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FPT-40 Fingerprint Terminal Installation & Operation Guide Page 2-7
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Caution! Use care when enrolling users at the terminal as the ESC
button can alter the entry fuctions during some
operations.
Introduction
User Identification/Verification
This is the process of comparing a user's finger against the stored map,
and/or verifying a user from a stored password number (5 digit max).
After performing the verification process the system will indicate success
or failure while also storing all verified punches for transfer to Time
Guardian.
Threshold
The threshold is a predefined number, often controlled by the
administrator, which establishes the degree of correlation necessary for
a sucessful match. If the score from the template comparison exceeds
the threshold, the templates are considered a match. The threshold
establishes a balance between False Acceptance Rate (FAR) and False
Rejection Rate (FRR). FAR indicates the probability that a biometric
system will incorrectly identify an individual or will fail to reject an
imposter.
You can set the threshold for all users. For a user who has a difficult
fingerprint verification, it is recommended to use ID & fingerprint
verification (match one-to-one). Raising the threshold increases security,
while lowering it increases the passing ratio. The correct balance can be
vital. For example, a user whose finger is worn or injured should have a
reduced threshold.
The FAR and FRR values affect each other. As FAR is increased, FRR
should be decreased. The default one-to-many threshold is 35, while the
1:1 matching default threshold is 15 (see the following table).
Table 2-1 Recommended Threshold Level Settings
FRR FAR One-to-Many One-to-One
High Low 45 25
Middle Middle 35 15
Low High 25 10