Vehicle tracking and fleet management systems, in its most basic form, help dispatchers, supervisors and managers track the positions of their assets in real time using global positioning systems (GPS). Like a lot of other modern day technologies, it is easy to simply take advantage of how truly extraordinary these everyday instruments are.
Intro to GPS Technology
GPS technology, in short, works when signals are sent from a satellite network that orbit the earth in its atmosphere to your GPS device situated on, or close to, the Earth’s surface. These signals are read and interpreted by the receiver, which then provides you with your relative location.
A standard GPS receiver must have the ability to detect broadcasts from a minimum of four satellites to calculate your position:
- Three of the satellites are used for determining your position
- The fourth is used as validation in the event that the other three happen to produce inconsistent data
The time it takes for each signal to reach the receiver is used to calculate the distance of the receiver from the satellites.
This data is used to determine your:
- Longitude & latitude accurate within about three meters
- Altitude
- Velocity
- Synchronized time
Factors That Can Impact GPS Performance
On the spectrum of signals, signal strength is considered to be relatively weak. This means that your GPS can be affected by certain factors that are uncontrollable. Here are some situations in which performance of your receiver may be compromised:
- There are poor weather conditions, such as heavy precipitation or dense clouds
- The receiver is in an environment where physical obstructions, such as deep valleys, mountains, bridges, overhangs, tall buildings or tunnels are apparent
- The receiver is blocked by something within the vehicle
Understanding GPS Jamming
To address the last point about local interference, also known as jamming, it is important to note that GoFleet’s Geotab GO6 device and other newer models have the ability to detect the occurrence of local GPS jamming. In the case that local jamming does occur, the modem will report a “debug log” which can be found in the Log Details within MyGeotab: “GPSJammingDetected”.
If you find that your device does not have the ability to track your vehicle accurately, you will want to check for any instances of this debug log being reported. If it has been reported, you will be able to begin to identify what could be causing the GPS jamming.
In certain trucks, some metal components in the steering column can interfere with the GPS signal. In other vehicles, such as limos, the signal may be obstructed by a special metallic coating on the windshield that is not visible to the eye.
It isn’t always easy to determine what is causing the jamming. For example, some of the newer models of Hino trucks use a certain Jensen radio system, that includes a CD laser reader that has been previously proven to obstruct the signals.
If you cannot determine what is jamming your signal, contact GoFleet and we will be happy to assist you in identifying the possible causes and suggest resolutions.
Original Article Written by: Jason Widla, Technical Support Engineer at Geotab
http://www.geotab.com/blog/gps-spotlight/