TV transmission standards.
(a) Transmission standards.
The width of the television broadcast channel shall be 6 MHz.
The visual carrier frequency shall be nominally 1.25 MHz above the lower boundary of the channel.
The aural center frequency shall be 4.5 MHz higher than the visual carrier frequency.
The visual transmission amplitude characteristic shall be in accordance with the chart designated as Figure 5 of § 73.699: Provided, however, That for stations operating on Channel 15 through 69 and employing a transmitter with maximum peak visual power output of 1 kW or less the visual transmission amplitude characteristic may be in accordance with the chart designated as Figure 5a of § 73.699.
The chrominance subcarrier frequency is 63/88 times precisely 5 MHz (3.57954545 . . . MHz). The tolerance is ±10 Hz and the rate of frequency drift must not exceed 0.1 Hz per second (cycles per second squared).
For monochrome and color transmissions the number of scanning lines per frame shall be 525, interlaced two to one in successive fields. The horizontal scanning frequency shall be 2/455 times the chrominance subcarrier frequency; this corresponds nominally to 15,750 Hz with an actual value of 15,734.264 ±0.044 Hz). The vertical scanning frequency is 2/525 times the horizontal scanning frequency; this corresponds nominally to 60 Hz (the actual value is 59.94 Hz). For monochrome transmissions only, the nominal values of line and field frequencies may be used.
The aspect ratio of the transmitted television picture shall be 4 units horizontally to 3 units vertically.
During active scanning intervals, the scene shall be scanned from left to right horizontally and from top to bottom vertically, at uniform velocities.
A carrier shall be modulated within a single television channel for both picture and synchronizing signals. The two signals comprise different modulation ranges in amplitude in accordance with the following:
Monochrome transmissions shall comply with synchronizing waveform specifications in Figure 7 of § 73.699.
Color transmissions shall comply with the synchronizing waveform specifications in Figure 6 of § 73.699.
All stations operating on Channels 2 through 14 and those stations operating on Channels 15 through 69 licensed for a peak visual transmitter output power greater than one kW shall comply with the picture transmission amplitude characteristics shown in Figure 5 of § 73.699.
Stations operating on Channels 15 through 69 licensed for a peak visual transmitter output power of one kW or less shall comply with the picture transmission amplitude characteristic shown in Figure 5 or 5a of § 73.699.
A decrease in initial light intensity shall cause an increase in radiated power (negative transmission).
The reference black level shall be represented by a definite carrier level, independent of light and shade in the picture.
The blanking level shall be transmitted at 75±2.5 percent of the peak carrier level.
The reference white level of the luminance signal shall be 12.5±2.5 percent of the peak carrier level.
It shall be standard to employ horizontal polarization. However, circular or elliptical polarization may be employed if desired, in which case clockwise (right hand) rotation, as defined in the IEEE Standard Definition 42A65-3E2, and transmission of the horizontal and vertical components in time and space quadrature shall be used. For either omnidirectional or directional antennas the licensed effective radiated power of the vertically polarized component may not exceed the licensed effective radiated power of the horizontally polarized component. For directional antennas, the maximum effective radiated power of the vertically polarized component shall not exceed the maximum effective radiated power of the horizontally polarized component in any specified horizontal or vertical direction.
The effective radiated power of the aural transmitter must not exceed 22% of the peak radiated power of the visual transmitter.
The peak-to-peak variation of transmitter output within one frame of video signal due to all causes, including hum, noise, and low-frequency response, measured at both scanning synchronizing peak and blanking level, shall not exceed 5 percent of the average scanning synchronizing peak signal amplitude. This provision is subject to change but is considered the best practice under the present state of the art. It will not be enforced pending a further determination thereof.
The reference black level shall be separated from the blanking level by the setup interval, which shall be 7.5±2.5 percent of the video range from blanking level to the reference white level.
For monochrome transmission, the transmitter output shall vary in substantially inverse logarithmic relation to the brightness of the subject. No tolerances are set at this time. This provision is subject to change but is considered the best practice under the present state of the art. It will not be enforced pending a further determination thereof.
The color picture signal shall correspond to a luminance component transmitted as amplitude modulation of the picture carrier and a simultaneous pair of chrominance components transmitted as the amplitude modulation sidebands of a pair of suppressed subcarriers in quadrature.
Equation of complete color signal.
