47 CFR Ch. I (10–1–10 Edition)

§ 73.681 47 CFR Ch. I (10–1–10 Edition)

number and/or visit a Web site for de- (i) The fact that Congress has tails. The duration must be at least changed the deadline for the national five (5) seconds. DTV transition to June 12, 2009; (iii) Graphic and audio display. Option (ii) The date and approximate time of #1 or option #2 with an added audio day when the station airing the infor- component. The duration must be at mational video is terminating analog least five (5) seconds. service; (iv) Longer form reminders. Stations (iii) The date and approximate time can choose from a variety of longer of day when all other full-power sta- form options to communicate the tions in the same market are termi- countdown message. Examples might nating analog service; include an ‘‘Ask the Expert’’ segment (iv) For stations covered by para- where viewers can call in to a phone graph (b)(5) of this section, the same bank and ask knowledgeable people service loss information required by their questions about the transition. paragraph (b)(5) of this section. The duration must be at least two (2) [74 FR 11315, Mar. 17, 2009] minutes. (Some stations may also choose to include during newscasts § 73.681 Definitions. DTV ‘‘experts’’ who may be asked ques- Amplitude modulation (AM). A system tions by the anchor or reporter about of modulation in which the envelope of the impending transition deadline.) the transmitted wave contains a com- (e) Consumer Education Campaign Op- ponent similar to the wave form of the tion Three: signal to be transmitted. (1) Only a licensee or permittee of a Antenna electrical beam tilt. The shap- noncommercial television station may ing of the radiation pattern in the elect this option. Under this option, vertical plane of a transmitting an- from March 27, 2008, through April 30, tenna by electrical means so that max- 2008, a noncommercial broadcaster imum radiation occurs at an angle must, at a minimum, air 60 seconds per below the horizontal plane. day of transition-related education Antenna height above average terrain. (PSAs), in variable timeslots, including The average of the antenna heights at least 7.5 minutes per month between above the terrain from approximately 6 p.m. and 12 a.m. From May 1, 2008, 3.2 (2 miles) to 16.1 kilometers (10 through October 31, 2008, a broadcaster miles) from the antenna for the eight must, at a minimum, air 120 seconds directions spaced evenly for each 45 de- per day of transition-related education grees of azimuth starting with True (PSAs), in variable timeslots, including North. (In general, a different antenna at least 15 minutes per month between height will be determined in each di- 6 p.m. and 12 a.m. From November 1, rection from the antenna. The average 2008, through the station’s termination of these various heights is considered of analog service, or, for stations sub- the antenna height above the average ject to the provisions of paragraph terrain. In some cases less than 8 direc- (b)(4) of this section, until the station tions may be used. See § 73.684(d)). completes construction of its full, au- Where circular or elliptical polariza- thorized post-transition digital facil- tion is employed, the antenna height ity, a broadcaster must, at a minimum, above average terrain shall be based air 180 seconds per day of transition-re- upon the height of the radiation center lated education (PSAs), in variable of the antenna which transmits the timeslots, including at least 22.5 min- horizontal component of radiation. utes per month between 6 p.m. and 12 Antenna mechanical beam tilt. The in- a.m. tentional installation of a transmitting (2) Noncommercial stations must air antenna so that its axis is not vertical, a 30-minute informational program on in order to change the normal angle of the digital television (DTV) transition maximum radiation in the vertical between 8 a.m.–11:35 p.m. on at least plane. one day after April 1, 2009, and prior to Antenna power gain. The square of the the station’s termination of analog ratio of the root-mean-square free service. The program must contain at space field strength produced at 1 kilo- least the following information: meter in the horizontal plane, in

