F Terms

F/Stop, F/Number: A calibrated measure of aperture lens opening. F/Stop is a numerical relationship between the diameter of the lens opening and the focal length of the lens. Common f/stops include f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22. The h n effect. The position of the level typically controls the amount of the A-Bus signal and the B-Bus signal that contributes to the mix, wipe, or key. On the DVS-2000C, the Fader Arm also controls the DME timeline.

FRB: Field Replaceable Block. An assembly, or circuit board that is repaired by Fremont repair center and sold as an "exchange" to repair a customer unit. Call parts in San Jose (800) 538-7550 to order.

FCC: Federal Communications Commission

FDDI: Fiber distributed data interface: High speed (l00+Mbps) LAN protocol.

FDMA: Frequency division multiple access: Uses FDM to allow multiple signal originators to contend for access to use the transmission media.

FEC: Forward Error Correction: Communications protocol that uses algorithms to detect errors and either request a resend or take corrective action to mask or compensate for the error.

Feed: Term generally used to indicate signals applied to satellite uplink terminals, or signals received from a satellite.

Feedback: 1.) The noise produced when the amplified sound from a loudspeaker is picked up by the microphone feeding that speaker. Also caused by feeding the output of a source directly back to its input.

2.) An interactive training term. The action of providing information to a user based on their input in order to reinforce concepts or facts that will improve performance or provide self-evaluation.

FFT: Fast Fourier Transformation: A fast algorithm for performing a discrete Fourier transform (an orthogonal transform).

Fiber Optics: A method of signal transmission sometimes used for CCTV video transmission. Fiber optics transmit light rather than electricity. Signals must be converted from an electronic to an optical signal prior to transmission and reconverted to an electronic signal at the receiving end. Fiber Optic transmission is capable of transmitting a great deal more information at very high resolution than traditional electronic methods without any of the associated problems of electromagnetic interference.

Field: 1.) A video term signifying one half of one television frame. In NTSC television broadcast, each frame (image) is made up of 525 lines. Two 262.5 horizontal line fields equal one frame. Each field represents either the even or the odd lines of a complete frame. A scanning system that uses even/odd field pairs is defined as interlace scanning. A field equals one-half of a complete television scanning cycle (1/60 of a second NTSC; 1/50 of a second PAL/SECAM). When interlaced, two fields combine to make one video frame with a scanning cycle of 1/30 of a second at a scanning rate of 1/30 of a second in NTSC.

2.) Computer term: The basic categories of information stored in the records in a file. For example, a file of bibliographic information might have Author, Title, and Date fields. Field is also used to describe portions of a sector that contain particular information, such as a sync field.

Field Dominance: In videodisc mastering, the order of the video fields established on the videotape during edits or transfers. A tape of field-one dominance has a new picture beginning on field one; with field-two dominance, the new picture begins on field two. The field dominance of the master tape determines on which field the videodisc frames will begin.

Field Frequency: The number of fields per second. NTSC field frequency is 60 per second; PAL frequency is 50 per second.

Field Rate: The number of fields per second.

Firmware: Software programs contained in Read Only Memory (ROM) in a hardware device, such as computer cards or boards; or cards containing programs.

FITL: Fiber in the loop: Telco term for fiber deployment in the local subscriber loop

Flicker: 1.) A visible fluctuation in the brightness of an image, often a problem in CRT displays if the vertical scan rate is lower than about 50 Hz.

2.) In videodisc applications, an undesirable result of freezing on a single frame that has mixed field dominance (see field Dominance). This results in a rapid oscillation between two images.

Flash Memory: Non-volatile, digital storage. Flash memory has slower access than SRAM or DRAM

FPS: Fast packet switch: Usually refers to ATM packet switching

Flip Flop: A feature where a switcher will always select the previous source as the next preview or preset source. The program/background bus flip flops with the preset bus. This feature is useful in live production situations to help you get back to the previous source quickly in case you make a mistake.

FM (Frequency Modulation): A method of modulation in which the frequency of the carrier voltage is varied with the frequency of the modulating voltage.

Focal Length: The distance between the optical center of a lens and the image plane (which in the case of a video camera is the CCD target area). The focal length is measured in millimeters (25mm = about 1 inch) and determines both the magnification and the angle of view of a lens. On a variable focal length lens or zoom lens this measure can be adjusted between two preset focal length extremes.

