Yamaha 02R Owner's Manual - Page 340
Modulation, Nyquist Sampling Theorem, over-sampling, Peaking, Phase, Program Change, Q bandwidth
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Glossary 229 Modulation - Using a low frequency oscillator (LFO) to control a signal's frequency (pitch) or amplitude (level). The internal effects programs use modulation for a number of their programs. See Internal Effects. Nyquist Sampling Theorem - This theorem defines the process of sampling audio with a digital system. Amongst other things, it states that the sampling frequency of a digital audio system must be at least twice that of the highest audio frequency, otherwise aliasing will occur. The Nyquist theorem was developed at Bell Labs by C. Shannon and H. Nyquist. See Aliasing. over-sampling - The input analog signal is sampled at a much higher rate than the normal sampling rate. Using the high sample rate, the digital data may be processed with a very steep slope digital filter. As the filter is in the digital domain, unpleasant side-effects, such as phase effects are eliminated. The 02R uses 64-times over-sampling for most of its analog inputs and 8-times over-sampling for most of its analog outputs. PCM - Pulse Code Modulation. A scheme for encoding audio data as a series of pulses. Each pulse defines a transition from binary one to binary zero. Peaking - An equalizer circuit that is used to cut and boost a signal, centered about a specific frequency. Using the bandwidth (Q) parameter, you can widen or narrow the effect of the circuit. Phase - Phase is the frequency coherence of a signal. If two signals are out of phase, the trough of the first waveform corresponds with the peak of the second, resulting in cancellation. The 02R can invert the phase of the input signals, which allows you to compensate for incorrectly wired conductors and so forth. Program Change - A MIDI message that is used to recall programs. On the 02R they recall scene memories. Q (bandwidth) - The bandwidth of an equalizer band. For high values the bandwidth is narrow. For low values, it is wide. See Equalizer . Quantization - The encoding process when the analog input is approximated (quantized) to the nearest binary value available. In the 20-bit system of the 02R, pulses are approximated to one of 1,048,576 binary values. These approximations are not an exact duplication of the analog waveform and are therefore contain quantization errors (noise). However, this noise is reduced by over-sampling. RAM (Random Access Memory) - A memory chip that stores data that can be edited and changed. It requires a continuous electrical charge. The 02R scenes memories and other libraries are stored in RAM. An internal backup battery provides the continuous charge. Contrast with ROM. ROM (Read Only Memory) - A memory chip that stores data that cannot be edited. The 02R operating system is stored in ROM. Contrast with RAM. Digital Recording Console 02R User's Guide