Yamaha 02R, Руководство пользователя

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Glossary 229
Digital Recording Console 02R User’s Guide
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 .