الفهرس 
Communication Channels ImpairmentsOnly 14 pages are availabe for public view
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Abstract
The output of the matched filter at the receiver is greatly distorted due to channel impairments such as noise, inter-symbol interference, non-tationarity in the channel. That is due to the fact that the matched filter is designed to be matched with the transmitted signal.
Adaptive filter may be used to avoid these drawbacks caused by the channel since it has the ability to track the channel variation. The present thesis presents two different systems based on using adaptive filter together with the matched filter at the receiver. In the first system, BARKER code is used to modulate four level data. At the receiver, the adaptive filter is used after the matched filter and adapts it’s output as the ideal auto-correlation function of the BARKER code. The basic idea in the adaptation process is based on the shape of the auto-correlation function, which has alternative zeroes. So, the adaptive filter adapts it’s output to zero at these instants and stops adaptation at the next instants thus solving the problem of• the distortion in the matched filter output. The main advantage of this method is that the adaptation processor of the adaptive filter will modify the tap. weights each double the baud interval i.e., slower processor is sufficient to be used.
In the second system, M-sequence is used to modulate binary’ data by using an EXOR gate. To recover the binary data at the receiver, an adaptive filter is used before a modified matched filter (MMF) to minimize the distortion caused by the channel impairments. The main advantage of this method is the simplicity in modulation and increasing security in data handling. Each of the two systems is derived mathematically and simulated on digital computer to measure the performance. Some computer simulation results are• shown to demonstrate the effect of various parameters on the performance of the system. The results show that an improvement is achieved on the performance for both stationary and non stationary channels.