Microphonic cable attached to a perimeter fence

Detection Technologies Ltd. are specialists in the design and manufacture of perimeter intrusion detection systems. Their core product is the VibraTek® vibration-sensitive linear sensor, which is basically a cable that is also a microphone. In addition to the cable, Detection Technologies also manufacture Analyser units that monitor the microphonic cable.

Our brief was to implement the digital signal processing that would distinguish cutting and climbing activities from 'false alarms' such as weather conditions. This involved utilising the wealth of experience within Detection Technologies and introducing some new innovations.

We also added significant value to their products with features such as pre- and post-alarm audio. This feature involved digitally recording audio in a circular buffer, enabling audio from before and after an event to be logged. The audio could then be played back using a standard HTTP interface to access the audio-over-Ethernet.

The Analysers are networked to a Base Station. This network demanded a sophisticated high-speed RS485 protocol that enabled alarm data and audio to be transported over standard CAT5 cable. Another great innovation was an auto-addressing feature to vastly improve ease of installation for the user.