A Primer On Satellite Car Tracking
Technology For Private Investigators

By Ralph Thomas

Automatic Vehicle Tracking (AVL) is making it's premier in the private sector. The idea of AVL combined computer technology with satellite tracking technology developed by the U.S. Military commonly known as GPS (Global Positioning Satellite). This type of surveillance system calls for the following four elements. They are:

A Transmitter
A Satellite
Software And Location Decoder

The reason GPS tracking is becoming so popular these days is that it is possible to conduct a surveillance that in unmanned. That is, the equipment tracks the movement of the vehicle and it's stop locations. Investigative agencies in the USA are starting to offer such services and it's time all investigative agencies become familiar with what this technology is all about.

A Little History Of Vehicle Tracking Non-GPS Tracking Systems
In the late 1960's and early 1970's, car trackers became available in the private sector. These early systems consisted of a receiver and a sender with at least two antennas that were placed on the vehicle. The surveillance investigator would keep the receiving end of the equipment with him in his vehicle. Basically all these units would do is tell you which direction the vehicle was located in and maybe the distance from the target vehicle. If you lost a vehicle, this type of system made is easier to locate the vehicle but they had their limits. It's important to point out that these units could not reveal the actual location of the target vehicle. They merely indicated which "direction" the target vehicle was in from the surveillance vehicle's location and the distance. One of the major problems with these units is that they had a limited range. Not only that, in huge metropolitan areas with tall buildings and lots of radio traffic, they rarely performed as needed and the range so sort in most instances, they become rather useless.

A Photo Of An Early Car Tracking System


Pictured Above is the ProTrack One Non-GPS Tracking System

These non-GPS car tracking systems have been improved over the years and the range on them somewhat expanded but they still have their limitations. Understanding their limitations is important but they can still be used in real time mode to help locate a lost vehicle.


Let us go over each element of what is involved in AVL or GPS tracking.

The Transmitter
An electronic transmitter that sends out signals from the vehicle. Naturally, this equipment will have to be placed somewhere on the vehicle in order for a signal to be transmitted.

A photo of a self contained magnetic mount made specifically for CarTracker

The typical equipment used for this employs very strong magnetic mount. You walk up to a vehicle and quickly place the entire box on the underside of the vehicle.

The Satellite
A Global positioning satellite obtains signals from the transmitter device placed on the vehicle. The use of only one satellite will give an accuracy rating of about 100 feet. This can be improved by using triangulation math which uses three satellites and gives more pinpointed accuracy down to about ten meters. Up until a short time ago, this was extremely expensive technology. However, the U.S. Deaprtment Of Defense has placed a series of 24 Global Postioning System (GPS) satellites in orbit around the earth. These GPS satellites broadcaste signals that contain time and identifer codes. GPS recievers use an antenna to acquire these signals from muttiple satellites to determine a person's postion, altitude, speed and direction of travel. These satellites are now being used by the public and can be used as online map plotting tracking in your vehicle as well are used as mobel vehicle locators in surveillance work.

The Sender And Receiver
Here is where options and different configurations come into play. There are what are called real time satellite tracking systems and none real time systems. Real time tracking systems tend to be more expensive than tracking systems that are not real time. With the lower end systems, you can not plot the location as it actually happens. With real time tracking equipment, you install software on your computer and must have a separate unit attached to your computer that will receive the satellite signal. With this type of set-up, you are in a position to track a vehicle as it's moving. The Protrack GPS system is one of the most popular configurations for real time tracking. The black box within the magnetic mount beans a signal to a GPS satellite and then receives it's location. That signal is then forwarded through a cell phone connection to the user's computer. In none-real time tracking systems, the satellite signal is send back to the original sending box and stored for latter pickup. With this simpler type of system, you retrieve the box after the surveillance and then load the data from it into your computer. The CarTracker is one of the more popular non-real time GPS tracking systems on the market today. Understanding the difference between real time GPS tracking and non-real time tracking is simple. Real time tracking let's you obtain the results right now from your computer desktop. Non-realtime tracking requires you to pick up the magnetic mount after the surveillance and obtain the results then.


The ProTrack GPS System. Tracks vehicles in real time through cellular connection.

At first look, realtime tracking seems to be the way to go. However, there are several draw backs to it. First, realtime tracking equipment is going to cost substantially more. Secondly, there are more signals that can get lost in the process. Remember, the signal is sent back to the magnetic mount then forwarded to the subject computer. An extra transmission step is involved. Any time that happens, more things have the potential of going wrong and there will be a greater potential of loss of signal in such a setup.

Power Supply Issues
No matter what type of GPS tracking system one uses, some sort of power supply is needed. In the typical fast-action magnetic mount systems, standard self-contained battery power can be used. However, you have a limit to the amount of power time you have. Products like CarTracker have an optional fuse box hardwire that can be wired into the vehicle power system but this, of course; requires position of the vehicle for such a technique. However, hardwiring can sometimes be employed in situations in which parents want to track their children's location for an extended period of time.

The Software And Location Decoder
A decoder converts the data received into an address. The location information which is generally in latitude and longitude is plotted with mapping software so the user can obtain actual maps of the location of the target vehicle. Thus computer generated map plotting programs are used to convert the latitude and longitude readings into an address on a computer generated digital map. This requires installing specific software onto your computer that will then covert the latitude and longitude data onto the map. Below is photos of typical mapping software.

The mapping software we use in conjunction with the equipment lets the user zoom in and out of the mapping plots. Many of the better software programs used in conjunction with the GPS hardware such as the software that comes with Cartracker, creates automatically generated reports with times, dates and locations.


Investigative Benefits
The benefits of this new technology in surveillance is profound. By using this technology, an actual physical surveillance by a human is not needed in many instances. When the goal of a surveillance is to determine physical location only, this technology can be employed. The transmitter is simply covertly placed on the target vehicle. A computer program is used to collect location data at predetermined intervals. After a few days, the investigator simply has the computer print out the location data of the target vehicle. Of course, this technology will not make human activity in physical surveillance obsolete for obvious reasons any more than online searching made background investigation obsolete.

Review The Cartracker!
The First Affordable GPS Covert Surveillance Vehicle Tracker



GPS History And Overview
By Terry Macy

A Primer On Global Positioning
From Phrack

Global Positioning System-An Overview
From Lowe Electronics

GPS Glossary
Everything you wanted to know about GPS
Tracking but didn't know who to ask.

Improvements In GPS Technology
US Government Article

Beyond Push Button GPS
Alfred Leick, Department of Spatial Information, University of Maine

GPS Overview
By The University Of Texas

The GPS Library
A huge links list to GPS topics

U.S. Latitude/Longitude Server
Enter location in the U.S. and receive the Lat/lon for that location. Slow but works.


A review of ProTrack One Non-GPS Tracking System

A review of: CarTracker GPS Tracking System

A review of: ProTrack Real-Time GPS Tracking System



Copyright: 2000, Ralph Thomas
All Rights Reserved