BS EN 60728-1-2-2009 电视信号、声音信号和交互式设备用电缆网络.运行系统出口信号传输的性能要求
Cable networks for television signals, sound signals and interactive services - Performance requirements for signals delivered at the system outlet in operation
This part of IEC 60728 provides the minimum performance requirements to be fulfilled in
operation at the system outlet or terminal input and describes the summation criteria for the impairments present in the received signals and those produced by the CATV/MATV/SMATV cable network, including individual receiving systems.
NOTE 1 When a change of signal format is made at the headend, the summation of the impairments does not
apply (see also Clause 57H 7).
In a building divided into apartment blocks, the signals received by the antennas are
distributed by the MATV/SMATV cable network up to the home network interface (HNI); the television signals are then distributed (inside the home) by home networks (HN) of various types up to the system outlet or terminal input. The cable network can support two way operation, from the system outlet (or terminal input) towards the headend.
The home network can use coaxial cables, balanced pair cables, fibre optic cables (glass or plastic) and also wireless links inside a room (or a small number of adjacent rooms) to replace wired cords.
This part of IEC 60728 is applicable to cable networks intended for television signals, sound
signals and interactive services operating between about 5 MHz and 3 000 MHz. The frequency range is extended to 6 000 MHz for home distribution techniques that replace wired cords with a wireless two way communication inside a room (or a small number of adjacent rooms) that uses the 5 GHz to 6 GHz frequency band.
64H64H64H58HFigure 1 shows the main sections of a general CATV/MATV/SMATV system, indicating the
parts of the IEC 60728-1 series documents where the relevant performance requirements are indicated.
• The requirements for the signals received at the headend are given in Clause 6 of IEC 60728-1.
• The requirements for the CATV/MATV/SMATV cable network, assuming an unimpaired input signal at the input of the headend, up to the system outlet are given in IEC 60728-1, Clause 5.
• The requirements for the CATV/MATV/SMATV cable network up to the home network interface (HNI) are given in IEC 60728-1, Clause 7, assuming an unimpaired input signal at the input of the headend.
• The specific requirements from HNI to the system outlet or terminal input are given in IEC 60728-1-1, Clause 5, assuming an unimpaired input signal at the HNI.
• The requirements at the system outlet in operation are given in Clause 7 of this standard.
The expression “in operation” means that the received signals, with their impairments, are
applied to the headend input of the CATV/MATV/SMATV cable network. The requirements at the system outlet “in operation” are derived, therefore, by summing the impairments of the various cascaded parts of the system and of the input signal.
When a change of signal format from analogue to analogue (e.g. from FM to AM-VSB) or from
digital to digital (e.g. from QPSK to QAM) or from digital to analogue (e.g. from DVB-S/S2 to
AM-VSB or DVB-T to AM-VSB) is made at the headend, the summation of the impairments that produce a relaxation of requirements at system outlet does not apply. Such a case will be the equivalence of unimpaired signals applied at the headend input. Therefore the requirements at system outlet given in IEC 60728-1 apply.
This standard also provides references for the basic methods of measurement of the operational characteristics of the downstream cable network in order to assess its performance.
All requirements refer to the performance limits to be achieved in operation at any system outlet when terminated in a resistance equal to the nominal load impedance of the system,
unless otherwise specified. Where system outlets are not used, the above applies to the terminal input.