Foldback Circuit: Audio routing option designed to give studio performers the ability to monitor pre-selected sources.

Footcandle: A measure of light equal to 1 lumen per square foot. One foot-candle = 10.76 lux. The foot-candle is the unit most commonly employed by light meters used in the United States. However, most camera literature specifies the amount of light required for a camera to operate in lux. It is easy to convert camera specifications in lux to the equivalent specification in foot-candles: divide the specified lux by 10 for equivalent foot-candles.

Footprint: The illumination pattern on the earth's surface from the satellite's signal energy transmitted by the spacecraft.

Forward Compatible: A new coding standard is forward compatible with an existing coding standard if new decoders (designed to operate with the new coding standard) continue to be able to decode bitstreams of the existing coding standard.

Forward Motion: A motion vector that is used for motion compensation from a reference picture at Vector an earlier time in display order.

Frame: One complete TV picture consisting of two interlaced scanned fields. The American and Japanese standard for TV, NTSC, scans a new TV frame consisting of 525 raster lines 30 times per second. One TV frame is a 1/30 second synchronized to the U.S. AC power frequency of 60 Hz. A frame contains lines of spatial information of a video signal. For progressive video, these lines contain samples starting from one time instant and continuing through successive lines to the bottom of the frame. For interlaced video, a frame consists of two fields, a top field and a bottom field. One of these fields will commence one field period later than the other.

Frame Address: On optical videodiscs, each frame (or complete picture) has an a that can capture a frame in 1/30th of a second. A real-time frame grabber can digitize and display full-motion video.

Frame Interline Transfer Device: A CCD which employs both vertical registers (found in IT devices) and a separate vertical storage register (as with FT devices) to facilitate charge transfer. While these devices are the most costly to produce, they have advantages over both FT and IT devices including reduced Smear and an electronic shutter. FIT sensors are found on high-quality broadcast cameras. FIT is a combination of IT (Interline Transfer) and FT (Frame Transfer).

Frame Relay: A type of fast packet switching technology with simplified error detection capability. It requires more intelligence to reside in the receiving terminal.

Frame Transfer Device: A CCD which employs a separate storage array mounted vertically next to the sensing array to facilitate image charge transfer. FT devices were the first CCD imagers commercially available and are not widely used today.

Freeze Frame: (1)The action taken or the device used to pull out a single field or a full frame from a sequence in full motion. (2) To hold a single frame or picture for a period of time.

Frequency: The number of cycles a wave completes in a given time interval. In audio, the rate of repetition in cycles per second (hertz) of musical pitch or electrical signals. Low frequencies are bass; high frequencies are treble.

Frequency Division Multiplexing:: A technique in which communications signals are contained in separate carrier frequencies and are transmitted as one combined signal.

Frequency Response: The range of frequencies from the lowest to the highest that a particular electronic circuit is capable of handling without distortion. Most circuits have limits to the range of frequencies that they can handle. Frequency response is measured in cycles per second or Hz. The human ear has a frequency response of about 20 to 20,0000 Hz because it can hear and distinguish sounds within this range. In audio systems, a frequency response matching this performance of the ear would be considered high-fidelity. For security systems, audio frequency responses of 50 to 12,000 Hz should be considered sufficient. Video monitors should be capable of at least 4 MHz (million Hertz) to retain the performance of cameras and recorders.

Front-Screen Projection: An image projected on the audience side of a light-reflecting screen.

FSN: Full Service Network: A switched digital network system that combines voice, data and video delivery over a single 'pipe'.

F/Stop, F/Number: A calibrated measure of aperture lens opening. F/Stop is a numerical relationship between the diameter of the lens opening and the focal length of the lens. Common f/stops include f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22. The higher the number, the smaller the lens opening and the less light falling on the imager. In low-light situations a large aperture (e.g. f/1.4) would be needed.

FTTC: Fiber to the curb: Installation of optical fiber stopping just short of the home.

FTTH: Fiber to the home: Installation of optical fiber to each individual home.

FTTP: Fiber to the pedestal: Installation of optical fiber from the CO to the phone company pedestal which serves a number of houses.

Full Duplex: Two-way communication as opposed to simplex or half duplex, or one-way communication. In a two-site duplex videoconference, both parties can send and receive video, audio, and data simultaneously.

Full-Motion Video: Video sequences that emulate those normally seen on television because they have enough images (30 frames per second) to impart smooth motion.