Calculation of the line spectrum frequencies using the quotient-difference scheme

Abstract

A new, computationally efficient technique for calculation of the line spectrum frequencies (LSF) that can be applied to any order of the LPC analysis is proposed. It is based on the quotient-difference (Q-D) root-finding algorithm that enables simultaneous solution for all the LSFs. It is an iterative procedure that offers the tradeoff between accuracy and complexity, what is especially important for the real-lime applications. To improve the convergence, a nonlinear mapping of the LSFs is also proposed for low accuracy applications, the method is even more effective then the fast converging Newton-Rapshon method, but is at the same time exceptionally simple, has a very regular structure and requires only basic mathematical operations.