def fold(file1, file2, dtype, fbottom, fwidth, nchan,
nt, ntint, nskip, ngate, ntbin, ntw, dm, fref, phasepol,
coherent=False, do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100):
"""Fold pre-channelized LOFAR data, possibly dedispersing it
Parameters
----------
file1, file2 : string
names of the files holding real and imaginary subchannel timeseries
dtype : numpy dtype
way the data are stored in the file (normally '>f4')
fbottom : float
frequency of the lowest channel (frequency units)
fwidth : float
channel width (frequency units, normally 200*u.MHz/1024.)
nchan : int
number of frequency channels
nt, ntint : int
number nt of sets to use, each containing ntint samples;
hence, total # of samples used is nt*(2*ntint).
nskip : int
number of bytes to skip before reading
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
the start of the file that is read (i.e., including nskip)
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
"""
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
# # of items to read from file.
itemsize = np.dtype(dtype).itemsize
count = nchan*ntint
if verbose:
print('Reading from {}\n and {}'.format(file1, file2))
with open(file1, 'rb', count*itemsize) as fh1, \
open(file2, 'rb', count*itemsize) as fh2:
if nskip > 0:
if verbose:
print('Skipping {0} bytes'.format(nskip))
fh1.seek(nskip)
fh2.seek(nskip)
foldspec = np.zeros((nchan, ngate))
icount = np.zeros((nchan, ngate))
dtsample = (1./fwidth).to(u.s)
tstart = dtsample * nskip // itemsize // nchan
# pre-calculate time delay due to dispersion in course channels
freq = fbottom + fwidth * np.arange(nchan)
dt = (dispersion_delay_constant * dm *
(1./freq**2 - 1./fref**2)).to(u.s).value
for j in xrange(nt):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, (tstart+dtsample*j*ntint).value))
# time since start of file
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data stored as series of floats in two files,
# one for real and one for imaginary
raw1 = fromfile(fh1, dtype, count).reshape(-1,nchan)
raw2 = fromfile(fh2, dtype, count).reshape(-1,nchan)
except(EOFError):
break
power = raw1**2+raw2**2
# power[#int, #block]
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if do_foldspec:
tsample = (tstart + dtsample * isr).value # times since start
for k in xrange(nchan):
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k] += np.bincount(iphase, power[:,k], ngate)
icount[k] += np.bincount(iphase, None, ngate)
ibin = j*ntbin//nt # bin in the time series: 0..ntbin-1
if (j+1)*ntbin//nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec/icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:,:,ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec2, waterfall
def fold(file1, dtype, samplerate, fedge, fedge_at_top, nchan,
nt, ntint, nhead, ngate, ntbin, ntw, dm, fref, phasepol,
coherent=False, do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100):
"""FFT ARO data, fold by phase/time and make a waterfall series
Parameters
----------
file1 : string
name of the file holding voltage timeseries
dtype : numpy dtype or '4bit' or '1bit'
way the data are stored in the file
samplerate : float
rate at which samples were originally taken and thus double the
band width (frequency units)
fedge : float
edge of the frequency band (frequency units)
fedge_at_top: book
whether edge is at top (True) or bottom (False)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*ntint, with each sample containing
a single polarisation
nhead : int
number of bytes to skip before reading (usually 0 for ARO)
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
"""
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (simple for ARO: 1 byte/sample)
recsize = nchan*ntint*{np.int8: 2, '4bit': 1}[dtype]
if verbose:
print('Reading from {}'.format(file1))
with open(file1, 'rb', recsize) as fh1:
if nhead > 0:
if verbose:
print('Skipping {0} bytes'.format(nhead))
fh1.seek(nhead)
foldspec = np.zeros((nchan, ngate), dtype=np.int)
icount = np.zeros((nchan, ngate), dtype=np.int)
dt1 = (1./samplerate).to(u.s)
if coherent:
# pre-calculate required turns due to dispersion
fcoh = (fedge - rfftfreq(nchan*ntint, dt1.value) * u.Hz
if fedge_at_top
else
fedge + rfftfreq(nchan*ntint, dt1.value) * u.Hz)
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1./fref-1./fcoh)**2) * 360. * u.deg
dedisperse = np.exp(dang.to(u.rad).value * 1j
).conj().astype(np.complex64).view(np.float32)
# get these back into order r[0], r[1],i[1],...r[n-1],i[n-1],r[n]
dedisperse = np.hstack([dedisperse[:1], dedisperse[2:-1]])
else:
# pre-calculate time delay due to dispersion;
# [::2] sets frequency channels to numerical recipes ordering
freq = (fedge - rfftfreq(nchan*2, dt1.value)[::2] * u.Hz
if fedge_at_top
else
fedge + rfftfreq(nchan*2, dt1.value)[::2] * u.Hz)
dt = (dispersion_delay_constant * dm *
(1./freq**2 - 1./fref**2)).to(u.s).value
# need 2*nchan samples for each FFT
dtsample = (nchan*2/samplerate).to(u.s).value
for j in xrange(nt):
if verbose and (j+1) % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, dtsample*j*ntint)) # equivalent time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data just a series of bytes, each containing one 8 bit or
# two 4-bit samples (set by dtype in caller)
raw = fromfile(fh1, dtype, recsize)
except(EOFError, IOError) as exc:
print("Hit {}; writing pgm's".format(exc))
break
vals = raw.astype(np.float32)
if coherent:
fine = rfft(vals, axis=0, overwrite_x=True)
fine *= dedisperse
vals = irfft(fine, axis=0, overwrite_x=True)
