Some Extended Results on the Search for Good Convolutional Codes

We provide useful results on two classes of convolutional
codes: binary codes and nonbinary codes. The best codes or the best
known codes for these two classes of convolutional codes are found
by computer search. Some of them are better than those found in
the past. We specify these codes by their transfer function matrices,
distance spectra, and information-weight spectra. Furthermore, we derive
an upper bound on the free distances of binary-to-M-ary codes and
q-ary-to-M-ary codes. Numerical values of this bound closely fit the
computer-searched values.