GXFFT class¶
-
class
GXFFT
(handle=0)[source]¶ GXFFT class.
This class allows for the application of predefined filters to data in an OASIS database. The system uses the Winograd algorithm to transform data in the spatial domain to the wavenumber or Fourier domain.
-
add_white_noise
(amp, option)[source]¶ Add white noise to the power spectrum of an FFT object.
- Parameters
amp (float) – The value added to the real part of all non-DC components of the current power spectrum
option (int) – FFT_WHITE_NOISE constants
New in version 9.9.
License: Geosoft Extended End-User License
-
app_dens
(thick, dens)[source]¶ Appparent density filter
- Parameters
thick (float) – Thickness (meters) of the earth model
dens (float) – Background density (g/cm3) (default = 0)
New in version 5.0.
License: Geosoft Extended End-User License
-
app_susc
(strength)[source]¶ Apparent susceptiblity filter
- Parameters
strength (float) – Total magnetic field strength
New in version 5.0.
License: Geosoft Extended End-User License
Note: Reduction to magnetic pole (
red_pol
) and downward continuation (contin
) should be called BEFORE usingapp_susc
.
-
b_worth
(clen, degree, filter_type)[source]¶ Butterworth filter
- Parameters
clen (float) – Central cutoff wavelength (meter)
degree (float) – Degree of the filter function (default = 8.0)
filter_type (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
New in version 5.0.
License: Geosoft Extended End-User License
-
band_pass
(llen, hlen, pass_defined)[source]¶ Bandpass filter (using low and high wavelength cutoffs)
- Parameters
llen (float) – Low Cutoff wavelength (meters)
hlen (float) – High Cutoff wavelength (meter)
pass_defined (int) – 1= Pass the defined band (default); 0= Reject the band
New in version 5.0.
License: Geosoft Extended End-User License
-
contin
(dist)[source]¶ Upward/Downward continuation filter
- Parameters
dist (float) – Distance to continue; positive = downwards negative = upwards
New in version 5.0.
License: Geosoft Extended End-User License
-
cos_roll
(llen, hlen, degree, type)[source]¶ Cosine roll-off filter
- Parameters
llen (float) – Low wavelength start point (meters)
hlen (float) – High wavelength end point (meters)
degree (float) – Degree of the filter function (default = 2.0)
type (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
New in version 5.0.
License: Geosoft Extended End-User License
-
classmethod
create
(gvv, interv, trend)[source]¶ Create a New
GXFFT
with detrend options.- Parameters
interv (float) – Element space interval
trend (int) – FFT_DETREND constants
- Returns
GXFFT
Object- Return type
New in version 5.0.
License: Geosoft Extended End-User License
Note: The detrending options control the removal of a trend from the data before the
GXFFT
is applied. The default data expansion is 10% beforeGXFFT
.
-
classmethod
create_ex
(gvv, interv, trend, expansion)[source]¶ Create a New
GXFFT
with detrend and expansion options.- Parameters
interv (float) – Element space interval
trend (int) – FFT_DETREND constants
expansion (float) – Minimum expansion %
- Returns
GXFFT
Object- Return type
New in version 5.1.8.
License: Geosoft Extended End-User License
Note: The detrending options control the removal of a trend from the data before the
GXFFT
is applied. The expansion options control the minimum data expansion before theGXFFT
is applied.
-
classmethod
create_ref
(gvv, interv, trend)[source]¶ Create
GXFFT
object with detrend options from reference (original) channel, but noGXFFT
process.- Parameters
gvv (GXVV) –
GXVV
contains channel data to performGXFFT
operations upon.interv (float) – Element space interval, should be the same as in
create_ex
calltrend (int) – FFT_DETREND constants
- Returns
GXFFT
Object- Return type
New in version 5.0.
License: Geosoft Extended End-User License
Note: This just creates an object. It is intended to be called immediately after with
set_vv
.
-
classmethod
create_ref_ex
(gvv, interv, trend, expansion, d_cmult)[source]¶ Create
GXFFT
object with detrend and expansion options from reference (original) channel, but noGXFFT
process.- Parameters
gvv (GXVV) –
GXVV
contains channel data to performGXFFT
operations upon.interv (float) – Element space interval, should be the same as in
create_ex
calltrend (int) – FFT_DETREND constants
expansion (float) – Minimum expansion %, should be the same as in
create_ex
calld_cmult (float) – DC level multiple
- Returns
GXFFT
Object- Return type
New in version 5.1.8.
