I have a .mat file which contains a message. I need to decode that signal using QPSK demod using the code below. I need to start work from the "Carrier Demod" section where Tx_Signal is the .mat file.help me extract the no of bits from .mat file.

%MY QPSK SYSTEM

clc; clear all; close all;

%% Data Initialization

Num_bits = 10; % Number of bits

P_length = 100; % Half Cycle Sinus length

Fs = 2*P_length;

%% Pulse Generation

t = 0:1/Fs:0.5;

t = t(1:end-1);

Pulse = sin(2*pi*t);

%% Bits Generation

bits = round(rand(1,Num_bits));

figure(1);stem(bits);

title ('Generated Bits');

%% QPSK Mod

a=bits(1:2:end);

b=bits(2:2:end);

qpsk=(-1+2*a)+i*(-1+2*b);

scatterplot(qpsk);

%% Pulse Shaping

Signal = [];

for i = 1:Num_bits/2

    Signal = [Signal, qpsk(i)*Pulse];

end

figure (3); stem(Signal);

title ('Modulated Signal')

%% Carrier Mod

fs=10000;

fc=1500;

T=(0:length(Signal)-1)*1/fs;

Real_Signal = real(Signal);

Imag_Signal = imag(Signal);

Re_Sig=Real_Signal.*(sqrt(2)*cos(2*pi*fc*T));

Im_Sig=Imag_Signal.*(-sqrt(2)*sin(2*pi*fc*T));

Tx_Signal=Re_Sig+Im_Sig;

fft_(fs,Tx_Signal)

%% Carrier Demod

Rx_Re_Sig=Tx_Signal.*(sqrt(2)*cos(2*pi*fc*T));

Rx_Im_Sig=Tx_Signal.*(-sqrt(2)*sin(2*pi*fc*T));

fft_(fs,Rx_Re_Sig)

fft_(fs,Rx_Im_Sig)

%% LPF

[B,A]=butter(10,0.2,'Low');

Re_filter=filter(B,A,Rx_Re_Sig);

Im_filter=filter(B,A,Rx_Im_Sig);

fft_(fs,Re_filter)

fft_(fs,Im_filter)

%% Matched Filter Estimation

Rx_Re_MF=conv(Pulse,Re_filter);

Rx_Im_MF=conv(Pulse,Im_filter);

figure(9);plot(Rx_Re_MF);

figure(10);plot(Rx_Im_MF);

%% Sampling of the received signal

Ts = P_length;

[X,Y] = max(abs(Rx_Re_MF(1:1.5*Ts)));

[A,B] = max(abs(Rx_Im_MF(1:1.5*Ts)));

Rx_QPSK_real = [];

Rx_QPSK_imag = [];

for i = 1:Num_bits/2

    Rx_QPSK_real = [Rx_QPSK_real, sign(Rx_Re_MF(Y+Ts*(i-1)))];      

    Rx_QPSK_imag = [Rx_QPSK_imag, sign(Rx_Im_MF(B+Ts*(i-1)))];

end

Rx_QPSK = Rx_QPSK_real+1j*Rx_QPSK_imag;

figure(11);stem (Rx_QPSK);

title ('Demodulated Signal')

%% QPSK Demod

c=real(Rx_QPSK);

d=imag(Rx_QPSK);

Rx_bits=[];

for i=1:Num_bits/2

if c(i)==-1

    Rx_bits=[Rx_bits,0];

else

    Rx_bits=[Rx_bits,1];

end

if d(i)==-1

    Rx_bits=[Rx_bits,0];

else

    Rx_bits=[Rx_bits,1];

end

end

figure(12);stem(Rx_bits);

title ('Received Bits')

%% Error Detection

N_Error = nnz(bits-Rx_bits);