§ 73.1 47 CFR Ch. I (10–1–10 Edition) Subpart J—Class A Television Broadcast Subpart M—Digital Broadcast Television Stations Redistribution Control 73.6000 Definitions. 73.9000 Definitions. 73.6001 Eligibility and service requirements. 73.9001 Redistribution control of digital tel- 73.6002 Licensing requirements. evision broadcasts. 73.6003–73.6005 [Reserved] 73.9002 Sale or distribution of demodulators, 73.6006 Channel assignments. covered demodulator products, and pe- 73.6007 Power limitations. ripheral TSP products. 73.6008 Distance computations. 73.9003 Compliance requirements for cov- 73.6010 Class A TV station protected con- ered demodulator products: Unscreened tour. content. 73.6011 Protection of TV broadcast stations. 73.9004 Compliance requirements for cov- 73.6012 Protection of Class A TV, low power ered demodulator products: Marked con- TV, and TV translator stations. tent. 73.6013 Protection of DTV stations. 73.9005 Compliance requirements for cov- 73.6014 Protection of digital Class A TV sta- ered demodulator products: Audio. tions. 73.9006 Add-in covered demodulator prod- 73.6016 Digital Class A TV station protec- ucts. tion of TV broadcast stations. 73.9007 Robustness requirements for covered 73.6017 Digital Class A TV station protec- demodulator products. tion of Class A TV and digital Class A TV 73.9008 Interim approval of authorized dig- stations. ital output protection technologies and 73.6018 Digital Class A TV station protec- authorized recording methods. tion of DTV stations. 73.9009 Manufacture for exportation. 73.6019 Digital Class A TV station protec- ALPHABETICAL INDEX—PART 73 tion of low power TV, TV translator, dig- ital low power TV and digital TV trans- AUTHORITY: 47 U.S.C. 154, 303, 334, 336, and lator stations. 339. 73.6020 Protection of stations in the land mobile radio service. 73.6022 Negotiated interference and reloca- Subpart A—AM Broadcast Stations tion agreements. 73.6023 Distributed transmission systems. § 73.1 Scope. 73.6024 Transmission standards and system This subpart contains those rules requirements. which apply exclusively to the AM 73.6025 Antenna system and station loca- broadcast service and are in addition to tion. those rules in Subpart H which are 73.6026 Broadcast regulations applicable to Class A television stations. common to all AM, FM and TV broad- 73.6027 Class A TV notifications concerning cast services, commercial and non- interference to radio astronomy, re- commercial. search and receiving installations. [47 FR 8587, Mar. 1, 1982] Subpart K—Application and Selection Pro- § 73.14 AM broadcast definitions. cedures for Reserved Noncommercial Educational Channels, and for Certain AM broadcast band. The band of fre- Applications for Noncommercial Edu- quencies extending from 535 to 1705 cational Stations on Non-Reserved kHz. Channels AM broadcast channel. The band of frequencies occupied by the carrier and 73.7000 Definition of terms (as used in sub- the upper and lower sidebands of an part K only). AM broadcast signal with the carrier 73.7001 Services subject to evaluation by point system. frequency at the center. Channels are 73.7002 Fair distribution of service on re- designated by their assigned carrier served band FM channels. frequencies. The 117 carrier frequencies 73.7003 Point system selection procedures. assigned to AM broadcast stations 73.7004 Petitions to deny tentative se- begin at 540 kHz and progress in 10 kHz lectee(s). steps to 1700 kHz. (See § 73.21 for the 73.7005 Holding period. classification of AM broadcast chan- nels). Subpart L—Digital Broadcast Television AM broadcast station. A broadcast sta- Redistribution Control tion licensed for the dissemination of 73.8000 Incorporation by reference. radio communications intended to be 10 VerDate Mar<15>2010 10:45 Nov 16, 2010 Jkt 220203 PO 00000 Frm 00020 Fmt 8010 Sfmt 8010 Y:\SGML\220203.XXX 220203 WReier-Aviles on DSKGBLS3C1PROD with CFR Federal Communications Commission § 73.14 received by the public and operated on may be accepted under conditions pre- a channel in the AM broadcast band. scribed by the FCC. Amplitude modulated stage. The radio- Critical hours. The two hour period frequency stage to which the modu- immediately following local sunrise lator is coupled and in which the car- and the two hour period immediately rier wave is modulated in accordance preceding local sunset. with the system of amplitude modula- Daytime. The period of time between tion and the characteristics of the local sunrise and local sunset. modulating wave. Effective field; Effective field strength. Amplitude modulator stage. The last The root-mean-square (RMS) value of amplifier stage of the modulating wave the inverse distance fields at a distance amplitude modulates a radio-frequency of 1 kilometer from the antenna in all stage. directions in the horizontal plane. The Antenna current. The radio-frequency term ‘‘field strength’’ is synonymous current in the antenna with no modu- with the term ‘‘field