NawfalMotii79
47 lines
1.2 KiB
Python
47 lines
1.2 KiB
Python
import numpy as np
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from numpy.fft import fft, ifft
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import matplotlib.pyplot as plt
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fs=125*pow(10,6) #sampling frequency
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Ts=1/fs # sampling time
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Tb=0.25*pow(10,-6) # burst time
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Tau=1.5*pow(10,-6) # pulse repetition time
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fmax=32*pow(10,6) # maximum frequency on ramp
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fmin=1*pow(10,6) # minimum frequency on ramp
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n=int(Tb/Ts) # number of samples per ramp
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N = np.arange(0, n, 1)
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theta_n= 2*np.pi*(pow(N,2)*pow(Ts,2)*(fmax-fmin)/(2*Tb)+fmin*N*Ts) # instantaneous phase
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y = 1 + np.sin(theta_n) # ramp signal in time domain
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M = np.arange(n, 2*n, 1)
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theta_m= 2*np.pi*(pow(M,2)*pow(Ts,2)*(-fmax+fmin)/(2*Tb)+(-fmin+2*fmax)*M*Ts)-2*np.pi*((fmin-fmax)*Tb/2+(2*fmax-fmin)*Tb) # instantaneous phase
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z = 1 + np.sin(theta_m) # ramp signal in time domain
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x = np.concatenate((y, z))
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t = Ts*np.arange(0,2*n,1)
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X = fft(x)
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L =len(X)
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l = np.arange(L)
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T = L*Ts
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freq = l/T
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plt.figure(figsize = (12, 6))
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plt.subplot(121)
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plt.stem(freq, np.abs(X), 'b', \
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markerfmt=" ", basefmt="-b")
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plt.xlabel('Freq (Hz)')
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plt.ylabel('FFT Amplitude |Y(freq)|')
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plt.xlim(0, (fmax+fmax/10))
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plt.ylim(0, 20)
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plt.subplot(122)
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plt.plot(2*n, y)
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plt.xlabel('Time (s)')
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plt.ylabel('Amplitude')
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plt.tight_layout()
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plt.show()
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