def get_power_scan(start, end, step, gain=0, num_samples=16384):
freqs = []
signlu = []
signll = []
pwru = []
pwrl = []
pwr = []
for freq in arange(start,end,step): # MHz
cf = rtlsdr.set_freq(int(freq*1000000))
freqs.append(cf/1e6-0.25*step)
freqs.append(cf/1e6+0.25*step)
status = rtlsdr.reset_buffer()
sleep(0.01)
rawdata = rtlsdr.synch_read(num=num_samples)
if rawdata.min() < -120 or rawdata.max() > 120:
mylogger.warning("%7.2f MHz, min=%d, max=%d",
cf/1.e6, rawdata.min(), rawdata.max())
data = unpack_to_complex(rawdata)
mylogger.info("%7.2f MHz, min=%s, max=%s",
cf/1.e6, str(data.min()),str(data.max()))
datalen = len(data)
lsb,usb = sideband_separate(data)
signll += list(lsb)
signlu += list(usb)
LSB = (lsb**2).sum()/datalen
USB = (usb**2).sum()/datalen
pwrl.append(LSB)
pwru.append(USB)
pwr.append(LSB)
pwr.append(USB)
return freqs,pwrl,pwru,pwr,signll,signlu
to bar graph spectra taken with various resolutions from 4 to 16 channels.
"""
from rtlsdr import *
from pylab import *
from Data_Reduction import sideband_separate, unpack_to_complex
rawdata = get_sdr_samples()
# Now do something with the data
colors = ["y", "r", "g", "b", "m", "c", "w"]
fig = figure()
data = unpack_to_complex(rawdata)
datalen = len(data)
lsb, usb = sideband_separate(data)
factor = 1024.0 / datalen
bar([0, 500], [(lsb ** 2).sum() * factor, (usb ** 2).sum() * factor], width=500, color=colors[0], label="LSB,USB")
for num_bins in [4, 8, 16]:
avg = zeros(num_bins)
for index in range(0, 64, num_bins):
dataslice = data[index : index + num_bins]
xform = fft(dataslice)
spectrum = fftshift(xform)
avg += abs(spectrum * conj(spectrum))
avg *= 64.0 / num_bins
print avg
freqs = arange(0, 1000, 1000.0 / num_bins)
bar(freqs, avg, width=1000.0 / num_bins, color=colors[int(log2(num_bins))], label=str(num_bins))
legend(numpoints=1)
xlabel("Frequency (kHz)")
