import numpy as np
import h5py
from scipy.interpolate import interp1d
from radiotools import helper as hp
from NuRadioReco.utilities import units, fft
import NuRadioReco.framework.base_trace
import logging
logger = logging.getLogger("NuRadioMC.SignalGen.emitter")
import os
import pickle, lzma
buffer_emitter_model = {}
[docs]def get_time_trace(amplitude, N, dt, model, full_output=False, **kwargs):
"""
returns the voltage trace of an emitter
We implement only the time-domain solution and obtain the frequency spectrum
via FFT (with the standard normalization of NuRadioMC). This approach assures
that the units are interpreted correctly. In the time domain, the amplitudes
are well defined and not details about fourier transform normalizations needs
to be known by the user.
Parameters
----------
amplitude : float
strength of a pulse
N : int
number of samples in the time domain
dt: float
time bin width, i.e. the inverse of the sampling rate
model: string
specifies the signal model
If the model string starts with "efield", the function provides the three dimensional electric field emitted
by the pulser/antena combination normalized to a distance of 1m.
If not, then the voltage of the pulser is returned (which needs to be folded with an antenna response pattern to obtain
the emitted electric field. This is automatically done in a NuRadioMC simulation).
* delta_pulse: a simple signal model of a delta pulse emitter
* cw : a sinusoidal wave of given frequency
* square : a rectangular pulse of given amplituede and width
* tone_burst : a short sine wave pulse of given frequency and desired width
* idl1 & hvsp1 : these are the waveforms generated in KU lab and stored in hdf5 files
* gaussian : represents a gaussian pulse where sigma is defined through the half width at half maximum
* ARA02-calPulser : a new normalized voltage signal which depicts the original CalPulser shape used in ARA-02
* efield_idl1_spice: direct measurement of the efield from the idl1 pulser and its antenna as used in the SPICE
calibration campaigns from 2018 and 2019.
The `launch_vector` needs to be specified in the kwargs. See Journal of Instrumentation 15 (2020) P09039,
doi:10.1088/1748-0221/15/09/P09039 arXiv:2006.03027 for details.
the `amplitude` is used to rescale the efield relatively, i.e., amplitude = 1 will return the measured efield amplitude, an
amplitude of 10 will return 10 times the measured efield amplitude, etc.
Use kwarg `iN` to select a specific pulse from the 10 available pulses. The default is a random selection.
* efield_delta_pulse: a simple signal model of a delta pulse emitter. The kwarg `polarization` needs
to be specified to select the polarization of the efield, defined as float between 0 and 1 with
0 = eTheta polarized and 1 = ePhi polarized. The default is 0.5, i.e. unpolarized. The amplitudes are
set to preserve the total power of the delta pulse, i.e. A_theta = sqrt(1-polarization)
and A_phi = sqrt(polarization).
full_output: bool (default False)
if True, can return additional output
kwargs: dict
specifies needed parameters for certain emitters.
* emitter_frequency: Frequency of the emitted pulse.
* half_width: Half width of the emitted pulse.
* launch_vector: Launch vector of the emitted pulse.
* polarization: Polarization of the emitted pulse.
* iN: Index of the measured pulse used for the propagation
* rnd: Random number generator used to select a pulse form.
Returns
-------
time trace: 1d or 2d array, shape (N) or (3, N) for `NuRadioReco.framework.electric_field`
the amplitudes for each time bin. In case of an efield, the the amplitude for the three componente eR, eTheta, ePhi are returned.
