I have signal which a sinous wave with frequency 1MHZ and DC signal at 0.9V.
The signal is sampled every T the total length is 5e-6 sec so for T=3.301028538570082e-09 i have 220 samples.
sampling frequency is Fs=302935884.4722904Hz
The original sinous plot is shown bellow.
As you can see Sinous amplitude is 0.1V
But is the last two FFT plot there is not destiguish between DC and my 1MHZ signal,also the amplitudes are not an in the analog picture.
Where did i go wrong?
The ful python code with the sample table is shown bellow.
Thanks.
Code:
# -*- coding: utf-8 -*-
"""
Created on Thu Mar 30 13:04:11 2023
@author: Asus
"""
from scipy.fftpack import fft
#import plotly
#import chart_studio.plotly as py
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.widgets import Cursor
#%matplotlib qt
dataset_fft=pd.read_table("sinus_1mhz.txt")
array_fft=dataset_fft.values
Ts=array_fft[4][0]-array_fft[3][0];
Fs=1/Ts #Hz
L=np.size(array_fft)
freq_vec=Fs*np.arange(0,1,1/220)
L=np.size(freq_vec)
fft_y=fft(array_fft[:,1],220)
fig=plt.figure()
ax=fig.subplots()
ax.grid()
cursor=Cursor(ax, horizOn=True,vertOn=True,useblit=True,color='r',linewidth =1)
#ax.plot(array_fft[:,0],array_fft[:,1])
ax.plot(freq_vec,abs(fft_y)/220)
plt.show()
sample table:
time V(n020)
0.000000000000000e+000 8.924428e-001
3.301028538570077e-009 8.922886e-001
6.602057077140153e-009 8.920012e-001
9.903085615710230e-009 8.915803e-001
1.320411415428031e-008 8.910261e-001
1.650514269285038e-008 8.903385e-001
1.980617123142046e-008 8.895176e-001
2.310719976999053e-008 8.885633e-001
3.310719976999053e-008 8.853104e-001
4.310719976999053e-008 8.813376e-001
5.310719976999053e-008 8.768258e-001
6.310719976999053e-008 8.719212e-001
7.310719976999052e-008 8.667433e-001
8.310719976999052e-008 8.613904e-001
9.310719976999052e-008 8.559445e-001
1.031071997699905e-007 8.504745e-001
1.231071997699905e-007 8.396893e-001
1.431071997699905e-007 8.294162e-001
1.631071997699906e-007 8.199491e-001
1.831071997699906e-007 8.115207e-001
2.131071997699906e-007 8.012237e-001
2.431071997699906e-007 7.941512e-001
2.731071997699906e-007 7.906163e-001
3.031071997699907e-007 7.907807e-001
3.331071997699907e-007 7.946613e-001
3.631071997699907e-007 8.021348e-001
3.931071997699908e-007 8.129446e-001
4.231071997699908e-007 8.267109e-001
4.531071997699908e-007 8.429437e-001
4.831071997699908e-007 8.610607e-001
5.131071997699908e-007 8.804088e-001
5.331071997699908e-007 8.936476e-001
5.631071997699909e-007 9.134864e-001
5.931071997699909e-007 9.326717e-001
6.231071997699909e-007 9.505267e-001
6.531071997699910e-007 9.664334e-001
6.831071997699910e-007 9.798563e-001
7.131071997699910e-007 9.903588e-001
7.431071997699911e-007 9.976145e-001
7.731071997699911e-007 1.001411e+000
8.031071997699911e-007 1.001653e+000
8.331071997699912e-007 9.983562e-001
8.531071997699912e-007 9.942504e-001
8.731071997699912e-007 9.886890e-001
8.931071997699912e-007 9.817557e-001
9.131071997699912e-007 9.735535e-001
9.331071997699913e-007 9.642041e-001
9.531071997699913e-007 9.538467e-001
9.731071997699911e-007 9.426368e-001
9.931071997699909e-007 9.307446e-001
