How do GPS tracking devices work?

Specifically, how do they transmit if they are, for example, inside a shipping container?
Is there a hole drilled for an antenna? Or a fiberglas patch made to replace
some of the steel top or side?
Thanks.
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Fester Bestertester wrote:

The antenna must be able to look outside at a big slice of the sky, or the device wont work.
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How does the implant in Green Xenon's head work? Does it have a wire tail that acts as an antenna? Is it just under the scalp?
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wrote:

They do not "transmit" at all.
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On 5/15/2010 3:41 AM, WarmUnderbelly wrote:

GPS _receivers_ do not transmit.
GPS _trackers_ may transmit.
GPS Fleet Trackers do transmit, depends an which country on how they transmit.
Some use cell phones, some use direct wireless transmitters.
hamilton
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wrote:

Those are PERIPHERAL sub-systems to a GPS system. GPS receivers do not transmit.

None of which make contact with any GPS hardware.
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On 5/15/2010 11:09 AM, WarmUnderbelly wrote:

I think we are agreeing here.
Glad to know I go it right. ;-)
hamilton
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wrote:

Nope. There is no such thing as a "GPS Tracker" other than some lame moniker some lame maker slapped onto one of their systems, which others then adopted. A system that USES a GPS receiver.
There are transmitting trackers, which USE a GPS receiver to gain a position resolution. Tying them together by naming the entire system using the receiver name as a key identifier doesn't change the facts. They are separate systems.
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On Sat, 15 May 2010 11:51:33 -0700, WarmUnderbelly

The fact is that at best, the damned things are nothing more than a trip log, even if they transmit their poll results to a remote storage location.
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Fester Bestertester wrote:

Your package does not have any thing put in it or on it that GPS systems detect, otherwise, it would be an expense.. The package is placed on the truck and logged in on the computer as to which truck it's on. They simply track the truck! Via Cell or dedicated system..
They simply scan in/out at the pickup/drop off places.. The scanner logs it to the current position location.
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On Sat, 15 May 2010 11:50:24 -0400, Jamie

Many also transmit several vehicle condition data blips as well, so they can track and prevent breakdowns, and catastrophic breakdowns being the most important to avoid.
Still has nothing to do with GPS other than that GPS is referenced when the system records a new system status file and transmits it back to a central server, which makes vehicle tracking a no brainer. It can even fail to get a reading sometimes, and it would still have no effect on tracking as a new, good reading will soon follow.
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wrote:

There are two types of GPS trackers:
1. Those that record their coordinates every X minutes and are retrieed and read to determine the data - what you put in a car to track a teenage driver.
2. Those that can either send data autonmously or be queried remotely. These usually have a large antenna dome - what you see on trucks/trailers carrying valuable loads.
John
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