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Following are the fundamentals of tracking and locating technologies
What is a ‘Locator’?
‘Locator’ is any device which enables the location of a remote person / child / object.
The 3 most common technologies that are used to built locators are GPS (Global Positioning System), RFID (Radio Frequency Identification) and Cellular.
Most locator products will provide the user the required location on an Ad-hoc basis. The media by which the info delivered is either a handheld device or a web interface.
On top of the basic location providing ability some of the products provide add-on advanced abilities (e.g. alarming the user once the tracked object/person is leaving a certain pre-defined area, etc.)
As with many other technologies people can use locating devices for good purposes or bad ones. In order to encourage people to use this technology in a positive manner this site will focus on potential good-cause applications the available locator devices can be used for.
See how locator device works using a demo of a leading vendor (wherify).
Locator Basic Terminology
RFID – Radio Frequency Identification.
RFID explained at Wikipedia
GPS – Global Positioning System. A GPS device is capable of providing space & time related information such as current position, motion direction, motion speed, current time, etc.
GPS explained at Wikipedia
Thorough explanation of how GPS works
A-GPS – Assisted GPS. Differently then regular GPS devices, A-GPS devices can provide positioning info indoors with greater accuracy and lower radiation.
A-GPS explained at Wikipedia
Cellular – A radio network made up of a number of radio cells.
Cellular Network explained at Wikipedia
GPRS – General Packet Radio Service. Mobile service geared on transferring data.
GPRS explained at Wikipedia
How does Locator work?
Below you can find explanation for each of the leading tracking technologies currently available at the market. Since one of the most common applications of locator devices is to locate lost children, the tracking methods below described in these terms.
Very simple devices based on Ad-Hoc alert triggered by the parent or the child.
Distance: Up to 150 feet
Cost: $20 - $30
The system composed of ‘watch-like’ bracelet carried by the child and hand-held unit carried by the parent. Once the child goes out of a pre-defined perimeter the parent will be alarmed about that and will be able to view the direction to follow in order to locate his/her child.
Distance: Up to 300 feet indoors, 600 feet outdoors
Cost: $60 - $200
The mobile cellular network is based on hexagonal cells each at the size of 0.25 to 20 or more miles. At each cell there is a station receiving the mobile signal and transmitting it forward to the communication service provider. The communication provider is capable of telling the location of the child holding a cellular device based on the cell that device is appearing to be at.
Coverage: Anywhere the cellular network is deployed at.
Cost: one time payment for the cellular device carried by the child, and recurring payment for the service itself. There might be additional payment per information request.
The GPS locator device carried by the tracked child might have different forms. Some of the widespread ones:
- Key holder locator
- Swatch style child watch
- Multi function cellular phone. The child is equipped with a phone which enables it’s location using the GPS technology.
The parent may track his child using the following methods:
- SMS messages sent by the GPS service provider specifying the child’s location.
- Web Based application the parent can log into and trace his child.
- Contact center that is providing the necessary info to the parent verbally.
All the methods above require a 3rd party infrastructure to enable the child’s location once queried by the parent. That 3rd party is termed Location Service Provider. The location service provider will be using a transmission technology such as GPRS or other RF method to receive the child's location form the locator device carried by the child. Depending on the ‘location service provider’ part or all of the above tracking methods might be available to the searching parent.
Coverage: Theoretically anywhere, however… The locator device need to be able to transmit it’s location back to the location service provider. In addition clouds or structured areas may limit the GPS capability.
Cost: one time payment for the device and recurring payment for the service which is one of the downsides of the GPS alternative.
Locator Tracking Methods Comparison
Technology
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Advantages
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Disadvantages
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Audio Alert |
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- Limited distance
- Limited assistance during emergency
- Highly visible and easily exposable
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RFID |
- Easy to Operate with respect to GPS technology
- No dependency on 3rd party operator
- Better operability indoors
- Higher accuracy than GPS (but not A-GPS)
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Cellular |
- Available and accessible technology
- Unified devices (phone + locator)
- Unified service provider (communication & location)
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- Dependent on cellular network distribution quality
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GPS |
- Not distance limitation.
- Can provide additional relevant data (velocity etc.)
- May have superior locator user interface
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- Recurring Charges and dependency on a 3rd party operator.
- Low accuracy (if not A-GPS)
- Limited when indoors (if not A-GPS)
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What is the use?
Following are some of the applications one may find for locator products:
- Child protection against kidnapping.
- Child protection against getting lost in public places.
- Pets protection against wondering and getting lost / stolen.
- Teenagers safe drive control.
- Tracking a fleet.
- Car protection against being stolen.
- Safety measure for travelers / skiers / soldiers.
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