These systems may involve sophisticated technology. Features can include night vision, computer assisted operation, and motion detection facilities which allows the operator to instruct the system to go on red alert when anything moves in view of the cameras. Camera systems increasingly employ bullet-proof casing, and automated self defense mechanisms which – as with the Liverpool system – ensure that cameras under attack are covered by neighboring cameras These can be legitimately described as military style systems.
The clarity of the pictures is often excellent, with many systems being able to recognize a cigarette packet at a hundred meters. The systems can often work in pitch blackness, bringing images up to daylight level.