Re: calibration= CFR 74 PART 76 Subpart K

Here are the requirements for fcc testing.

§ 76.601 Performance tests.

(a) The operator of each cable television system shall be responsible for insuring that each such system is designed, installed, and operated in a manner that fully complies with the provisions of this subpart. Each system operator shall be prepared to show, on request by an authorized representative of the Commission or the local franchiser, that the system does, in fact, comply with the rules.
(b) The operator of each cable television system shall maintain at its local office a current listing of the cable television channels which that system delivers to its subscribers.
(c) The operator of each cable television system shall conduct complete performance tests of that system at least twice each calendar year (at intervals not to exceed seven months), unless otherwise noted below, and shall maintain the resulting test data on file at the operator’s local business office for at least five (5) years. The test data shall be made available for inspection by the Commission or the local franchiser, upon request. The performance tests shall be directed at determining the extent to which the system complies with all the technical standards set forth in § 76.605(a) and shall be as follows:
(1) For cable television systems with 1000 or more subscribers but with 12,500 or fewer subscribers, proof-of-performance tests conducted pursuant to this section shall include measurements taken at six (6) widely separated points. However, within each cable system, one additional test point shall be added for every additional 12,500 subscribers or fraction thereof (e.g., 7 test points if 12,501 to 25,000 subscribers; 8 test points if 25,001 to 37,500 subscribers, etc.). In addition, for technically integrated portions of cable systems that are not mechanically continuous (i.e., employing microwave connections), at least one test point will be required for each portion of the cable system served by a technically integrated microwave hub. The proof-of-performance test points chosen shall be balanced to represent all geographic areas served by the cable system. At least one-third of the test points shall be representative of subscriber terminals most distant from the system input and from each microwave receiver (if microwave transmissions are employed), in terms of cable length. The measurements may be taken at convenient monitoring points in the cable network: Provided, that data shall be included to relate the measured performance of the system as would be viewed from a nearby subscriber terminal. An identification of the instruments, including the makes, model numbers, and the most recent date of calibration, a description of the procedures utilized, and a statement of the qualifications of the person performing the tests shall also be included.
(2) Proof-of-performance tests to determine the extent to which a cable television system complies with the standards set forth in § 76.605(a) (3), (4), and (5) shall be made on each of the NTSC or similar video channels of that system. Unless otherwise as noted, proof-of-performance tests for all other standards in § 76.605(a) shall be made on a minimum of four (4) channels plus one additional channel for every 100 MHz, or fraction thereof, of cable distribution system upper frequency limit (e.g., 5 channels for cable television systems with a cable distribution system upper frequency limit of 101 to 216 MHz; 6 channels for cable television systems with a cable distribution system upper frequency limit of 217–300 MHz; 7 channels for cable television systems with a cable distribution upper frequency limit to 300 to 400 MHz, etc.). The channels selected for testing must be representative of all the channels within the cable television system.
(3) The operator of each cable television system shall conduct semiannual proof-of-performance tests of that system, to determine the extent to which the system complies with the technical standards set forth in § 76.605(a)(4) as follows. The visual signal level on each channel shall be measured and recorded, along with the date and time of the measurement, once every six hours (at intervals of not less than five hours or no more than seven hours after the previous measurement), to include the warmest and the coldest times, during a 24-hour period in January or February and in July or August.
(4) The operator of each cable television system shall conduct triennial proof-of-performance tests of its system to determine the extent to which the system complies with the technical standards set forth in § 76.605(a)(11).
(d) Successful completion of the performance tests required by paragraph (c) of this section does not relieve the system of the obligation to comply with all pertinent technical standards at all subscriber terminals. Additional tests, repeat tests, or tests involving specified subscriber terminals may be required by the Commission of the local franchiser to secure compliance with the technical standards.
(e) The provisions of paragraphs (c) and (d) of this section shall not apply to any cable television system having fewer than 1,000 subscribers: Provided, however, that any cable television system using any frequency spectrum other than that allocated to over-the-air television and FM broadcasting (as described in § 73.603 and § 73.210 of this chapter) is required to conduct all tests, measurements and monitoring of signal leakage that are required by this subpart. A cable television system operator complying with the monitoring, logging and the leakage repair requirements of § 76.614, shall be considered to have met the requirements of this paragraph. However, the leakage log, shall be retained for five years rather than the two years prescribed in § 76.614.

