Typical MDT features

9 VDC to 36 VDC input power.
Electrical transient protection, such as described in ISO 7637, Electrical disturbance on road vehicles.
Serial port to connect to a satellite or terrestrial radio transceiver.
Digital I/O to monitor external events.
Removable medial or I/O port of retrieving data or upgrading software.
Wide operating temperature -10 C to 70 C or better.
Drop tested to MIL-STD 810E, which specifies multiple drops from 48" to plywood over concrete.
Sealed against dust and liquid.
Connections to industry specific equipment, such as J1708 data bus for commercial truck applications.
Display technology specific to viewing conditions for the intended industry (LCD, TFT LCD, Vacuum fluorescent display, CSTN).
Integrated un-interruptible power supply, which will ride through electrical brown-outs typical in vehicle installations.
Internal 802.11b transceiver (depending on target application), possibly with external antenna connection.
A related device classification, specific to the transportation industry, is called automatic vehicle location (AVL). Mobile data terminals are often used in conjunction with a ¨black box¨ that contains GPS receiver, cell phone transceiver, other radio devices, or interfaces to industry-specific equipment. AVL devices may be simple stand-alone modems or may include operating systems with application space for the system integrator.