الفهرس 
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Abstract
There is considerable cuurent inerest in the application of frequency hopping FH spread(SS)tehniques for comatting in radio communication systems.These systems use m-ary frequency shift keying modulation and,for practical reason,tend to be noncoherent from hop-to-hop.In order to thwart follower jamming fast hopping is required.In this thesis,the performance of fast-frequency-hopped M-ary NCFSK in the presence of partial-band noise jammingPBNJ plus system noise is considered Methods of enchancing performance by proper selection of M,Diversity and error correction EC coding are considered.This thesis performed error probability analysis for a coded m-ary FSK system employing L hopes per M-ary word FH spread spectrum waveforms transmitted over a partial-band noise jamming channel.
The bit error probabilities are obtained for a square-law nonlinear combining soft-decision receiver strategy under the assumption of worst-case partial-band noise jamming (PBNJ with forward error correction control (FEC coding.The receiver employs,prior to combing,nonlinear weighting strategy of soft limiting clipping of the detector of each channel of the dehopped waveform.
Performance curves are obtained for both block and convolutional codes with both binary and m-ary channel modulations.Both thermal noise and jamming noise are included in our analysis.