Voici le programme que j’utilise pour récupérer les échos de météores de façon autonome. Il s’agit d’une boucle infinie qui récupère les données de l’antenne, applique une FFT et si les résultats sont intéressants crée une image.
La library RTLSDR pour python :
https://pypi.org/project/pyrtlsdr/
#!/usr/bin/env python3.5
print("""
.:'
_.::'
.-;;-. (_.'
/ ;;;' \\
|. `: | METEOR SCATTER SERVER V1.0 by flo
\: `;/
'-..-'
""")
from matplotlib.pyplot import psd
from matplotlib.pyplot import clf
from rtlsdr import *
import numpy as np
import gc
from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw
from Console import Console
import datetime
def rgb(minimum, maximum, value):
minimum, maximum = float(minimum), float(maximum)
ratio = 2 * (value-minimum) / (maximum - minimum)
b = int(max(0, 255*(1 - ratio)))
r = int(max(0, 255*(ratio - 1)))
g = 255 - b - r
return r, g, b
def addLineToPNG(png, line, y):
mi = min(line)
ma = 14
for i in range(len(line)):
if line[i] > ma:
line[i] = ma
png[i,y] = rgb(mi,ma,line[i])
def img_save(arr, time):
l = len(arr)
band = len(arr[0])
new_im = Image.new('RGB', (band,l))
png = new_im.load()
for i in range(l):
addLineToPNG(png, arr[i], i)
new_im.save('out/'+time+".png", "PNG")
Console.print("Start")
while True:
height = 90
sample_rate = 250000
band = 512
gain = 50
freq = 143050000
sdr = RtlSdr()
sdr.sample_rate = sample_rate
sdr.center_freq = freq
sdr.gain = gain
z = 0
arr = [[]] * height
count = 0
while(True):
if(z == 500):
sdr.close()
z = 0
sdr = RtlSdr()
sdr.sample_rate = sample_rate
sdr.center_freq = freq
sdr.gain = gain
Pxx, f = psd(sdr.read_samples(sample_rate/2), NFFT=sample_rate, Fs=band/1e6, Fc=freq/1e6)
X = Pxx[int((sample_rate/2)-(band/2)) : int((sample_rate/2)+(band/2))]
X = np.float16(Pxx)
mn = np.mean(X)
if (mn > 3.5 and count == 0):
count = height - 5
if count > 0:
count -= 1
if count == 0:
now = str(datetime.datetime.now()).replace(':', '-').replace(' ', '_')
print('save : '+now)
img_save(arr, now)
i = height-1
while i > 0:
arr[i] = arr[i-1]
i -= 1
arr[0] = X
del Pxx
del f
clf()
gc.collect()
z += 1
Console.print('Stop send')