Coding theoryCoding theory is the study of the properties of codes and their respective fitness for specific applications. Codes are used for data compression, cryptography, error detection and correction, data transmission and data storage. Codes are studied by various scientific disciplines—such as information theory, electrical engineering, mathematics, linguistics, and computer science—for the purpose of designing efficient and reliable data transmission methods.
Finite fieldIn mathematics, a finite field or Galois field (so-named in honor of Évariste Galois) is a field that contains a finite number of elements. As with any field, a finite field is a set on which the operations of multiplication, addition, subtraction and division are defined and satisfy certain basic rules. The most common examples of finite fields are given by the integers mod p when p is a prime number. The order of a finite field is its number of elements, which is either a prime number or a prime power.
Acknowledgement (data networks)In data networking, telecommunications, and computer buses, an acknowledgment (ACK) is a signal that is passed between communicating processes, computers, or devices to signify acknowledgment, or receipt of message, as part of a communications protocol. The negative-acknowledgement (NAK or NACK) is a signal that is sent to reject a previously received message or to indicate some kind of error. Acknowledgments and negative acknowledgments inform a sender of the receiver's state so that it can adjust its own state accordingly.
Wake-on-LANWake-on-LAN (WoL or WOL) is an Ethernet or Token Ring computer networking standard that allows a computer to be turned on or awakened from sleep mode by a network message. Equivalent terms include wake on WAN, remote wake-up, power on by LAN, power up by LAN, resume by LAN, resume on LAN and wake up on LAN. If the computer being awakened is communicating via Wi-Fi, a supplementary standard called Wake on Wireless LAN (WoWLAN) must be employed. The message is usually sent to the target computer by a program executed on a device connected to the same local area network.
Ghosting (television)In television, a ghost is a replica of the transmitted image, offset in position, that is superimposed on top of the main image. It is often caused when a TV signal travels by two different paths to a receiving antenna, with a slight difference in timing. Common causes of ghosts (in the more specific sense) are: Mismatched impedance along the communication channel, which causes unwanted reflections. The technical term for this phenomenon is ringing.