chan2 = rfft(vals.reshape(-1, nchan*2), axis=-1,
overwrite_x=True)**2
# rfft: Re[0], Re[1], Im[1], ..., Re[n/2-1], Im[n/2-1], Re[n/2]
# re-order to Num.Rec. format: Re[0], Re[n/2], Re[1], ....
power = np.hstack((chan2[:,:1]+chan2[:,-1:],
chan2[:,1:-1].reshape(-1,nchan-1,2).sum(-1)))
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if do_foldspec:
tsample = dtsample*isr # times since start
for k in xrange(nchan):
if coherent:
t = tsample # already dedispersed
else:
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k] += np.bincount(iphase, power[:,k], ngate)
icount[k] += np.bincount(iphase, None, ngate)
ibin = j*ntbin//nt # bin in the time series: 0..ntbin-1
if (j+1)*ntbin//nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec/icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:,:,ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec2, waterfall
def fold(file1, file2, dtype, fbottom, fwidth, nchan,
nt, ntint, nskip, ngate, ntbin, ntw, dm, fref, phasepol,
coherent=False, do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100, comm=None):
"""Fold pre-channelized LOFAR data, possibly dedispersing it
Parameters
----------
file1, file2 : string
names of the files holding real and imaginary subchannel timeseries
dtype : numpy dtype
way the data are stored in the file (normally '>f4')
fbottom : float
frequency of the lowest channel (frequency units)
fwidth : float
channel width (frequency units, normally 200*u.MHz/1024.)
nchan : int
number of frequency channels
nt, ntint : int
number nt of sets to use, each containing ntint samples;
hence, total # of samples used is nt*ntint for each channel.
nskip : int
number of records (nskip*ntint*4*nchan bytes) to skip before reading
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
the start of the file that is read (i.e., including nskip)
coherent : bool
Whether to do dispersion coherently within finer channels
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
comm : MPI communicator (default: None
"""
if comm is not None:
rank = comm.rank
size = comm.size
else:
rank = 0
size = 1
def mpilofile(comm, file):
return open(file)
# initialize folded spectrum and waterfall
if do_foldspec:
foldspec = np.zeros((nchan, ngate, ntbin))
icount = np.zeros((nchan, ngate, ntbin))
else:
foldspec = None
icount = None
if do_waterfall:
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
else:
waterfall = None
# # of items to read from file.
itemsize = np.dtype(dtype).itemsize
count = nchan*ntint
if verbose and rank == 0:
print('Reading from {}\n and {}'.format(file1, file2))
with mpilofile(comm, file1) as fh1, \
mpilofile(comm, file2) as fh2:
if nskip > 0:
if verbose and rank == 0:
print('Skipping {0} bytes'.format(nskip))
# if # MPI processes > 1 we seek in for-loop
if size == 1:
fh1.seek(nskip * count * itemsize)
fh2.seek(nskip * count * itemsize)
dtsample = (1./fwidth).to(u.s)
tstart = dtsample * nskip * ntint
# pre-calculate time delay due to dispersion in course channels
freq = fbottom + fwidth*np.arange(nchan)
dt = (dispersion_delay_constant * dm *
(1./freq**2 - 1./fref**2)).to(u.s).value
if coherent:
# pre-calculate required turns due to dispersion in fine channels
fcoh = (freq[np.newaxis,:] +
fftfreq(ntint, dtsample.value)[:,np.newaxis] * u.Hz)
# fcoh[fine, channel]
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1./freq - 1./fcoh)**2) * u.cycle
dedisperse = np.exp(dang.to(u.rad).value * 1j
).conj().astype(np.complex64)
for j in xrange(rank, nt, size):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, (tstart+dtsample*j*ntint).value))
# time since start of file
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data stored as series of floats in two files,
# one for real and one for imaginary
if size > 1:
fh1.seek((nskip + j)*count*itemsize)
fh2.seek((nskip + j)*count*itemsize)
raw1 = fromfile(fh1, dtype, count*itemsize).reshape(-1,nchan)
raw2 = fromfile(fh2, dtype, count*itemsize).reshape(-1,nchan)
except(EOFError):
break
# int 8 test
iraw = (raw1*128.).astype(np.int8)
raw1 = iraw.astype(np.float32)/128.
iraw = (raw2*128.).astype(np.int8)
raw2 = iraw.astype(np.float32)/128.
if coherent:
chan = raw1 + 1j*raw2
# vals[#int, #chan]; FT channels to finely spaced grid
fine = fft(chan, axis=0, overwrite_x=True)
# fine[#fine, #chan]; correct for dispersion w/i chan
fine *= dedisperse
# fine[#fine, #chan]; FT back to channel timeseries
chan = ifft(fine, axis=0, overwrite_x=True)
# vals[#int, #chan]
power = chan.real**2 + chan.imag**2
# power[#int, #chan]; timeit -> 0.6x shorter than abs(chan)**2
else:
power = raw1**2 + raw2**2
# power[#int, #chan]
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if do_foldspec:
tsample = (tstart + isr*dtsample).value # times since start
ibin = j*ntbin//nt
for k in xrange(nchan):
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k,:,ibin] += np.bincount(iphase, power[:,k], ngate)
icount[k,:,ibin] += np.bincount(iphase, None, ngate)
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec, icount, waterfall
def record_read(self, count):
return fromfile(self, self.dtype,
count).reshape(-1, self.nchan).squeeze()
def fold(file1, samplerate, fmid, nchan,
nt, ntint, nhead, ngate, ntbin, ntw, dm, fref, phasepol,
coherent=False, do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100):
"""FFT Effelsberg data, fold by phase/time and make a waterfall series
Parameters
----------
file1 : string
name of the file holding voltage timeseries
samplerate : float
rate at which samples were originally taken and thus band width
(frequency units))
fmid : float
mid point of the frequency band (frequency units)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*(2*ntint), with each sample containing
real,imag for two polarisations
nhead : int
number of bytes to skip before reading (usually 4096 for Effelsberg)
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
coherent : bool
Whether to do dispersion coherently within finer channels
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
"""
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (each nchan contains 4 bytes:
