def scint(self, psr, snr):
""" Add scintillation effects and modify the pulsar's S/N"""
# calculate the scintillation strength (commonly "u")
# first, calculate scint BW, assume Kolmogorov, C=1.16
if hasattr(psr, 't_scatter'):
tscat = go.scale_bhat(psr.t_scatter, self.freq, psr.scindex)
else:
tscat = go.scatter_bhat(psr.dm, psr.scindex, self.freq)
# convert to seconds
tscat /= 1000.
scint_bandwidth = 1.16 / 2.0 / math.pi / tscat # BW in Hz
scint_bandwidth /= 1.0E6 # convert to MHz (self.freq is in MHz)
scint_strength = math.sqrt(self.freq / scint_bandwidth)
if scint_strength < 1.0:
# weak scintillation
# modulation index
u_term = math.pow(scint_strength, 1.666666)
mod_indx = math.sqrt(u_term)
else:
# strong scintillation
# m^2 = m_riss^2 + m_diss^2 + m_riss * m_diss
# e.g. Lorimer and Kramer ~eq 4.44
m_riss = math.pow(scint_strength, -0.33333)
# lorimer & kramer eq 4.44
kappa = 0.15 # taking this as avrg for now
# calculate scintillation timescale
scint_ts, scint_bw = go.ne2001_scint_time_bw(
psr.dtrue, psr.gl, psr.gb, self.freq)
# calc n_t and n_f
if scint_ts is None:
n_t = 1.
else:
n_t = self._calc_n_t(kappa, scint_ts)
if scint_bw is None:
n_f = 1.
else:
n_f = self._calc_n_f(kappa, scint_bw)
# finally calc m_diss
m_diss = 1. / math.sqrt(n_t * n_f)
m_tot_sq = m_diss * m_diss + m_riss * m_riss + m_riss * m_diss
# modulation index for strong scintillation
mod_indx = math.sqrt(m_tot_sq)
return self._modulate_flux_scint(snr, mod_indx)
def scint(self, psr, snr):
""" Add scintillation effects and modify the pulsar's S/N"""
# calculate the scintillation strength (commonly "u")
# first, calculate scint BW, assume Kolmogorov, C=1.16
if hasattr(psr, "t_scatter"):
tscat = go.scale_bhat(psr.t_scatter, self.freq, psr.scindex)
else:
tscat = go.scatter_bhat(psr.dm, psr.scindex, self.freq)
# convert to seconds
tscat /= 1000.0
scint_bandwidth = 1.16 / 2.0 / math.pi / tscat # BW in Hz
scint_bandwidth /= 1.0e6 # convert to MHz (self.freq is in MHz)
scint_strength = math.sqrt(self.freq / scint_bandwidth)
if scint_strength < 1.0:
# weak scintillation
# modulation index
u_term = math.pow(scint_strength, 1.666666)
mod_indx = math.sqrt(u_term)
else:
# strong scintillation
# m^2 = m_riss^2 + m_diss^2 + m_riss * m_diss
# e.g. Lorimer and Kramer ~eq 4.44
m_riss = math.pow(scint_strength, -0.33333)
# lorimer & kramer eq 4.44
kappa = 0.15 # taking this as avrg for now
# calculate scintillation timescale
scint_ts, scint_bw = go.ne2001_scint_time_bw(psr.dtrue, psr.gl, psr.gb, self.freq)
# calc n_t and n_f
if scint_ts is None:
n_t = 1.0
else:
n_t = self._calc_n_t(kappa, scint_ts)
if scint_bw is None:
n_f = 1.0
else:
n_f = self._calc_n_f(kappa, scint_bw)
# finally calc m_diss
m_diss = 1.0 / math.sqrt(n_t * n_f)
m_tot_sq = m_diss * m_diss + m_riss * m_riss + m_riss * m_diss
# modulation index for strong scintillation
mod_indx = math.sqrt(m_tot_sq)
return self._modulate_flux_scint(snr, mod_indx)