small time sampling interval

[julia-ou]

Hello,
I have generated synthetic SU-seismograms with a time sampling interval dt=3*10^(-7). To add Gaussian noise to these seismograms in Seismic Unix, I used the following commands:

suoldtonew < my_seismograms.su.shotx | suaddnoise sn=100 seed=from_clock | suswapbytes > my_seismograms.su.shotx

But the results I got after using these new seismograms seem unrealistic. Since I did the same thing many times with other models at higher sampling rates and everything worked perfectly, I guess the problem is the dt, which is probably too small.
Is it possible to process SU files with a very small time sampling interval in Seismic Unix?
Thank you in advance!