§  73.682   TV transmission standards.

   Link to an amendment published at  77 FR 40298 , July 9, 2012.

   (a) Transmission standards. (1) The width of the television broadcast
   channel shall be 6 MHz.

   (2) The visual carrier frequency shall be nominally 1.25 MHz above the
   lower boundary of the channel.

   (3) The aural center frequency shall be 4.5 MHz higher than the visual
   carrier frequency.

   (4) 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.

   (5) 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).

   (6) 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.

   (7) The aspect ratio of the transmitted television picture shall be 4
   units horizontally to 3 units vertically.

   (8) During active scanning intervals, the scene shall be scanned from
   left to right horizontally and from top to bottom vertically, at
   uniform velocities.

   (9) 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:

   (i) Monochrome transmissions shall comply with synchronizing waveform
   specifications in Figure 7 of §  73.699.

   (ii) Color transmissions shall comply with the synchronizing waveform
   specifications in Figure 6 of §  73.699.

   (iii) 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.

   (iv) 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.

   (10) A decrease in initial light intensity shall cause an increase in
   radiated power (negative transmission).

   (11) The reference black level shall be represented by a definite
   carrier level, independent of light and shade in the picture.

   (12) The blanking level shall be transmitted at 75±2.5 percent of the
   peak carrier level.

   (13) The reference white level of the luminance signal shall be
   12.5±2.5 percent of the peak carrier level.

   (14) 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.

   (15) The effective radiated power of the aural transmitter must not
   exceed 22% of the peak radiated power of the visual transmitter.

   (16) 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.

   (17) 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.

   (18) 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.

   (19) 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.

   (20) Equation of complete color signal.

   (i) The color picture signal has the following composition:

   E M = E Y ′+[ E Q ′ sin ( ω t +33�°)+ E I ′ cos ( ω t +33�°)]

   Where:

   E Q ′=0.41( E B ′− E Y ′)+0.48( E R ′− E Y ′).

   E I ′=−0.27( E B ′− E Y ′)+0.74( E R ′− E Y ′).

   E Y ′=0.30 E R ′+0.59 E G ′+0.−1 E B ′.

   For color-difference frequencies below 500 kHz (see (iii) below), the
   signal can be represented by:

   E M = E Y ′+[(1/1.14)[(1/1.78)( E B ′− E Y ′) sin ω t +( E R ′− E Y ′)
   cos ω t ]]

   (ii) The symbols in paragraph (a)(20)(i) of this section have the
   following significance:

   E M is the total video voltage, corresponding to the scanning of a
   particular picture element, applied to the modulator of the picture
   transmitter.

   E Y ′ is the gamma-corrected voltage of the monochrome
   (black-and-white) portion of the color picture signal, corresponding to
   the given picture element.

   Note: 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.

   E Q ′ and E I ′ are the amplitudes of two orthogonal components of the
   chrominance signal corresponding respectively to narrow-band and
   wide-band axes.

   E R ′, E G ′, and E B ′ are the gamma-corrected voltages corresponding
   to red, green, and blue signals during the scanning of the given
   picture element.

   ω is the angular frequency and is 2 times the frequency of the
   chrominance subcarrier.

   The portion of each expression between brackets in (i) represents the
   chrominance subcarrier signal which carries the chrominance
   information.

   The phase reference in the E M equation in (i) is the phase of the
   burst+180�°, as shown in Figure 8 of §  73.699. The burst corresponds to
   amplitude modulation of a continuous sine wave.

   (iii) The equivalent bandwidth assigned prior to modulation to the
   color difference signals E Q ′ and E I ′ are as follows:

   Q-channel bandwidth:

   At 400 kHz less than 2 dB down.

   At 500 kHz less than 6 dB down.

   At 600 kHz at least 6 dB down.

   I-channel bandwidth:

   At 1.3 MHz less than 2 dB down.

   At 3.6 MHz at least 20 dB down.

   (iv) 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:
              x    y
   Red (R)   0.67 0.33
   Green (G) 0.21 0.71
   Blue (B)  0.14 0.08

   and having a transfer gradient (gamma exponent) of 2.2 associated with
   each primary color. The voltages E R ′, E G ′, and E B ′ may be
   respectively of the form E R  1 /γ, E G  1 /γ, and E B  1 /γ although
   other forms may be used with advances in the state of the art.

   Note: 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.

   (v) The radiated chrominance subcarrier shall vanish on the reference
   white of the scene.

   Note: The numerical values of the signal specification assume that this
   condition will be reproduced as CIE Illuminant C ( x =0.310, y =0.316).

   (vi) E Y ′, E Q ′, E I ′, and the components of these signals shall
   match each other in time to 0.05 µsecs.

   (vii) 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.

   (21) 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.

   (i) 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.

   (ii) 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.

   (iii) Such signals may not be transmitted during that portion of each
   line devoted to horizontal blanking.

   (iv) 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.

   (22)(i) 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.

   Note: 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.

   (ii) 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.

   (iii) 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.

   (iv) The data signal shall cause no significant degradation to any
   portion of the visual signal nor produce emissions outside the
   authorized television channel.

   (v) 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.

   (23) 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:

   (i) 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.

   (ii) No observable degradation may be caused to any portion of the
   visual or aural signals.

   (iii) 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.

   (iv) 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.

   (v) 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.

   (vi) All lines authorized for telecommunications transmissions may be
   used for other purposes upon prior approval by the Commission.

   (24) 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:

   (i) 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;

   (ii) 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

   (iii) 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:

   (A) 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;

   (B) 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

   (C) Where required, system receiving or decoding devices must meet the
   TV interface device provisions of Part 15, Subpart H of this chapter.

   (iv) No protection from interference of any kind will be afforded to
   reception of inserted non-video data.

   (v) 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.

   (c) TV multiplex subcarrier/stereophonic aural transmission standards.

   (1) The modulating signal for the main channel shall consist of the sum
   of the stereophonic (biphonic, quadraphonic, etc.) input signals.

   (2) 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.

   (3) 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.

   (4) Aural baseband information above 120 kHz must be attenuated 40 dB
   referenced to 25 kHz main channel deviation of the aural carrier.

   (5) 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.

   (6) For electrical performance standards of the transmitter, the
   requirements of §  73.687(b) apply to the main channel.

   (7) 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.

   (8) The arithmetic sum of non-multiphonic baseband signals between 15
   kHz and 120 kHz must not exceed ±50 kHz deviation of the aural carrier.

   (9) Total modulation of the aural carrier must not exceed ±75 kHz.

   (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 .

   (Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, 1082 (47 U.S.C.
   154, 155, 303))

   [ 28 FR 13660 , Dec. 14, 1963]

   Editorial Note: 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 .

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