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.
['Jinn-Ja Chang', 'Der-June Hwang', 'M. C. Lin']
Some extended results on the search for good convolutional codes