New rate 1/2, 1/3, and 1/4 binary convolutional encoders with an optimum distance profile

Tabulations of binary systematic and nonsystematic polynomial convolutional encoders with an optimum distance profile for rate 1/2, 1/3, and 1/4 are given. The reported encoders are found by computer searches that optimize over the weight spectra. The free distances for rate 1/3 and 1/4 are compared with Heller's (1968) and Griesmer's (1960) upper bounds.