i would like to know about the limitations, in terms of deph, for scpt (source=hammer +plank). better; what is the critical deph for the geophone to receive a good signal? maybe it depends on the estratigraphy,but would to hear your comments......
I agree with Paul's comments, although 80 to 100 meters for a max depth is optimistic.
As Paul stated, the determining factor regarding the depth you achieve is your "source". I have found that a steel beam, placed under the jacks of the drill is usually suitable to depths of 30 to 40 meters. Ensuring the beam is level and coupled to the ground surface with the drills weight will produce better results.
In addition to the wave source generators that Paul mentioned you might want to try using a "Buffalo Gun". This wave source simply fires a 12 gauge shot gun shell into the ground and produces a higher energy wave. I am not sure if a specific company makes a buffalo gun as the ones I have seen were home made. ( A welder, some scrap steel and some shotgun shells....voila! Buffalo Gun)
Note: If you have a surficial layer of peat you might have problems get deep s-wave data as peat tends to dampen your signal.