# real,imag for 2 polarisations).
recsize = 4*nchan*ntint
if verbose:
print('Reading from {}'.format(file1))
myopen = gzip.open if '.gz' in file1 else open
with myopen(file1, 'rb', recsize) as fh1:
if nhead > 0:
if verbose:
print('Skipping {0} bytes'.format(nhead))
fh1.seek(nhead)
foldspec = np.zeros((nchan, ngate))
icount = np.zeros((nchan, ngate))
dt1 = (1./samplerate).to(u.s)
dtsample = nchan * dt1
# pre-calculate time delay due to dispersion in course channels
freq = fmid + fftfreq(nchan, dt1.value) * u.Hz
dt = (dispersion_delay_constant * dm *
(1./freq**2 - 1./fref**2)).to(u.s).value
if coherent:
# pre-calculate required turns due to dispersion in fine channels
fcoh = (freq +
fftfreq(ntint, dtsample.value)[:,np.newaxis] * u.Hz)
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1./freq-1./fcoh)**2) * 360. * u.deg
dedisperse = np.exp(dang.to(u.rad).value * 1j
).conj().astype(np.complex64)
for j in xrange(nt):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, dtsample.value*j*ntint)) # time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data stored as series of two two-byte complex numbers,
# one for each polarization
raw = fromfile(fh1, np.int8, recsize).reshape(-1,2,2)
except(EOFError):
break
# use view for fast conversion from float to complex
vals = raw.astype(np.float32).view(np.complex64).reshape(
-1, nchan, 2)
# vals[#int, #block, #pol]
if coherent:
# FT to channels, then FT those to finely spaced grid
fine = fft2(vals, axes=(0,1), overwrite_x=True)
# fine[#fine, #chan, #pol]; correct for dispersion w/i chan
fine *= dedisperse[:,:,np.newaxis]
# fine[#fine, #chan, #pol]; FT back to channel timeseries
chan = ifft(fine, axis=0, overwrite_x=True)
# vals[#int, #block, #pol]
else:
# FT channels
chan = fft(vals, axis=1, overwrite_x=True)
# chan[#int, #chan, #pol]
power = np.sum(chan.real**2+chan.imag**2, axis=-1)
# power[#int, #block]
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if do_foldspec:
tsample = dtsample.value * isr # times since start
for k in xrange(nchan):
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k] += np.bincount(iphase, power[:,k], ngate)
icount[k] += np.bincount(iphase, None, ngate)
ibin = j*ntbin//nt # bin in the time series: 0..ntbin-1
if (j+1)*ntbin//nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec/icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:,:,ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
if do_foldspec:
# swap two halfs in frequency, so that freq increases monotonically
foldspec2 = fftshift(foldspec2, axes=0)
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
# swap two halfs in frequency, so that freq increases monotonically
waterfall = fftshift(waterfall, axes=0)
return foldspec2, waterfall
def fold(file1,
file2,
dtype,
fbottom,
fwidth,
nchan,
nt,
ntint,
nskip,
ngate,
ntbin,
ntw,
dm,
fref,
phasepol,
coherent=False,
do_waterfall=True,
do_foldspec=True,
verbose=True,
progress_interval=100,
comm=None):
"""Fold pre-channelized LOFAR data, possibly dedispersing it
Parameters
----------
file1, file2 : string
names of the files holding real and imaginary subchannel timeseries
dtype : numpy dtype
way the data are stored in the file (normally '>f4')
fbottom : float
frequency of the lowest channel (frequency units)
fwidth : float
channel width (frequency units, normally 200*u.MHz/1024.)
nchan : int
number of frequency channels
nt, ntint : int
number nt of sets to use, each containing ntint samples;
hence, total # of samples used is nt*ntint for each channel.
nskip : int
number of records (nskip*ntint*4*nchan bytes) to skip before reading
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
the start of the file that is read (i.e., including nskip)
coherent : bool
Whether to do dispersion coherently within finer channels
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
comm : MPI communicator (default: None
"""
if comm is not None:
rank = comm.rank
size = comm.size
else:
rank = 0
size = 1
def mpilofile(comm, file):
return open(file)
# initialize folded spectrum and waterfall
if do_foldspec:
foldspec = np.zeros((nchan, ngate, ntbin))
icount = np.zeros((nchan, ngate, ntbin))
else:
foldspec = None
icount = None
if do_waterfall:
nwsize = nt * ntint // ntw
waterfall = np.zeros((nchan, nwsize))
else:
