Goto Section: 76.602 | 76.606 | Table of Contents
Revised as of December 2, 2020
Goto Year:2020 |
§ 76.605 Technical standards.
(a) The following requirements apply to the performance of a cable
television system as measured at the input to any terminal device with
a matched impedance at the termination point or at the output of the
modulating or processing equipment (generally the headend) of the cable
television system or otherwise noted here or in ANSI/SCTE 40 2016. The
requirements of paragraph (b) of this section are applicable to each
NTSC or similar video downstream cable television channel in the
system. Each cable system that uses QAM modulation to transport video
programming shall adhere to ANSI/SCTE 40 2016 (incorporated by
reference, see § 76.602). Cable television systems utilizing other
technologies to distribute programming must respond to consumer
complaints under paragraph (d) of this section.
(b) For each NTSC or similar video downstream cable television channel
in the system:
(1) The cable television channels delivered to the subscriber's
terminal shall be capable of being received and displayed by TV
broadcast receivers used for off-the-air reception of TV broadcast
signals, as authorized under part 73 of this chapter; and cable
television systems shall transmit signals to subscriber premises
equipment on frequencies in accordance with the channel allocation plan
set forth in CTA-542-D (incorporated by reference, see § 76.602).
(2) The aural center frequency of the aural carrier must be 4.5 MHz ┬±5
kHz above the frequency of the visual carrier at the output of the
modulating or processing equipment of a cable television system, and at
the subscriber terminal.
(3) The visual signal level, across a terminating impedance which
correctly matches the internal impedance of the cable system as viewed
from the subscriber terminal, shall not be less than 1 millivolt across
an internal impedance of 75 ohms (0 dBmV). Additionally, as measured at
the end of a 30 meter (100 foot) cable drop that is connected to the
subscriber tap, it shall not be less than 1.41 millivolts across an
internal impedance of 75 ohms (+3 dBmV). (At other impedance values,
the minimum visual signal level, as viewed from the subscriber
terminal, shall be the square root of 0.0133 (Z) millivolts and, as
measured at the end of a 30 meter (100 foot) cable drop that is
connected to the subscriber tap, shall be 2 times the square root of
0.00662(Z) millivolts, where Z is the appropriate impedance value.)
(4) The visual signal level on each channel, as measured at the end of
a 30 meter cable drop that is connected to the subscriber tap, shall
not vary more than 8 decibels within any six-month interval, which must
include four tests performed in six-hour increments during a 24-hour
period in July or August and during a 24-hour period in January or
February, and shall be maintained within:
(i) 3 decibels (dB) of the visual signal level of any visual carrier
within a 6 MHz nominal frequency separation;
(ii) 10 dB of the visual signal level on any other channel on a cable
television system of up to 300 MHz of cable distribution system upper
frequency limit, with a 1 dB increase for each additional 100 MHz of
cable distribution system upper frequency limit (e.g., 11 dB for a
system at 301-400 MHz; 12 dB for a system at 401-500 MHz, etc.); and
(iii) A maximum level such that signal degradation due to overload in
the subscriber's receiver or terminal does not occur.
(5) The rms voltage of the aural signal shall be maintained between 10
and 17 decibels below the associated visual signal level. This
requirement must be met both at the subscriber terminal and at the
output of the modulating and processing equipment (generally the
headend). For subscriber terminals that use equipment which modulate
and remodulate the signal (e.g., baseband converters), the rms voltage
of the aural signal shall be maintained between 6.5 and 17 decibels
below the associated visual signal level at the subscriber terminal.
(6) The amplitude characteristic shall be within a range of ┬±2 decibels
from 0.75 MHz to 5.0 MHz above the lower boundary frequency of the
cable television channel, referenced to the average of the highest and
lowest amplitudes within these frequency boundaries. The amplitude
characteristic shall be measured at the subscriber terminal.
(7) The ratio of RF visual signal level to system noise shall not be
less than 43 decibels. For class I cable television channels, the
requirements of this section are applicable only to:
(i) Each signal which is delivered by a cable television system to
subscribers within the predicted Grade B or noise-limited service
contour, as appropriate, for that signal;
(ii) Each signal which is first picked up within its predicted Grade B
or noise-limited service contour, as appropriate;
(iii) Each signal that is first received by the cable television system
by direct video feed from a TV broadcast station, a low power TV
station, or a TV translator station.
