SUSPIKE - make a small spike data set

 suspike [optional parameters] > out_data_file             

 Creates a common offset su data file with up to four spikes     
 for impulse response studies                        

 Optional parameters:                                
      nt=64             number of time samples             
      ntr=32            number of traces             
      dt=0.004    time sample rate in seconds        
      offset=400 offset                             
      nspk=4            number of spikes             
      ix1= ntr/4  trace number (from left) for spike #1    
      it1= nt/4   time sample to spike #1            
      ix2 = ntr/4 trace for spike #2                 
      it2 = 3*nt/4      time for spike #2            
      ix3 = 3*ntr/4;    trace for spike #3                 
      it3 = nt/4; time for spike #3            
      ix4 = 3*ntr/4;    trace for spike #4                 
      it4 = 3*nt/4;     time for spike #4            


 Credits:
      CWP: Shuki Ronen, Chris Liner

 Trace header fields set: ns, dt, offset