SUATTRIBUTES - trace ATTRIBUTES instantanteous amplitude, phase, or frequency suattributes 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 normalize=0 =1 normalize by instantaneous amplitude verbose=0 silent =1 chatty 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