diff --git a/lib/fsk4hf/costasxcorr.m b/lib/fsk4hf/costasxcorr.m
new file mode 100644
index 000000000..7d104c25d
--- /dev/null
+++ b/lib/fsk4hf/costasxcorr.m
@@ -0,0 +1,14 @@
+# Gnu Octave script to calculate
+# cross correlation between 2 Costas arrays
+costas1=[2,5,6,0,4,1,3];
+costas2=[3,1,4,0,6,5,2];
+array1=zeros(7,7);
+array2=zeros(7,7);
+for i=1:7
+  array1(i,costas1(i)+1)=1;
+  array2(i,costas2(i)+1)=1;
+endfor
+xcorr2(array1,array1,"none")
+xcorr2(array2,array2,"none")
+xcorr2(array1,array2,"none")
+