additional information: dict
only available if `full_output` enabled
"""
trace = None
additional_output = {}
if(amplitude == 0):
if(model.startswith("efield_")):
trace = np.zeros((3, N))
else:
trace = np.zeros(N)
if(model == 'delta_pulse'): # this takes delta signal as input voltage
trace = np.zeros(N)
trace[N // 2] = amplitude
elif(model == 'cw'): # generates a sine wave of given frequency
if 'emitter_frequency' not in kwargs.keys():
raise KeyError("emitter_frequency has to be passed as a parameter")
time = np.linspace(-(N / 2) * dt, ((N - 1) - N / 2) * dt, N)
trace = amplitude * np.sin(2 * np.pi * kwargs["emitter_frequency"] * time)
elif(model == 'square' or model == 'tone_burst'): # generates a rectangular or tone_burst signal of given width and frequency
if 'half_width' not in kwargs.keys():
raise KeyError("half_width has to be passed as a parameter")
half_width = kwargs.get("half_width")
if(half_width > int(N / 2)):
raise NotImplementedError(" half_width {} should be < half of the number of samples N " . format(half_width))
time = np.linspace(-(N / 2) * dt, ((N - 1) - N / 2) * dt, N)
voltage = np.zeros(N)
for i in range(0, N):
if time[i] >= -half_width and time[i] <= half_width:
voltage[i] = amplitude
if(model == 'square'):
trace = voltage
else:
if 'emitter_frequency' not in kwargs.keys():
raise KeyError("emitter_frequency has to be passed as a parameter")
trace = voltage * np.sin(2 * np.pi * kwargs["emitter_frequency"] * time)
elif(model == 'gaussian'): # generates gaussian pulse where half_width represents the half width at half maximum
if 'half_width' not in kwargs.keys():
raise KeyError("half_width has to be passed as a parameter")
time = np.linspace(-(N / 2) * dt, ((N - 1) - N / 2) * dt, N)
sigma = kwargs["half_width"] / (np.sqrt(2 * np.log(2)))
trace = 1 / (sigma * np.sqrt(2 * np.pi)) * np.exp(-1 / 2 * ((time - 500) / sigma) ** 2)
trace = amplitude * 1 / np.max(np.abs(trace)) * trace
elif(model == 'idl1' or model == 'hvsp1' or model == 'ARA02_calPulser'): # the idl1 & hvsp1 waveforms gemerated in KU Lab stored in hdf5 file
path = os.path.dirname(os.path.dirname(__file__))
if(model == 'idl1'):
input_file = os.path.join(path, 'data/idl1_data.hdf5')
elif(model == 'hvsp1'):
input_file = os.path.join(path, 'data/hvsp1_data.hdf5')
else:
input_file = os.path.join(path, 'data/ARA02_Cal_data.hdf5')
read_file = h5py.File(input_file, 'r')
time_original = read_file.get('time')
voltage_original = read_file.get('voltage')
time_new = np.linspace(time_original[0], time_original[len(time_original) - 1], (int((time_original[len(time_original) - 1] - time_original[0]) / dt) + 1))
interpolation = interp1d(time_original, voltage_original, kind='cubic')
voltage_new = interpolation(time_new)
# if the interpolated waveform has larger sample size than N , it will truncate the data keeping peak amplitude at center
if len(voltage_new) > N:
peak_amplitude_index = np.where(np.abs(voltage_new) == np.max(np.abs(voltage_new)))[0][0]
voltage_new = np.roll(voltage_new, int(len(voltage_new) / 2) - peak_amplitude_index)
lower_index = int(len(voltage_new) / 2 - N / 2)
trace = voltage_new[lower_index: lower_index + N] # this truncate data making trace lenght of N
# for the case with larger N, trace size will be adjusted depending on whether the number (N + len(voltage_new)) is even or odd
else:
add_zeros = int((N - len(voltage_new)) / 2)
adjustment = 0
if ((N + len(voltage_new)) % 2 != 0):
adjustment = 1
trace = np.pad(voltage_new, (add_zeros + adjustment, add_zeros), 'constant', constant_values=(0, 0))
trace = amplitude * trace / np.max(np.abs(trace)) # trace now has dimension of amplitude given from event generation file
peak_amplitude_index_new = np.where(np.abs(trace) == np.max(np.abs(trace)))[0][0]
