Open AccessImprove channel signal quality using adaptive filters
Author(s) -
Ana-Maria Travediu
Publication year - 2020
Publication title -
scientific bulletin
Language(s) - English
Resource type - Journals
eISSN - 2392-8956
pISSN - 1454-864X
DOI - 10.21279/1454-864x-20-i1-012
Subject(s) - adaptive equalizer , channel (broadcasting) , adaptive filter , filter (signal processing) , distortion (music) , equalization (audio) , root raised cosine filter , computer science , electronic engineering , transmitter , bandwidth (computing) , signal (programming language) , data transmission , transmission (telecommunications) , telecommunications , engineering , low pass filter , computer network , amplifier , computer vision , programming language
A channel can be modelled by trying to calculate the physical processes which modify the transmitted signal. In this article we simulated the adaptive equalization of some communication channels. A system of data transmission in the basic band will be considered in order to illustrate the principle of adaptive equalization. In such a system, the data sequence is applied, upon emission, to a formation filter( low pass filter), with the purpose of limiting the occupied bandwidth. A relatively wide band noise is also introduced on the communication channel. The transmission channel can also be modelled as a linear filter, this is represented by the distortion filter. We used another filter to avoid the distortion introduced by the channel, with the role of equalizer. This should compensate for the distortion introduced by the channel. The channel transfer function is not generally known, and in addition, it may vary slowly over time. Therefore, the need for this filter appears to be adaptive. In order to perform the adaptation initially, a training sequence, known at the reception, can be transmitted first and the output of the filter is compared with a locally generated reference signal, but identical to the one emitted. After this initial adaptation phase, the transmitter transmits the information symbols, the useful signal, thus the application can be used to improve the signal quality of maritime communications channels.