diff --git a/test/runtests.jl b/test/runtests.jl
index 41f7cbc..0261b4b 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -16,6 +16,9 @@ include("test_bitMapping.jl");
 include("test_bitDemapping.jl");
 include("test_hardConstellation.jl");
 
+# NRZI Mapping 
+include("test_NRZI.jl");
+
 # Symbol demapper 
 include("test_symbolDemapper.jl");
 
diff --git a/test/test_nrzi.jl b/test/test_nrzi.jl
new file mode 100644
index 0000000..4c39872
--- /dev/null
+++ b/test/test_nrzi.jl
@@ -0,0 +1,29 @@
+# ---------------------------------------------------- 
+# --- Import modules  
+# ---------------------------------------------------- 
+using DigitalComm 
+using Test
+# ---------------------------------------------------- 
+# --- Tests 
+# ---------------------------------------------------- 
+# Note --> The mapping system is described in bitMapping.jl
+println("Tests for symbol mapper with NRZI sequences");
+
+@testset  "NRZI" begin 
+	# Create a bit squence (already tested) 
+	nbBits	= 2 * 2048;
+	bitSeq  = genBitSequence(nbBits);
+	# Pass trough the function 
+	buff	= zeros(Complex{Float64},nbBits)
+	# Call 
+	encodeNRZI!(buff,bitSeq); 
+	buff2	= encodeNRZI(bitSeq);
+	@test all( buff .== buff2)
+        # Ensure Tx // Rx is Ok 
+        @test all(bitSeq .== decodeNRZI(encodeNRZI(bitSeq)))
+        @test all(bitSeq .== decodeNRZI(encodeNRZI(bitSeq,:high),:high))
+	# Some manual check for both transitions
+	buff  = [0x01;0x00;0x00;0x01;0x00;0x00;0x00;0x01 ];
+        @test all( encodeNRZI(buff,:low) .== [0;1;0;0;1;0;1;1])  # Transitions on 0 
+        @test all( encodeNRZI(buff,:high) .== [1;1;1;0;0;0;0;1]) # Transitions on 1
+end