Glossary

In a cable or circuit, any extraneous signal (electromagnetic energy) that interferes with the desired signal normally present in or passing through the system.

A DuPont trademark for a temperature-resistant, flameretardant nylon.

A type of single-mode optical fiber designed to reduce the effects of chromatic dispersion while minimizing four-wave mixing.

A path drawn perpendicular to the interface, or boundary layer between two media, that is used to determine the angle of incidence of light reaching the interface.

The angle that is perpendicular to a surface.

A digital code in which the signal level is low for a 0 bit and high for a 1 bit and which does not return to zero volts between successive 1 bits or between successive 0 bits.

The U.S. government agency responsible for protecting U.S. communications and producing foreign intelligence information. It was established by presidential directive in 1952 as a separately organized agency within the Department of Defense.

Nokia Siemens Networks

Used to terminate ISDN at the customer premises. It converts a two-wire ISDN U interface to a four-wire S/T interface.

The speed that a signal propagates through a cable expressed as a decimal fraction of the speed of light in a vacuum. Typical copper cables have an NVP value of between 0.6c and 0.9c.

The calculated minimum effective sampling rate for a given analog signal based on its highest expected frequency. The Nyquist Minimum requires sampling to take place at a minimum of twice the expected highest frequency of an analog signal. For example, if an analog signal

Orange, when used in conjunction with color-coding for twisted-pair cabling.

Optical carrier level one, equal to 51.84Mbps. This is a SONET channel, whose format measures 90 bytes and is composed of the transport overhead and the synchronous payload envelope.

SONET channel of 622.08Mbps.

SONET channel of 10Gbps, currently the highest level now available.