Frequency Hop Spread Spectrum System Communication System
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Date
2003-01
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Addis Ababa University
Abstract
Among the various types of the spread spectrum systems the slow frequency hop spread
spectrum system is discussed.In the transmitter the data input ,which is, text is converted to
binary data by the ASCII code conversion table.This binary data is modulated using the the
FSK modulator.Then pseudo-random frequencies are generated from pseudo-random code
generators and a frequency synthesizer. Using these generated frequencies the modulator
output signal is hopped or spread to different frequencies. After the spreading process, the
final signal output is then transmitted through a non Gaussian plus Gaussian noise channel. At
the receiver before the demodulation process the initial estimate of the receiver phase is made
using the sequential detection method. Using the intial estimate of the phase the rest of the
received phase is tracked using a second order tracking loop. After tracking the phase at the
receiver end the next step is to dispread the frequency hopped signal. Then demodulation is
carried out using the matched filter FSK detector .After detection the data output of the
demodulator is converted back to text using the ASCII code table. Finally the receiver gets
back the text data which was sent at the transmitter
Description
Keywords
Spread Spectrum, Frequency Hop