matlab-(含教程)基于Matlab的跳频扩频通信系统仿真

clc; clear; close all; warning off; addpath(genpath(pwd)); sequence=round(rand(1,20)); % Generating 20 bits input_signal=[]; % input signal declaration carrier_signal=[]; % carrier signal declaration time=[0:2*pi/119:2*pi]; % Number of samples - Creating a vector of 120 total values including end point [0:0.052:6.28] for k = 1 :20 if sequence(1,k)==0 sig=-ones(1,120); % -1 value for binary input 0 else sig=ones(1,120); % +1 value for binary input 1 end c=cos(time); % Carrier frequency is calculated. carrier_signal = [carrier_signal c]; %signal that is generated which will transmitted with input signal input_signal = [input_signal sig]; %Original signal to be transmitted end figure(1) subplot(4,1,1); plot(input_signal); % Plotting input signal axis([-100 2400 -1.5 1.5]); title('\bf\it Original 20 bit Sequence'); % BPSK Modulation of the signal bpsk_mod_signal=input_signal.*carrier_signal; % Modulating the signal subplot(4,1,2); plot(bpsk_mod_signal); %Plotting BPSK Modulated signal axis([-100 2400 -1.5 1.5]); title('\bf\it BPSK Modulated Signal'); % Preparation of 6 new carrier frequencies %6 frequencies are randomly selected by the PN sequence generator time1=[0:2*pi/9:2*pi]; %[0:0.698:6.28] time2=[0:2*pi/19:2*pi]; %[0:0.331:6.28] time3=[0:2*pi/29:2*pi]; %[0:0.217:6.28] time4=[0:2*pi/39:2*pi]; %[0:0.161:6.28] time5=[0:2*pi/59:2*pi]; %[0:0.106:6.28] time6=[0:2*pi/119:2*pi];%[0:0.052:6.28] carrier1=cos(time1); carrier1=[carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1 carrier1]; carrier2=cos(time2); carrier2=[carrier2 carrier2 carrier2 carrier2 carrier2 carrier2]; carrier3=cos(time3); carrier3=[carrier3 carrier3 carrier3 carrier3]; carrier4=cos(time4); carrier4=[carrier4 carrier4 carrier4]; carrier5=cos(time5); carrier5=[carrier5 carrier5]; carrier6=cos(time6); % Random frequency hopps to form a spread signal spread_signal=[]; for n=1:20 c=randi([1 6],1,1); %6 frequencies are randomly are selected by the PN generator switch(c) case(1) spread_signal=[spread_signal carrier1]; case(2) spread_signal=[spread_signal carrier2]; case(3) spread_signal=[spread_signal carrier3]; case(4) spread_signal=[spread_signal carrier4]; case(5) spread_signal=[spread_signal carrier5]; case(6) spread_signal=[spread_signal carrier6]; end end subplot(4,1,3) plot([1:2400],spread_signal); axis([-100 2400 -1.5 1.5]); title('\bf\it Spread Signal with 6 frequencies'); % Spreading BPSK Signal freq_hopped_sig=bpsk_mod_signal.*spread_signal; %This is the signal which is being finallay transmitted subplot(4,1,4) plot([1:2400],freq_hopped_sig); axis([-100 2400 -1.5 1.5]); title('\bf\it Frequency Hopped Spread Spectrum Signal'); % Demodulation of BPSK Signal bpsk_demodulated=freq_hopped_sig./spread_signal; %The received signal is FFH demodualted figure(2) subplot(2,1,1) plot([1:2400],bpsk_demodulated); axis([-100 2400 -1.5 1.5]); title('\bf Demodulated BPSK Signal from Wide Spread'); original_BPSK_signal=bpsk_demodulated./carrier_signal; %FFH demodulated signal is data demodulated by means of BPSK Signal subplot(2,1,2) plot([1:2400],original_BPSK_signal); axis([-100 2400 -1.5 1.5]); title('\bf Transmitted Original Bit Sequence');