Download Antiderivative Antialiasing in Nonlinear Wave Digital Filters A major problem in the emulation of discrete-time nonlinear systems, such as those encountered in Virtual Analog modeling, is
aliasing distortion. A trivial approach to reduce aliasing is oversampling. However, this solution may be too computationally demanding for real-time applications. More advanced techniques
to suppress aliased components are arbitrary-order Antiderivative
Antialiasing (ADAA) methods that approximate the reference nonlinear function using a combination of its antiderivatives of different orders. While in its original formulation it is applied only
to memoryless systems, recently, the applicability of first-order
ADAA has been extended to stateful systems employing their statespace description. This paper presents an alternative formulation
that successfully applies arbitrary-order ADAA methods to Wave
Digital Filter models of dynamic circuits with one nonlinear element. It is shown that the proposed approach allows us to design
ADAA models of the nonlinear elements in a fully local and modular fashion, independently of the considered reference circuit. Further peculiar features of the proposed approach, along with two
examples of applications, are discussed.
Download Bistable Digital Audio Effect A mechanical system is said to be bistable when its moving parts
can rest at two equilibrium positions. The aim of this work is to
model the vibration behaviour of a bistable system and use it to
create a sound effect, taking advantage of the nonlinearities that
characterize such systems. The velocity signal of the bistable system excited by an audio signal is the output of the digital effect.
The latter is coded in C++ language and compiled into VST3 format that can be run as an audio plugin within most of the commercial digital audio workstation software in the market and as a
standalone application. A Web Audio API demonstration is also
available online as a support material.
Download Fully-Implicit Algebro-Differential Parametrization of Circuits This paper is concerned with the conception of methods tailored
for the numerical simulation of power-balanced systems that are
well-posed but implicitly described. The motivation is threefold:
some electronic components (such as the ideal diode) can only
be implicitly described, arbitrary connection of components can
lead to implicit topological constraints, finally stable discretization
schemes also lead to implicit algebraic equations.
In this paper we start from the representation of circuits using a
power-balanced Kirchhoff-Dirac structure, electronic components
are described by a local state that is observed through a pair of
power-conjugated algebro-differential operators (V, I) to yield the
branch voltages and currents, the arc length is used to parametrize
switching and non-Lipschitz components, and a power balanced
functional time-discretization is proposed. Finally, the method is
illustrated on two simple but non-trivial examples.