The color picture signal has the following composition:
Q′ sin (ω
t 33°) E
I′ cos (ω
For color-difference frequencies below 500 kHz (see (iii) below), the signal can be represented by:
Y′) sin ω
Y′) cos ω
The symbols in paragraph (a)(20)(i) of this section have the following significance:
Forming of the high frequency portion of the monochrome signal in a different manner is permissible and may in fact be desirable in order to improve the sharpness on saturated colors.
The equivalent bandwidth assigned prior to modulation to the color difference signals E
Q ′ and E
I ′ are as follows:
The gamma corrected voltages E
R ′, E
G ′, and E
B ′ are suitable for a color picture tube having primary colors with the following chromaticities in the CIE system of specification:
and having a transfer gradient (gamma exponent) of 2.2 associated with each primary color. The voltages E
G′, and E
B′ may be respectively of the form E
1/γ, and E
1/γ although other forms may be used with advances in the state of the art.
At the present state of the art it is considered inadvisable to set a tolerance on the value of gamma and correspondingly this portion of the specification will not be enforced.
The radiated chrominance subcarrier shall vanish on the reference white of the scene.
The numerical values of the signal specification assume that this condition will be reproduced as CIE Illuminant C (x=0.310, y=0.316).
Y ′, E
Q ′, E
I ′, and the components of these signals shall match each other in time to 0.05 µsecs.
The angles of the subcarrier measured with respect to the burst phase, when reproducing saturated primaries and their complements at 75 percent of full amplitude, shall be within ±10° and their amplitudes shall be within ±20 percent of the values specified above. The ratios of the measured amplitudes of the subcarrier to the luminance signal for the same saturated primaries and their complements shall fall between the limits of 0.8 and 1.2 of the values specified for their ratios. Closer tolerances may prove to be practicable and desirable with advance in the art.
The interval beginning with line 17 and continuing through line 20 of the vertical blanking interval of each field may be used for the transmission of test signals, cue and control signals, and identification signals, subject to the conditions and restrictions set forth below. Test signals may include signals designed to check the performance of the overall transmission system or its individual components. Cue and control signals shall be related to the operation of the TV broadcast station. Identification signals may be transmitted to identify the broadcast material or its source, and the date and time of its origination. Figures 6 and 7 of § 73.699 identify the numbered lines referred to in this paragraph.
Modulation of the television transmitter by such signals shall be confined to the area between the reference white level and the blanking level, except where test signals include chrominance subcarrier frequencies, in which case positive excursions of chrominance components may exceed reference white, and negative excursions may extend into the synchronizing area. In no case may the modulation excursions produced by test signals extend beyond peak-of-sync, or to zero carrier level.
The use of such signals shall not result in significant degradation of the program transmission of the television broadcast station, nor produce emission outside of the frequency band occupied for normal program transmissions.
Such signals may not be transmitted during that portion of each line devoted to horizontal blanking.
Regardless of other provisions of this paragraph, after June 30, 1994, Line 19, in each field, may be used only for the transmission of the ghost-canceling reference signal described in OET Bulletin No. 68, which is available from the FCC Warehouse, 9300 East Hampton Drive, Capitol Heights, MD 20743. Notwithstanding the modulation limits contained in paragraph (a)(23)(i) of this section, the vertical interval reference signal formerly permitted on Line 19 and described in Figure 16 of § 73.699, may be transmitted on any of lines 10 through 16 without specific Commission authorization, subject to the conditions contained in paragraphs (a)(21)(ii) and (a)(22)(ii) of this section.
Line 21, in each field, may be used for the transmission of a program-related data signal which, when decoded, provides a visual depiction of information simultaneously being presented on the aural channel (captions). Line 21, field 2 may be used for transmission of a program-related data signal which, when decoded, identifies a rating level associated with the current program. Such data signals shall conform to the format described in figure 17 of § 73.699 of this chapter, and may be transmitted during all periods of regular operation. On a space available basis, line 21 field 2 may also be used for text-mode data and extended data service information.
The signals on Fields 1 and 2 shall be distinct data streams, for example, to supply captions in different languages or at different reading levels.
At times when Line 21 is not being used to transmit a program related data signal, data signals which are not program related may be transmitted, Provided: the same data format is used and the information to be displayed is of a broadcast nature.
The use of Line 21 for transmission of other data signals conforming to other formats may be used subject to prior authorization by the Commission.
