Comparison of interpolation methods in modulation and demodulation.

摘要

As an electrical engineer working with the Navy, I am assigned to the Under Water Acoustic Communication (UWAC) project where the implementation of a software defined acoustic modem has been ongoing for the past years. My responsibility in this project is to investigate the most efficient interpolating and decimating filters that fit the specifications. The reasoning behind using these filters is a common problem addressed in Digital Signal Processing. This problem stems from the different rates used, in a single communication system, to operate analog to digital convertors, sensors, processors, as well as digital to analogue convertors. In the case of the UWAC project, the signal bandwidth to be transmitted is 22 KHz, the sample rate is 16.5 KHz, yet the digital to analog convertor operates at 2816 KHz in the transmitter and will require an up-sampling filter. On the receiver end, the Analog to Digital convertor will need a filter that performs down sampling to obtain the original sample rate.;The purpose of this thesis is to contribute in the UWAC project through researching, testing, and evaluating of the best method to interpolate a signal's sample frequency at the modulator of the acoustic modem and a matching decimation method, at the de-modulator end, that would result in the original signal. The work on this problem should result in published paper that will serve as a thesis to earn a Master's Degree in Electrical Engineering from San Diego State University under the supervision of Professor fred j. harris Ph.D. will overlook and provide guidance along the way in this effort.