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millivolts per meter for one kW an- kW (dBk). (If specified for a particular tenna input power to 221.4 mV/m. This direction, effective radiated power is ratio should be expressed in decibels based on the antenna power gain in (dB). (If specified for a particular direc- that direction only. The licensed effec- tion, antenna power gain is based on tive radiated power is based on the the field strength in that direction maximum antenna power gain. When a only.) station is authorized to use a direc- Aspect ratio. The ratio of picture tional antenna or an antenna beam width to picture height as transmitted. tilt, the direction of the maximum ef- Aural center frequency. (1) The aver- fective radiated power will be speci- age frequency of the emitted wave fied.) Where circular or elliptical polar- when modulated by a sinusoidal signal; ization is employed, the term effective (2) the frequency of the emitted wave radiated power is applied separately to without modulation. the horizontally and vertically polar- Aural transmitter. The radio equip- ized components of radiation. For as- ment for the transmission of the aural signment purposes, only the effective signal only. radiated power authorized for the hori- Auxiliary facility. An auxiliary facility is an antenna separate a from the zontally polarized component will be main facility’s antenna, permanently considered. installed on the same tower or at a dif- Equivalent isotropically radiated power ferent location, from which a station (EIRP). The term ‘‘equivalent may broadcast for short periods with- isotropically radiated power’’ (also out prior Commission authorization or known as ‘‘effective radiated power notice to the Commission while the above isotropic’’) means the product of main facility is not in operation (e.g., the antenna input power and the an- where tower work necessitates turning tenna gain in a given direction relative off the main antenna or where light- to an isotropic antenna. ning has caused damage to the main Field. Scanning through the picture antenna or transmission system) (See area once in the chosen scanning pat- § 73.1675). tern. In the line interlaced scanning BTSC. Broadcast Television systems pattern of two to one, the scanning of committee recommendation for multi- the alternate lines of the picture area channel television sound transmission once. and audio processing as defined in FCC Frame. Scanning all of the picture Bulletin OET 60. area once. In the line interlaced scan- Baseband. Aural transmitter input ning pattern of two to one, a frame signals between 0 and 120 kHz. consists of two fields. Blanking level. The level of the signal Free space field strength. The field during the blanking interval, except strength that would exist at a point in the interval during the scanning syn- the absence of waves reflected from the chronizing pulse and the chrominance earth or other reflecting objects. subcarrier synchronizing burst. Frequency departure. The amount of Chrominance. The colorimetric difference between any color and a ref- variation of a carrier frequency or cen- erence color of equal luminance, the ter frequency from its assigned value. reference color having a specific chro- Frequency deviation. The peak dif- maticity. ference between the instantaneous fre- Chrominance subcarrier. The carrier quency of the modulated wave and the which is modulated by the chro- carrier frequency. minance information. Frequency modulation (FM). A system Color transmission. The transmission of modulation where the instantaneous of color television signals which can be radio frequency varies in proportion to reproduced with different values of the instantaneous amplitude of the hue, saturation, and luminance. modulating signal (amplitude of modu- Effective radiated power. The product lating signal to be measured after pre- of the antenna input power and the an- emphasis, if used) and the instanta- tenna power gain. This product should neous radio frequency is independent of be expressed in kW and in dB above 1 the frequency of the modulating signal.

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Frequency swing. The peak difference Negative transmission. Where a de- between the maximum and the min- crease in initial light intensity causes imum values of the instantaneous fre- an increase in the transmitted power. quency of the carrier wave during mod- Peak power. The power over a radio ulation. frequency cycle corresponding in am- Interlaced scanning. A scanning proc- plitude to synchronizing peaks. ess in which successively scanned lines Percentage modulation. As applied to are spaced an integral number of line frequency modulation, the ratio of the widths, and in which the adjacent lines actual frequency deviation to the fre- are scanned during successive cycles of quency deviation defined as 100% mod- the field frequency. ulation expressed in percentage. For IRE standard scale. A linear scale for the aural transmitter of TV broadcast measuring, in IRE units, the relative stations, a frequency deviation of ±25 amplitudes of the components of a tele- kHz is defined as 100% modulation. vision signal from a zero reference at Pilot subcarrier. A subcarrier used in blanking level, with picture informa- the reception of TV stereophonic aural tion falling in the positive, and syn- or other subchannel broadcasts. chronizing information in the negative Polarization. The direction of the domain. electric field as radiated from the transmitting antenna. NOTE: When a carrier is amplitude modu- Program related data signal. A signal, lated by a television signal in accordance consisting of a series of pulses rep- with § 73.682, the relationship of the IRE resenting data, which is transmitted si- standard scale to the conventional measure multaneously with and directly related of modulation is as follows: to the accompanying television program. IRE stand- Modulation Level ard scale percentage Reference black level. The level cor- (units) responding to the specified maximum Zero carrier ...... 120 0 excursion of the luminance signal in Reference white ...... 100 12.5 the black direction. Blanking ...... 0 75 Reference white level of the luminance Synchronizing peaks (maximum signal. The level corresponding to the carrier level) ...... ¥40 100 specified maximum excursion of the lu- Luminance. Luminous flux emitted, minance signal in the white direction. The process of analyzing reflected, or transmitted per unit solid Scanning. successively, according to a predeter- angle per unit projected area of the mined method, the light values of pic- source. ture elements constituting the total Main channel. The band of fre- picture area. quencies from 50 to 15,000 Hertz which Scanning line. A single continuous frequency modulate the main aural narrow strip of the picture area con- carrier. taining highlights, shadows, and half- Monochrome transmission. The trans- tones, determined by the process of mission of television signals which can scanning. be reproduced in gradations of a single Standard television signal. A signal color only. which conforms to the television trans- Multichannel Television Sound (MTS). mission standards. Any system of aural transmission that Synchronization. The maintenance of utilizes aural baseband operation be- one operation in step with another. tween 15 kHz and 120 kHz to convey in- Television broadcast band. The fre- formation or that encodes digital infor- quencies in the band extending from 54 mation in the video portion of the tele- to 806 megahertz which are assignable vision signal that is intended to be de- to television broadcast stations. These coded as audio information. frequencies are 54 to 72 megahertz Multiplex Transmission (Aural). A sub- (channels 2 through 4), 76 to 88 mega- channel added to the regular aural car- hertz (channels 5 and 6), 174 to 216 rier of a television broadcast station by megahertz (channels 7 through 13), and means of frequency modulated subcar- 470 to 806 megahertz (channels 14 riers. through 69).

