Glossary

Accumulator   Logic circuit which adds a series of numbers which are fed to it.

AES/EBU Interface   Standardized interface for transmitting digital audio down cable between two devices (see Channel status).

Aliasing   Beat frequencies produced when sampling rate (q.v.) is not high enough.

Auditory masking   Reduced ability to hear one sound in the presence of another.

Azimuth recording   Magnetic recording technique which reduces crosstalk between adjacent tracks.

Bit   Abbreviation for Binary Digit.

Byte   Group or word of bits (q.v.), generally eight.

Channel coding   Method of expressing data as a waveform which can be recorded or transmitted.

Channel status   Additional information sent with AES/EBU (q.v.) audio signal.

CLV   Constant linear velocity. In disks, the rotational speed is controlled by the radius to keep the track speed constant.

Codeword   Entity used in error correction which has constant testable characteristic.

Coefficient   Pretentious word for a binary number used to control a multiplier.

Coercivity   Measure of the erasure difficulty, hence replay energy of a magnetic recording.

Companding   Abbreviation of compression and expanding; increases dynamic range of a system.

Concealment   Means of rendering uncorrectable errors less audible; e.g. interpolation.

Critical band   Band of frequencies in which the ear analyses sound.

Crossinterleaving   Method of coding data in two dimensions to increase power of error correction.

Crosstalk   Unwanted signal breaking through from adjacent wiring or track on recording.

Curie temperature   Temperature at which magnetic materials demagnetize.

Cylinder   In disks, set of tracks having same radius.

Decimation   Reduction of sampling rate by omitting samples.

Dither   Noise added to analog signal to linearize quantizer.

DSP   Digital signal processor; computer processor optimized for audio use.

EDL   Edit decision list; used to control editing process with timecode.

EFM   Eight to fourteen modulation; channel code (q.v.) of Compact Disc.

Entropy   The useful information in a signal.

Faraday effect   Rotation of plane of polarization of light by magnetic field.

Ferrite   Hard non-conductive magnetic material used for tape heads and transformers.

Flash convertor   High-speed ADC technology used with oversampling.

Fourier transform   Frequency domain or spectral representation of a signal.

Galois field   Mathematical entity on which Reed–Solomon coding (q.v.) is based.

Gibb’s phenomenon   Shortcoming of digital filters causing ripple in frequency response.

Hamming distance   Number of bits different between two words.

Headroom   Area between normal operating level and clipping.

Interleaving   Reordering data on recording medium to reduce effect of defects.

Interpolation   Replacing missing sample with the average of those either side.

Jitter   Time instability, similar to flutter in analog.

Kerr effect   see Faraday effect.

Limit cycle   Unwanted oscillation mode entered by digital filter.

MTF   Modulation transfer function; measure of the resolving ability of a lens.

Non-monotonicity   Convertor defect which causes distortion.

Oversampling   Using a sampling rate which is higher than necessary.

Phase linear   Describes circuit which has constant delay at all frequencies.

Product code   Combination of two one-dimensional error-correcting codes in an array.

Pseudo-random code   Number sequence which is sufficiently random for practical purposes but which is repeatable.

Reconstruction   Creating continuous analog signal from samples.

Reed–Solomon code   Error-correcting code which is popular because it is as powerful as theory allows.

Requantizing   Shortening sample wordlength.

Sampling rate   Rate at which samples of audio waveform are taken (see Aliasing).

SDIF-2   Digital audio interface for consumer use.

Seek   Moving the heads on a disk drive.

Subcode   Additional non-audio data stored on recording media.

Wordlength   Number of bits describing sample.