License: Geosoft Extended End-User License
Note: This just creates an object. It is intended to be called immediately after with
set_vv
.
-
gaus
(dev, type)[source]¶ Gaussian filter
- Parameters
dev (float) – Standard deviation cutoff of function (meters)
type (int) – Filter type: 1= Low-pass (residual) filter (default) 0= High-pass (regional) filter
New in version 5.0.
License: Geosoft Extended End-User License
-
get_vv
(gv_vr, gv_vi)[source]¶ Copies real and imaginary
GXVV
’s to userGXVV
’s.New in version 5.0.
License: Geosoft Extended End-User License
-
h_drv
(order)[source]¶ Horizontal derivative
- Parameters
order (float) – Order of differentiation (default = 1)
New in version 5.0.
License: Geosoft Extended End-User License
-
h_int
()[source]¶ Horizontal integration
New in version 5.1.4.
License: Geosoft Extended End-User License
-
high_pass
(wlen, fid_int)[source]¶ High bandpass filter
- Parameters
wlen (float) – Cutoff wavelength (meter)
fid_int (float) – Fiducial increment of the
GXFFT
’s channel data
New in version 5.0.
License: Geosoft Extended End-User License
-
inverse
(gvv, gv_vm)[source]¶ Inverse the
GXFFT
from wave number domain to space domain- Parameters
New in version 5.0.
License: Geosoft Extended End-User License
-
is_null
()[source]¶ Check if this is a null (undefined) instance
- Returns
True if this is a null (undefined) instance, False otherwise.
- Return type
bool
-
low_pass
(wlen)[source]¶ Low bandpass filter
- Parameters
wlen (float) – Cutoff wavelength (meters)
New in version 5.0.
License: Geosoft Extended End-User License
-
nyquist
()[source]¶ Gets the Nyquist frequency (wavenumbers/sample unit).
- Returns
Nyquist frequency (wavenumbers/sample unit).
- Return type
float
New in version 5.0.
License: Geosoft Extended End-User License
-
rc_filter
(clen, filter_type)[source]¶ RC filter
- Parameters
clen (float) – Central cutoff wavelength (meter)
filter_type (int) – Filter type: 1= Low-pass (regional) filter (default) 0= High-pass (residual) filter
New in version 8.5.
License: Geosoft Extended End-User License
-
red_pol
(inc, dec, incp, dir)[source]¶ Reduction to magnetic pole
- Parameters
inc (float) – Geomagnetic inclination (degrees)
dec (float) – Geomagnetic declination (degrees)
incp (float) – Inclination (degrees) for amplitude correction (default = 20.0)
dir (float) – Direction (degrees) of Line from North
New in version 5.0.
License: Geosoft Extended End-User License
-
samp_incr
()[source]¶ Gets the original sample increment.
- Returns
Original sample increment.
- Return type
float
New in version 5.0.
License: Geosoft Extended End-User License
-
set_vv
(gv_vr, gv_vi)[source]¶ Sets real and imaginary VVs in
GXFFT
.New in version 5.0.
License: Geosoft Extended End-User License
Note: The
GXVV
must have been obtained from the sameGXFFT
using theset_vv
method.
-
spectrum
(gvv)[source]¶ Calculates a power spectrum
New in version 5.0.
License: Geosoft Extended End-User License
-
v_drv
(order)[source]¶ Vertical derivative
- Parameters
order (float) – Order of differentiation (default = 1)
New in version 5.0.
License: Geosoft Extended End-User License
-
v_int
()[source]¶ Vertical integration
New in version 5.0.
License: Geosoft Extended End-User License
-
wave_incr
()[source]¶ Get the wave number increment.
- Returns
Wave number increment
- Return type
float
New in version 5.0.
License: Geosoft Extended End-User License
-
write_spectrum
(gvv, out_file)[source]¶ Writes a power spectrum to a file
New in version 5.0.
License: Geosoft Extended End-User License
-
FFT_DETREND constants¶
Detrending option