Error Correction Chips Information
Error correction chips are semiconductor ICs that are used to check and to correct data transmission errors. They are designed for use with forward error correction (FEC), a data-transmission technique that adds redundant data to a message. This redundant data, an error correction code, enables the receiver to detect and correct errors without having to request and receive additional information and occupy valuable bandwidth. Because FEC eliminates the need for back-channel connections, the re-transmission of data is minimized. This feature, an important consideration in applications with high data rates and stringent reliability requirements, enables error correction chips to help minimize communication costs.
Error correction chips use two main types of forward error correction (FEC): block coding and convolutional coding. Block codes are packets with bits or symbols of a predetermined size. Convolutional codes are streams of bits or symbols with arbitrary lengths. Error correction chips use several different types of block codes. Reed-Solomon coding, the most common type, is used with compact disks (CDs) and digital video disks (DVDs). Error correction chips that use Golay codes, BCH codes, and Hamming codes are also available. In some applications, both block and convolutional codes are used. For example, satellite communications often use a concatenated coding system where Reed-Solomon codes correct residual errors from convolutional decoding.
Turbo codes and low-density parity-check codes (LDPCs) are now used in some error correction chips. Turbo codes permit increased data rates, but also have a relatively high latency that makes them unsuitable for some applications. Error correction chips that use LDPC codes are well-suited for transmissions over noisy channels. The Viterbi algorithm, an older technique, is also used in error-correction schemes for relatively noisy digital communication links.
High-performance error correction chips may include features such helical interleaving, synchronization, scrambling, and higher-order modulation symbol mapping. Error chips, security chips, and semiconductor components with advanced encoding and decoding features are also available. Typically, these error correction devices are used in satellite modems, broadband wireless systems, and wireless local area networks (LANs). Although some error correction chips are separate semiconductor chips, other are incorporated into memory modules such as single inline memory modules (SIMMs) and dual inline memory modules (DIMMs).