NOTE: Prior to requiring any additional testing pursuant to § 76.601(d), the local franchising authority shall notify the cable operator who will be allowed thirty days to come into compliance with any perceived signal quality problems which need to be corrected. The Commission may request cable operators to test their systems at any time.
[57 FR 11001, Apr. 1, 1992, as amended at 57 FR 61010, Dec. 23, 1992]

§ 76.605 Technical standards.

(a) As of December 30, 1992, unless otherwise noted, the following requirements apply to the performance of a cable television system as measured at any subscriber terminal with 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 the Electronics Industries Association’s ‘‘Cable Television Channel Identification Plan, EIA IS–132, May 1994’’ (EIA IS–132). This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 522(a) and 1 CFR Part 51. Cable systems are required to use this channel allocation plan for signals transmitted in the frequency range 54 MHz to 1002 MHz. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 522(a) and 1 CFR Part 51. Copies of EIA IS–132 may be obtained from: Global Engineering Documents, 2805 McGraw Ave., Irvine CA 92714. Copies of EIA IS–132 may be inspected during normal business hours at the following locations: Federal Communications Commission, 1919 M Street, NW, Dockets Branch (Room239), Washington, DC, or the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. This requirement is applicable on May 31, 1995, for new and rebuilt cable systems, and on June 30, 1997, for all cable systems.
(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 30meter (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 (+3dBmV). (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 30meter 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.
(i) Prior to December 30, 1999, the amplitude characteristic may be measured after a subscriber tap and before a converter that is provided and maintained by the cable operator.
(ii) As of December 30, 1999, the amplitude characteristic shall be measured at the subscriber terminal.
(7) The ratio of RF visual signal level to system noise shall be as follows:
(i) From June 30, 1992, to June 30,1993, shall not be less than 36 decibels.
(ii) From June 30, 1993 to June 30,1995, shall not be less than 40 decibels.
(iii) As of June 30, 1995, shall not be less then 43 decibels.
(iv) For class I cable television channels, the requirements of paragraphs (a)(7)(i), (a)(7)(ii) and (a)(7)(iii) of this section are applicable only to:
(A) Each signal which is delivered by a cable television system to subscribers within the predicted Grade B contour for that signal;
(B) Each signal which is first picked up within its predicted Grade B contour;
(C) 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 level limit (microvolt/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 provisions of §§ 15.601 through 15.626.

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(c)(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(c)(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]

§ 76.609 Measurements.

