Thankyou for your valueable input. This is exactly the type of information I was looking for as it highlights some concerns that others may also have. The concern of false detection and annoyance to operators if the system was continually being activated during the normal part of their operation.

Our systems use an "active" monitoring where a device is located on the areas,people or objects that must be avoided. This means the alert will not be activated on objects that are not fitted with a device. The range of detection can be set individually for each device. For example it may be that the system activates when within 4m of a person wearing a device but is set to 1m for another object.

Any other ideas/comments please ?

Regards

David