% DRFM Phase-Amplitude Imbalance
% ------------------------------

clear;clf;clc;

% Input Spurious Levels

spur=-[10 15 20 30];	% db
spur=10.^(spur/10);
	

% Define Phase Imbalance Vector

phi=-40:.1:40;		% deg
phir=phi*pi/180;	% radians

% Calculate x=xq/xi Amplitude Imbalance

for k=1:4;
b=(1+spur(k))*cos(phir)/(1-spur(k));
xx=b+sqrt(b.^2-1);
cc=real(20*log10(xx));
aa=find(cc);
l=length(aa);
bb=cc(aa(1)-1:aa(l)+1);
dd=phi(aa(1)-1:aa(l)+1);

% Plot Phase-Amplitude Contour

plot(bb,dd,'k',-bb,dd,'k');
axis([-6 6 -40 40]);
xlabel('Amplitude Ratio xq/xi - db')
ylabel('Phase Difference - degrees');
title(['Phase-Amplitude Balance for Sideband Suppression']);
text(5,20,'-10 dB');
text(2.85,12,'-15 dB');
text(1.6,7,'-20 dB');
text(.4,4,'-30 dB');
grid on;hold on;
end;