04_CM0340_DSP

# 04_CM0340_DSP - Recap of Basic Digital Audio Signal...

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81 JJ II J I Back Close Recap of Basic Digital Audio Signal Processing Recall some basic aspects of Digital Audio Signal Processing from CM0268: Some basic deﬁnitions and principles Filtering

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82 JJ II J I Back Close Simple Waveforms Frequency is the number of cycles per second and is measured in Hertz (Hz) Wavelength is inversely proportional to frequency i.e. Wavelength varies as 1 frequency
83 JJ II J I Back Close The Sine Wave and Sound The general form of the sine wave we shall use (quite a lot of) is as follows: y = A.sin (2 π.n.F w /F s ) where: A is the amplitude of the wave, F w is the frequency of the wave, F s is the sample frequency, n is the sample index. MATLAB function: sin() used — works in radians

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84 JJ II J I Back Close Cosine, Square and Sawtooth Waveforms MATLAB functions cos() (cosine), square() and sawtooth() similar.
85 JJ II J I Back Close The Decibel (dB) When referring to measurements of power or intensity, we express these in decibels (dB): X dB = 10 log 10 ± X X 0 ² where: X is the actual value of the quantity being measured, X 0 is a speciﬁed or implied reference level, X dB is the quantity expressed in units of decibels, relative to X 0 . X and X 0 must have the same dimensions — they must measure the same type of quantity in the same units. The reference level itself is always at 0 dB — as shown by setting X = X 0 ( note: log 10 (1) = 0 ).

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86 JJ II J I Back Close Why Use Decibel Scales? When there is a large range in frequency or magnitude, logarithm units often used.
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## This note was uploaded on 01/26/2012 for the course CM 0340 taught by Professor Davidmarshall during the Fall '09 term at Cardiff University.

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04_CM0340_DSP - Recap of Basic Digital Audio Signal...

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