INSPIRE Project Description: Summer 2007
1. Acoustic Echo Canceling: Echo Quality Index
Acoustic Echo Canceling is widely used in teleconferencing applications as well as in telephony for full duplex hands free operation. It is a challenging digital signal processing problem due to various conditions, e.g. very strong acoustic echo, nonlinear distortion, time-varying acoustic echo path.
This project uses Fuzzy Logic in the design of an intelligent inference system which implements a quality index indicating potential problems in handling of acoustic echo within a VoIP (voice over packet) based telephony communication system. The project would include work in the laboratory environment (acoustic measurements), the inference system modeling and testing, and software programming (using MATLAB). The inference system rules will be based on the expert knowledge and the results of various laboratory experiments.
2. Optimizing the Dynamic Range of Fixed-Point IIR Filters
Implementation of IIR filters using fixed-point math on a digital signal processor is challenging problem. Overflows may occur within the internal stages of the filter, while the quantization noise must be minimized in order to improve the SNR (Signal-to-Noise-Ratio).
This project focuses on numerical methods for optimizing the dynamic range of fixed-point IIR filters implemented on a digital signal processor. Existing theoretical methods can prevent either overflows or underflows when designing fixed-point IIR digital filters. However, none of the theoretical solutions offer both. In order to maximize the dynamic range of a digital filter, one must prevent both overflows and underflows at the same time. These two criteria conflict each other. The project would include developing new ideas on how to solve this problem using optimization methods. Programming and simulations will be done using MATLAB.