In optical fiber technology, a method of measuring the transmission loss by (a) using a stable optical source, at the wavelength of interest, to drive a mode scrambler, the output of which overfills (drives) a 1-meter to 2-meter reference fiber having physical and optical characteristics matching those of the fiber under test, (b) measuring the power level at the output… (Read More →)

A class of tributary office which does not have direct access to its toll center, but which is connected to its toll center office by means of circuits which are switched through to the toll center at another tributary office. [47 CFR Pt.36-A]

A channel with a bandwidth narrower than that of a voice-grade channel.
Note: A subvoice-grade channel is usually a subchannel of a voice-grade line.

The transfer of a nonduplicate user information block between the source user and intended destination user.
Note: Successful block delivery includes the delivery of correct and incorrect blocks.

The transfer of a correct, nonduplicate, user information block between the source user and intended destination user.
Note: Successful block transfer occurs when the last bit of the transferred block crosses the functional interface between the telecommunications system and the intended destination user. Successful block transfer can only occur within a defined maximum block transfer time after initiation of a… (Read More →)

The termination of user information transfer between a source user and a destination user in response to a disengagement request.
Note: Successful disengagement occurs at the earliest moment at which either user is able to initiate a new information transfer transaction.

An abnormally high ionization density in the D region caused by an occasional sudden solar flare, i.e., outburst of ultraviolet light from the Sun.
Note: The SID results in a sudden increase in radio-wave absorption that is most severe in the upper medium-frequency (MF) and lower high-frequency (HF) ranges.

An aspect of the assessment of the effectiveness of a Target of Evaluation, namely the suitability of its security enforcing functions and mechanisms to in fact counter the threats to the security of the Target of Evaluation identified in its security target [ITSEC].

Synonym summation check.

1. A check based on the formation of the sum of the digits of a numeral.
Note: The sum of the individual digits is usually compared with a previously computed value.
2. A comparison of checksums on the same data on different occasions or on different representations of the data in order to verify data integrity. Synonym sum check.