NAME
dbrfcn - calculates receiver functions via frequency-domain deconvolution (css3.0)
SYNOPSIS
dbrfcn db dbout {orid | arid:azim} sta [pf-file-prefix]
SUPPORT
Contributed code: NO BRTT support.
THIS PIECE OF SOFTWARE WAS CONTRIBUTED BY THE ANTELOPE USER COMMUNITY. BRTT DISCLAIMS ALL OWNERSHIP, LIABILITY, AND SUPPORT FOR THIS PIECE OF SOFTWARE.
FOR HELP WITH THIS PIECE OF SOFTWARE, PLEASE CONTACT THE CONTRIBUTING AUTHOR.
DESCRIPTION
Dbfrcn is a database-communicative version of a frequency-domain deconvolution
routine for calculating receiver functions. The input consists of a database
dbin
with Z, N, and E, along with a few inversion parameters. Prior to receiver
function inversion, the routine selects a time window about desired P arrival, components
are rotated into Z-R-T coordinates, records are optionally decimated, and
detrended. Graphical display shows original 3 components, rotated horizontals,
and 3 receiver functions for Z, R, and T components (Z component RF will be
a delta-function if no filtering/stabilizing is applied). Two records are
output, the standard R-component receiver function (channel "rfcn") and a
T-component receiver function (channel "rf_T").
Deconvolution parameters are specified in a parameter file, and include a
frequency-domain water level,
a low-pass Gaussian filter, a high-pass Butterworth filter, and
a phase shift to allow negative lag times to be seen.
Rotation and time-window selection
are specified for a single station and either by event (orid) or by
a combination of arrival pick and azimuth (arid:azim). Additional
parameters are specified in an Antelope-style parameter file (ending in .pf),
including all deconvolution parameters,
the time window about P, a decimation interval, and a flag that
chooses whether to plot or not. Sign conventions for rotated components are same as for "ahrot".
Decimation is specified by the "decimate" parameter, as an integer fraction
of the current sample rate. Decimation is done by fourier-series truncation
with a 6-pole two-way (zero phase) Butterworth filter applied at the
new Nyquist frequency.
Amplitudes of receiver functions are rescaled to correct for filter effects. The scale
factor is the peak amplitude of the "Z-component" receiver function, which would be
unity if no scaling were applied. This factor is printed to screen, and its inverse
is stored in calib field (as of 11/00).
COMMAND LINE ARGUMENTS
-
db
Input database. Must include wfdisc, and either arrival OR origin+site tables
depending upon how the time window/rotation is specified.
-
dbout
Output database. A wfdisc table is created/added to. Data go into a relative
directory wf/rfcns/yyyy/ddd, for both radial AND tangential component receiver
functions.
-
orid
Index pointing to description of event in the db.origin table. If this option
is selected, the azimuth and distance to sta is calculated and a window
about the predicted P arrival is output.
-
arid:azim
Another way of selecting the window/rotation parameters: uses the arrival
time arid instead of the predicted P time. Also uses the specified azimuth
azim instead of a calculated one for rotation.
-
sta
The station to be processed.
ENVIRONMENT
TAUP_PATH is used to specify travel-time calculation for P.
PARAMETER FILE
-
pf-file-prefix
The name of a parameter file (ending in .pf) that contains other parameters.
A default file is hardwired, in the src directory. Defaults exist for any missing
parameters []. Parameters include:
-
tstart
Start time of output window desired, relative to arid or predicted P. [-10.]
-
tend
End time of output window desired, relative to arid or predicted P. [50.]
-
gaussfreq
Corner frequency, in Hz, for low-pass Gaussian filter. [.25]
-
hpfreq
Corner frequency, in Hz, for high-pass 6-pole two-way (zero phase) Butterworth filter. [.02]
-
phaseshift
Time, in s, to shift receiver functions [10.]
-
waterlevel
Minimum allowed fraction of peak spectral amplitude; frequency-domain points
with lower amplitudes are replaced by waterlevel*peak-amplitude, retaining
phase. [.01]
-
decimate
Decimation interval: an integer fraction of the current sample rate to use
as the new sample rate. A value of 0 or 1 results in no decimation. [8]
-
graphics
A flag; 1 for graphical output and interactive questionning, 0 otherwise. [1]
EXAMPLE
dbrfcn geytel rftestdb 62 ORGH dbrfcn
reads parameter file dbrfcn.pf, which looks like:
cat dbrfcn.pf
tstart -10.
tend 50.
gaussfreq 0.5
hpfreq 0.02
phaseshift 10.0
waterlevel 0.01
decimate 0
graphics 1
LIBRARY
-ltr -lgpl2 -lol -lxcom -lgrx -ldb -lcoords -ltttaup -lresponse -lstock ./FFT/fftlib.a -lX11 -lF77 -lM77 -lsunmath -lm
SEE ALSO
dbtimerf, trrotd
BUGS AND CAVEATS
Unclear what happens if more than one Z, N, or E channel exists for a
given station-time combination.
This method has all of the problems typically associated with frequency-domain
deconvolutions.
AUTHOR
Geoff Abers, Boston University
Antelope User Group Contributed Software