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function [Amp_Imb_DB, Ph_Imb_Deg] = iqcoef2imbal(Comp_Coef)
// This function returns the amplitude imbalance and phase imbalance
// that a given compensator coefficient will correct.
// Calling sequence
// [AMP_IMB_DB, PH_IMB_DEG] = IQCOEF2IMBAL(COMP_COEF)
// Description
// [AMP_IMB_DB, PH_IMB_DEG] = IQCOEF2IMBAL(COMP_COEF) returns
// the amplitude imbalance and phase imbalance
// that a given compensator coefficient will correct.
// Comp_Coef is a scalar or a vector of complex numbers.
// AMP_IMB_DB and PH_IMB_DEG are the amplitude imbalance in dB
// and the phase imbalance in degrees.
// Examples
// [a_imb_db,ph_imb_deq] = iqcoef2imbal([4 2 complex(-0.1145,0.1297) complex(-0.0013,0.0029)])
// disp(a_imb_db,'amplitude imbalance in dB =')
// disp(ph_imb_deq,'phase imbalance in degrees=')
// Bibliography
// http://in.mathworks.com/help/comm/ref/iqcoef2imbal.html
// See also
// iqimbal2coef
// Authors
// Pola Lakshmi Priyanka, IIT Bombay//
//*************************************************************************************************************************************//
//Input argument check
[out_a,inp_a]=argn(0);
if (inp_a > 1) | (out_a >2) then
error('comm:iqcoef2imbal: Invalid number of arguments')
end
if (or(Comp_Coef==%nan) | or(Comp_Coef==%inf))
error('comm:iqcoef2imbal: Input arguments should be finte')
end
Amp_Imb_DB = zeros(size(Comp_Coef));
Ph_Imb_Deg = zeros(size(Comp_Coef));
for i = 1:length(Comp_Coef)
if imag(Comp_Coef(i)) == 0 // To avoid division by zero
c = real(Comp_Coef(i));
if abs(c) <= 1
Amp_Imb_DB(i) = 20*log10((1-c)/(1+c));
Ph_Imb_Deg(i) = 0;
else
Amp_Imb_DB(i) = 20*log10((c+1)/(c-1));
Ph_Imb_Deg(i) = 180;
end
else
R11 = 1 + real(Comp_Coef(i));
R22 = 1 - real(Comp_Coef(i));
R21 = imag(Comp_Coef(i));
R12 = imag(Comp_Coef(i));
K0 = [R22 -R21; -R12 R11];
if R11 == 1
a = 0;
else
C1 = -K0(1,1)*K0(1,2) + K0(2,2)*K0(2,1);
C2 = K0(1,2)^2 + K0(2,1)^2 - K0(1,1)^2 - K0(2,2)^2;
if abs(Comp_Coef(i)) <= 1
a = (-C2 - sqrt(C2^2 + 4*C1^2))/(2*C1);
else
a = (-C2 + sqrt(C2^2 + 4*C1^2))/(2*C1);
end
end
K = K0 * [1 -a; a 1];
Amp_Imb_DB(i) = 20*log10(K(1,1)/K(2,2));
Ph_Imb_Deg(i) = -2*atan(K(2,1)/K(1,1))/%pi*180;
end
end
endfunction
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