Glossary

1. Farad(s): Unit of capacitance.

Femtoampere(s): 10 to the -15 Ampere; a millionth a nanoampere.

A technique used in RS-485 interface transceivers which forces the output to a predefined state in the event of a line short or open circuit.

An integrated circuit that varies the speed and airflow of a cooling fan using a variable voltage in response to temperature or system commands.

An integrated circuit that varies the speed and airflow of a cooling fan using a pulse-width-modulated (PWM) voltage in response to temperature or system commands.

A function that ignores a fault for a predetermined period. This is done to eliminate nuisance fault indication.

Will tolerate excessive voltage during a fault condition.

Feedback

Fan count divisor

Fan conversion rate

Frequency-division duplex

Fiber Distributed Data Interface: A standard for transmitting data on optical fiber cables at a rate of around 100,000,000 bits-per-second (10 times as fast as 10 Base-T Ethernet; about twice as fast as T-3).

Facility data link: Embedded communications channel in ESF DS1 framing. Used to convey both bit-oriented and message-oriented signals.

A method for carrying multiple channels of information on one channel by dividing the available bandwidth among the channels.

Functional equivalent (in component cross-reference data); also field engineer; also framing error

Forward Error Correction: A technique for detecting and correcting errors from imperfect transmission by adding a small number of extra bits. FEC allows optical transmission over longer distances by correcting errors that can happen as the signal-to-noise

A femto base station (also called an Access Point Base Station, femtocell, femtobasestation or femto basestation) is an in-home base station. Like a standard base station, it connects cell phone voice and data to the cell phone network, but it serves a sm

Field-Effect Transistor: A transistor in which the voltage on one terminal (the gate) creates a field that allows or disallows conduction between the other two terminals (the source and drain).

A Fourier transform (FT) converts a signal from the time domain (signal strength as a function of time) to the frequency domain (signal strength as a function of frequency). It shows the signal's spectral content, divided into discrete bins (frequency ban

Fan gain

Frequency Hopping Spread Spectrum: A transmission technology in which the data signal is modulated by a narrowband carrier signal which changes frequency ("hops") over a wide band of frequencies. The hopping seems random but is prescribed by an algorithm

A highly-reliable, gigabit interconnect technology that allows concurrent communications among workstations, mainframes, servers, data storage systems, and other peripherals using SCSI and IP protocols. It provides interconnect systems for multiple topolo

First-In First Out: A type of memory that stores data serially, where the first bit read is the first bit that was stored.

Electronic filters are circuits which perform signal processing functions, specifically to remove unwanted frequency components from the signal, to enhance wanted ones, or both.

Apple Computer trademarked name for the IEEE 1394 serial interface standard: A high-speed interface between computers and peripherals such as external disk drives, cameras, and camcorders. Also referred to by Sony trademarked name, "I-Link."

Failures in time

An analog-to-digital converter that uses a series of comparators with different threshold voltages to convert an analog signal to a digital output.

Flash memory is an electronic (solid-state) non-volatilecomputer storage medium that can be electrically erased and reprogrammed.

A signal line is said to be "floating" if it is not connected to any voltage supply, ground, or ground-referenced signal source.

Frequency Modulation: A modulation method in which the carrier frequency changes with the input signal amplitude.

Fields oriented control

A circuit which reduces the current limit once the device enters current-limited operation. Commonly seen on RS-422/RS-485 drivers and some power circuits.

Measurement technique in which a voltage (or current) is forced at a remote point in a circuit; then the resulting current (or voltage) is measured (sensed).

A power-supply switching circuit that transfers energy to the transformer secondary when the switching transistor is on.

Fast-on oscillator

Full-power bandwidth

A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by a customer or a designer after manufacturing – hence "field-programmable".

A high-speed, packet-switched data communications service similar to X.25. Frame relay is a leading contender for LAN-to-LAN interconnect services, and is well suited to the burst-intensive demands of LAN environments.

A device used to align/synchronize to an embedded framing pattern in a serial bit stream. Once synchronized and data fields are properly aligned, overhead bits for alarms, performance monitoring, embedded signaling, etc. may be extracted and processed.

The frequency range and resolution on the frequency axis of a spectrum graph depends on the sampling rate and the size of the data record (the number of acquisition points). The number of frequency points or lines or bands in the power spectrum is NRECORD

In radio systems, Frequency Diversity spreads a signal across multiple channels by transmitting multiple versions of the signal on different frequencies.

A frequency synthesizer is an electronic circuit that uses an oscillator to generate a preprogrammed set of stable frequencies with minimal phase noise. Primary applications include wireless/RF devices such as radios, set top boxes, and GPS.

Full scale; frame sync

Fan-speed control

Frequency Shift Keying: A method of transmitting digital data by shifting the frequency of a carrier signal to represent binary 1s and 0s.

Full-span output

Full-span output temperature coefficient

Full-scale range

Fan tachometer count

Fan tachometer count limit

Fiber-to-the-business

Fiber-to-the-home: A method for broadband data (voice, Internet, multimedia, etc.) delivery to the home via optical fiber.

FTTN is "Fiber-to-the-node."

A channel providing simultaneous transmission in both directions.

An electrical safety device that operates to provide overcurrent protection of an electrical circuit.