| 摘要 |
A terrestrial digital video broadcast (DVB-T) network comprises a content provider 2 and first to third transmitters 3 to 5. Each transmitter may transmit more than one signal, different signals having different frequencies, multiplexes and the like and relating to different network types. An integrated receiver/decoder (IRD) 6 is mobile in the area around transmitters 3 to 5. As well as transmitting service information as part of a network information table on a data layer, the transmitters 3 to 5 provide in their output signals transmitter parameter information as TPS data on a physical layer. This TPS information includes one bit identifying the type of the network to which the signal relates and information identifying whether or not the signal contains time-sliced data streams. This information is used by the IRD 6 both in signal scan, or initialising the IRD with parameters needed for OSI layers 1 to 2 service discovery, and for deselecting signals as handover candidates. Since the transmission parameter information is transmitted more frequently and in a lower OSI layer than the network information table, the IRD 6 can more efficiently make decisions as to whether or not a signal is suitable for handover, or is otherwise a signal of interest. The network identifying data is positioned in bits S48-S53 of the TPS signal and can be used to distinguish between DVB-T and Internet Protocol Data Cart (IPDC) networks. |
