FCC 76.605 Revised as of October 1, 2005
Goto Year:2004 |
2006
Sec. 76.605 Technical standards.
(a) The following requirements apply to the performance of a cable
television system as measured at any subscriber terminal 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 as noted. The requirements are applicable to each NTSC or
similar video downstream cable television channel in the system:
(1)(i) 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
(ii) Cable television systems shall transmit signals to subscriber premises
equipment on frequencies in accordance with the channel allocation plan set
forth in CEA–542–B: “Standard: Cable Television Channel Identification
Plan,” (Incorporated by reference, see Sec. 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 contour for that signal;
(ii) Each signal which is first picked up within its predicted Grade B
contour;
(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) As of June 30, 1995, 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 O IRE), shall not exceed 10 degrees.
(12) 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 Sec. 76.609(h) and shall be limited as follows:
------------------------------------------------------------------------
Signal
leakage
Frequencies limit Distance in
(micro-volt/ meters (m)
meter)
------------------------------------------------------------------------
Less than and including 54 MHz, and over 216 15 30
MHz..........................................
Over 54 up to and including 216 MHz........... 20 3
------------------------------------------------------------------------
(b) Cable television systems distributing signals by using methods such as
nonconventional coaxial cable techniques, noncoaxial copper cable
techniques, specialized coaxial cable and fiber optical cable hybridization
techniques or specialized compression techniques or specialized receiving
devices, and which, because of their basic design, cannot comply with one or
more of the technical standards set forth in paragraph (a) of this section,
may be permitted to operate: Provided, That an adequate showing is made
pursuant to Sec. 76.7 which establishes that the public interest is benefited.
In such instances, the Commission may prescribe special technical
requirements to ensure that subscribers to such systems are provided with an
equivalent level of good quality service.
Note 1: Local franchising authorities of systems serving fewer than 1000
subscribers may adopt standards less stringent than those in Sec. 76.605(a). 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 Sec. 76.5, the system may
negotiate with its local franchising authority for standards less stringent
than those in Sec. Sec. 76.605(a)(3), 76.605(a)(7), 76.605(a)(8), 76.605(a)(10) and
76.605(a)(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
Sec. 76.605(a)(6) prior to December 30, 1999, the cable operator will be
required to provide a converter that will allow the system to meet the
standard immediately at the complaining subscriber's terminal. Further,
should the problem be found to be system-wide, the Commission may order all
converters on the system be changed to meet the standard.
Note 5: Should subscriber complaints arise from a system failing to meet
Sec. 76.605(a)(10), the cable operator will be required to remedy the complaint
and perform test measurements on Sec. 76.605(a)(10) containing the full number
of channels as indicated in Sec. 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
Sec. 76.601(b)(2) be tested at all required locations for future
proof-of-performance tests.
Note 6: 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.
[ 37 FR 3278 , Feb. 12, 1972, as amended at 37 FR 13867 , July 14, 1972; 40 FR 2690 , Jan. 15, 1975; 40 FR 3296 , Jan. 21, 1975; 41 FR 53028 , Dec. 3, 1976;
42 FR 21782 , Apr. 29, 1977; 47 FR 21503 , May 18, 1982; 50 FR 52466 , Dec. 24,
1985; 51 FR 1255 , Jan. 10, 1986; 52 FR 22461 , June 12, 1987; 57 FR 11002 ,
Apr. 1, 1992; 57 FR 61010 , Dec. 23, 1992; 58 FR 44952 , Aug. 25, 1993; 59 FR 25342 , May 16, 1994; 61 FR 18510 , Apr. 26, 1996; 61 FR 18978 , Apr. 30, 1996;
65 FR 53616 , Sept. 5, 2000; 69 FR 2849 , Jan. 21, 2004; 69 FR 57861 , Sept.
28, 2004]
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