The false acceptance rate(FAR) is an error indicator for biometric procedures. The FAR value is of interest for biometric recognition procedures. Faulty measurements of biometric characteristics can falsely grant people access to confidential data or access to restricted areas.
The FAR value is about the fact that the biometric data of one person was recognized although the biometric data of another person was captured. Thus, a person was falsely recognized as the person whose data was available as reference data.
The FAR value indicates the probability with which an unauthorized person is recognized as authorized. It is calculated from the ratio of the number of false acceptances, Number of False Acceptances (NFA), to the number of attempts by unauthorized persons, Number of Imposter Attempts( NIA), given as a percentage. The false acceptance rate is highly dependent on the tolerance limits entered. The smaller these limits are, the higher the false acceptance rate. The lower the false acceptance rate, the more likely the error-free identification.
In addition to the False Acceptance Rate, there is also the Constant False Alarm Rate (CFAR) quality measure in radar technology. The CFAR value is used by the radar systems to keep the false acceptance rate constant depending on the environmental conditions. This technique is supported by Sensitive Time Control( STC) and the time-dependent gain control, Gain Time Control( GTC).