waterfall = None
# # of items to read from file.
itemsize = np.dtype(dtype).itemsize
count = nchan * ntint
if verbose and rank == 0:
print('Reading from {}\n and {}'.format(file1, file2))
with mpilofile(comm, file1) as fh1, \
mpilofile(comm, file2) as fh2:
if nskip > 0:
if verbose and rank == 0:
print('Skipping {0} bytes'.format(nskip))
# if # MPI processes > 1 we seek in for-loop
if size == 1:
fh1.seek(nskip * count * itemsize)
fh2.seek(nskip * count * itemsize)
dtsample = (1. / fwidth).to(u.s)
tstart = dtsample * nskip * ntint
# pre-calculate time delay due to dispersion in course channels
freq = fbottom + fwidth * np.arange(nchan)
dt = (dispersion_delay_constant * dm *
(1. / freq**2 - 1. / fref**2)).to(u.s).value
if coherent:
# pre-calculate required turns due to dispersion in fine channels
fcoh = (freq[np.newaxis, :] +
fftfreq(ntint, dtsample.value)[:, np.newaxis] * u.Hz)
# fcoh[fine, channel]
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1. / freq - 1. / fcoh)**2) * u.cycle
dedisperse = np.exp(dang.to(u.rad).value * 1j).conj().astype(
np.complex64)
for j in xrange(rank, nt, size):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j + 1, nt, (tstart + dtsample * j * ntint).value))
# time since start of file
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data stored as series of floats in two files,
# one for real and one for imaginary
if size > 1:
fh1.seek((nskip + j) * count * itemsize)
fh2.seek((nskip + j) * count * itemsize)
raw1 = fromfile(fh1, dtype,
count * itemsize).reshape(-1, nchan)
raw2 = fromfile(fh2, dtype,
count * itemsize).reshape(-1, nchan)
except (EOFError):
break
# int 8 test
iraw = (raw1 * 128.).astype(np.int8)
raw1 = iraw.astype(np.float32) / 128.
iraw = (raw2 * 128.).astype(np.int8)
raw2 = iraw.astype(np.float32) / 128.
if coherent:
chan = raw1 + 1j * raw2
# vals[#int, #chan]; FT channels to finely spaced grid
fine = fft(chan, axis=0, overwrite_x=True)
# fine[#fine, #chan]; correct for dispersion w/i chan
fine *= dedisperse
# fine[#fine, #chan]; FT back to channel timeseries
chan = ifft(fine, axis=0, overwrite_x=True)
# vals[#int, #chan]
power = chan.real**2 + chan.imag**2
# power[#int, #chan]; timeit -> 0.6x shorter than abs(chan)**2
else:
power = raw1**2 + raw2**2
# power[#int, #chan]
# current sample positions in stream
isr = j * ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0] // ntw, isr[-1] // ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:, iw] += np.sum(power[isr // ntw == iw],
axis=0)
if do_foldspec:
tsample = (tstart + isr * dtsample).value # times since start
ibin = j * ntbin // nt
for k in xrange(nchan):
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase * ngate, ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k, :,
ibin] += np.bincount(iphase, power[:, k], ngate)
icount[k, :, ibin] += np.bincount(iphase, None, ngate)
if verbose:
print('read {0:6d} out of {1:6d}'.format(j + 1, nt))
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(
nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec, icount, waterfall
def record_read(self, count):
return fromfile(self, self.dtype,
count).reshape(-1, self.nchan).squeeze()
def fold(fh1, dtype, samplerate, fedge, fedge_at_top, nchan,
nt, ntint, nskip, ngate, ntbin, ntw, dm, fref, phasepol,
dedisperse='incoherent',
do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100, comm=None):
"""FFT GMRT data, fold by phase/time and make a waterfall series
Parameters
----------
fh1 : file handle
handle to file holding voltage timeseries
dtype : numpy dtype or '4bit' or '1bit'
way the data are stored in the file
samplerate : float
rate at which samples were originally taken and thus double the
band width (frequency units)
fedge : float
edge of the frequency band (frequency units)
fedge_at_top: bool
whether edge is at top (True) or bottom (False)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*ntint, with each sample containing
a single polarisation
nskip : int
number of records (nchan*ntint*2 for phased data w/ np.int8 real,imag)
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
dedisperse : None or string
None, 'incoherent', 'coherent', 'by-channel'
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
comm : MPI communicator (default: None)
"""
if comm is None:
rank = 0
size = 1
else:
rank = comm.rank
size = comm.size
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (simple for ARO: 1 byte/sample)
# double since we need to get ntint samples after FFT
itemsize = {np.int8: 2}[dtype]
recsize = nchan*ntint*itemsize
if verbose:
print('Reading from {}'.format(fh1))
if nskip > 0:
if verbose:
print('Skipping {0} {1}-byte records'.format(nskip, recsize))
if size == 1:
fh1.seek(nskip * recsize)
foldspec = np.zeros((nchan, ngate, ntbin), dtype=np.int)
icount = np.zeros((nchan, ngate, ntbin), dtype=np.int)
dt1 = (1./samplerate).to(u.s)
# but include 2*nchan real-valued samples used for each FFT
# (or, equivalently, real and imag for channels)
dtsample = nchan * 2 * dt1
tstart = dt1 * nskip * recsize
# pre-calculate time delay due to dispersion in coarse channels
freq = fftshift(fftfreq(nchan, 2.*dt1.value)) * u.Hz
freq = (fedge - (freq-freq[0])
if fedge_at_top
else fedge + (freq-freq[0]))
# [::2] sets frequency channels to numerical recipes ordering
dt = (dispersion_delay_constant * dm *
(1./freq**2 - 1./fref**2)).to(u.s).value
