AVL FAQ

GSM and GPS coverage

Q: Why GSM?

Because GSM is the European standard and is being used in many  other countries. Even more, it's very reliable and has a very high coverage rate  compared to other communication networks.

Q: Are there any places the Vehicle Tracking Unit cannot be used?

A: The GPS satellite system covers the whole world. There are more then 170 countries with GSM coverage worldwide. More about the coverage you will found at http://www.gsmworld.com .

Q: Is the data send as voice, SMS or GSM data channel?

The VTU  only uses  SMS and GSM data. It takes only a very short period of time to send a SMS data  package, and it only needs a very weak GSM signal (field strenght).  However, transmission of a data message  using the GSM modem call is still the cheapest solution at this moment.

Q: What if the vehicle is outside the GSM coverage?

The memory of the  VTU stores all the messages, and sends a message immediately when it's in  reach of a GSM bas station.

Q: What is GPS and how does it work?

A: GPS was developed by the U.S. military to  enable accurate navigation. 24 satellites have been placed in orbit some 20.000  km from the earth's centre.  GPS satellites are continuously transmitting a radio message containing  information including when the data was sent, which satellite sent it and the  current reliability of the system. More about that topic at link GPS tracking.

Q: When is the vehicle invisible for the GPS?

When the GPS antenna  doesn't have a clear sight off the sky, and therefore cannot see the satellites.  For instance if the car is in a deep underground garage or under a metal roof. More about that at link GPS antenna installation .

Q: Does this mean that no more tracking and tracing can be done?

A: No,  the VTU can still send a message by GSM, and transmit the latest known  position (for instance the entrance of the garage).