21 December 2004: After years of discussion in different standardisation forums, an important milestone has been achieved: a common specification for the Inter-Facility Link (IFL) of DVB-RCS terminals has been agreed.

A common IFL specification is important for the DVB-RCS community because it simplifies interoperability and allows the optimisation of the production of IDU and ODU models, thus allowing higher production volumes and hence lower costs.

The IFL is the interface between the In-Door Unit (IDU) and the Out-Door Unit (ODU).

The ODUconsists of a transmission module or block up-converter (BUC), comprising a frequency up-converter and a Solid State Power Amplifier (SSPA), a DVB-S low-noise block down-converter (LNB) and an antenna. The IDU comprises the interface with user equipment, and the satellite modem, which transmits the signal in IF range to the ODU and receives control and traffic information from the Hub via the ODU.

The Transmit IFL system interfaces between the modem and BUC. A single coaxial cable carries:

• The TX IF signal in L-band
• The TX Local Oscillator frequency reference signal
• A low frequency sub-carrier for DiSEqC signaling
• The DC power supplying the BUC

The Receive IFL system interfaces between LNB and modem and is based on the DVB-S requirements used in satellite TV receivers.