Signal Processing - Digital Signal Processing


Digital signal processing (DSP)


Digital signal processing (DSP) is concerned with representation of signals as numbers and processing of these sequences. DSP has fixed processing characteristics, i.e. they are independent of the external factors of the environment at that moment. No need of a realignment over a life time, component tolerance does not affect the system performances, and no adjustments needed during the time of process, an increase of 1bit in representation results in increasing 6 db, using of standard digital circuits for implementation and also more importantly, multiplexing which describes the same equipment can be shared between several signals are some major advantages of DSP.

DSP is applied in different paths such as acoustic acquisition and presentation, signal coding and compression, machine synthesis of signals and also more importantly to the drum device which is to be produced by HEX, Digital sound synthesis. Furthermore there are four major ways which could results in Digital Sound Synthesis. They are Wavetable Synthesis, Spectral Synthesis, Non Linear Synthesis and Synthesis by Physical Modeling.

Wavetable Synthesis is recorded or synthesized musical events stored in internal memory and played back on demand. Here the playback tools consists of various techniques for sound variation such as pitch shifting, Looping, Enveloping, and filtering.

In spectral Synthesis the sound is produced from frequency domain models. The signal is represented as a super position of the basis functions with time varying amplitudes. The practical implementations consist of additive synthesis, substractive synthesis and granular synthesis.

Non linear Synthesis is a frequency modulation method which is time dependent phase term in the sinusoidal basis functions. This is a kind of an inexpensive method which is usually used in sound cards of PCs.


In Physical modeling, the sound production method is modeled, i.e. the physical structure of the main vibrating structure is given by partial differential equations. Most of these methods are based on wave equations describing the wave propagation in air as well as in solids.



Author : Pavarindu Sahansith

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