.com/link?cid=EDITORIAL_184774
It's called the LD-4W:
http://europe.nokia.com/link?cid=EDITORIAL_350700
It's so small it comes with a suction cup to stick it to any window so
it doesn't fall off the little windowsill....and a keyring so you can
also use it as the world's most expensive RF key fob.
Both these receivers use the SiRF Star III LT, 20 parallel channels
receiver on a chip, which cold starts in 45 seconds and hot starts in 2
seconds (last fix within 2 hours from start).
Bluetooth is just better because of the clearview-to-the-birds
requirement of this UHF analog GPS system. It's much more flexible to
use. Walking? Carry it in your watch pocket, shirt pocket, best would
be a little pocket sewn into the very top of your ballcap for best
reception....(c;
Recharges on same Nokia power supplies the sellphones, Linux tablets
use...(c;
Linear Mode
