Cable networks for television signals, sound signals and interactive services – Part 5: Headend equipment
|Publication Date:||1 December 2015|
|ICS Code (Cabled distribution systems):||33.060.40|
This part of IEC 60728 specifies the characteristics of equipment used in the headends of terrestrial broadcast and satellite receiving systems (without satellite outdoor units and without those broadband amplifiers in the headend as described in IEC 60728-3). The satellite outdoor units for fixed satellite systems (FSS) are described in ETSI ETS 300 158, and for broadcast satellite systems (BSS) in ETSI ETS 300 249. Test methods for both types (FSS and BSS) of satellite outdoor units are laid down in ETSI ETS 300 457.
This part of IEC 60728
a) covers the frequency range 5 MHz to 3 000 MHz;
b) identifies performance requirements for certain parameters;
c) lays down data publication requirements for certain parameters;
d) stipulates methods of measurements;
e) introduces minimum requirements defining quality grades (Q-grades).
This part of IEC 60728 specifies the overall characteristics for upstream/downstream signals between external sources/sinks (for example, antennas, cable modem termination systems, etc.) and the system interface to the cable network. In the case of modular headend systems, single equipment items such as modulators, converters, etc. are also described. Cable modem termination systems, encrypters, decrypters, etc. are not described in this part of IEC 60728. If such equipment is used in headends, the relevant parameters for RF, video, audio and data interfaces should be met.
According to the definitions in 3.1, the headends are divided into the following three quality grades:
• Grade 1: central headend;
• Grade 2: hub headend or hubsite;
• Grade 3: MATV headend/individual reception headend.
Figure 1 shows the block diagram of a headend consisting of typical processing units with the corresponding interfaces at the input and output.
For IP interfaces, specifications from the transmission standard ETSI TS 102 034 are taken into account where applicable. The content of the data streams can be digital video, audio or other digital data.
The necessary characteristics and parameters of equipment such as IP gateways or IP interfaces on equipment at the input of headends (Figure 2) as well as at the output of headends (Figure 3) are described in CLC/TR 50083-5-1.
Equipment at the input of headends can be either IP gateways
which enable the connection to a Digital Video
Equipment at the output of headends can be either IP gateways which enable the connection from DVB-ASI interfaces according to EN 50083-9 to IP based networks or, in the case of modular headend systems, can also be single equipment with IP interfaces such as encoders, multiplexers and switches