chirp_pulse.m
Chirp pulse waveform with a sine bell power or a quarter-sine amplitude fade-in and fade-out. Generates unidirectional chirps or saltire chirps which are super-positions of two counter-sweeping chirps.
Syntax
[Cx,Cy,durs,ints,amps,phis,frqs]=chirp_pulse(npts,dur,bwidth,smp,type)
Parameters
npts - number of discretization points in
the waveform
duration - pulse duration, seconds
bwidth - chirp sweep bandwidth around
zero frequency, Hz
type - 'wurst', 'smoothed', or 'saltire'; the
default is uniform time grid, to get
adaptive sampling, add '-adaptive'
smp - smoothing parameter; for 'wurst', this
is the power in
1-|sin(x)^smp|
as x approaches pi/2 at either the edge
of the pulse. For 'smoothed' and 'salti-
re', this is the fraction of the pulse
duration (in percent) that is affected
by a sine bell fade-in and fade-out: 0
means square amplitude envelope and 50
means sine bell envelope.
Outputs
Cx - real part of the waveform, calibrated to
produce an inversion pulse, rad/s
Cy - imag part of the waveform, calibrated to
produce an inversion pulse, rad/s
durs - slice durations for piecewise-constant
approximation, seconds
ints - interval durations for piecewise-linear
approximation, seconds
amps - waveform amplitudes, rad/s
phis - waveform phases, rad
frqs - waveform frequencies, Hz
intv_grid - normalised interval grid, npts-1 elements
Notes
Cy is zero for the saltire pulse, this radically changes its phase and amplitude profiles.
See also
bruker_write.m, cartesian2polar.m, grad_pulse.m, grad_sandw.m, pmlg5.m, polar2cartesian.m, pulse_shape.m, read_wave.m, restrans.m, rseq_compiler.m, rsequence.m, sawtooth.m, sech_pulse.m, shaped_pulse_af.m, shaped_pulse_xy.m, spinal.m, triwave.m, vg_pulse.m, wave_basis.m, Kernel_functions
Version 2.9, authors: Ilya Kuprov, Jean-Nicolas Dumez, Ludmilla Guduff, Maria Grazia Concilio, Mohammadali Foroozandeh