# if dedisperse in {'coherent', 'by-channel'}:
# # pre-calculate required turns due to dispersion
# fcoh = (fedge - fftfreq(nchan*ntint, 2.*dt1)
# if fedge_at_top
# else
# fedge + fftfreq(nchan*ntint, 2.*dt1))
# # set frequency relative to which dispersion is coherently corrected
# if dedisperse == 'coherent':
# _fref = fref
# else:
# _fref = np.repeat(freq.value, ntint) * freq.unit
# # (check via eq. 5.21 and following in
# # Lorimer & Kramer, Handbook of Pulsar Astrono
# dang = (dispersion_delay_constant * dm * fcoh *
# (1./_fref-1./fcoh)**2) * 360. * u.deg
# # order of frequencies is r[0], r[1],i[1],...r[n-1],i[n-1],r[n]
# # for 0 and n need only real part, but for 1...n-1 need real, imag
# # so just get shifts for r[1], r[2], ..., r[n-1]
# dang = dang.to(u.rad).value[1:-1:2]
# dd_coh = np.exp(dang * 1j).conj().astype(np.complex64)
for j in xrange(rank, nt, size):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, (tstart+dtsample*j*ntint).value)) # time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
if size > 1:
fh1.seek((nskip + j) * recsize)
# data just a series of byte pairs, of real and imag
raw = fromfile(fh1, dtype, recsize)
except(EOFError, IOError) as exc:
print("Hit {}; writing pgm's".format(exc))
break
if verbose == 'very':
print("Read {} items".format(raw.size), end="")
vals = raw.astype(np.float32).view(np.complex64).squeeze()
# if dedisperse in {'coherent', 'by-channel'}:
# fine = rfft(vals, axis=0, overwrite_x=True, **_fftargs)
# fine_cmplx = fine[1:-1].view(np.complex64)
# fine_cmplx *= dd_coh # this overwrites parts of fine, as intended
# vals = irfft(fine, axis=0, overwrite_x=True, **_fftargs)
# if verbose == 'very':
# print("... dedispersed", end="")
chan = vals.reshape(-1, nchan)
if verbose == 'very':
print("... power", end="")
power = chan.real**2+chan.imag**2
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if verbose == 'very':
print("... waterfall", end="")
if do_foldspec:
tsample = (tstart + isr*dtsample).value # times since start
ibin = j*ntbin//nt # bin in the time series: 0..ntbin-1
for k in xrange(nchan):
if dedisperse == 'coherent':
t = tsample # already dedispersed
else:
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k,:,ibin] += np.bincount(iphase, power[:,k], ngate)
icount[k,:,ibin] += np.bincount(iphase, None, ngate)
if verbose == 'very':
print("... folded", end="")
if 0: #done in gmrt.py (j+1)*ntbin//nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec/icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:,:,ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose == 'very':
print("... added", end="")
if verbose == 'very':
print("... done")
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
if 0: # done in gmrt.py do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec, icount, waterfall
def fold(fh1,
dtype,
samplerate,
fedge,
fedge_at_top,
nchan,
nt,
ntint,
nskip,
ngate,
ntbin,
ntw,
dm,
fref,
phasepol,
dedisperse='incoherent',
do_waterfall=True,
do_foldspec=True,
verbose=True,
progress_interval=100,
comm=None):
"""FFT GMRT data, fold by phase/time and make a waterfall series
Parameters
----------
fh1 : file handle
handle to file holding voltage timeseries
dtype : numpy dtype or '4bit' or '1bit'
way the data are stored in the file
samplerate : float
rate at which samples were originally taken and thus double the
band width (frequency units)
fedge : float
edge of the frequency band (frequency units)
fedge_at_top: bool
whether edge is at top (True) or bottom (False)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*ntint, with each sample containing
a single polarisation
nskip : int
number of records (nchan*ntint*2 for phased data w/ np.int8 real,imag)
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
dedisperse : None or string
None, 'incoherent', 'coherent', 'by-channel'
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
comm : MPI communicator (default: None)
"""
if comm is None:
rank = 0
size = 1
else:
rank = comm.rank
size = comm.size
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt * ntint // ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (simple for ARO: 1 byte/sample)
# double since we need to get ntint samples after FFT
itemsize = {np.int8: 2}[dtype]
recsize = nchan * ntint * itemsize
if verbose:
print('Reading from {}'.format(fh1))
if nskip > 0:
if verbose:
print('Skipping {0} {1}-byte records'.format(nskip, recsize))
if size == 1:
fh1.seek(nskip * recsize)
foldspec = np.zeros((nchan, ngate, ntbin), dtype=np.int)
icount = np.zeros((nchan, ngate, ntbin), dtype=np.int)
dt1 = (1. / samplerate).to(u.s)
# but include 2*nchan real-valued samples used for each FFT
# (or, equivalently, real and imag for channels)
dtsample = nchan * 2 * dt1
tstart = dt1 * nskip * recsize
# pre-calculate time delay due to dispersion in coarse channels
freq = fftshift(fftfreq(nchan, 2. * dt1.value)) * u.Hz
freq = (fedge - (freq - freq[0]) if fedge_at_top else fedge +
(freq - freq[0]))
# [::2] sets frequency channels to numerical recipes ordering
dt = (dispersion_delay_constant * dm * (1. / freq**2 - 1. / fref**2)).to(
u.s).value
# if dedisperse in {'coherent', 'by-channel'}:
# # pre-calculate required turns due to dispersion
# fcoh = (fedge - fftfreq(nchan*ntint, 2.*dt1)
# if fedge_at_top
# else
# fedge + fftfreq(nchan*ntint, 2.*dt1))
# # set frequency relative to which dispersion is coherently corrected
# if dedisperse == 'coherent':
# _fref = fref
# else:
# _fref = np.repeat(freq.value, ntint) * freq.unit
# # (check via eq. 5.21 and following in
# # Lorimer & Kramer, Handbook of Pulsar Astrono
# dang = (dispersion_delay_constant * dm * fcoh *
# (1./_fref-1./fcoh)**2) * 360. * u.deg
# # order of frequencies is r[0], r[1],i[1],...r[n-1],i[n-1],r[n]
# # for 0 and n need only real part, but for 1...n-1 need real, imag
# # so just get shifts for r[1], r[2], ..., r[n-1]
# dang = dang.to(u.rad).value[1:-1:2]
# dd_coh = np.exp(dang * 1j).conj().astype(np.complex64)
for j in xrange(rank, nt, size):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j + 1, nt,
(tstart + dtsample * j * ntint).value)) # time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
if size > 1:
fh1.seek((nskip + j) * recsize)
