The following is the data transmission methodology which enables reliable connectivity
and visibility to vehicles and assets.
The mobile units, which are installed on the locomotives / vehicles, are equipped
by Reltronics Technologies' versatile edge-ware system known as SmartInstrument™-AU
to determine their position using a GPS receiver. They communicate with the control
centre in a wireless way. The control centre communicates with the SmartInstrument™-AU
installed in different mobile units and offers location services to the end users.
SmartInstrument™-AU provides required accuracy for the locomotives' position
is about 5 meters using differential GPS technology, which can't be achieved with
just about any GPS receiver available off the shelf. Special care is taken by Reltronics
Technologies to provide such accuracy throughout the transportation channel to ensure
no pilferage or unwanted stops or to check the idle conditions of the vehicles involved
in transportation. The central station also needs reference position data of the
rail track network over the entire organization as well as point of interest data
along the rail tracks such as the position of each entity involved in the operation.
Obtained data can then be overlaid on a map with the help of GIS/mapping software
such as ArcGIS™, MapPoint™, Google Maps etc. based on the customer requirements.
The most important of the SmartInstrument™-AU is the communication link. Various
means of wireless communication could be used: VHF/UHF radio links, cellular telephony,
satellite based data communication systems such as ORBCOMMTM / AT&T etc. The
means of wireless communication can be used in two ways: a continuous or a polled
setup. In a polled setup, the central station requests position reports from the
mobile units. When the position of a mobile unit is required, the central station
sends out a request to SmartInstrument™-AU mobile unit, which replies to the
central station with a position report. The central station is able to retrieve
the position of all SmartInstrument™-AU units by means of two-way communication
between the central station and the mobile units.
In a continuous setup, the mobile units send a position report to the central station
on a regular basis. As a result, a recent position report of each SmartInstrument™-AU
unit is available at the central station at any time. Only one-way communication,
i.e. from the SmartInstrument™-AU units to the central station, is required.
However, Reltronics Technologies took special care to prevent simultaneous transmissions
by synchronizing in time of the SmartInstrument™-AU units by making additional
use of their GPS receiver for accurate synchronization.