Transmission of HDMAC via communication satellites

Identifies modulation parameters for HDMAC transmissions which make best use of the 36 MHz bandwidth that is available on several satellites operating in the FSS (fixed satellite service) frequency bands. With these modulation parameters, it has been shown in formal subjective tests that a C/N of 14 dB gives good quality (impairment grade 4.5) for most picture material. Very critical pictures require a higher C/N for the same grade, however this situation could be improved through the use of the new nonlinear pre-emphasis technique. The required protection ratio for just perceptible HDMAC interference into HDMAC has typical values of 20 dB and 11.5 dB for co-channel interference and adjacent channel interference respectively. A direct-to-home service via FSS satellites is feasible with a receive antenna diameter of the order of 90 cm. For cable distribution, an antenna of around 3 m in diameter would be required