Using a PC-based Skyplex multiplex adapter and an adapted DVB modulator combined with a small dish and medium power amplifier, a broadcaster can send a signal from anywhere in the coverage zone up to the Skyplex unit.

Available on Eutelsat's HOT BIRD™ 6 and W3A satellites, the Skyplex unit can receive low bitrate uplink signals in the range 350 Kbps to 6 Mbps. It then demodulates them for multiplexing into a single digital stream at 38Mbps, which is then remodulated on board the satellite for broadcast.

The output of the Skyplex modulator, a completely standard DVB QPSK signal at 27.5 Msymb/s, feeds a 33 MHz satellite transponder at full power. The resulting downlink signal is identical in structure to all the other digital transmissions emitted from HOT BIRD™ transponders that were originally multiplexed on the ground. It can be received by standard equipment, that is, by every MPEG-2/DVB compatible decoder.

Small uplink stations can choose single channel per carrier (SCPC) or shared modes. In the shared mode, up to six stations can simultaneously access an uplink channel in time division multiple access (TDMA) mode. As a result, uplinks can be set up over a wide range of data rates, from 6 Mbps (single station accessing a 6 Mbps Skyplex channel in SCPC) down to 350 Kbps (six stations accessing a 2 Mbps Skyplex channel in TDMA mode). The satellite bandwidth leased by the broadcaster can therefore be more closely matched to the precise needs of the application.

Since Skyplex enables DVB transmission direct-to-home, the broadcaster can decide whether to encrypt the uplink streams - with a choice of conditional access systems - or to simply leave them in the clear. With such influence over encryption, the broadcaster is able to closely define and manage the target audience.