Brief introduction to the measurement standards of front-end detectors

When choosing a perimeter defense product, security professionals should focus on the following performance criteria: detection rate (PD), false alarm rate (VD), false alarm rate (FAR), false alarm rate (NAR). These standards fully reflect the strengths and weaknesses of different products. Fully understanding these four indicators is the key to choosing the right technology for an application.

Detection rate: PD is expressed as a percentage, that is, the probability that the detector detects an intruder in the defense zone. The detection probability of the detector is affected by the characteristics of the target (such as quantity, volume, speed and direction), sensitivity devices, weather conditions, location conditions and periodic maintenance of the instrument. The detection rate can reach 100%, but it will be accompanied by a very high false alarm rate. The detection probability of outdoor detectors is usually specified as 99%, and any less than 95% is not considered. (The detection probability of 95% means that there is one underreport every 20 intrusions)

Missed report rate: VD is also expressed as a percentage, that is, the probability that the detector cannot detect an intruder in the defense zone, which is an indicator corresponding to the detection rate. In the security industry, the underreporting rate is a very important indicator, and it is generally not considered if it is greater than 3%.

Misreporting rate: Misreporting refers to false alarms caused by unknown reasons. The alarm caused by the noise generated by the detector itself is the most typical false alarm. In addition, the detector electronic components exceed the tolerable temperature limit, poor grounding, incorrect line connection, power supply voltage fluctuations, instrument damage during installation, and improper maintenance of the detector. The false alarm rate is usually expressed in terms of the number of occurrences per day / month / year per zone. The false alarm rate is generally negligible. Low-grade detectors have false alarms once a month, while high-end products are once a year.

False alarm rate: False alarm refers to a false alarm caused by a non-threatening and determinable cause. The false alarm rate is also expressed as the number of occurrences per day / month / year per zone. Unlike FAR, the cause of NAR's alarm can be determined by the system operator and recognized by the remote CCTV. The causes of false positives are mostly related to small animals, or affected by the environment (such as strong winds, rain, snow, fog, hail, day / night, etc.) or topographical conditions, vegetation factors, and non-threatening people walking around the defense area. The size of the false alarm rate depends on the technology, practical application and site conditions. The false alarm rate of high-end detectors is usually once a month, while the low-end one is once a day. According to the security requirements of different places, it is up to the security experts to determine the acceptable false alarm rate under specific circumstances.

From an objective and scientific point of view, it is impossible to achieve a zero false alarm rate in any application. As a security practitioner, you must never use "zero false alarms" to mislead the market. Appropriate false positives and false positives are necessary for the effectiveness of the perimeter protection system.

According to the site environment, user budget, and safety assessment in specific applications.