The data signal shall cause no significant degradation to any portion of the visual signal nor produce emissions outside the authorized television channel.
Transmission of visual emergency messages pursuant to § 73.1250 shall take precedence and shall be cause for interrupting transmission of data signals permitted under this paragraph.
Specific scanning lines in the vertical blanking interval may be used for the purpose of transmitting telecommunications signals in accordance with § 73.646, subject to certain conditions:
Telecommunications may be transmitted on Lines 10-18 and 20, all of Field 2 and Field 1. Modulation level shall not exceed 70 IRE on lines 10, 11, and 12; and, 80 IRE on lines 13-18 and 20.
No observable degradation may be caused to any portion of the visual or aural signals.
Telecommunications signals must not produce emissions outside the authorized television channel bandwidth. Digital data pulses must be shaped to limit spectral energy to the nominal video baseband.
Transmission of emergency visual messages pursuant to § 73.1250 must take precedence over, and shall be cause for interrupting, a service such as teletext that provides a visual depiction of information simultaneously transmitted on the aural channel.
A reference pulse for a decoder associated adaptive equalizer filter designed to improve the decoding of telecommunications signals may be inserted on any portion of the vertical blanking interval authorized for data service, in accordance with the signal levels set forth in paragraph (a)(23)(i) of this section.
All lines authorized for telecommunications transmissions may be used for other purposes upon prior approval by the Commission.
Licensees and permittees of TV broadcast and low power TV stations may insert non-video data into the active video portion of their TV transmission, subject to certain conditions:
The active video portion of the visual signal begins with line 22 and continues through the end of each field, except it does not include that portion of each line devoted to horizontal blanking. Figures 6 and 7 of § 73.699 identify the numbered line referred to in this paragraph;
Inserted non-video data may be used for the purpose of transmitting a telecommunications service in accordance with § 73.646. In addition to a telecommunications service, non-video data can be used to enhance the station's broadcast program service or for purposes related to station operations. Signals relating to the operation of TV stations include, but are not limited to program or source identification, relay of broadcast materials to other stations, remote cueing and order messages, and control and telemetry signals for the transmitting system; and
A station may only use systems for inserting non-video information that have been approved in advance by the Commission. The criteria for advance approval of systems are as follows:
The use of such signals shall not result in significant degradation to any portion of the visual, aural, or program-related data signals of the television broadcast station;
No increase in width of the television broadcast channel (6 MHz) is permitted. Emissions outside the authorized television channel must not exceed the limitations given in § 73.687(e). Interference to reception of television service either of co-channel or adjacent channel stations must not increase over that resulting from the transmission of programming without inserted data; and
Where required, system receiving or decoding devices must meet the TV interface device provisions of Part 15, Subpart H of this chapter.
No protection from interference of any kind will be afforded to reception of inserted non-video data.
Upon request by an authorized representative of the Commission, the licensee of a TV station transmitting encoded programming must make available a receiving decoder to the Commission to carry out its regulatory responsibilities.
(b) Subscription TV technical systems.
The FCC may specify, as part of the advance approval of the technical system for transmitting encoded subscription programming, deviations from the power determination procedures, operating power levels, aural or video baseband signals, modulation levels or other characteristics of the transmitted signal as otherwise specified in this Subpart. Any decision to approve such operating deviations shall be solely at the discretion of the FCC.
TV multiplex subcarrier/stereophonic aural transmission standards.
The modulating signal for the main channel shall consist of the sum of the stereophonic (biphonic, quadraphonic, etc.) input signals.
The instantaneous frequency of the baseband stereophonic subcarrier must at all times be within the range 15 kHz to 120 kHz. Either amplitude or frequency modulation of the stereophonic subcarrier may be used.
One or more pilot subcarriers between 16 kHz and 120 kHz may be used to switch a TV receiver between the stereophonic and monophonic reception modes or to activate a stereophonic audio indicator light, and one or more subcarriers between 15 kHz and 120 kHz may be used for any other authorized purpose; except that stations employing the BTSC system of stereophonic sound transmission and audio processing may transmit a pilot subcarrier at 15,734 Hz, ±2 Hz. Other methods of multiplex subcarrier or stereophonic aural transmission systems must limit energy at 15,734 Hz, ±20 Hz, to no more than ±0.125 kHz aural carrier deviation.
Aural baseband information above 120 kHz must be attenuated 40 dB referenced to 25 kHz main channel deviation of the aural carrier.