(8) The ratio of visual signal level to the rms amplitude of any
coherent disturbances such as intermodulation products, second and
third order distortions or discrete-frequency interfering signals not
operating on proper offset assignments shall be as follows:
(i) The ratio of visual signal level to coherent disturbances shall not
be less than 51 decibels for noncoherent channel cable television
systems, when measured with modulated carriers and time averaged; and
(ii) The ratio of visual signal level to coherent disturbances which
are frequency-coincident with the visual carrier shall not be less than
47 decibels for coherent channel cable systems, when measured with
modulated carriers and time averaged.
(9) The terminal isolation provided to each subscriber terminal:
(i) Shall not be less than 18 decibels. In lieu of periodic testing,
the cable operator may use specifications provided by the manufacturer
for the terminal isolation equipment to meet this standard; and
(ii) Shall be sufficient to prevent reflections caused by
open-circuited or short-circuited subscriber terminals from producing
visible picture impairments at any other subscriber terminal.
(10) The peak-to-peak variation in visual signal level caused by
undesired low frequency disturbances (hum or repetitive transients)
generated within the system, or by inadequate low frequency response,
shall not exceed 3 percent of the visual signal level. Measurements
made on a single channel using a single unmodulated carrier may be used
to demonstrate compliance with this parameter at each test location.
(11) The following requirements apply to the performance of the cable
television system as measured at the output of the modulating or
processing equipment (generally the headend) of the system:
(i) The chrominance-luminance delay inequality (or chroma delay), which
is the change in delay time of the chrominance component of the signal
relative to the luminance component, shall be within 170 nanoseconds.
(ii) The differential gain for the color subcarrier of the television
signal, which is measured as the difference in amplitude between the
largest and smallest segments of the chrominance signal (divided by the
largest and expressed in percent), shall not exceed ┬±20%.
(iii) The differential phase for the color subcarrier of the television
signal which is measured as the largest phase difference in degrees
between each segment of the chrominance signal and reference segment
(the segment at the blanking level of 0 IRE), shall not exceed ┬±10
(c) As an exception to the general provision requiring measurements to
be made at subscriber terminals, and without regard to the type of
signals carried by the cable television system, signal leakage from a
cable television system shall be measured in accordance with the
procedures outlined in § 76.609(h) and shall be limited as shown in
table 1 to paragraph (c):
Table 1 to Paragraph (c)
Analog signals less than and including 54 MHz, and over 216 MHz 15 ┬ÁV/m
Digital signals less than and including 54 MHz, and over 216 MHz 13.1
Analog signals over 54 MHz up to and including 216 MHz 20 ┬ÁV/m 3
Digital signals over 54 MHz up to and including 216 MHz 17.4 ┬ÁV/m 3
(d) Cable television systems distributing signals by methods other than
6 MHz NTSC or similar analog channels or 6 MHz QAM or similar channels
on conventional coaxial or hybrid fiber-coaxial cable systems and
which, because of their basic design, cannot comply with one or more of
the technical standards set forth in paragraphs (a) and (b) of this
section, are permitted to operate without Commission approval, provided
that the operators of those systems adhere to all other applicable
Commission rules and respond to consumer and local franchising
authorities regarding industry-standard technical operation as set
forth in their local franchise agreements and consistent with § 76.1713.
Note 1: Local franchising authorities of systems serving fewer than
1,000 subscribers may adopt standards less stringent than those in
§ 76.605(a) and (b). Any such agreement shall be reduced to writing and
be associated with the system's proof-of-performance records.
Note 2: For systems serving rural areas as defined in § 76.5, the system
may negotiate with its local franchising authority for standards less
stringent than those in § 76.605(b)(3), (7), (8), (10) and (11). Any
such agreement shall be reduced to writing and be associated with the
system's proof-of-performance records.
Note 3: The requirements of this section shall not apply to devices
subject to the TV interface device rules under part 15 of this chapter.
Note 4: Should subscriber complaints arise from a system failing to
meet § 76.605(b)(10), the cable operator will be required to remedy the
complaint and perform test measurements on § 76.605(b)(10) containing
the full number of channels as indicated in § 76.601(b)(2) at the
complaining subscriber's terminal. Further, should the problem be found
to be system-wide, the Commission may order that the full number of
channels as indicated in § 76.601(b)(2) be tested at all required
locations for future proof-of-performance tests.
Note 5: No State or franchising authority may prohibit, condition, or
restrict a cable system's use of any type of subscriber equipment or
any transmission technology.
[ 83 FR 7627 , Feb. 22, 2018]
Goto Section: 76.602 | 76.606
Goto Year: 2020 |
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