(a) Measurements made to demonstrate conformity with the performance requirements set forth in §§ 76.601 and 76.605 shall be made under conditions which reflect system performance during normal operations, including the effect of any microwave relay operated in the Cable Television Relay (CARS) Service intervening between pickup antenna and the cable distribution network. Amplifiers shall be operated at normal gains, either by the insertion of appropriate signals or by manual adjustment. Special signals inserted in a cable television channel for measurement purposes should be operated at levels approximating those used for normal operation. Pilot tones, auxiliary or substitute signals, and nontelevision signals normally carried on the cable television system should be operated at normal levels to the extent possible. Some exemplary, but not mandatory, measurement procedures are set forth in this section.
(b) When it may be necessary to remove the television signal normally carried on a cable television channel in order to facilitate a performance measurement, it will be permissible to disconnect the antenna which serves the channel under measurement and to substitute therefor a matching resistance termination. Other antennas and inputs should remain connected and normal signal levels should be maintained on other channels.
(c) As may be necessary to ensure satisfactory service to a subscriber, the Commission may require additional tests to demonstrate system performance or may specify the use of different test procedures.
(d) The frequency response of a cable television channel may be determined by one of the following methods, as appropriate:
(1) By using a swept frequency or a manually variable signal generator at the sending end and a calibrated attenuator and frequency-selective voltmeter at the subscriber terminal; or
(2) By using either a multiburst generator or vertical interval test signals and either a modulator or processor at the sending end, and by using either a demodulator and either an oscilloscope display or a waveform monitor display at the subscriber terminal.
(e) System noise may be measured using a frequency-selective voltmeter (field strength meter) which has been suitably calibrated to indicate rms noise or average power level and which has a known bandwidth. With the system operating at normal level and with a properly matched resistive termination substituted for the antenna, noise power indications at the subscriber terminal are taken in successive increments of frequency equal to the bandwidth of the frequency-selective voltmeter, summing the power indications to obtain the total noise power present over a 4 MHz band centered within the cable television channel. If it is established that the noise level is constant within this bandwidth, a single measurement may be taken which is corrected by an appropriate factor representing the ratio of 4 MHz to the noise bandwidth of the frequency-selective voltmeter. If an amplifier is inserted between the frequency-selective voltmeter and the subscriber terminal in order to facilitate this measurement, it should have a bandwidth of at least 4 MHz and appropriate corrections must be made to account for its gain and noise figure. Alternatively, measurements made in accordance with the NCTA Recommended Practices for Measurements on Cable Television Systems, 2nd edition, November 1989, on noise measurement may be employed.
(f) The amplitude of discrete frequency interfering signals within a cable television channel may be determined with either a spectrum analyzer or with a frequency-selective voltmeter (field strength meter), which instruments have been calibrated for adequate accuracy. If calibration accuracy is in doubt, measurements may be referenced to a calibrated signal generator, or a calibrated variable attenuator, substituted at the point of measurement. If an amplifier is used between the subscriber terminal and the measuring instrument, appropriate corrections must be made to account for its gain.
(g) The terminal isolation between any two terminals in the cable television system may be measured by applying a signal of known amplitude to one terminal and measuring the amplitude of that signal at the other terminal. The frequency of the signal should be close to the midfrequency of the channel being tested. Measurements of terminal isolation are not required when either:
(1) The manufacturer’s specifications for subscriber tap isolation based on a representative sample of no less than 500 subscribers taps or
(2) Laboratory tests performed by or for the operator of a cable television system on a representative sample of no less than 50 subscriber taps, indicates that the terminal isolation standard of § 76.605(a)(9) is met.
To demonstrate compliance with § 76.605(a)(9), the operator of a cable television system shall attach either such manufacturer’s specifications or laboratory measurements as an exhibit to each proof-of-performance record.
(h) Measurements to determine the field strength of the signal leakage emanated by the cable television system shall be made in accordance with standard engineering procedures. Measurements made on frequencies above 25 MHz shall include the following:
(1) A field strength meter of adequate accuracy using a horizontal dipole antenna shall be employed.
(2) Field strength shall be expressed in terms of the rms value of synchronizing peak for each cable television channel for which signal leakage can be measured.
(3) The resonant half wave dipole antenna shall be placed 3 meters from and positioned directly below the system components and at 3 meters above ground. Where such placement results in a separation of less than 3 meters between the center of the dipole antenna and the system components, or less than 3 meters between the dipole and ground level, the dipole shall be repositioned to provide a separation of 3 meters from the system components at a height of 3 meters or more above ground.
(4) The horizontal dipole antenna shall be rotated about a vertical axis and the maximum meter reading shall be used.
(5) Measurements shall be made where other conductors are 3 or more meters (10 or more feet) away from the measuring antenna.
(i) For systems using cable traps and filters to control the delivery of specific channels to the subscriber terminal, measurements made to determine compliance with § 76.605(a) (5) and (6) may be performed at the location immediately prior to the trap or filter for the specific channel. The effects of these traps or filters, as certified by the system engineer or the equipment manufacturer, must be attached to each proof-of-performance record.
(j) Measurements made to determine the differential gain, differential phase and the chrominance-luminance delay inequality (chroma delay) shall be made in accordance with the NCTA Recommended Practices for Measurements on Cable Television Systems, 2nd edition November 1989, on these parameters.
[37 FR 3278, Feb. 12, 1972, as amended at 37 FR 13867, July 14, 1972; 41 FR 10067, Mar. 9, 1976; 42 FR 21782, Apr. 29, 1977; 49 FR 45441, Nov. 16, 1984; 57 FR 11004, Apr. 1, 1992; 57 FR 61011, Dec. 23, 1992; 58 FR 44952, Aug. 25, 1993]
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