Nouveau dispositif d’annulation d’écho utilisant un filtre interpolateur

This paper presents a new over-sampling echocanceller structure in which a simple structured interpolator is introduced and replaces half the number of echo-cancellers used in a classical structure. If dis-symmetrical equipments are authorized at the extremities of the transmission system (different carrier frequencies), the cascade of an echo-canceller and an interpolator reaches much better performances than those of a classical system. This is due to the interpolator which reduces the noise of the gradient algorithm governing the echo-cancellers evolution. Using such an interpolator decreases the computational complexity in very attractive proportions (up to 44%). Computer simulations confirm theoretical developments and let appreciate the good robustness of the depicted system.     

The encephalus of the pond-loach, Misgurnus fossilis (L.), 1758 (fish, teleosts, Cobitidae). An example of sexual dimorphism]

The brain of the Pond-loach (Misgurnus fossilis) is very closely related to that of Cyprinidae. In the Medulla oblongata, the facial lobe-in relation with the skin taste buds, especially on the barbels-is bigger than the vagal lobes-which are related with the mouth taste buds. The intraspecific relations between brainweight and bodyweight or various body lengths show a real sexual dimorphism (brain dimegaly). The interspecific brain-bodyweight relationship shows an allometric coefficient of 0.505 in males and 0.485 in females, very close to that of the Rainbow trout. The encephalization index (63) is very close to that of the Tench, and a little lower than that of the Cyprinidae as a whole.     

Wireless LAN design alternatives

The authors have discussed several alternatives in wireless LAN design: media choice, operating frequency, operating mode, network topology, and access method. Although each technical choice presents both advantages and disadvantages, they argue that there is a design point that provides the best fit with present and future wireless LAN user needs. Considering all factors-including robustness, regulatory considerations, and interference avoidance-using a product based on the slow frequency-hopping spread spectrum, in the 2.4 GHz ISM band, relying on a base station remote station network topology and using a TDMA-based access method is the best way to meet the needs of radio-frequency wireless LAN users. The choices are many, but slow frequency-hopping at 2.4 GHz and TDMA-based medium access control provide the best mix of cost, range, interference, and performance