|F||1. Farad(s): Unit of capacitance.
2. f in lower case is the standard abbreviation for femto, a metric prefix for 10 to the -15.
3. Fahrenheit temperature scale.
|fA||Femtoampere(s): 10 to the -15 Ampere; a millionth a nanoampere.|
|Facility Data Link||See FDL|
|Fail-Safe||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.|
|Fan Control||See Fan Controller - Linear|
|Fan Controller - Linear||An integrated circuit that varies the speed and airflow of a cooling fan using a variable voltage in response to temperature or system commands.|
|Fan Controller - PWM||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.|
|Fast Fourier Transform||See FFT|
|Fault Blanking||A function that ignores a fault for a predetermined period. This is done to eliminate nuisance fault indication.|
|Fault Tolerant||Will tolerate excessive voltage during a fault condition.|
|FCD||Fan count divisor|
|FCR||Fan conversion rate|
|FDDI||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).|
|FDL||Facility data link: Embedded communications channel in ESF DS1 framing. Used to convey both bit-oriented and message-oriented signals.|
|FDM||A method for carrying multiple channels of information on one channel by dividing the available bandwidth among the channels.|
|FE||Functional equivalent (in component cross-reference data); also field engineer; also framing error|
|FEC||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 ratio decreases with distance.|
|Femto Base Station||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 smaller area (the home).
A femto base station benefits the service provider because it offloads cell tower traffic. Subscribers benefit from superior signal strength, due to the proximity of the unit -- especially where a cellular signal is weak or not available.
Femto base stations augment the normal network and replicates the usual telecommunications infrastructure. Connection to the cell phone network is provided by VoIP over the Internet.
|femto basestation||See Femto Base Station|
|femtobasestation||See Femto Base Station|
|femtocell||See Femto Base Station|
|FET||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).
There are three varieties: The JFET (Junction Field-Effect Transistor); the MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor); and the MESFET (Metal-Semiconductor Field-Effect Transistor).
The FET is one of two major kinds of transistor, the other being the Bipolar Junction Transistor.
|FFT||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 bands).
The Fast Fourier Transform is a common algorithm for Fourier transforms. It is more efficient (faster) than the DFT, Discrete Fourier Transform.
|FHSS||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 known to the receiving system.|
|Fiber Channel||See Fibre Channel|
|Fiber Distributed Data Interface||See FDDI|
|Fibre Channel||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 topologies that can scale to a total system bandwidth on the order of a terabit per second. (The standardized spelling is "fibre channel" but often misspelled as "fiber channel.")|
|Field Programmable Gate Array||See FPGA|
|Field-Effect Transistor||See FET|
|FIFO||First-In First Out: A type of memory that stores data serially, where the first bit read is the first bit that was stored.|
|Finagle's Law||See Murphy's Law|
|FireWire||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."|
|First In First Out||See FIFO|
|FIT||Failures in time: See FIT calculator: /tools/calculators/index.cfm/path/qa/calc_id/qafits|
|Flash ADC||See Flash ADCs|
|Flash ADCs||An analog-to-digital converter that uses a series of comparators with different threshold voltages to convert an analog signal to a digital output.|
|FlexSound||FlexSound describes a set of digital audio signal processing blocks used in Maxim's products to provide or enhance audio functions such as compression, limiting, or equalization.
FlexSound® processor is a fully programmable digital audio signal processing system that includes a programmable DSP core, hard-wired digital macros, and an associated memory architecture.
FlexSound is a registered trademark of Maxim Integrated Products, Inc.
|FM||Frequency Modulation: A modulation method in which the carrier frequency changes with the input signal amplitude.|
|FM Modulator||See VCO|
|FOC||Fields oriented control|
|Foldback Current Limit||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.|
|Foldback Mode||See Foldback Current Limit|
|Force-Sense||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).|
|Forward Converter||A power-supply switching circuit that transfers energy to the transformer secondary when the switching transistor is on.|
|Forward Error Correction||See FEC|
|Fourier Transform||See FFT|
|FPGA||Field Programmable Gate Array: A family of general-purpose logic devices that can be configured by the end user to perform many, different, complex logic functions. It is often used for prototyping logic hardware.|
|FR||See Frame Relay|
|Frame Relay||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.|
|Framer||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.|
|Frequency Bin||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/2, where NRECORD is the number of signal points captured in the time domain.
The first frequency line in the power spectrum always represents DC (frequency=0). The last frequency line can be found at fSAMPLE/2 - fSAMPLE/NRECORD. Frequency lines are spaced at even intervals of fSAMPLE/NRECORD. They are commonly referred to as frequency bins or FFT bins. Bins can also be computed with reference to a data converter's sampling period:
Bin = fSAMPLE/NRECORD = 1/(NRECORD × ΔtSAMPLE)Example: We apply a sampling frequency of 82MHz and take 8192 records. The frequency bin is 10kHz.
|Frequency Diversity||In radio systems, Frequency Diversity spreads a signal across multiple channels by transmitting multiple versions of the signal on different frequencies.|
|Frequency Division Multiplexing||See FDM|
|Frequency Hopping||See DSSS|
|Frequency Hopping Spread Spectrum||See FHSS|
|Frequency Modulation||See FM|
|Frequency Shift Keying||See FSK|
|Frequency Synthesizer||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.|
|FS||Full scale; frame sync|
|FSK||Frequency Shift Keying: A method of transmitting digital data by shifting the frequency of a carrier signal to represent binary 1s and 0s.|
|FSOTC||Full-span output temperature coefficient|
|FTC||Fan tachometer count|
|FTCL||Fan tachometer count limit|
|FTTH||Fiber-to-the-home: A method for broadband data (voice, Internet, multimedia, etc.) delivery to the home via optical fiber.
Contrast with FTTN (fiber-to-the-node) which uses fiber up to a node outside the home and uses copper to bring the data into the home.
|FTTN||FTTN is "Fiber-to-the-node."
There are two technologies for delivering broadband: Fiber-to-the-node (FTTN) uses fiber to bring data to a node and uses copper to bring the data into the home. Fiber-to-the-home (FTTH) brings fiber all the way into the home.
|Fuel Gauge||See Battery Fuel Gauge|
|Full Duplex||A channel providing simultaneous transmission in both directions.|
|Full-Duplex||See Full Duplex|