A linearizing approach to code design for generalized MSK with four symbol pulse duration

Quadruple repetition code exhibits unique properties when combined with precoded generalized minimum-shift keying signals of up to four symbol period pulse duration. It is shown that using two stages of channel encoding, the last being a quadruple repetition code, the code design for such modulation schemes simplifies. Also, it is shown that the nonlinear continuous-phase frequency-shift keying modulator can be replaced by a simple linear I-Q modulator to generate the same coded signals. The detection problem for the recovery of the symbols sequence from the decision variables is shown to be one corresponding to memoryless modulation, avoiding the use of maximum likelihood sequence detection.