For required transmitter performance, all of the requirements of § 73.687(b) shall apply to the main channel, with the transmitter in the multiplex subcarrier or stereophonic aural mode.
For electrical performance standards of the transmitter, the requirements of § 73.687(b) apply to the main channel.
Multiplex subcarrier or stereophonic aural transmission systems must be capable of producing and must not exceed ±25 kHz main channel deviation of the aural carrier.
The arithmetic sum of non-multiphonic baseband signals between 15 kHz and 120 kHz must not exceed ±50 kHz deviation of the aural carrier.
Total modulation of the aural carrier must not exceed ±75 kHz.
(d) Digital broadcast television transmission standard.
Effective May 29, 2008 transmission of digital broadcast television (DTV) signals shall comply with the standards for such transmissions set forth in ATSC A/52: “ATSC Standard Digital Audio Compression (AC-3)” (incorporated by reference, see § 73.8000 ), ATSC A/53, Parts 1-6: 2007 “ATSC Digital Television Standard,” (January 3, 2007), except for section 6.1.2 (“Compression Format Constraints”) of A/53 Part 4: 2007 (“MPEG-2 Video Systems Characteristics”) and the phrase “see Table 6.2” in section 6.1.1 Table 6.1 and section 6.1.3 Table 6.3 (incorporated by reference, see § 73.8000 ), and ATSC A/65C: “ATSC Program and System Information Protocol for Terrestrial Broadcast and Cable, Revision C With Amendment No. 1 dated May 9, 2006,” (January 2, 2006) (incorporated by reference, see § 73.8000 ). Although not incorporated by reference, licensees may also consult ATSC A/54A: “Recommended Practice: Guide to Use of the ATSC Digital Television Standard, including Corrigendum No. 1,” (December 4, 2003, Corrigendum No. 1 dated December 20, 2006, and ATSC A/69: “Recommended Practice PSIP Implementation Guidelines for Broadcasters,” (June 25, 2002) ( Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, 1082 (47 U.S.C. 154, 155, 303 )). ATSC A/54A and ATSC A/69 are available from Advanced Television Systems Committee (ATSC), 1750 K Street, NW., Suite 1200, Washington, DC 20006, or at the ATSC Web site: http://www.atsc.org/standards.html.
(Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, 1082 (
47 U.S.C. 154, 155, 303
[28 FR 13660, Dec. 14, 1963]
For Federal Register citations affecting § 73.682
, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.fdsys.gov.
Effective Date Note:
At 76 FR 55603, Sept. 8, 2011, § 73.682 was amended by revising paragraph (d), effective Oct. 11, 2011. For the convenience of the user, the revised text is set forth as follows:
TV transmission standards.
(d) Digital broadcast television transmission standard.
Effective October 11, 2011 transmission of digital broadcast television (DTV) signals shall comply with the standards for such transmissions set forth in ATSC A/52: “ATSC Standard Digital Audio Compression (AC-3)”, ATSC A/53, Parts 1-4 and 6: 2007 “ATSC Digital Television Standard,” (January 3, 2007), and ATSC A/53 Part 5:2010 “ATSC Digital Television Standard: Part 5 —AC-3 Audio System Characteristic,” (July 6, 2010), except for section 6.1.2 (“Compression Format Constraints”) of A/53 Part 4: 2007 (“MPEG-2 Video Systems Characteristics”) and the phrase “see Table 6.2” in section 6.1.1 Table 6.1 and section 6.1.3 Table 6.3, and ATSC A/65C: “ATSC Program and System Information Protocol for Terrestrial Broadcast and Cable, Revision C With Amendment No. 1 dated May 9, 2006,” (January 2, 2006) (all standards incorporated by reference, see § 73.8000 ). Although not incorporated by reference, licensees may also consult ATSC A/54A: “Recommended Practice: Guide to Use of the ATSC Digital Television Standard, including Corrigendum No. 1,” (December 4, 2003, Corrigendum No. 1 dated December 20, 2006, and ATSC A/69: “Recommended Practice PSIP Implementation Guidelines for Broadcasters,” (June 25, 2002) ( Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, 1082 (47 U.S.C. 154, 155, 303 )). ATSC A/54A and ATSC A/69 are available from Advanced Television Systems Committee (ATSC), 1750 K Street, NW., Suite 1200, Washington, DC 20006, or at the ATSC Web site: http://www.atsc.org/standards.html.