Sixteen-State Feedback Convolutional Encoder
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-08
A preference has been established for trellis-coded modulation for use in data modems which transmit data at a rate of 9,600 bits/s. over the Public Switched Networks, and those which transmit data at a rate higher than 9,600 bits/s. over leased voice grade telephone lines. This article describes a 16-state feedback convolutional encoder which is a feedback version of the 16-state forward convolutional encoder described in the IBM Technical Disclosure Bulletin 28, 6, 2466-2468 (November 1985). The feedback encoder is as much insensitive to 90Œ phase jumps of the carrier as the forward encoder, thus allowing carrier phase to relock in any one of four phase positions after a temporary loss of carrier phase synchronization.