intensity’’ as con- lation. tained elsewhere in this Part. Equipment performance measurements. Antenna input power. The product of The measurements performed to deter- the square of the antenna current and mine the overall performance charac- the antenna resistance at the point teristics of a broadcast transmission where the current is measured. system from point of program origina- Antenna resistance. The total resist- tion at main studio to sampling of sig- ance of the transmitting antenna sys- nal as radiated. (See § 73.1590) tem at the operating frequency and at Experimental period. the time between the point at which the antenna current 12 midnight local time and local sun- is measured. rise, used by AM stations for tests, Auxiliary facility. An auxiliary facil- maintenance and experimentation. ity is an AM antenna tower(s) separate Frequency departure. The amount of from the main facility’s antenna variation of a carrier frequency or cen- tower(s), permanently installed at the ter frequency from its assigned value. same site or at a different location, Incidental phase modulation. The peak from which an AM station may broad- phase deviation (in radians) resulting cast for short periods without prior from the process of amplitude modula- Commission authorization or notice to tion. the Commission while the main facil- Input power. Means the product of the ity is not in operation (e.g., where direct voltage applied to the last radio tower work necessitates turning off the stage and the total direct current flow- main antenna or where lightning has ing to the last radio stage, measured caused damage to the main antenna or without modulation. transmission system) (See § 73.1675). Intermittent service area. Means the Blanketing. The interference which is area receiving service from the caused by the presence of an AM broad- groundwave of a broadcast station but cast signal of one volt per meter (V/m) beyond the primary service area and or greater strengths in the area adja- subject to some interference and fad- cent to the antenna of the transmit- ing. ting station. The 1 V/m contour is re- Last radio stage. The radio-frequency ferred to as the blanket contour and power amplifier stage which supplies the area within this contour is referred power to the antenna. to as the blanket area. Left (or right) signal. The electrical Carrier-amplitude regulation (Carrier output of a microphone or combination shift). The change in amplitude of the of microphones placed so as to convey carrier wave in an amplitude-modu- the intensity, time, and location of lated transmitter when modulation is sounds originated predominately to the applied under conditions of symmet- listener’s left (or right) of the center of rical modulation. the performing area. Combined audio harmonics. The arith- Left (or right) stereophonic channel. metical sum of the amplitudes of all The left (or right) signal as electrically the separate harmonic components. reproduced in reception of AM stereo- Root sum square harmonic readings phonic broadcasts. 11 VerDate Mar<15>2010 10:45 Nov 16, 2010 Jkt 220203 PO 00000 Frm 00021 Fmt 8010 Sfmt 8010 Y:\SGML\220203.XXX 220203 WReier-Aviles on DSKGBLS3C1PROD with CFR § 73.14 47 CFR Ch. I (10–1–10 Edition) Main channel. The band of audio fre- M = C¥MIN × 100 quencies from 50 to 10,000 Hz which am- ————–—––— plitude modulates the carrier. c Maximum percentage of modulation. Where: The greatest percentage of modulation M = Modulation level in percent. that may be obtained by a transmitter MAX = Instantaneous maximum level of the modulated radio frequency envelope. without producing in its output, MIN = Instantaneous minimum level of the harmonics of the modulating frequency modulated radio frequency envelope. in excess of those permitted by these C = (Carrier) level of radio frequency enve- regulations. (See § 73.1570) lope without modulation. Maximum rated carrier power. The Plate modulation. The modulation maximum power at which the trans- produced by introduction of the modu- mitter can be operated satisfactorily lating wave into the plate circuit of and is determined by the design of the any tube in which the carrier fre- transmitter and the type and number quency wave is present. of vacuum tubes or other amplifier de- Primary service area. Means the serv- vices used in the last radio stage. ice area of a broadcast station in which Model I facility. A station operating the groundwave is not subject to objec- in the 1605–1705 kHz band featuring tionable interference or objectionable fulltime operation with stereo, com- fading. petitive technical quality, 10 kW day- Proof of performance measurements or time power, 1 kW nighttime power, antenna proof of performance measure- non-directional antenna (or a simple ments. The measurements of field directional antenna system), and sepa- strengths made to determine the radi- rated by 400–800 km from other co- ation pattern or characteristics of an channel stations.