# Number of noise photons
noise = noise_photons(wavelength=wavelength,
z=distance * au / u.meter,
d0=diameter,
fractional_bandwidth=fractional_bandwidth)
# Classucal aperture equivalent
aperture = classical_aperture(wavelength=wavelength,
z=distance * au / u.meter,
d0=diameter)
# number of signal photons
signal = photons_received(D_r=aperture,
D_t=1,
P=power,
wavelength=wavelength,
R=1.3 * pc / u.meter,
Q_R=1.22)
M = signal / modes # Number of photons per mode (the signal)
N_th = noise / modes # average number of noise photons per mode (the noise)
capacity = holevo_thermal(M=M, N_th=N_th, eta=receiver_efficiency)
SNR = signal / noise
data_rate = (capacity * signal) / 10**6 # Mbits/s
image[dist_id - 1, diam_id - 1] = data_rate
# print(diameter, distance, SNR, capacity, data_rate)
print(distance)
print(numpy.amax(image), numpy.amin(image))
plt.rc('font', family='serif', serif='Computer Modern Roman')
# Move it to z=2200 to compare influence of z
eq8_at_z_2200 = integrated_flux(wavelength=wavelength,
z=2200 * au / u.meter,
d0=d)
print('Gain at z=2200 {:.2e}'.format(eq8_at_z_2200))
print('Ratio z=600 / z=2200 {:.2f}'.format(eq8_at_z_2200 / eq8_at_z_600))
# Equivalent classical aperture
ap_600 = classical_aperture(wavelength=wavelength, z=600 * au / u.meter, d0=d)
print('Classical aperture at z=600 {:.2f} [km]'.format(ap_600 / 1000))
### Section 3.1 Photon flux
flux = photons_received(D_r=1,
D_t=1,
P=1,
wavelength=wavelength,
R=1.3 * pc / u.meter,
Q_R=1.22)
print(
'Signal photons received (d_r=d_t=1m, P=1W, Alpha Cen) {:.2e} [m^-2 s^-1]'.
format(flux))
### Section 4.6 Noise calculations
noise = noise_photons(wavelength=wavelength,
z=600 * au / u.meter,
d0=d,
fractional_bandwidth=1 / 2700.)
print('Noise photons received {:.2e} [s^-1]'.format(noise))
### Section 5.1 Capacity
if math.isclose(result, expected_result, rel_tol=1e-6):
print('PASS b_of_t test case 1, result', result)
else:
print('FAILED b_of_t test case 1, result', result)
result = z_of_b(b=2.0) / au * u.meter
expected_result = 2189.2121278750956
if math.isclose(result, expected_result, rel_tol=1e-6):
print('PASS z_of_b, result', result)
else:
print('FAILED z_of_b, result', result)
"""Test photons_received"""
wavelength = 1000 * 10**-9 # 1000 nm = 1um = 10**-6m
result = photons_received(D_r=39, D_t=1, P=1, wavelength=wavelength, R=3.09E+16, Q_R=1.22)
expected_result = 1.3469636550722477
if math.isclose(result, expected_result, rel_tol=1e-6):
print('PASS photons_received, result', result)
else:
print('FAILED photons_received, result', result)
"""Test noise_photons"""
result = noise_photons(
wavelength=0.000001,
z=600 * au / u.meter,
d0=1,
fractional_bandwidth=1/2700.)
expected_result = 1905694.5888717826
if math.isclose(result, expected_result, rel_tol=1e-6):
gridsize = 500
image = numpy.zeros(shape=(gridsize, gridsize))
distances = numpy.logspace(start=0, stop=4, num=gridsize)
wavelengths = numpy.logspace(start=2, stop=4, num=gridsize)
dist_id = 0
wave_id = 0
for distance in distances:
dist_id = dist_id + 1
wave_id = 0
for wavelength in wavelengths:
real_wavelength = wavelength * 10**-9 # [m], Q is in [m], extinction in [nm]
wave_id = wave_id + 1
p = photons_received(D_r=D_r,
D_t=D_t,
P=P,
wavelength=wavelength,
R=distance * pc / u.meter,
Q_R=Q(real_wavelength))
e = get_extinction(distance=distance, wavelength=wavelength)
t = transparency(wavelength=wavelength)
Noise = sky_background(wavelength=wavelength)
M = p / modes # Number of photons per mode (the signal)
N_th = Noise / modes # average number of noise photons per mode (the noise)
bits_per_photon = holevo_thermal(M=M, N_th=N_th, eta=eta)
#bits_per_photon = 1
tot = p * e * t * bits_per_photon
# print(distance, wavelength, p, M, N_th, bits_per_photon)
image[dist_id - 1, wave_id - 1] = tot
print(distance)
print(numpy.amin(image), numpy.amax(image))