You can use the tape.exe application that was installed on your computer when you installed the Seismodule program. Read in the SEG-file, convert it to ASCII by selecting the File menu and Convert to ASCII. Check the box to convert to mV. Once you have converted the waveform to ASCII voltages, you can multiply by the sensitivity of the geophone to recover true ground amplitudes. You can also download the Tape program from Here.  IMPORTANT - Be sure to back up your data files before running this program.