1.013107199769991e-006 9.183531e-001
1.033107199769991e-006 9.056551e-001
1.053107199769990e-006 8.928512e-001
1.073107199769990e-006 8.801460e-001
1.093107199769990e-006 8.677447e-001
1.113107199769990e-006 8.558499e-001
1.133107199769990e-006 8.446571e-001
1.153107199769989e-006 8.343519e-001
1.173107199769989e-006 8.251061e-001
1.203107199769989e-006 8.135566e-001
1.233107199769989e-006 8.051701e-001
1.263107199769988e-006 8.002657e-001
1.293107199769988e-006 7.990336e-001
1.323107199769988e-006 8.015288e-001
1.353107199769987e-006 8.076692e-001
1.383107199769987e-006 8.172396e-001
1.413107199769987e-006 8.298985e-001
1.443107199769987e-006 8.451898e-001
1.473107199769986e-006 8.625590e-001
1.503107199769986e-006 8.813735e-001
1.523107199769986e-006 8.943822e-001
1.543107199769986e-006 9.075180e-001
1.573107199769985e-006 9.269971e-001
1.603107199769985e-006 9.455855e-001
1.633107199769985e-006 9.626255e-001
1.663107199769985e-006 9.775270e-001
1.693107199769984e-006 9.897886e-001
1.723107199769984e-006 9.990119e-001
1.753107199769984e-006 1.004910e+000
1.783107199769983e-006 1.007312e+000
1.813107199769983e-006 1.006159e+000
1.843107199769983e-006 1.001504e+000
1.873107199769983e-006 9.935084e-001
1.903107199769982e-006 9.824341e-001
1.933107199769982e-006 9.686427e-001
1.963107199769982e-006 9.525865e-001
1.993107199769981e-006 9.348007e-001
2.023107199769981e-006 9.158893e-001
2.053107199769981e-006 8.965079e-001
2.083107199769981e-006 8.773422e-001
2.113107199769980e-006 8.590813e-001
2.143107199769980e-006 8.423911e-001
2.173107199769980e-006 8.278856e-001
2.203107199769979e-006 8.161016e-001
2.233107199769979e-006 8.074761e-001
2.263107199769979e-006 8.023291e-001
2.293107199769978e-006 8.008513e-001
2.323107199769978e-006 8.030988e-001
2.353107199769978e-006 8.089899e-001
2.373107199769978e-006 8.148408e-001
2.393107199769978e-006 8.221229e-001
2.413107199769977e-006 8.307174e-001
2.433107199769977e-006 8.404839e-001
2.453107199769977e-006 8.512621e-001
2.473107199769977e-006 8.628752e-001
2.493107199769977e-006 8.751321e-001
2.513107199769976e-006 8.878315e-001
2.533107199769976e-006 9.007647e-001
2.553107199769976e-006 9.137201e-001
2.573107199769976e-006 9.264866e-001
2.593107199769976e-006 9.388579e-001
2.613107199769975e-006 9.506359e-001
2.633107199769975e-006 9.616345e-001
2.653107199769975e-006 9.716824e-001
2.673107199769975e-006 9.806260e-001
2.703107199769975e-006 9.916830e-001
2.733107199769974e-006 9.995958e-001
2.763107199769974e-006 1.004115e+000
2.793107199769974e-006 1.005104e+000
2.823107199769973e-006 1.002543e+000
2.853107199769973e-006 9.965196e-001
2.883107199769973e-006 9.872273e-001
2.913107199769973e-006 9.749626e-001
2.943107199769972e-006 9.601180e-001
2.973107199769972e-006 9.431753e-001
3.003107199769972e-006 9.246952e-001
3.033107199769971e-006 9.053026e-001
3.063107199769971e-006 8.856674e-001
3.093107199769971e-006 8.664808e-001
3.123107199769971e-006 8.484289e-001
3.153107199769970e-006 8.321643e-001
3.183107199769970e-006 8.182788e-001
3.213107199769970e-006 8.072786e-001