# data just a series of byte pairs, of real and imag
raw = fromfile(fh1, dtype, recsize)
except (EOFError, IOError) as exc:
print("Hit {}; writing pgm's".format(exc))
break
if verbose == 'very':
print("Read {} items".format(raw.size), end="")
vals = raw.astype(np.float32).view(np.complex64).squeeze()
# if dedisperse in {'coherent', 'by-channel'}:
# fine = rfft(vals, axis=0, overwrite_x=True, **_fftargs)
# fine_cmplx = fine[1:-1].view(np.complex64)
# fine_cmplx *= dd_coh # this overwrites parts of fine, as intended
# vals = irfft(fine, axis=0, overwrite_x=True, **_fftargs)
# if verbose == 'very':
# print("... dedispersed", end="")
chan = vals.reshape(-1, nchan)
if verbose == 'very':
print("... power", end="")
power = chan.real**2 + chan.imag**2
# current sample positions in stream
isr = j * ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0] // ntw, isr[-1] // ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:, iw] += np.sum(power[isr // ntw == iw], axis=0)
if verbose == 'very':
print("... waterfall", end="")
if do_foldspec:
tsample = (tstart + isr * dtsample).value # times since start
ibin = j * ntbin // nt # bin in the time series: 0..ntbin-1
for k in xrange(nchan):
if dedisperse == 'coherent':
t = tsample # already dedispersed
else:
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase * ngate, ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k, :, ibin] += np.bincount(iphase, power[:, k], ngate)
icount[k, :, ibin] += np.bincount(iphase, None, ngate)
if verbose == 'very':
print("... folded", end="")
if 0: #done in gmrt.py (j+1)*ntbin//nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec / icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(
nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:, :, ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose == 'very':
print("... added", end="")
if verbose == 'very':
print("... done")
if verbose:
print('read {0:6d} out of {1:6d}'.format(j + 1, nt))
if 0: # done in gmrt.py do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(
nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec, icount, waterfall
def fold(fh1,
dtype,
samplerate,
fedge,
fedge_at_top,
nchan,
nt,
ntint,
nhead,
ngate,
ntbin,
ntw,
dm,
fref,
phasepol,
dedisperse='incoherent',
do_waterfall=True,
do_foldspec=True,
verbose=True,
progress_interval=100):
"""FFT ARO data, fold by phase/time and make a waterfall series
Parameters
----------
fh1 : file handle
handle to file holding voltage timeseries
dtype : numpy dtype or '4bit' or '1bit'
way the data are stored in the file
samplerate : float
rate at which samples were originally taken and thus double the
band width (frequency units)
fedge : float
edge of the frequency band (frequency units)
fedge_at_top: bool
whether edge is at top (True) or bottom (False)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*ntint, with each sample containing
a single polarisation
nhead : int
number of bytes to skip before reading (usually 0 for ARO)
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
dedisperse : None or string
None, 'incoherent', 'coherent', 'by-channel'
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
"""
# initialize folded spectrum and waterfall
foldspec2 = np.zeros((nchan, ngate, ntbin))
nwsize = nt * ntint // ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (simple for ARO: 1 byte/sample)
# double since we need to get ntint samples after FFT
recsize = nchan * ntint * {np.int8: 2, '4bit': 1}[dtype]
if verbose:
print('Reading from {}'.format(fh1))
if nhead > 0:
if verbose:
print('Skipping {0} bytes'.format(nhead))
fh1.seek(nhead)
foldspec = np.zeros((nchan, ngate), dtype=np.int)
icount = np.zeros((nchan, ngate), dtype=np.int)
dt1 = (1. / samplerate).to(u.s)
# need 2*nchan real-valued samples for each FFT
dtsample = nchan * 2 * dt1
# pre-calculate time delay due to dispersion in coarse channels
freq = (fedge -
rfftfreq(nchan * 2, dt1.value) * u.Hz if fedge_at_top else fedge +
rfftfreq(nchan * 2, dt1.value) * u.Hz)
# [::2] sets frequency channels to numerical recipes ordering
dt = (dispersion_delay_constant * dm *
(1. / freq[::2]**2 - 1. / fref**2)).to(u.s).value
if dedisperse in {'coherent', 'by-channel'}:
# pre-calculate required turns due to dispersion
fcoh = (fedge - rfftfreq(nchan * 2 * ntint, dt1.value) * u.Hz
if fedge_at_top else fedge +
rfftfreq(nchan * 2 * ntint, dt1.value) * u.Hz)
# set frequency relative to which dispersion is coherently corrected
if dedisperse == 'coherent':
_fref = fref
else:
# _fref = np.round((fcoh * dtsample).to(1).value) / dtsample
_fref = np.repeat(freq.value, ntint) * freq.unit
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1. / _fref - 1. / fcoh)**2) * 360. * u.deg
# order of frequencies is r[0], r[1],i[1],...r[n-1],i[n-1],r[n]
# for 0 and n need only real part, but for 1...n-1 need real, imag
# so just get shifts for r[1], r[2], ..., r[n-1]
dang = dang.to(u.rad).value[1:-1:2]
dd_coh = np.exp(dang * 1j).conj().astype(np.complex64)
for j in xrange(nt):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j + 1, nt, dtsample.value * j * ntint)) # time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data just a series of bytes, each containing one 8 bit or
# two 4-bit samples (set by dtype in caller)
raw = fromfile(fh1, dtype, recsize)
except (EOFError, IOError) as exc:
print("Hit {}; writing pgm's".format(exc))
break
if verbose == 'very':
print("Read {} items".format(raw.size), end="")
vals = raw.astype(np.float32)
if dedisperse in {'coherent', 'by-channel'}:
fine = rfft(vals, axis=0, overwrite_x=True, **_fftargs)
fine_cmplx = fine[1:-1].view(np.complex64)
fine_cmplx *= dd_coh # this overwrites parts of fine, as intended
vals = irfft(fine, axis=0, overwrite_x=True, **_fftargs)
if verbose == 'very':
print("... dedispersed", end="")
