§  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:   ForFederal Registercitations affecting § 76.605 see
   the List of CFR Sections Affected, which appears in the Finding Aids
   section of the printed volume and on GPO Access.