IEC 60728-9:2000 pdf download
IEC 60728-9:2000 pdf download.Cabled distribution systems for televisionand sound signals -Part 9:Interfaces of cabled distribution systemsfor digitally modulated signals.
4 Interfaces for MPEG-2 data signals
4.1 IntroductIon
This subclause describes possible interfaces for devices transmitting or receivin9 MPEG2 data as transport packets, such as QPSK demodulators, OAM modulators, mull iplexers, demultiplexers, or telecom network adapters.
This specification is similar to ETS 300429 and ETS 300421.
NOTE Both standards describe a first functional block representing the MPEG2 source coding and multiptex’ng as standardized in ISO’iEC 13818-I. a second functional block reptesenling the channel adaptation, whereas an Interface in between shall be based on MPEO2 transport stream specification according to ISGIEC 13818-1.
The function of the channel modulator/demodulator is to adapt the signal to the characteristics of the transmission channel: satellite, terrestrial or cable as specified in the DVB base line documents.
Also the case where data signals are transmitted to or from a headend via a telecom network, or if a headend serves to insert data signals into such networks, is considered to be covered by the generic channel modulator/demodulator functional block. The interface parameters valid for this network have to be met. For the latter, reterence is made to ITU-T G.703 for Plesiochronic Digital Hierarchy (PDH) networks.
4.1.1 Application requirements
In order to avoid any unnecessary processing at the transmitting or receiving station of an interface In certain applications, it is considered an application requirement that the interface supports 204-byte packet length in such cases, in addition to or instead of the 188-byte packet length specified in ISO/IEC 13818-1. These two cases are identified in the protocol diagrams of figures 1 and 2. where also the scope of this specification is delineated. The relevant associated packet structures are illustrated in figures 3 and 4.
4.1.2 Interfaces
Three interlaces and two serial transmission media are specified as follows:
• SPI (Synchronous Parallel Interlace);
• SSI-C (Synchronous Serial Interface on coaxial cable);
• SSI•O (Synchronous Serial Interlace on optical fibre):
• ASI-C (Asynchronous Serial Interface on coaxial cable);
• ASI-O (Asynchronous Serial Interface on optical fibre).
Each of these interfaces feature a BER such that FEC Is not required for reliable data transport.
The synchronous parallel interface is specified to cover short or medium distances, i.e. for devices arranged near each other. Subclause 4.2 describes the definitions for such a parallel interface derived from ITU-R Recommendation BT.656-4. Flags are provided to distinguish 188-byte packets from 204-byte packets and to signal the existence of valid RS bytes. Note that the interlace, as such, is transparent to the AS bytes.
The synchronous serial interface (SSI) which can be seen as an extension of the parallel interlace, is briefly introduced in 4.3 and described in detail in annexes A and 0. The packet length and the existence of valid AS bytes are conveyed through suitable coding mechanisms.
Subclause 4.4 introduces the Asynchronous Serial Interface (ASI). Details of the ASI are provided in annexes B and E. The ASI is configurable to either convey 188-byte packets (which is mandatory) or optionally 204-byte packets.
4.1.3 Packet length and contents
Each of the interface specifications can be used to convey either 188-byte packets or 204-byte packets in order to enable selection of the appropriate interface characteristics dependent on the kind of equipment to be interconnected. Mandatory and optional packet sizes are specified in table 1.
In case the data stream is packetized in 188-byte packets and the interface is configured to convey 204-byte packets, the extra packet length can be used for additional data. The contents of the 16 bytes in this extra packet length are not specified in this standard. One application could be the transmission of 16 RS bytes associated with the preceding transport package.
4.1.4 Compliance
For an equipment to be compliant to this standard it is sufficient for the equipment to show at least one instance of at least one of the interface specifications as described in 4.1.2 and specified in detail in subsequent subclauses of this standard, while at least the mandatory packet sizes as indicated In 4.1.3 shall be supported.
4.1.5 System integration
The interfaces specified In this standard define physical connections between various pieces of equipment. It is important to notice that various parameters which are important for Interoperatlon are not specified in this standard. This is Intentional as it leaves maximum Implementation flexibility for different applications. In order to facilitate system Integration, equipment suppliers shall provide the following Information about the characteristics of the interlaces in their equipment.