chan2 = rfft(vals.reshape(-1, nchan * 2),
axis=-1,
overwrite_x=True,
**_fftargs)**2
# rfft: Re[0], Re[1], Im[1], ..., Re[n/2-1], Im[n/2-1], Re[n/2]
# re-order to Num.Rec. format: Re[0], Re[n/2], Re[1], ....
power = np.hstack((chan2[:, :1] + chan2[:, -1:],
chan2[:, 1:-1].reshape(-1, nchan - 1, 2).sum(-1)))
if verbose == 'very':
print("... power", end="")
# current sample positions in stream
isr = j * ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0] // ntw, isr[-1] // ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:, iw] += np.sum(power[isr // ntw == iw], axis=0)
if verbose == 'very':
print("... waterfall", end="")
if do_foldspec:
tsample = dtsample.value * isr # times since start
for k in xrange(nchan):
if dedisperse == 'coherent':
t = tsample # already dedispersed
else:
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase * ngate, ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k] += np.bincount(iphase, power[:, k], ngate)
icount[k] += np.bincount(iphase, None, ngate)
if verbose == 'very':
print("... folded", end="")
ibin = j * ntbin // nt # bin in the time series: 0..ntbin-1
if (j + 1) * ntbin // nt > ibin: # last addition to bin?
# get normalised flux in each bin (where any were added)
nonzero = icount > 0
nfoldspec = np.where(nonzero, foldspec / icount, 0.)
# subtract phase average and store
nfoldspec -= np.where(
nonzero,
np.sum(nfoldspec, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0)
foldspec2[:, :, ibin] = nfoldspec
# reset for next iteration
foldspec *= 0
icount *= 0
if verbose == 'very':
print("... added", end="")
if verbose == 'very':
print("... done")
if verbose:
print('read {0:6d} out of {1:6d}'.format(j + 1, nt))
if do_waterfall:
nonzero = waterfall == 0.
waterfall -= np.where(
nonzero,
np.sum(waterfall, 1, keepdims=True) /
np.sum(nonzero, 1, keepdims=True), 0.)
return foldspec2, waterfall
def fold(fh1, dtype, samplerate, fedge, fedge_at_top, nchan,
nt, ntint, nskip, ngate, ntbin, ntw, dm, fref, phasepol,
dedisperse='incoherent',
do_waterfall=True, do_foldspec=True, verbose=True,
progress_interval=100, rfi_filter_raw=None, rfi_filter_power=None,
comm=None):
"""FFT ARO data, fold by phase/time and make a waterfall series
Parameters
----------
fh1 : file handle
handle to file holding voltage timeseries
dtype : numpy dtype or '4bit' or '1bit'
way the data are stored in the file
samplerate : float
rate at which samples were originally taken and thus double the
band width (frequency units)
fedge : float
edge of the frequency band (frequency units)
fedge_at_top: bool
whether edge is at top (True) or bottom (False)
nchan : int
number of frequency channels for FFT
nt, ntint : int
total number nt of sets, each containing ntint samples in each file
hence, total # of samples is nt*ntint, with each sample containing
a single polarisation
nskip : int
number of records (ntint * nchan * 2 / 2 bytes) to skip
ngate, ntbin : int
number of phase and time bins to use for folded spectrum
ntbin should be an integer fraction of nt
ntw : int
number of time samples to combine for waterfall (does not have to be
integer fraction of nt)
dm : float
dispersion measure of pulsar, used to correct for ism delay
(column number density)
fref: float
reference frequency for dispersion measure
phasepol : callable
function that returns the pulsar phase for time in seconds relative to
start of part of the file that is read (i.e., ignoring nhead)
dedisperse : None or string
None, 'incoherent', 'coherent', 'by-channel'
do_waterfall, do_foldspec : bool
whether to construct waterfall, folded spectrum (default: True)
verbose : bool
whether to give some progress information (default: True)
progress_interval : int
Ping every progress_interval sets
comm : MPI communicator (default None)
"""
if comm is None:
rank = 0
size = 1
else:
rank = comm.rank
size = comm.size
# initialize folded spectrum and waterfall
foldspec = np.zeros((nchan, ngate, ntbin))
icount = np.zeros((nchan, ngate, ntbin), dtype=np.int64)
nwsize = nt*ntint//ntw
waterfall = np.zeros((nchan, nwsize))
# size in bytes of records read from file (simple for ARO: 1 byte/sample)
# double since we need to get ntint samples after FFT
recsize = nchan*ntint*{np.int8: 2, '4bit': 1}[dtype]
if verbose:
print('Reading from {}'.format(fh1))
if nskip > 0:
if verbose:
print('Skipping {0} records = {1} bytes'
.format(nskip, nskip*recsize))
