FCC 73.682 Revised as of October 1, 2007
Goto Year:2006 |
2008
Sec. 73.682 TV transmission standards.
(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 Sec. 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 Sec. 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 Sec. 73.699.
(ii) Color transmissions shall comply with the synchronizing waveform
specifications in Figure 6 of Sec. 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 Sec. 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 Sec. 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′) sinω t +( E R′− E Y′) cosω t ]]
(ii) The symbols in paragraph (a)(20)(i) of this section have the following
significance:
E Mis 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.
ωis 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 Mequation in (i) is the phase of the
burst+180 °, as shown in Figure 8 of Sec. 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 secs.
(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
Sec. 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 Sec. 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 Sec. 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 Sec. 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 Sec. 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 Sec. 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
Sec. 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 Sec. 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 Sec. 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
Sec. 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 Sec. 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 February
1, 2005, 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 Sec. 73.8000), ATSC Doc. A/53B, Revision B with Amendment 1 and Amendment 2:
“ATSC Digital Television Standard,” except for Section 5.1.2 (“Compression
format constraints”) of Annex A (“Video Systems Characteristics”) and the
phrase “ see Table 3” in Section 5.1.1. Table 2 and Section 5.1.2 Table 4
(incorporated by reference, see Sec. 73.8000), and ATSC A/65B: “ATSC Program and
System Information Protocol for Terrestrial Broadcast and Cable,” (Revision
B) 2003 (incorporated by reference, see Sec. 73.8000). Although not incorporated
by reference, licensees may also consult ATSC Doc. A/54, Guide to Use of the
ATSC Digital Television Standard, (October 4, 1995), and ATSC Doc. 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))
[ 28 FR 13660 , Dec. 14, 1963]
Editorial Note: ForFederal Registercitations affecting Sec. 73.682, see the
List of CFR Sections Affected, which appears in the Finding Aids section of
the printed volume and on GPO Access.
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