Pulse shape design considerations for self-synchronizing systems

The authors consider fundamental relationships between signaling pulse shapes used in 1-D pulse amplitude modulation and 2-D quadrature amplitude modulation bauded transmission systems and their envelope spectra. In particular, they seek to establish necessary and sufficient conditions which guarantee the existence of a signal baud timing component (sinewave) in the mean envelope. It is shown that excess pulse bandwidth is not sufficient nor is Nyquist's first pulse shaping criterion. On the contrary, additional constraints must be imposed on the pulse to guarantee that timing information can be derived from the envelope function.<
>