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- Long distance real-time echo cancellationPublication . J. Ferreira, Artur; Marques, Paulo; Carvalho, HélderThis paper describes an implementation of a long distance echo canceller, operating on full-duplex with handsfree and in real-time with a single Digital Signal Processor (DSP). The proposed solution is based on short length adaptive filters centered on the positions of the most significant echoes, tracked by time delay estimators. To deal with double talking situations a speech detector is employed. The floating-point DSP TMS320C6713 from Texas Instruments is used with software written on the C++ programming language using some compiler optimizations to reduce execution time. The resulting algorithm enables long distance echo cancellation with low computational requirements. It reaches greater echo return, loss enhancement and shows faster convergence speed than the conventional solu tion. Our experimental results also approach the CCITT G.165 recommendation for echo cancellers.
- Directional Moving Target Indication for Civil Traffic Monitoring Using Single Channel SARPublication . Marques, PauloThis paper presents a novel moving target indicator which is selective with respect to a direction of interest. Preliminary results indicate that the obtained selectivity may have high interest in civil traffic monitoring using single channel SAR data.
- An efficient long distance echo cancellerPublication . Ferreira, Artur; Marques, PauloThis paper describes an implementation of a long distance echo canceller, operating on full-duplex with hands-free and in real-time with a single Digital Signal Processor (DSP). The proposed solution is based on short length adaptive filters centered on the positions of the most significant echoes, which are tracked by time delay estimators, for which we use a new approach. To deal with double talking situations a speech detector is employed. The floating-point DSP TMS320C6713 from Texas Instruments is used with software written in C++, with compiler optimizations for fast execution. The resulting algorithm enables long distance echo cancellation with low computational requirements, suited for embbeded systems. It reaches greater echo return loss enhancement and shows faster convergence speed when compared to the conventional approach. The experimental results approach the CCITT G.165 recommendation levels.