% Communication Jamming
% --------------------------

clear;clc;clf; 

% Define Jammer Erp from Erpmin to Erpmax

Erpmin=100;Erpmax=10000;  % watts
Erp=Erpmin:Erpmax;

% Communications System & Jammmer Parameters

Jsrdbx=5; 	% JSR for Effective Jamming - db
Pt=4;	   	% Comm Transmit Pwr - watts
Gtr=0; 		% Antenna Gain	Comm Xmit-Comm Rcv - dbi
Grj=0;		% Antenna Gain Comm Rcv-Jam - dbi
Grt=0;		% Antenna Gain Comm Rcv-Comm Xmit - dbi
Br=.025; 	% Comm Receiver Bandwidth -Mhz
Bj=6.4;		% Jammer Transmitter Bandwidth- Mhz
Rtr=10;		% Range between Comm Xmit & Rcv - km
Rjr=15;		% Range between Jam & Comm Rcv - km
Lj=0;	   	% Jammer Loss(includes Pol)- dB
Lr=0;	   	% Comm Loss- dB
 	    
% Convert dB to ratio

Gtr=10^(Gtr/10);Jsrx=10^(Jsrdbx/10);
Grj=10^(Grj/10);Grt=10^(Grt/10);
Lj=10^(Lj/10);Lr=10^(Lr/10);


% Compute Jam-to-Signal Ratio for Frequency Hopping

x=Grj*Rtr^2*Lr*Br;
y=Pt*Gtr*Grt*Rjr^2*Lj*Bj;
JSR=Erp.*x/y;
Jsrdb=10*log10(JSR);

% Find Jammer ERP for Jsrdbx

Erpj=Jsrx*y/x;

% Plot JSR vs Jammer Erp

Jsrdb0=Jsrdbx*ones(size(Erp));
plot(Erp,Jsrdb,Erp,Jsrdb0);grid;
xlabel('Jammer ERP - watts');
ylabel('Jam-to-Signal Ratio -dB');
title(['Communication Jamming ERP   ' ...
'(ERPj =',int2str(Erpj),'  watts)']);