PERIMETER BARRIER SYSTEMS AND METHOD OF PERIMETER BARRIER MONITORING

摘要

A perimeter barrier and method of monitoring a perimeter barrier are disclosed. The perimeter barrier includes posts (12, 14) and rails (16). A taut string (24) is suspended in one of the rails (16) and is tensioned by a spring (28) which is connected to post (12) and to the string (24). An optical fibre is coupled to the string (24) by attachment members (32) so that when the barrier element is disturbed, the taut string vibrates at one of its natural harmonic frequencies and imparts a vibrational movement to the waveguide to change a parameter of the light travelling through the waveguide so the change in parameter can be detected by a detector to provide an indication of the disturbance to the perimeter barrier.