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Gregory Ashton
PyFstat
Commits
0ca51fa7
Commit
0ca51fa7
authored
May 04, 2017
by
Gregory Ashton
Browse files
Adds method to calculate frequency range of signal
parent
286b576c
Changes
2
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pyfstat/__init__.py
View file @
0ca51fa7
...
...
@@ -3,4 +3,5 @@ from __future__ import division as _division
from
.core
import
BaseSearchClass
,
ComputeFstat
,
Writer
,
SemiCoherentSearch
,
SemiCoherentGlitchSearch
from
.mcmc_based_searches
import
MCMCSearch
,
MCMCGlitchSearch
,
MCMCSemiCoherentSearch
,
MCMCFollowUpSearch
,
MCMCTransientSearch
from
.grid_based_searches
import
GridSearch
,
GridUniformPriorSearch
,
GridGlitchSearch
,
FrequencySlidingWindow
from
.injection_helper_functions
import
get_frequency_range_of_signal
pyfstat/injection_helper_functions.py
0 → 100644
View file @
0ca51fa7
""" Code used with permissision from Sylvia Zhu to calculate the range in
frequency space that a signal occupies due to spindown and Doppler
modulations
"""
import
numpy
as
np
from
astropy
import
units
as
u
from
astropy.coordinates
import
SkyCoord
from
astropy.time
import
Time
# Assume Earth goes around Sun in a non-wobbling circle at constant speed;
# Still take the zero longitude to be the Earth's position during the March
# equinox, or March 20.
# Each day the Earth moves 2*pi/365 radians around its orbit.
def
_eqToEcl
(
alpha
,
delta
):
source
=
SkyCoord
(
alpha
*
u
.
radian
,
delta
*
u
.
radian
,
frame
=
'gcrs'
)
out
=
source
.
transform_to
(
'geocentrictrueecliptic'
)
return
np
.
array
([
out
.
lon
.
radian
,
out
.
lat
.
radian
])
def
_eclToEq
(
lon
,
lat
):
source
=
SkyCoord
(
lon
*
u
.
radian
,
lat
*
u
.
radian
,
frame
=
'geocentrictrueecliptic'
)
out
=
source
.
transform_to
(
'gcrs'
)
return
np
.
array
([
out
.
ra
.
radian
,
out
.
dec
.
radian
])
def
_calcDopplerWings
(
s_freq
,
s_alpha
,
s_delta
,
lonStart
,
lonStop
,
numTimes
=
100
):
e_longitudes
=
np
.
linspace
(
lonStart
,
lonStop
,
numTimes
)
v_over_c
=
1e-4
s_lon
,
s_lat
=
_eqToEcl
(
s_alpha
,
s_delta
)
vertical
=
s_lat
horizontals
=
s_lon
-
e_longitudes
dopplerShifts
=
s_freq
*
np
.
sin
(
horizontals
)
*
np
.
cos
(
vertical
)
*
v_over_c
return
np
.
amin
(
dopplerShifts
),
np
.
amax
(
dopplerShifts
)
def
_calcSpindownWings
(
freq
,
fdot
,
minStartTime
,
maxStartTime
):
timespan
=
maxStartTime
-
minStartTime
return
0.5
*
timespan
*
np
.
abs
(
fdot
)
*
np
.
array
([
-
1
,
1
])
def
get_frequency_range_of_signal
(
F0
,
F1
,
Alpha
,
Delta
,
minStartTime
,
maxStartTime
):
""" Calculate the frequency range that a signal will occupy
Parameters
----------
F0, F1, Alpha, Delta: float
Frequency, derivative, and sky position for the signal (all angles in
radians)
minStartTime, maxStartTime: float
GPS time of the start and end of the data span
Returns
-------
[Fmin, Fmax]: array
The minimum and maximum frequency span
"""
YEAR_IN_DAYS
=
365.25
tEquinox
=
79
minStartTime_t
=
Time
(
minStartTime
,
format
=
'gps'
).
to_datetime
().
timetuple
()
maxStartTime_t
=
Time
(
minStartTime
,
format
=
'gps'
).
to_datetime
().
timetuple
()
tStart_days
=
minStartTime_t
.
tm_yday
-
tEquinox
tStop_days
=
maxStartTime_t
.
tm_yday
-
tEquinox
tStop_days
+=
(
maxStartTime_t
.
tm_year
-
minStartTime_t
.
tm_year
)
*
YEAR_IN_DAYS
tStart_days
=
280
-
tEquinox
# 7 October is day 280 in a non leap year
tStop_days
=
19
+
YEAR_IN_DAYS
-
tEquinox
# the next year
lonStart
=
2
*
np
.
pi
*
tStart_days
/
YEAR_IN_DAYS
-
np
.
pi
lonStop
=
2
*
np
.
pi
*
tStop_days
/
YEAR_IN_DAYS
-
np
.
pi
dopplerWings
=
_calcDopplerWings
(
F0
,
Alpha
,
Delta
,
lonStart
,
lonStop
)
spindownWings
=
_calcSpindownWings
(
F0
,
F1
,
minStartTime
,
maxStartTime
)
return
np
.
array
([
F0
,
F0
])
+
dopplerWings
+
spindownWings
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