dqpskencoder.m

实现pi/4DQPSK调制

% pi/4 shifter DQPSK Encoder.
function [I_Symbols, Q_Symbols] = DQPSKEncoder(BitStreamOneTx, BitStreamTwoTx)
% This is supposed to be (I(-1) + jQ(-1)).
InitialSymbol = (1+0i);
I_StreamLength = length(BitStreamOneTx);
Q_StreamLength = I_StreamLength;
% -------------------> Differential Modulation <------------------------------- %
% Do the Differential Modulation and generate the baseband-complex signal.
% Calculate the phase-shift due to the first symbol.
PhaseShift(1) = CalcPhase([BitStreamOneTx(1),BitStreamTwoTx(1)]);
% The first modulated symbol.
ModulatedSymbol(1) = (InitialSymbol)*exp(i*PhaseShift(1));
% The other symbols calculated iteratively.
for index = 2:1:I_StreamLength
% The phase shift due to the ith modulated symbol.
PhaseShift(index) = CalcPhase([BitStreamOneTx(index),BitStreamTwoTx(index)]);
% Rotated the modulated symbol phasor to the new position.
ModulatedSymbol(index) = ModulatedSymbol(index-1)*exp(j*PhaseShift(index));
end
% Extract the I and Q parts of the Symbol.
I_Symbols = real(ModulatedSymbol);
Q_Symbols = imag(ModulatedSymbol);