This paper describes "BI-CELP: baseline and implied CELP", which is a high quality speech coding method based on a code excited linear prediction (CELP) model employing excitation vectors combined from two codebooks, one from the baseline codebook and the other from the implied codebook. In this method the index of the baseline codebook is coded and transmitted to the receiver while the index of the implied codebook is extracted from the synthesized speech. This method has been applied to a lower rate voice coder at 8 kbit/s to produce high quality voice comparable to that of the 16 kbit/s G.728 LD-CELP. The performance of the 8 kbit/s BI-CELP coder is measured in terms of SNRseg and MOS. The average SNRseg is 12.14 dB which is 0.6 dB higher than that of the 8 kbit/s G.729 CS-ACELP. The MOS for the quiet input is 3.8 which is 0.02 higher than that of G.729 CS-ACELP. BI-CELP algorithm is implemented in real-time on a single TMS320C31 with 27 MIPS of CPU.

This paper describes the implementation of the test system of the ITT System 1240 digital switch that was developed for line, trunk, and service circuit maintenance and diagnostics. At the core of the test system is a problem-oriented, remotely programmable, digital signal processor called the test signal analyzer (TSA). The TSA is a versatile signal generation and measurement tool, whose signal processing power is made readily available to the test engineer as a set of high-level functional instructions, rather than as a primitive register transfer language, or as inflexible test-specific instructions. Specifically, this paper briefly describes the TSA implementation, identifies the functions that are fundamental to any telecommunications test system, presents some of the digital signal processing algorithms, and gives a measurement example.

The use of semicausal or half-plane filters in image processing generally requires a large amount of extra grid points to produce the output image compared with the case employing causal or quarter-plane filters. This is due to the inherent nature of semicausal filters. In this paper, a practical aspect of implementing 2D semicausal filters for image processing is investigated in terms of state-space realization, and a method to reduce the total number of spatial grid points necessary to evaluate the output image, termed simplified implementation, is presented.

In this paper we present a new stabilization procedure based on the spectral factorization capability of PLSI (planar least square inverse) polynomials of semicausal form. It is not involved with an intermediate PLSI polynomial since stabilization of an unstable filter is directly obtained from its autocorrelation function. We also introduce a measure of amplitude distortion due to stabilization. The new procedure offers a remedy for flaws in Shanks' original procedure for stabilization.

A procedure for the design of 2D recursive filters is developed using the Semicausal or half-plane filters. For recursive filters, semicausal or half-plane filters are more general than causal or quarter-plane filters to approximate the arbitrary magnitude characteristics. In approximating the given characteristics, the concept of 2D spectral factorization is utilized. A stabilization procedure is also presented and incorporated to produce the finite order stable filters. The transfer function of the resulting filter consists of both numerator and denominator polynomials.