In this article, the author James Monahan talks about how GPS tracking devices work and the technologies that run them. I think this article goes into some good detail about tne nature of GPS tracking devices and generally how they are used today by users. A great follow-up article to this one would be to talk about specific uses of GPS tracking devices and when it would be appropriate to use them.

Tracking devices, also called 6-degree-of-freedom (6-DOF)
devices, are defined as technological tools that are used to
observe a specific person's movements by the use of a
transmitter to relay radio signals back to a receiver which then
enables one to pinpoint the exact location of that particular
person.

Global Positioning Satellite, homing devices and cell phones are
part of the tracking device technology, and they have all very
useful purposes.

GPS, for instance, enables car drivers to have a knowledgeable
virtual "companion" that can give out directions and help you be
located by the proper authorities if and when you've gotten into
an accident.

As a corollary, this technology can also be implanted on very
important persons just in case they go missing or worse,
kidnapped, and need to be found pronto. In fact, even
non-celebrities are afforded this option.

In Mexico, for instance, senior staff of a company is required
to have these chips as kidnapping is on the rise on that
country.

On a more practical note, rental car companies like Payless have
incorporated this type of technology on their cars so that they
could tell when renters are crossing into forbidden states.

The guilty parties can be assured of an extra $1 charge for
every mile driven on non-permissible states. The costs of these
devices and their maintenance can vary greatly.

So we all know what tracking devices are and what they could do.
But what exactly makes them tick? Such devices are based on
electromagnetic, acoustic, mechanical or optical technology.

Mechanical tracking devices can measure orientation and position
with the use of a direct mechanical connection between a
reference point and the target. The advantage of this type of
gadget is that they are accurate and their lag is short. The
main drawback is that the operator's motion is limited to the
mechanical arm.

Optical GPS Tracking Devices

Optical tracking devices use the information contained in the
projection of the LED's to identify the position and orientation
of the head.

There come in two kinds: in the first one, cameras are placed on
top of HMD's while a set of infrared LED's are placed above the
head at specific locations in a given environment.

The other type has cameras mounted on a fixed frame with fewer
LED's located at known position on the HMD. These types of
tracking devices both have high update rates and short lags,
although they usually suffer from line of sight problem.

Electromagnetic tracking devices work by measuring the magnetic
fields' strength generated by sending current through three tiny
wire coils, placed perpendicular to each other.

These are then implanted in a small unit attached to the entity
the system needs to track. These types of devices can track
multiple objects simultaneously although they may experience
interference with mechanisms that produce magnetic fields of
their own.

Acoustic GPS Tracking Devices

Acoustic tracking devices employ ultrasonic sound waves that
measure the position and orientation of the entity being
tracked. This can be done through time-of-flight tracking and
phase-coherence tracking.

The first type works by measuring the time needed to take for
the sound sent out by transmitters placed on the target to reach
sensors located at specific points.

The second type works by measuring the difference in phase
between the sound waves produced by a transmitter on the target
and those given off by a transmitter at some reference point.

About the author:
James Monahan is the owner and Senior Editor of TrackingBase.com and
writes expert articles about tracking.

Tags: gps - tracking - device - technology - optical - acoustic