# If MPI threading, the threads hop over one-another
# and seeking is done in for-loop.
if size == 1:
fh1.seek(nskip * recsize)
dt1 = (1./samplerate).to(u.s)
# need 2*nchan real-valued samples for each FFT
dtsample = nchan * 2 * dt1
tstart = dtsample * ntint * nskip
# pre-calculate time delay due to dispersion in coarse channels
freq = (fedge - rfftfreq(nchan*2, dt1.value) * u.Hz
if fedge_at_top
else
fedge + rfftfreq(nchan*2, dt1.value) * u.Hz)
# [::2] sets frequency channels to numerical recipes ordering
dt = (dispersion_delay_constant * dm *
(1./freq[::2]**2 - 1./fref**2)).to(u.s).value
if dedisperse in {'coherent', 'by-channel'}:
# pre-calculate required turns due to dispersion
fcoh = (fedge - rfftfreq(nchan*2*ntint, dt1.value) * u.Hz
if fedge_at_top
else
fedge + rfftfreq(nchan*2*ntint, dt1.value) * u.Hz)
# set frequency relative to which dispersion is coherently corrected
if dedisperse == 'coherent':
_fref = fref
else:
# _fref = np.round((fcoh * dtsample).to(1).value) / dtsample
_fref = np.repeat(freq.value, ntint) * freq.unit
# (check via eq. 5.21 and following in
# Lorimer & Kramer, Handbook of Pulsar Astrono
dang = (dispersion_delay_constant * dm * fcoh *
(1./_fref-1./fcoh)**2) * 360. * u.deg
# order of frequencies is r[0], r[1],i[1],...r[n-1],i[n-1],r[n]
# for 0 and n need only real part, but for 1...n-1 need real, imag
# so just get shifts for r[1], r[2], ..., r[n-1]
dang = dang.to(u.rad).value[1:-1:2]
dd_coh = np.exp(dang * 1j).conj().astype(np.complex64)
for j in xrange(rank, nt, size):
if verbose and j % progress_interval == 0:
print('Doing {:6d}/{:6d}; time={:18.12f}'.format(
j+1, nt, (tstart+dtsample*j*ntint).value)) # time since start
# just in case numbers were set wrong -- break if file ends
# better keep at least the work done
try:
# data just a series of bytes, each containing one 8 bit or
# two 4-bit samples (set by dtype in caller)
if size > 1:
fh1.seek((j+nskip)*recsize)
raw = fromfile(fh1, dtype, recsize)
except(EOFError, IOError) as exc:
print("Hit {}; writing pgm's".format(exc))
break
if verbose == 'very':
print("Read {} items".format(raw.size), end="")
if rfi_filter_raw:
raw = rfi_filter_raw(raw)
print("... raw RFI", end="")
vals = raw.astype(np.float32)
if dedisperse in {'coherent', 'by-channel'}:
fine = rfft(vals, axis=0, overwrite_x=True, **_fftargs)
fine_cmplx = fine[1:-1].view(np.complex64)
fine_cmplx *= dd_coh # this overwrites parts of fine, as intended
vals = irfft(fine, axis=0, overwrite_x=True, **_fftargs)
if verbose == 'very':
print("... dedispersed", end="")
chan2 = rfft(vals.reshape(-1, nchan*2), axis=-1,
overwrite_x=True, **_fftargs)**2
# rfft: Re[0], Re[1], Im[1], ..., Re[n/2-1], Im[n/2-1], Re[n/2]
# re-order to Num.Rec. format: Re[0], Re[n/2], Re[1], ....
power = np.hstack((chan2[:,:1]+chan2[:,-1:],
chan2[:,1:-1].reshape(-1,nchan-1,2).sum(-1)))
if verbose == 'very':
print("... power", end="")
if rfi_filter_power:
power = rfi_filter_power(power)
print("... power RFI", end="")
# current sample positions in stream
isr = j*ntint + np.arange(ntint)
if do_waterfall:
# loop over corresponding positions in waterfall
for iw in xrange(isr[0]//ntw, isr[-1]//ntw + 1):
if iw < nwsize: # add sum of corresponding samples
waterfall[:,iw] += np.sum(power[isr//ntw == iw],
axis=0)
if verbose == 'very':
print("... waterfall", end="")
if do_foldspec:
tsample = (tstart + isr*dtsample).value # times since start
ibin = j*ntbin//nt # bin in the time series: 0..ntbin-1
for k in xrange(nchan):
if dedisperse == 'coherent':
t = tsample # already dedispersed
else:
t = tsample - dt[k] # dedispersed times
phase = phasepol(t) # corresponding PSR phases
iphase = np.remainder(phase*ngate,
ngate).astype(np.int)
# sum and count samples by phase bin
foldspec[k, :, ibin] += np.bincount(iphase, power[:, k], ngate)
icount[k, :, ibin] += np.bincount(iphase, power[:, k] != 0.,
ngate)
if verbose == 'very':
print("... folded", end="")
if verbose == 'very':
print("... done")
if verbose:
print('read {0:6d} out of {1:6d}'.format(j+1, nt))
return foldspec, icount, waterfall
