definition from wikipedia:
Guard Patrol monitoring system:

A Guard tour patrol system is a system for logging the rounds of employees in a variety of situations such as Security guards patrolling property, technicians monitoring climate-controlled environments, and correctional officers[1] checking prisoner living areas. It helps ensure that the employee makes his or her appointed rounds at the correct intervals and can offer a virtually indisputable record for legal or insurance reasons. Such systems have existed for many years using mechanical watchclock-based systems (watchman clocks/guard tour clocks/patrol clocks). Computerized systems were first introduced in Europe in the early 80s, and in North America in 1986.[2] Modern systems are based on handheld data loggers and RFID sensors.

Essentially, the system provides a means to record the time when the employee reaches certain important points on their tour (and, of course, the fact that they reached these points at all). Checkpoints or Watchstations are commonly placed at the extreme ends of the tour route and at critical points such as vaults, specimen refrigerators, vital equipment, access points, etc. Some systems are set so that the interval between stations is timed so if the employee fails to reach each point within a set time, other staff are dispatched to investigate and ensure the employee's well-being.

Though widely used throughout the security industry, these systems are best used in situations that require regular checks for fire, atmospheric conditions and/or malfunctions that could possibly endanger workers and/or assets. Regular patrols by security personnel offer predictability and therefore improve the criminal's chance of committing a crime. For routes which have significant outdoor exposure GPS units have proven to be a far more effective means of tracking security and law enforcement patrol behavior. Unfortunately GPS systems do not function in the most vulnerable areas such as indoors, underground or within floors of a building. So, systems using assisted GPS have been developed.