trace = np.roll(trace, int(N / 2) - peak_amplitude_index_new) # this rolls the array(trace) to keep peak amplitude at center
elif(model == 'efield_delta_pulse'): # this takes delta signal as input voltage
if 'polarization' not in kwargs.keys():
raise KeyError("polarization has to be passed as a parameter")
trace = np.zeros((3, N))
trace[1, N // 2] = (1.0 - kwargs.get("polarization", 0.5)) ** 0.5 * amplitude
trace[2, N // 2] = kwargs.get("polarization", 0.5) ** 0.5 * amplitude
elif(model == "efield_idl1_spice"):
if 'launch_vector' not in kwargs.keys():
raise KeyError("launch_vector has to be passed as a parameter")
launch_zenith, _ = hp.cartesian_to_spherical(*kwargs["launch_vector"])
if model not in buffer_emitter_model:
path = os.path.dirname(os.path.dirname(__file__))
SPice_pulses = os.path.join(path,"SignalProp/examples/birefringence_examples/extra_files/SPice_pulses.xz")
with lzma.open(SPice_pulses, "r") as f:
buffer_emitter_model[model] = pickle.load(f)
launch_keys = np.array(list(buffer_emitter_model[model]['efields'].keys()))
launch_angles = launch_keys * units.deg
launch_angle = launch_keys[np.argmin(np.abs(launch_angles - launch_zenith))]
n_pulses = len(buffer_emitter_model[model]['efields'][launch_angle])
if "iN" in kwargs:
iN = kwargs["iN"]
if iN >= n_pulses:
raise ValueError(f"the selected pulse iN {iN} is out of range. Only {n_pulses} different pulses are available")
else:
if "rnd" in kwargs:
iN = kwargs["rnd"].integers(0, n_pulses)
else:
iN = np.random.randint(0, n_pulses)
logger.warning(f"no random number generator provided, using np.random.randint to select pulse {iN} from {n_pulses} available pulses. This might not be reproducible.")
additional_output['iN'] = iN
spice_pulse = buffer_emitter_model[model]['efields'][launch_angle][iN]
voltage_original_theta = spice_pulse[0]
voltage_original_phi = spice_pulse[1]
sampling_rate_tmp = buffer_emitter_model[model]['sampling_rate']
btrace = NuRadioReco.framework.electric_field.ElectricField([1], position=None,
shower_id=None, ray_tracing_id=None)
btrace.set_trace(np.array([np.zeros_like(voltage_original_theta), voltage_original_theta, voltage_original_phi]), sampling_rate_tmp)
btrace.resample(1/dt) # this resamples the trace to have 1/dt sampling rate
trace = btrace.get_trace()
if len(trace[1]) > N:
peak_amplitude_index_theta = np.where(np.abs(trace[1]) == np.max(np.abs(trace[1])))[0][0]
trace[1] = np.roll(trace[1], int(len(trace[1]) / 2) - peak_amplitude_index_theta)
lower_index = int(len(trace[1]) / 2 - N / 2)
final_theta = trace[1, lower_index: lower_index + N] # this truncate data making trace lenght of N
# for the case with larger N, trace size will be adjusted depending on whether the number (N + len(voltage_new)) is even or odd
else:
add_zeros = int((N - len(trace[1])) / 2)
adjustment = 0
if ((N + len(trace[1])) % 2 != 0):
adjustment = 1
final_theta = np.pad(trace[1], (add_zeros + adjustment, add_zeros), 'constant', constant_values=(0, 0))
if len(trace[2]) > N:
peak_amplitude_index_phi = np.where(np.abs(trace[2]) == np.max(np.abs(trace[2])))[0][0]
trace[2] = np.roll(trace[2], int(len(trace[2]) / 2) - peak_amplitude_index_phi)
lower_index = int(len(trace[2]) / 2 - N / 2)
final_phi = trace[2][lower_index: lower_index + N] # this truncate data making trace lenght of N
# for the case with larger N, trace size will be adjusted depending on whether the number (N + len(voltage_new)) is even or odd
else:
add_zeros = int((N - len(trace[2])) / 2)
adjustment = 0
if ((N + len(trace[2])) % 2 != 0):
adjustment = 1
final_phi = np.pad(trace[2], (add_zeros + adjustment, add_zeros), 'constant', constant_values=(0, 0))
#trace_theta = amplitude * trace_theta / np.max(np.abs(trace_theta)) # trace now has dimension of amplitude given from event generation file
peak_amplitude_index_theta_new = np.where(np.abs(final_theta) == np.max(np.abs(final_theta)))[0][0]