3.243107199769969e-006 7.995634e-001
3.273107199769969e-006 7.954113e-001
3.303107199769969e-006 7.949686e-001
3.333107199769969e-006 7.982451e-001
3.353107199769968e-006 8.024388e-001
3.373107199769968e-006 8.081621e-001
3.393107199769968e-006 8.153199e-001
3.413107199769968e-006 8.237936e-001
3.423107199769968e-006 8.284810e-001
3.433107199769968e-006 8.334432e-001
3.443107199769967e-006 8.386596e-001
3.453107199769967e-006 8.441087e-001
3.463107199769967e-006 8.497679e-001
3.473107199769967e-006 8.556136e-001
3.483107199769967e-006 8.616217e-001
3.493107199769967e-006 8.677673e-001
3.503107199769967e-006 8.740249e-001
3.513107199769967e-006 8.803685e-001
3.523107199769967e-006 8.867720e-001
3.533107199769967e-006 8.932088e-001
3.543107199769967e-006 8.996524e-001
3.553107199769966e-006 9.060764e-001
3.563107199769966e-006 9.124544e-001
3.573107199769966e-006 9.187604e-001
3.593107199769966e-006 9.310538e-001
3.613107199769966e-006 9.427583e-001
3.633107199769966e-006 9.536871e-001
3.663107199769965e-006 9.682541e-001
3.693107199769965e-006 9.801879e-001
3.723107199769965e-006 9.890857e-001
3.753107199769965e-006 9.946566e-001
3.783107199769964e-006 9.967242e-001
3.813107199769964e-006 9.952271e-001
3.843107199769964e-006 9.902158e-001
3.873107199769964e-006 9.818498e-001
3.903107199769963e-006 9.703925e-001
3.933107199769963e-006 9.562072e-001
3.963107199769963e-006 9.397500e-001
3.993107199769963e-006 9.215599e-001
4.023107199769962e-006 9.022462e-001
4.053107199769962e-006 8.824695e-001
4.083107199769962e-006 8.629198e-001
4.113107199769961e-006 8.442901e-001
4.143107199769961e-006 8.272491e-001
4.173107199769961e-006 8.124120e-001
4.203107199769961e-006 8.003163e-001
4.233107199769960e-006 7.913983e-001
4.263107199769960e-006 7.859771e-001
4.293107199769960e-006 7.842424e-001
4.323107199769959e-006 7.862490e-001
4.353107199769959e-006 7.919157e-001
4.373107199769959e-006 7.976262e-001
4.393107199769959e-006 8.047760e-001
4.413107199769959e-006 8.132467e-001
4.423107199769959e-006 8.179345e-001
4.433107199769958e-006 8.228985e-001
4.443107199769958e-006 8.281181e-001
4.453107199769958e-006 8.335719e-001
4.463107199769958e-006 8.392373e-001
4.473107199769958e-006 8.450908e-001
4.483107199769958e-006 8.511083e-001
4.493107199769958e-006 8.572647e-001
4.503107199769958e-006 8.635347e-001
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4.553107199769957e-006 8.956727e-001
4.563107199769957e-006 9.020725e-001
4.573107199769957e-006 9.084017e-001
4.583107199769957e-006 9.146345e-001
4.603107199769957e-006 9.267105e-001
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4.673107199769956e-006 9.624765e-001
4.703107199769956e-006 9.735320e-001
4.733107199769956e-006 9.814385e-001
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4.793107199769955e-006 9.868951e-001
4.823107199769955e-006 9.842795e-001
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4.913107199769954e-006 9.564171e-001
4.943107199769954e-006 9.414513e-001
4.973107199769953e-006 9.243839e-001
4.993107199769953e-006 9.121249e-001
5.000000000000000e-006 9.077891e-001