(1) The lack of precision in digital sampling times, leading to amplitude errors in signals with rapidly changing amplitudes, resulting in distortion of the sampled signal which rises with frequency. The starting time of the sampling aperture is the non-zero time that it takes for the sample-and-hold circuitry to determine the level of the signal waveform and to hold this level until the next sample is called for. Because the time required to establish a new value of charge depends on the amount of change in the signal level from one sample to the next, the aperture time will vary with the rate of change in the signal level, increasing for high-level, high-frequency signals. The starting time of the sampling aperture is also slightly uncertain, and this is called jitter. Also called sampling offset uncertainty. See aperture time errors.
(2) Timing errors introduced into channel-coded interfaces such as AES/EBU and S/PDIF where the word clock is embedded within the data stream. Cable capacitance reduces HF signal, resulting in founded corners and sloping edges, as opposed to a sharply divided on/off pulse wave. As the word clock timing is defined by the midpoint of the pulse wave, any str
