| Popis: |
This paper deals with the digital video broadcasting- satellited (DVB-S2) test bed (called the DTB) implemented by space engineering in the context of the ESA ARTES-4 DEDICATION project. After illustrating the general scopes of the project, the paper begins with a description of the overall architecture of the DTB, which comprises a physical-layer (modem + codec) compliant with the DVB-S2 standard and operating in fully dynamic adaptive coding & modulation (ACM) mode, as well as the upper layers, i.e. those functionalities, such as generic stream (GS) encapsulation [5]of IP packets and physical-layer ACM management, that are needed to make the DTB fully representative of a real DVB-S2 forward-link (FL), with an IP-level interface to the external world. In addition to hub and user terminal DVB-S2 equipments, the DTB also features comprehensive testing facilities for FL performance assessment, while the return-link is emulated by an Ethernet link. The paper then illustrates the DTB implementation aspects, separately addressing the modem, the codec, the encapsulator, the satellite channel emulator and a traffic emulator, which permits to verify the equipment behaviour in an emulated operational environment, taking into account the effects of all relevant elements present in the chain. The overall hardware implementation is then presented together with the test measurement results. The tests included specific performance results for the individual blocks and a verification of some Internet services in presence of the typical channel effects. (9 pages) |