final_theta = np.roll(final_theta, int(N / 2) - peak_amplitude_index_theta_new)
#trace_phi = amplitude * trace_phi / np.max(np.abs(trace_phi)) # trace now has dimension of amplitude given from event generation file
peak_amplitude_index_phi_new = np.where(np.abs(final_phi) == np.max(np.abs(final_phi)))[0][0]
final_phi = np.roll(final_phi, int(N / 2) - peak_amplitude_index_phi_new)
trace = np.zeros((3,N))
trace[1,:] = final_theta * amplitude
trace[2,:] = final_phi * amplitude
else:
raise NotImplementedError("model {} unknown".format(model))
if(full_output):
return trace, additional_output
else:
return trace
[docs]def get_frequency_spectrum(amplitude, N, dt, model, full_output=False, **kwargs):
"""
returns the complex amplitudes of the frequency spectrum of an emitter
Parameters
----------
amplitude : float
strength of a pulse
N : int
number of samples in the time domain
dt: float
time bin width, i.e. the inverse of the sampling rate
model: string
specifies the signal model
If the model string starts with "efield", the function provides the three dimensional electric field emitted
by the pulser/antena combination normalized to a distance of 1m.
If not, then the voltage of the pulser is returned (which needs to be folded with an antenna response pattern to obtain
the emitted electric field. This is automatically done in a NuRadioMC simulation).
* delta_pulse: a simple signal model of a delta pulse emitter
* cw : a sinusoidal wave of given frequency
* square : a rectangular pulse of given amplituede and width
* tone_burst : a short sine wave pulse of given frequency and desired width
* idl1 & hvsp1 : these are the waveforms generated in KU lab and stored in hdf5 files
* gaussian : represents a gaussian pulse where sigma is defined through the half width at half maximum
* ARA02-calPulser : a new normalized voltage signal which depicts the original CalPulser shape used in ARA-02
* efield_idl1_spice: direct measurement of the efield from the idl1 pulser and its antenna as used in the SPICE
calibration campaigns from 2018 and 2019.
The `launch_vector` needs to be specified in the kwargs. See Journal of Instrumentation 15 (2020) P09039,
doi:10.1088/1748-0221/15/09/P09039 arXiv:2006.03027 for details.
the `amplitude` is used to rescale the efield relatively, i.e., amplitude = 1 will return the measured efield amplitude, an
amplitude of 10 will return 10 times the measured efield amplitude, etc.
Use kwarg `iN` to select a specific pulse from the 10 available pulses. The default is a random selection.
* efield_delta_pulse: a simple signal model of a delta pulse emitter. The kwarg `polarization` needs
to be specified to select the polarization of the efield, defined as float between 0 and 1 with
0 = eTheta polarized and 1 = ePhi polarized. The default is 0.5, i.e. unpolarized. The amplitudes are
set to preserve the total power of the delta pulse, i.e. A_theta = sqrt(1-polarization)
and A_phi = sqrt(polarization).
full_output: bool (default False)
if True, can return additional output
kwargs: dict
specifies needed parameters for certain emitters.
* emitter_frequency: Frequency of the emitted pulse.
* half_width: Half width of the emitted pulse.
* launch_vector: Launch vector of the emitted pulse.
* polarization: Polarization of the emitted pulse.
* iN: Index of the measured pulse used for the propagation
* rnd: Random number generator used to select a pulse form.
Returns
-------
frequency spectrum: 1d or 2d array, shape (N/2+1) or (3, N/2+1) for `NuRadioReco.framework.electric_field`
additional information: dict
only available if `full_output` enabled
"""
tmp = get_time_trace(amplitude, N, dt, model, full_output=full_output, **kwargs)
if(full_output):
return fft.time2freq(tmp[0], 1 / dt), tmp[1]
else:
return fft.time2freq(tmp, 1 / dt)