BT were suffering massive losses from copper cable theft. Thieves were finding two nearby manhole covers, cutting the wire cable between them and using a vehicle to pull the copper out.
Our experience in low power electronics with GSM communications put us in an ideal place to provide a solution to the problem. We designed and built a covert GSM signalling device to send a text message to several pre programmed phone numbers upon detection of a manhole cover being raised.
This was achieved by using a standard IP rated enclosure used by BT for terminating and splicing wires, fitting an LDR to the lid and housing a custom PCB and a SAFT LSH20 3.6V D Cell Lithium battery.