fid = fopen('DAT_0942_A1.rd3','r');
[A, COUNT]=fread(fid, [656,1], 'short');

Fs=4180799805         % sampling frequency
T = 1/Fs;             % Sampling period       
L = 656;              % Length of signal
t = (0:L-1)*T;        % Time vector

figure(8)
plot(t,A)
title('GPR TRACE A(t)')
xlabel('Time s)')
ylabel('|Amplitude')


Y=fft(A);
P2 = abs(Y/L);
P1 = P2(1:L/2+1);
P1(2:end-1) = 2*P1(2:end-1);

f = Fs*(0:(L/2))/L;
figure(9)
plot(f,P1) 
title('Single-Sided Amplitude Spectrum of A(t)')
xlabel('f (Hz)')
ylabel('|P1(f)|')

fclose(fid);