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Television broadcast station. A station power output of 1 kW or less the visual in the television broadcast band trans- transmission amplitude characteristic mitting simultaneous visual and aural may be in accordance with the chart signals intended to be received by the designated as Figure 5a of § 73.699. general public. (5) The chrominance subcarrier fre- Television channel. A band of frequency is 63/88 times precisely 5 MHz quencies 6 MHz wide in the television (3.57954545 . . . MHz). The tolerance is broadcast band and designated either ±10 Hz and the rate of frequency drift by number or by the extreme lower and must not exceed 0.1 Hz per second (cy- upper frequencies. cles per second squared). Television transmission standards. The (6) For monochrome and color trans- standards which determine the charac- missions the number of scanning lines teristics of a television signal as radi- per frame shall be 525, interlaced two ated by a television broadcast station. to one in successive fields. The hori- Television transmitter. The radio zontal scanning frequency shall be 2/455 transmitter or transmitters for the times the chrominance subcarrier fre- transmission of both visual and aural quency; this corresponds nominally to signals. 15,750 Hz with an actual value of Vestigial sideband transmission. A sys- 15,734.264 ±0.044 Hz). The vertical scan- tem of transmission wherein one of the ning frequency is 2/525 times the hori- generated sidebands is partially at- zontal scanning frequency; this cor- tenuated at the transmitter and radi- responds nominally to 60 Hz (the actual ated only in part. value is 59.94 Hz). For monochrome Visual carrier frequency. The fre- transmissions only, the nominal values quency of the carrier which is modu- of line and field frequencies may be lated by the picture information. used. Visual transmitter. The radio equip- (7) The aspect ratio of the trans- ment for the transmission of the visual mitted television picture shall be 4 signal only. units horizontally to 3 units vertically. Visual transmitter power. The peak (8) During active scanning intervals, power output when transmitting a the scene shall be scanned from left to standard television signal. right horizontally and from top to bot- [28 FR 13660, Dec. 14, 1963, as amended at 35 tom vertically, at uniform velocities. FR 5692, Apr. 8, 1970; 36 FR 5505, Mar. 24, 1971; (9) A carrier shall be modulated with- 36 FR 17429, Aug. 31, 1971; 41 FR 56325, Dec. 28, in a single television channel for both 1976; 42 FR 20823, Apr. 22, 1977; 44 FR 36039, picture and synchronizing signals. The June 20, 1979; 47 FR 35990, Aug. 18, 1982; 49 FR two signals comprise different modula- 18106, Apr. 27, 1984; 49 FR 38131, Sept. 27, 1984; 49 FR 50048, Dec. 26, 1984; 50 FR 23699, June 5, tion ranges in amplitude in accordance 1985; 51 FR 12616, Apr. 14, 1986; 56 FR 49707, with the following: Oct. 1, 1991; 58 FR 44951, Aug. 25, 1993; 62 FR (i) Monochrome transmissions shall 51059, Sept. 30, 1997] comply with synchronizing waveform specifications in Figure 7 of § 73.699. § 73.682 TV transmission standards. (ii) Color transmissions shall comply (a) Transmission standards. (1) The with the synchronizing waveform spec- width of the television broadcast chan- ifications in Figure 6 of § 73.699. nel shall be 6 MHz. (iii) All stations operating on Chan- (2) The visual carrier frequency shall nels 2 through 14 and those stations op- be nominally 1.25 MHz above the lower erating on Channels 15 through 69 li- boundary of the channel. censed for a peak visual transmitter (3) The aural center frequency shall output power greater than one kW be 4.5 MHz higher than the visual car- shall comply with the picture trans- rier frequency. mission amplitude characteristics (4) The visual transmission ampli- shown in Figure 5 of § 73.699. tude characteristic shall be in accord- (iv) Stations operating on Channels ance with the chart designated as Fig- 15 through 69 licensed for a peak visual ure 5 of § 73.699: Provided, however, That transmitter output power of one kW or for stations operating on Channel 15 less shall comply with the picture through 69 and employing a trans- transmission amplitude characteristic mitter with maximum peak visual shown in Figure 5 or 5a of § 73.699.

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