This part of IEC 60728 is applicable to any cable network(including individual receiving
systems)having in the forward path a coaxial cable output and primarily intended for
television and sound signals operating between about 30 MHz and 3 000 MHz.
This standard specifies the basic methods of measurement of the operational characteristics
of cable network having coaxial cable outputs in order to assess lhe performance of these
systems and their performance limits.
AIl requirements refer to the performance limits,which shall be obtained between the input(s)
to the headend or headends and any system outlet when terminated in a resistance equal to
the nominal load impedance of fhe system.unless otherwise specified.Where system outlets
are not used,the above applies at the subscriber's end of the subscriber's feeder.Also the
requirements which are obtained between the input(s) to the headend or headends and any
home network interface(HNI)are given.
NOTE 1 Methods of measurement described in this standard are considered as basic.However,any equivalent
method that ensures at least the same accuracy may be used.
NOTE 2 If the system operator wishes to subdivide the system into a number of parts or wishes to use different
transmission media(for example,coaxial cabling,balanced cabling.optical cabling),the accumulation of
aegraaations should not exceed the fIgures given in this standard.
NOTE 3 System performance requirements of return paths as well as specific methods of measurement for the
use of the return paths in cable networks are described in IEC 60728—10.
Clause 5 defines the system performance limits which will,with an unimpaired input,
(headend input signal),produce picture and sound signals(at system outlets)where the
impairment to any single parameter wiII be not worse.in normaI operating conditions for any
analogue channeI,than Grade four on the five—grade impairment scale contained in ITU-BT
500-10.For digitally modulated signals.the quality requirement is a quasi-error-free(QEF)
reception.
Appropriate performance requirements for the signals at the receiving antennas site are giyen
in Clause 6 in order to provide at the input of the headend of the cable network both analogue
and digital television signals with suitable quality. 一
Clause 7 is applicable to home networks(including those of individual receiving systems)
using coaxial cables,balanced cables or optical cables and primarily intended for television
signals,sound signals and interactive services,operating between about 30 MHz and
3 000 MHz.
This clause,considering the basic operational characteristics of a home network,specifies the
requirements which shall be obtained at the home network interface(HNI)taking into account
the performance requirements given at the system outlet or at the terminal input.