diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..002fe32
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "python.pythonPath": "/Users/morteza/miniconda3/bin/python"
+}
\ No newline at end of file

diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..002fe32
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "python.pythonPath": "/Users/morteza/miniconda3/bin/python"
+}
\ No newline at end of file
diff --git a/icom/encoder.py b/icom/encoder.py
index 9b6336b..1887b8b 100644
--- a/icom/encoder.py
+++ b/icom/encoder.py
@@ -1,23 +1,47 @@
+#%%
 import numpy as np
-
+import matplotlib.pyplot as plt
 
 # encode a message using poisson rate coding
 def encode_message(symbol: str,
                    signal_rate: float,
-                   noise_rate: float,
-                   duration: int, # in seconds
+                   duration: int,
                    **kwargs):
   codebook = kwargs.get("codebook",None)
+  noise_rate = kwargs.get("noise_rate", 0)
 
   if codebook is None: raise TypeError("Invalid code book.")
 
-  #TODO
-  spikes = np.random.poisson(lam=signal_rate, size=duration)
-  spikes = [np.sum(spikes[1:i]) for i in range(len(spikes))]
 
-  print(np.mean(spikes))
+  rate = signal_rate + noise_rate
+
+  # generate spikes more than the required size.
+  isi = np.random.poisson(lam=rate, size= 2 * rate * duration)
+  spikes = np.cumsum(isi) # convert intervals to a train
+  spikes = spikes * (2*duration/spikes[-1]) # normalize
 
   # add leak spikes
+
+  # cull spikes
+  spikes = spikes[np.where(spikes<=duration)]
   return spikes
 
-encode_message("1", 5, .3, 10, codebook=[])
+# generate spike train with signal rate of 2 and noise rate of 2.
+spikes = encode_message("A", 2, duration=10, codebook=['A','B'],noise_rate=2)
+
+
+#%% [markdown]
+
+# the following code plots signal train alognside the noise spikes.
+
+# generate signal spikes
+spikes = encode_message("A", 2, duration=10, codebook=['A','B'])
+
+# generate noise spikes
+noise_spikes = encode_message("", 2, duration=10, codebook=[])
+
+plt.eventplot(spikes, color='white')
+plt.eventplot(noise_spikes, color='red')
+plt.show()
+
+#%%

diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..002fe32
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,3 @@
+{
+  "python.pythonPath": "/Users/morteza/miniconda3/bin/python"
+}
\ No newline at end of file
diff --git a/icom/encoder.py b/icom/encoder.py
index 9b6336b..1887b8b 100644
--- a/icom/encoder.py
+++ b/icom/encoder.py
@@ -1,23 +1,47 @@
+#%%
 import numpy as np
-
+import matplotlib.pyplot as plt
 
 # encode a message using poisson rate coding
 def encode_message(symbol: str,
                    signal_rate: float,
-                   noise_rate: float,
-                   duration: int, # in seconds
+                   duration: int,
                    **kwargs):
   codebook = kwargs.get("codebook",None)
+  noise_rate = kwargs.get("noise_rate", 0)
 
   if codebook is None: raise TypeError("Invalid code book.")
 
-  #TODO
-  spikes = np.random.poisson(lam=signal_rate, size=duration)
-  spikes = [np.sum(spikes[1:i]) for i in range(len(spikes))]
 
-  print(np.mean(spikes))
+  rate = signal_rate + noise_rate
+
+  # generate spikes more than the required size.
+  isi = np.random.poisson(lam=rate, size= 2 * rate * duration)
+  spikes = np.cumsum(isi) # convert intervals to a train
+  spikes = spikes * (2*duration/spikes[-1]) # normalize
 
   # add leak spikes
+
+  # cull spikes
+  spikes = spikes[np.where(spikes<=duration)]
   return spikes
 
-encode_message("1", 5, .3, 10, codebook=[])
+# generate spike train with signal rate of 2 and noise rate of 2.
+spikes = encode_message("A", 2, duration=10, codebook=['A','B'],noise_rate=2)
+
+
+#%% [markdown]
+
+# the following code plots signal train alognside the noise spikes.
+
+# generate signal spikes
+spikes = encode_message("A", 2, duration=10, codebook=['A','B'])
+
+# generate noise spikes
+noise_spikes = encode_message("", 2, duration=10, codebook=[])
+
+plt.eventplot(spikes, color='white')
+plt.eventplot(noise_spikes, color='red')
+plt.show()
+
+#%%
diff --git a/py/poisson_generator.py b/py/poisson_generator.py
index 3feab60..1bb04df 100644
--- a/py/poisson_generator.py
+++ b/py/poisson_generator.py
@@ -36,6 +36,7 @@
 #poi = [i-j for i,j in zip(poi[:-1],poi[1:])]
 
 poi2 = [np.sum(poi[1:i]) for i in range(len(poi))]
+# or poin2=np.cumsum(poi)
 print(poi2)
 #poi = np.diff(poi) # alternative numpy solution for inter-interval durations
 #plt.plot(poi2)
@@ -55,4 +56,6 @@
 rate = 5
 ks = np.arange(20)
 ps = events_prob(5,20,ks)
-print(np.argmax(ps), np.max(ps))
\ No newline at end of file
+print(np.argmax(ps), np.max(ps))
+
+#%%