diff --git a/schainpy/model/graphics/jroplot_data.py b/schainpy/model/graphics/jroplot_data.py
index 6253a0a..1e30239 100644
--- a/schainpy/model/graphics/jroplot_data.py
+++ b/schainpy/model/graphics/jroplot_data.py
@@ -409,11 +409,15 @@ class PlotData(Operation, Process):
         i = 1 if numpy.where(abs(ymax-ymin) <= Y)[0][0] < 0 else numpy.where(abs(ymax-ymin) <= Y)[0][0]
         ystep = Y[i] / 10.
 
+        if self.xaxis is not 'time':
+            X = numpy.array([1, 2, 5, 10, 20, 50, 100, 200, 500, 1000, 2000, 5000])/2.
+            i = 1 if numpy.where(abs(xmax-xmin) <= X)[0][0] < 0 else numpy.where(abs(xmax-xmin) <= X)[0][0]
+            xstep = X[i] / 10.
+
         for n, ax in enumerate(self.axes):
             if ax.firsttime:
                 ax.set_facecolor(self.bgcolor)
                 ax.yaxis.set_major_locator(MultipleLocator(ystep))
-                ax.xaxis.set_major_locator(MultipleLocator(ystep))
                 if self.xscale:
                     ax.xaxis.set_major_formatter(FuncFormatter(lambda x, pos: '{0:g}'.format(x*self.xscale)))
                 if self.xscale:
@@ -421,6 +425,8 @@ class PlotData(Operation, Process):
                 if self.xaxis is 'time':
                     ax.xaxis.set_major_formatter(FuncFormatter(self.__fmtTime))
                     ax.xaxis.set_major_locator(LinearLocator(9))
+                else:
+                    ax.xaxis.set_major_locator(MultipleLocator(xstep))
                 if self.xlabel is not None:
                     ax.set_xlabel(self.xlabel)
                 ax.set_ylabel(self.ylabel)
diff --git a/schainpy/model/io/jroIO_spectra.py b/schainpy/model/io/jroIO_spectra.py
index bebef63..51f5a65 100644
--- a/schainpy/model/io/jroIO_spectra.py
+++ b/schainpy/model/io/jroIO_spectra.py
@@ -263,7 +263,7 @@ class SpectraReader(JRODataReader, ProcessingUnit):
             dc = dc.reshape( (self.systemHeaderObj.nChannels, self.processingHeaderObj.nHeights) ) #transforma a un arreglo 2D
 
 
-        if self.processingHeaderObj.shif_fft:
+        if not self.processingHeaderObj.shif_fft:
             #desplaza a la derecha en el eje 2 determinadas posiciones
             shift = int(self.processingHeaderObj.profilesPerBlock/2)
             spc = numpy.roll( spc, shift , axis=2 )
@@ -510,7 +510,7 @@ class SpectraWriter(JRODataWriter, Operation):
         """
 
         spc = numpy.transpose( self.data_spc, (0,2,1) )
-        if self.processingHeaderObj.shif_fft:
+        if not self.processingHeaderObj.shif_fft:
             spc = numpy.roll( spc, self.processingHeaderObj.profilesPerBlock/2, axis=2 ) #desplaza a la derecha en el eje 2 determinadas posiciones
         data = spc.reshape((-1))
         data = data.astype(self.dtype[0])
@@ -519,7 +519,7 @@ class SpectraWriter(JRODataWriter, Operation):
         if self.data_cspc is not None:
             data = numpy.zeros( self.shape_cspc_Buffer, self.dtype )
             cspc = numpy.transpose( self.data_cspc, (0,2,1) )
-            if self.processingHeaderObj.shif_fft:
+            if not self.processingHeaderObj.shif_fft:
                 cspc = numpy.roll( cspc, self.processingHeaderObj.profilesPerBlock/2, axis=2 ) #desplaza a la derecha en el eje 2 determinadas posiciones
             data['real'] = cspc.real
             data['imag'] = cspc.imag