47 CFR Ch. I (10–1–10 Edition)

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 206 VerDate Mar<15>2010 10:45 Nov 16, 2010 Jkt 220203 PO 00000 Frm 00216 Fmt 8010 Sfmt 8010 Y:\SGML\220203.XXX 220203 WReier-Aviles on DSKGBLS3C1PROD with CFR Federal Communications Commission § 73.681 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 facil- ity 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 dif- ference 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. 207 VerDate Mar<15>2010 10:45 Nov 16, 2010 Jkt 220203 PO 00000 Frm 00217 Fmt 8010 Sfmt 8010 Y:\SGML\220203.XXX 220203 WReier-Aviles on DSKGBLS3C1PROD with CFR § 73.681 47 CFR Ch. I (10–1–10 Edition) 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.

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