With the advent of high-speed digital signal processing circuits, it is now practicable to transmit television signals by satellite using a variety of digitally derived modulation techniques. By using the concept ofES/NO, the ratio of the energy needed to transmit each sample to the noise spectral density, several different signal formats are critically compared in the paper. It is shown that the wide bandwidths associated with high-definition television may be supported by relatively narrow transponder bandwidths through the use of signal formats using phase-modulated discrete symbols. Furthermore, the bandwidth efficiency is shown to be better than the classical technique of frequency modulation for satellite TV transmission. A digitally implemented system is described and results are given of successful satellite tests using the Eutelsat F1 satellite and the Westar V satellite.