Time-varying wave digital filters for modeling analog systems
Hans Werner Strube · IEEE Transactions on Acoustics Speech and Signal Processing · 1982
The theory of wave digital filters, which are well suited to model analog networks including those containing transmission lines, is extended to the time-varying case. This allows simulation of the moving vocal tract or parametric amplifiers. A representation consistent with the physics of time-varying reactances and transmission lines requires not only time-varying filter coefficients, but also structural modifications in the n-port adaptors and reactance one-ports of the filter. The number of coefficients in the adaptors is increased, and stability and pseudopassivity are not assured.