Intrinsically Safe Radio Transceiver

2009-11-07

Protecting our Emergency Services

An OEM customer providing a data communication system for emergency services required a radio transceiver and software operating protocol for use in an intrinsically safe environment.   This particular customer had already commissioned a radio module development from W&D for a another product range.  The new radio would require a new operating band and a complex mesh networking protocol embedded in the system architecture.  It would have to meet ETS 300 113 type approval.

The project was further complicated in that the customer had a large installed client base of radios from a third party source already deployed in service.   These radios had proved to be difficult to commission and had inherent protocol non compliance issues.   The new radio had to be capable of correctly meeting the protocol and accommodating the shortcomings in the third party incarnation.

The W&D hardware team had experience of Intrinsically Safe design techniques (IS) after many years of operating in diverse sectors such as oil and gas and mining.  An IS design requires each section of a design to be electrically isolated from another such that a failure in one area cannot result in a component becoming overheat or burn out.   

When the design is battery powered it is critical that the battery energy cannot be instantaneously discharged which could also lead to a heat or flame effect.   This design requirement was particularly demanding on the supply available from the battery and the ability of the engineers to decouple it from the rest of the circuit without losing too much from the supply voltage.

The mesh technology algorithm needed to allow the various users and assets to automatically log on and off from the network was conceived and then simulated by the W&D software team before committing to real software code.   This algorithm has proved resilient and robust in the field.   Apart from direct users logging on and off it has the ability to accommodate repeater stations deployed randomly about the operational scenario.

Perhaps the most demanding aspect of the development was trying to understand and accommodate the issues arising from the third party product compatibility request and the impact this had on testing and timescale.

The resulting module met the customer requirements in all respects.  The backward compatibility requirement while having the potential to create havoc has so far been successfully put to rest.

Since completion of the design process over 2,000 pieces have been and will continue to be produced through the W&D surface mount production line