SUATTRIBUTES - trace ATTRIBUTES instantanteous amplitude, phase, or frequency

suattributes <stdin >stdout mode=amp

Required parameters:
none

Optional parameter:
mode=amp output flag
=amp envelope traces
=phase phase traces
=freq frequency traces
unwrap= default unwrap=0 for mode=phase
default unwrap=1 for mode=freq
dphase_min=PI/unwrap

Notes:
This program performs complex trace attribute analysis, a la Taner,
Kohler, and Sheriff, 1979.

The unwrap parameter is active only for mode=freq and mode=phase. The
quantity dphase_min is the minimum change in the phase angle taken to be
the result of phase wrapping, rather than natural phase variation in the
data. Setting unwrap=0 turns off phase-unwrapping altogether. Choosing
unwrap > 1 makes the unwrapping function more sensitive to phase changes.
Setting unwrap > 1 may be necessary to resolve higher frequencies in
data (or sample data more finely). The phase unwrapping is crude. The
differentiation needed to compute the instantaneous frequency
freq(t)= d(phase)/dt is a simple centered difference.

Examples:
suvibro f1=10 f2=50 t1=0 t2=0 tv=1 | suattributes mode=amp | ...
suvibro f1=10 f2=50 t1=0 t2=0 tv=1 | suattributes mode=phase | ...
suvibro f1=10 f2=50 t1=0 t2=0 tv=1 | suattributes mode=freq | ...
suplane | suattributes mode=... | supswigb |...


Credits:
CWP: Jack Cohen
CWP: John Stockwell (added freq and unwrap features)

Algorithm:
c(t) = hilbert_tranform_kernel(t) convolved with data(t)

amp(t) = sqrt( c.re^2(t) + c.im^2(t))
phase(t) = arctan( c.im(t)/c.re(t))
freq(t) = d(phase)/dt

Reference: Taner, M. T., Koehler, A. F., and Sheriff R. E.
"Complex seismic trace analysis", Geophysics, vol.44, p. 1041-1063, 1979

Trace header fields accessed: ns, trid
Trace header fields modified: d1, trid