Bitfejl

Bitfejl, or bit error, is a flip in a stored or transmitted bit from 0 to 1 or from 1 to 0. It is a common imperfection in digital communications and data storage, caused by noise, interference, timing inaccuracies, or hardware faults. The rate at which bit errors occur is described by the bit error rate (BER), defined as the number of bit errors divided by the total number of transmitted bits. BER depends on the communication channel, modulation, bandwidth, and signal-to-noise ratio (SNR). In practice, BER is expressed for a given system and often measured during testing or observed in operation. Burst errors, where consecutive bits are corrupted, are also important in some contexts.

To detect and correct bit errors, systems use error-detection codes and error-correction codes. Parity bits and CRCs enable error detection; forward error correction (FEC) codes such as Hamming, Reed-Solomon, LDPC and LDPC-based codes enable recovery of the original data without retransmission. Memory systems and storage devices employ error-correcting codes (ECC); DRAM may use SECDED ECC, NAND flash uses BCH or LDPC codes. Interleaving and redundancy further reduce the impact of errors.

Bit errors influence reliability and performance. In networks and storage, BER and related metrics (frame error rate, page error rate) guide design choices, such as modulation, coding gains, error concealment, and retransmission strategies. Reducing bit errors involves improved shielding, impedance matching, clock recovery, and more robust coding schemes.