Welcome to Elite Security Supplies, Guide to Tracking Systems
A tracking device can be made up of three main components. A GPS receiver, a GSM modem and a Radio Frequency (RF) beacon.
They all have their own unique and invaluable functions, but they also all have their own weaknesses and limitations.
GPS – This is used to receive Global positioning data from the GPS satellites orbiting the earth.
GSM modem – This is used to communicate this data back to our servers and also to receive instructions FROM our servers. It can also be used as a means of basic location by utilising the GSM networks own cell triangulation services. It is Quad-band and so can operate on any GSM network anywhere in the world.
RF – This is used to send out a pulsing radio frequency that can be received and tracked by ground-based or airborne search teams.
“Knowing how these individual systems work is key to understanding how best to protect your assets.”
Advantages and Disadvantages of each system
Global Positioning System satellites transmit signals to the units on the ground. The Tracking units receive satellite signals; they do not transmit them. All GPS receivers prefer an unobstructed view of the sky to operate at their best., so they are usually only ever accurate outdoors and their performance can often be dramatically affected when used within forested areas or near tall buildings.
Every GPS satellite transmits data that indicates its location and the current time. All GPS satellites synchronize operations so that these signals are transmitted at the same instant. The signals, moving at the speed of light, arrive at the Tracking unit at slightly different times because some satellites are farther away than others.
The distance from the C.A.T.S.eye™ to the GPS satellites can be determined by estimating the amount of time it takes for their signals to reach the receiver. When the unit has estimated the distance to at least four GPS satellites, it can calculate its own position in three dimensions.
There are at least 24 operational GPS satellites at all times. The satellites, operated by the U.S. Air Force, orbit with a period of 12 hours.
The Advantages of GPS:
when available, GPS positions are highly accurate, usually to within a few feet.
The Disadvantages of GPS:
GPS signals are easily blocked by physical obstructions, such as buildings and foliage.
GSM LBS (location based services a.k.a. Cell triangulation)
LBS works by feeding certain data and other information back from the GSM network cell towers that the device is currently logged onto. This data is then visually displayed on a map. Currently the information fed back will include the exact location of the GSM tower (cell) that the device is logged to and its direction from it. When combined with the signal strength data a general area can be calculated.
The benefits of LBS:
A general location fix can be achieved irrespective of indoor/outdoor coverage provided there is GSM coverage.
The disadvantages of LBS:
The accuracy of the location is not as good as GPS
The density of cells available in the area defines the accuracy of the location
Currently a ‘location request’ incurs a cost from the GSM network operator
The simple fact that LBS will operate indoors as well as outdoors means that it is preferred in applications involving people, particularly those like many lone workers who face issues when they are inside a building. However, the lower level of accuracy means that it is often not possible to rely on LBS alone to identify the exact location of a person. Typically in urban or well populated areas the level of accuracy achieved will be 50-250m. In rural locations though, accuracy can often be several kilometers. It is therefore beneficial in many applications to ‘cross reference’ an LBS position with any other known data. Examples of this could include the known route of a bus (for location transport workers) or the known home addresses of patients (for social care workers or healthcare staff).
Radio Frequency Beacon (RF)
Radio frequency DF or direction finding has been around for decades. It is the oldest of the tracking units features but Arguably the most important.
When commanded to do so, the unit will transmit a pre-determined code at regular pulse intervals.(n.b. This signal is transmitted in all directions) This data can be programmed to include the identification of the unit itself or its latitude and longitude if it is available..
Any nearby agents who are searching for the unit can pick up this signal from up to 500m away at ground level and 2k if in the air. And, by using a handheld or vehicle mounted directional finding (DF) receiver, they can follow this transmission directly to the source. Thus locating the System itself or at least the hiding place that it is in.
The Advantages of RF: RF will penetrate most solid structures including buildings and vehicles and effectively “leak” out of most enclosures.
The Disadvantages of RF: RF is not easy to follow in built up areas as it can ‘reflect’ or ‘bounce’ off of flat surfaces and thus cause a certain degree of confusion to the un-trained tracker. Once trained however, almost anyone can be relied upon to locate the unit once a signal has been detected.
Many tracking units incorporate one or two of the features for tracking,