FFT <Fast Fourier transform>

Reading: F f tea
Full spelling: Fast Fourier Transform
Field:
IT and society > information science > FFT

The technique which James W of the Bell Telephone Laboratories. Cooley and John W. Tukey devised in 1965, calculates discrete fourier transform and adverse change exchanging in high speed. It is the important algorithm which is used with processing of the multimedia data of the picture and sound and image etc.

The processing which extracts which frequency component just which is included in the signal, is called fourier transform. Dividing the input ripple mark into several groups, the algorithm which makes the computational complexity decrease substantially by calculating, devise computation sequence is FFT. When designating the number of groups as N, frequency of operation with usual conversion is proportionate to the square of N, but with FFT it is proportionate to NlogN.

FHS

Reading: F h s
Full spelling: Filesystem Hierarchy Standard
Field:
OS > UNIX > FHS

In the Linux system, the standard which makes the role of the file and the position of the directory correspond where that file should exist. One of the result of the LSB project which decides Linux-related standard specification. As a main correspondence attaching, as for basic command as for the foam/home directory “of /bin” and the general user as for the relation “of /home” and the boot loader it has become “/boot” and as for the logs “/var” etc. This way as for the user it is possible by making the position decide where each file should exist, to search the intended file easily with any kind of environment. In addition, FHS distinguishes the data which is specific to each computer and the data which can be shared with the plural computers strictly, makes the data sharing with the plural stands easy.

FHSS <Frequency hopping system>

Full spelling: Frequency Hopping Spread Spectrum
Field:
Portable telephone > 3G > FHSS

At one of systems of spectrum spread, those which modify the frequency which every brief quite (0.1 seconds are many,) the signal transmits. One after another, in order to keep modifying transmission frequency, when noise occurs at specific frequency also correction being possible with the data which is communicated at other frequency, selecting the frequency whose noise is little, it is possible also to transmit. Resistance obstacle characteristic is high, also hiding characteristic of communication is superior, is suitable for multi anti- multi large-scale communications. However, when it compares with DS-SS, in the aspect of transmission rate it is inferior. Bluetooth of short-range radio communication standard and IEEE 802.11 of the wireless LAN have used FH-SS (as for IEEE 802.11b DS-SS use). There is a hybrid system which mixes FH-SS and DS-SS and both in the CDMA system which is used by the portable telephone.

Fibre Channel <Fiber channel>

Reading: Fiber channel
Field:
Personal computer > I/O > SCSI > Fibre Channel

One of data transfer systems in order to tie the computer and the peripheral device. Although mainly, with the server whose high efficiency is necessary, you connect the computer itself and the external memory unit, it is utilized. In connection of the equipment range maximum between the equipment with in case of the optical fiber is 30m with in case of 10km and the coaxial cable making use of the coaxial cable or the optical fiber. As for maximum transfer rate with in case of coaxial cable with in case of 133Mbps and optical fiber in 1.0625Gbps and emergency high speed. It can connect maximum of 125 equipment to 1 computers. It is adopted ANSI (the American National Standards Institute) as portion of SCSI-3 standard.

FIFO

Reading: [huaihuo]
Full spelling: First-In First-Out
Field:
Programming > algorithm > FIFO

The system which it tries to remove to the order which houses the data which is housed in a certain place, old. The data which is housed most newly is removed most lastly. Queue/cue (queue) with the data structure which is called handles the data with this system.