§ 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 § 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 § 76.609(h) and shall be limited as follows:
   Frequencies Signal leakage limit (micro-volt/meter) Distance in meters (m)
   Less than and including 54 MHz, and over 216 MHz 15 30
   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 § 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 § 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 § 76.5, the system may
   negotiate with its local franchising authority for standards less stringent
   than those in § § 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
   § 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
   § 76.605(a)(10), the cable operator will be required to remedy the complaint
   and perform test measurements on § 76.605(a)(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  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]

   Editorial Note: For Federal Register citations affecting § 76.605 see the
   List of CFR Sections Affected, which appears in the Finding Aids section of
   the printed volume and at www.fdsys.gov.

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