Transmission using MAC signal formats

The MAC signal format in its most basic form will offer improved picture and sound quality compared with existing terrestrial services. The establishment of MAC on the early DBS transmissions will moreover provide the foundation for further developments towards the ultimate goal of HDTV. The first MAC decoders will allow the transmission of wide aspect ratio (16:9) by providing 2 alternative decompression ratios. The next stage will be to increase the bandwidth and adopt a 625 line progressive scan in the display to produce extended definition (EDTV). Finally, the use of HD-MAC will result in high definition (HDTV) transmissions to 1250 line displays. These HD-MAC signals will be compatible with basic MAC reception on non-HDTV receivers, thus allowing the compatible introduction of HDTV.