COVER STORY
It would be wrong of me to claim infrared has no negatives. Whilst the infrared signal is contained within the room by walls and doors, if there is a glass wall (or window(s)) to the corridor the signal can leak through and activate a receiver in the corridor. In practice, this has never been a problem as the response team are alerted to both the corridor and ‘attack room’. They can instantly see that the event isn’t in the corridor and proceed directly into the indicated room.
NETWORKS
In any system, once a receiver has been triggered by an incoming alarm signal, it still has to transmit that information to somewhere it can be processed and displayed. A network is required to link the individual units and permit communication between them. Although a radio network (such as Wi-Fi) could be used, it would be susceptible to interference and other signal degradation, rendering it unreliable – far from ideal in a safety critical system! Wired networks (running over cables) are the preferred method and, broadly speaking, use either an Ethernet LAN or a proprietary protocol.
Systems using an Ethernet LAN run the risk that ‘call for assistance service messages’ could get delayed as they contend with other traffic on a busy network. Systems using the Ethernet are also designed around a centralised processing unit. A failure in that central unit could jeopardise the operation of entire segments or, in the worst case, the whole system – so any system that is totally dependent on central processing should be avoided at all costs.
From the outset, the Pinpoint system has always been based
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on distributed intelligence (or processing). No device on the network is dependent on any other device on the network to raise the alarm. Each receiver in a Pinpoint system has its own, unique address and, when activated, it broadcasts an alarm message over our network to every other device. The message is broadcast using our own data protocol and contains the address of the receiver, plus additional information relating to the level of alarm. This allows the system to respond to multiple types of alarm. All devices have their own ‘local intelligence’ and are configured to respond to appropriate messages according to a pre-programmed mandate. Alarm messages will typically set off visual displays, over door lights, PC screens, smartphone apps, sirens and any integrated third- party systems – as dictated by this mandate.
At Pinpoint, we have also steadfastly kept to our principle of dedicated cabling to avoid critical messages getting lost on a shared network. For added resilience, we use a ‘ring’ network so that, even if a cable is cut, the signals still have a pathway around the other side of the ring.
CONCLUSION
This approach of absolute simplicity, no centralised processing and dedicated cabling, ensures the Pinpoint system achieves a timescale from activation on the person-worn alarm transmitter to activation of all alert devices (lights, sirens, indicator screens etc.) typically in under 100 milliseconds. That’s under a tenth of a second!
It’s so simple, and that’s why it works so well.
www.pinpoint.ltd.uk
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