ETSI Satellite Digital Radio
（重定向自ESDR）
ETSI Satellite Digital Radio (SDR or ETSI SDR) describes a standard of satellite digital radio. It is an activity of the European standardisation organisation ETSI.
It addresses systems where a satellite broadcast directly to mobile and handheld receivers in L band or S band and is complemented by terrestrial transmitters. The broadcast content consists of multicast audio (digital radio), video (mobile TV) and data (program guide, text and graphical information, as well as off-line content). The satellite component allows geographical coverage at low cost, whereas the terrestrial component improves reception quality in built up areas. The specifications considers conditional access and Digital Rights Management.