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Echo has disturbed us under many conditions for a long time.
For example, it might occur in telephone or satellite
communication system or in microphone-loudspeaker based system.
The appearance of echo in these communication systems will
reduce the communication quality and cause the user feel
uncomfortable. Thus in this thesis, we developed a LMS algorithm
and adaptive filter based asynchronous echo canceller to solve
this problem. During the design procedure, we firstadopt a
simplified LMS algorithm with power of two convergence factor to
reduce the complexity of the algorithm. Following, we design the
hardware structure using pipeline style. These two methods
drastically reduce the requirement of hardware area. Additional,
in order to improve the speed of the echo canceller, we adopt
asynchronous design styleinstead of conventional synchronous
style. Besides, the advantages of lower power consumptionand
easy to extend and modify are also the reasonsthat appeal us.
The whole design is simulated using Altera MAXPLUS II ver.8.0
software and it successfully fits into the EPF10K100GC503-3 of
FLEX 10k series. The sampling rate of final implement can
operate at the high speed of 400k HZ.
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