Showing papers by "Raymond Knopp published in 2001"
24 Jun 2001
TL;DR: It is found that MD codes appear to be outperformed by a more traditional system in which source and channel code parameters are jointly optimized to minimize end-to-end distortion.
Abstract: Multiple description (MD) codes have been proposed to provide robustness against data loss in packet-switched networks. We report results on the performance of MD codes when used on bit error channels with error correcting codes, in order to handle loss of blocks when the number of errors in a black exceeds the correcting ability of the code. We find that MD codes appear to be outperformed by a more traditional system in which source and channel code parameters are jointly optimized to minimize end-to-end distortion.
17 citations
Patent•
24 Jan 2001
TL;DR: In this paper, a frequency spectral representation of the data is obtained, and the watermark is inserted into those frequencies whose variance lies in a range between two thresholds, minimal and maximal.
Abstract: A watermark applied to audio, image, video or multimedia data can serve to verify the authenticity of the data. For the watermark to be imperceptible, e.g. invisible or inaudible, it is inserted into selected parts of the data that are neither significant nor insignificant perceptually. Examples for the domain of embedding are complex Fourier coefficients and wavelet coefficients. A frequency spectral representation of the data is obtained, preferably a complex Fourier transform, and the watermark is inserted into those frequencies whose variance lies in a range between two thresholds, minimal and maximal. In the Fourier transform the block size is large enough for the components to be approximately Gaussian. The resultant watermarked spectral data is subjected to an inverse transform to produce the watermarked data.
8 citations
TL;DR: This paper describes a software-radio architecture developed for providing real-time wide-band radio communication capabilities in a form attractive for advanced 3G systems research and currently being used to implement signaling methods and protocols similar to evolving 3G radio standards.
Abstract: Cet article decrit une plate-forme radio logicielle reconfigurable, permettant de realiser ďune maniere souple des traitements en temps reel sur une interface radio de type 3G Cette plate-forme est actuellement utilisee pour implementer des methodes de transmission-reception ainsi que des protocoles, inspires des normes 3G (umts, cdma2000) Une vue ďensemble de ľarchitecture materielle est donnee dans cet article ainsi que des exemples ďimplantations logicielles, aussi bien sur processeurs de traitement du signal (dsp) que sur des processeurs classiaues
1 citations