Appendix A
NOT E
Emulation of Analog Instruments
The computer emulates the functions of analog instruments by
mathematical algorithms. For example:
Low-pass filters are emulated by integration.
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High-pass filters are emulated by differentiation.
Spectral (band-pass) filters are emulated by Fourier
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transformation.
A DSP-based test system cannot reliably analyze stochastic (non-
periodic) waveforms. It does not wait endlessly for steady-state
conditions. It requires periodic waveforms for making precise AC
measurements.
This is not really a drawback—most performance parameters can
be measured precisely with periodic stimulus signals.
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