diff --git a/src/urh/signalprocessing/Modulator.py b/src/urh/signalprocessing/Modulator.py
index f22860e0..90248536 100644
--- a/src/urh/signalprocessing/Modulator.py
+++ b/src/urh/signalprocessing/Modulator.py
@@ -187,13 +187,21 @@ class Modulator(object):
         else:
             f = self.carrier_freq_hz
 
-        #self.modulated_samples.real[:total_samples - pause] = paramvector[:]
+        #c = np.zeros(len(paramvector))
+        #for ii in range(0, len(paramvector) -1):
+        #    c[ii+1] = c[ii] + paramvector[ii] * (self.sample_rate/ self.samples_per_bit)
+
+        #i = np.cos(c)
+        #q = np.sin(c)
+        #m = np.sin(2*np.pi*fmid*t)*i + np.cos(2*np.pi*fmid*t)*q
+        #m = np.cos(2*np.pi*self.carrier_freq_hz*t + 2*np.pi*3*c)
+        #self.modulated_samples.real[:total_samples - pause] = m
         self.modulated_samples.imag[:total_samples - pause] = a * np.sin(2 * np.pi * f * t + phi)
         self.modulated_samples.real[:total_samples - pause] = a * np.cos(2 * np.pi * f * t + phi)
 
 
 
-    def gauss_fir(self, bt=0.5):
+    def gauss_fir(self, bt=0.5, filter_width=1):
         """
 
         :param bt: normalized 3-dB bandwidth-symbol time product
@@ -201,7 +209,7 @@ class Modulator(object):
         :return:
         """
         # http://onlinelibrary.wiley.com/doi/10.1002/9780470041956.app2/pdf
-        k = range(-6, 7)
+        k = range(-int(filter_width * self.samples_per_bit), int(filter_width * self.samples_per_bit)+1)
         ts = self.samples_per_bit / self.sample_rate # symbol time
         a = np.sqrt(np.log(2)/2)*(ts/bt)
         B = a / np.sqrt(np.log(2)/2) # filter bandwidth
diff --git a/tests/GFSK.py b/tests/GFSK.py
index 057ff642..2ad24526 100644
--- a/tests/GFSK.py
+++ b/tests/GFSK.py
@@ -17,16 +17,17 @@ class GFSK(unittest.TestCase):
         modulator.sample_rate = 1e6
         modulator.param_for_one = 20e3
         modulator.param_for_zero = -10e3
+        modulator.carrier_freq_hz = 15e3
 
 
-        modulator.modulate([True, False, True, False], 77)
+        modulator.modulate([True, False, True, False, False], 77)
         data = copy.deepcopy(modulator.modulated_samples)
-        modulator.modulate([False, True, True, False, True], 100, start=len(data))
+        modulator.modulate([False, True, True, True, True, False, True], 100, start=len(data))
         data = np.concatenate((data, modulator.modulated_samples))
 
         plt.subplot(2, 1, 1)
         axes = plt.gca()
-        #axes.set_ylim([-2,2])
+        axes.set_ylim([-2,2])
         plt.plot(data.real)
         plt.title("Modulated Wave")