Case Studies: Display Terminal

"Making Technology Work"

Case Study - In Vehicle Radio Communications Terminal

Radio Supplies were looking for a terminal to replace a unit supplied some years ago into the vehicle fleet of a well known security company. The terminal was required to communicate to the security company's base stations via the Vodafone Paknet® radio service. The unit had to mimic the operation of the existing panel both in terms of operator interface and in terms of the radio communications.

EGS designed a terminal based around an INTEL® processor with twin serial ports for radio communications. The unit has an 8 by 40 character LCD display with a full QWERTY membrane keypad for data entry, the membrane being designed in keeping with Radio Supplies' company colours and branding.

The unit also has built in digital I/O to allow interface to special features such as an emergency button.

A single 26 way connector was built into the terminal carrying all the interface signals between the vehicle and the terminal. This facilitated connection of the terminal into the vehicle wiring loom.

EGS also developed the firmware application allowing the operators to log in to a base station and send / receive messages to allow the base station to monitor and control the movements of the vehicle. This application was written in embedded C and is compiled and then downloaded to the terminal where it is stored in flash memory.

The whole project was completed in 6 weeks, electronics, mechanical and software.

EGS are now supplying terminals to Radio Supplies in order to retrofit the entire fleet of vehicles with the new terminals.

The Mark-II terminal has just been produced which has an illuminated keypad for greater night-time visibility. The new panel automatically fades a series of orange LEDs behind the keyboard membrane to introduce a soft glow to all of the keys in low ambient light conditions. A picture will be available here soon.

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