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Portable Garmin GPS - Never Get Lost Again

We now expect our new cars to come with a GPS receiver as standard, and hopefully it's a portable Garmin GPS. Gone are the days when you have to fumble through the street directory as you're driving, or have to rely on someone else giving you spurious directions. The portable GPS is now almost as familiar as the cell phone and without it, many of us would be completely and hopelessly lost.

So we all know what they are and do, but where did it all start? Not surprisingly, they were originally developed for military purposes, to keep track of ships, submarines, planes etc. but it obviously wasn't long before the commercial viability of the GPS for everyday use became apparent.

The GPS receiver as we know it relies on 24 operational satellites orbiting the earth at all times at a set distance of more than 12000 miles above the earth, although your portable garmin gps receiver only uses information from 4 of these satellites at any one time.

Every one of the 24 satellites orbits on a very precise line which ensures that your receiver is always in contact with at least 3 of the satellites. The 4th satellite is required to synchronize the other 3 satellites clocks with your receivers clock. Because the GPS system needs incredibly accurate time measurement, this is provided by atomic clocks courtesy of the U.S. Naval Observatory. All 24 of the orbiting GPS satellites is fitted with it's own atomic clock.

Every portable Garmin GPS receiver needs to know where to find it's closest 4 satellites at any given time. To enable this, there is a chip installed inside every device that contains a log book for every satellites position at any given time.Likewise, when any satellite sends your receiver a signal, it also updates the log book of the satellite on your devices chip if necessary.

When you determine your position with a GPS device, the accuracy really depends on the type and model you are using. The majority of portable Garmin GPS units will give you an accuracy of around 10 mtrs. If you had a GPS system back in the 1990's, you will probably remember that you were lucky to be within a hundred meters of where you were told you were. When the military first allowed commercial use of the GPS system, it was agreed that the new receivers accuracy would be limited to approx. 100 meters and this was done by coding a timing error into each devices software. Thankfully, this stipulation was done away with in 2000.

The portable Garmin GPS is as accurate, if not more so, than any comparable device. You can happily and safely use it to get you from A to B and even C via D without ever needing to ask directions again. I know as a guy that the only hurdle I now have to get over is that the lady giving me directions, really is right this time!

About the Author

Derick has been a high school english teacher for many years. During school vacations he likes to go on road trip to parts of his home state of Ill. that he hasn't yet visited. To help him get around he uses a Garmin GPS Nuvi 350

Derick bought his Portable Garmin GPS here

Electricity?

can u guys help me please.

The temperature coefficient of resistance for copper is 0.0039 1/ºC. The resistance is

R(T) = R(20ºC) *[1 + ∆T*0.0039]

An increase of 20% from 20ºC is R(20ºC)*(1+0.2), so
∆T*0.0039 = 0.2, ∆T = 51.28ºC

The initial resistance of the aluminum wire is 10.00/0.4212 = 23.74 ohms, and this is at 20ºC In the new environment, R = 10.00/0.3618 = 27.64 ohms. ∆R = 3.9 ohms.

From the above equation, R(T)= R(20ºC)*(1+∆T*K). For aluminum, K = 0.0039, so

R(T) = R(20ºC)*(1+∆T*0.0039)

27.64 = 23.74*(1+∆T*0.0039)

1.164 = 1 + ∆T*0.0039

0.164 = 0.0039*∆T

∆T = 42.12ºC

The new temp is this plus 20ºC, or 62.12ºC

Power = Voltage * Current, 9.0*0.350 = 3.15W

MTI Instruments Acquires Strategic Line of Products
ALBANY, N.Y.----MTI Instruments, Inc. of Albany, NY, a worldwide leader in precision measurement solutions, and a subsidiary of Mechanical Technology Incorporated , announced the acquisition of the tensile stage line of products from Ernest F.

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