SPTM-1.1

ADAPTIVE ITERATIVE REWEIGHTED LEAST SQUARES DESIGN OF $L_p$ FIR FILTERS
Ricardo A Vargas, Charles S Burrus (Rice University)

This paper presents an efficient adaptive algorithm for designing FIR digital filters that are efficient according to an $L_p$ error criteria. The algorithm is an extension of Burrus' iterative reweighted least-squares (IRLS) method for approximating $L_p$ filters. Such algorithm will converge for most significant cases in a few iterations. In some cases however, the transition bandwidth is such that the number of iterations increases significantly. The proposed algorithm controls such problem and drastically reduces the number of iterations required.

SPTM-1.2

Quantization Noise Analysis of Wave Digital and Lossless Digital Integrator Allpass/Lattice Filters
Johnny Holmberg, Lennart Harnefors (Malardalen Univ.), Svante Signell (Ericsson Radio Systems)

Quantization noise levels of two low-sensitive allpass filter structures, namely wave digital circulator filters (WDCF) and lossless digital integrator filters (LDIF), are compared. Allpass filters are of interest for design of lowpass and bandpass lattice filters. The results show, primarily, that second-order LDIFs have lower total quantization noise gains than corresponding WCDFs for any pole configuration within the right half-circle of the z plane. The benefit of using ladder LDIFs rather than cascaded first and second order sections is also demonstrated.

SPTM-1.3

A new normalized relatively stable lattice structure
Chris W Schwarz (NADS & Simulation Ctr., The University of Iowa), Soura Dasgupta (Department of Electrical and Computer Engineering, The University of Iowa)

This paper proposes a new lattice filter structure that has the following properties. When the filter is Linear Time Invariant (LTI), it is equivalent to the celebrated Gray Markel Lattice. When the lattice parameters vary with time it sustains arbitrary rate of time variations without sacrificing a prescribed degree of stability, provided that the lattice coefficients are magnitude bounded in a region where all LTI lattices have the same degree of stability. We also show that the resulting LTV lattice obeys an energy contraction condition. This structure thus generalizes the normalized Gray-Markel lattice which has similar properties but only with respect to stability as opposed to relative stability.

SPTM-1.4

Tunable Digital Heterodyne IIR Filters
Karl E Nelson (ECE Dept. University of California, Davis CA 95616), Michael A Soderstrand (ECEN Dept. Oklahoma State University, Stillwater OK 74078)

A new digital heterodyne filter is proposed that allow a prototype IIR or FIR filter to be shifted through the entire range of digital frequencies from DC to the Nyquist frequency. The unique properties of this new tunable filter are the range of tunability and the fact that all images created by the heterodyne process are cancelled. The proposed heterodyne filter is suitable both as a tunable filter and for use with standard adaptive algorithms to design adaptive digital filters --- especially adaptive notch filters.

SPTM-1.5

Optimal Design of Real and Complex Minimum Phase Digital FIR Filters
Niranjan Damera-Venkata, Brian L Evans (The University of Texas at Austin)

We present a generalized optimal minimum phase digital FIR filter design algorithm that supports (1) arbitrary magnitude response specifications, (2) high coefficient accuracy, and (3) real and complex filters. The algorithm uses the Discrete Hilbert Transform relationship between the magnitude spectrum of a causal real sequence and its minimum phase delay phase spectrum given by Cizek. We extend the transform pair to the complex case. We show that the algorithm gives arbitrary coefficient accuracy. We present design examples that exceed the coefficient accuracy of the optimal real minimum phase filters reported by Chen and Parks and reduce the length of the optimal complex linear phase filters designed by Karam and McClellan.

SPTM-1.6

A Multiple Exchange Algorithm for Constrained Design of FIR Filters in the Complex Domain
Mathias C LANG (Vienna University of Technology)

We present a fast multiple exchange algorithm that designs FIR filters with magnitude and phase specifications subject to constraints on the error function. We use a constrained least squares criterion which minimizes error energy and imposes bounds on the magnitude of the error. We can trade error energy versus peak error, and complex least squares and complex Chebyshev filters result as special cases. We provide a Matlab program implementing the proposed algorithm. This program has proved to be efficient and reliable.

SPTM-1.7

Robust Envelope-Constrained Filter Design with Laguerre Bases
C.H Tseng, K. L Teo, Antoni Cantoni, Z Zang (Australian Telecommunications Research Institute)

The envelope-constrained filtering problem is concerned with the design of a filter such that the noise enhancement is minimized while the noiseless filter response stays within an envelope. Naturally, the optimum filter response to the prescribed input signal tends to touch the output boundaries at some points. Consequently, any disturbance to the prescribed input signal could result in the output constraints being violated. In this paper, we formulate a semi-infinite constrained optimization problem in which the margin of the constraint robustness of the filter is maximized. Using a smoothing technique, it is shown that the solution of the optimization problem can be obtained by solving a sequence of strictly convex optimization problems with integral cost.

SPTM-1.8

A contribution to the stability test for one dimensional discrete time linear systems
Anthony Constantinides, Tania Stathaki (Signal Processing Section, Imperial College, UK)

The objective of this paper is to produce a general formulation of an order reduction procedure for testing the stability of discrete time linear systems. The order reduction procedure involves a series of iterations and, at each step of the iteration process, the the aim is to derive a new polynomial of order lower than the given one. The new polynomial serves as the input to the following iteration. A specific form of the formulation is considered in which first order auxiliary polynomials are employed in the order reduction process. There follows from this a new testing procedure. The current methods appear as special cases of the new test. An extension is further proposed which employs second order auxiliary polynomials within the order reduction formulation. This second order form is however for all practical cases the limit to which such a procedure can be put.

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Last Update: February 4, 1999 Ingo Höntsch