mv i11_ch01_avg.dat i11_ch01_avg.txt
mv i11_ch02_avg.dat i11_ch02_avg.txt
mv i11_ch03_avg.dat i11_ch03_avg.txt
mv i11_ch04_avg.dat i11_ch04_avg.txt
mv i11_ch05_avg.dat i11_ch05_avg.txt