Federal Communications Commission § 2.1049

§ 2.1049 Measurements required: Occu- used as modulating frequencies, upon a pied bandwidth. sufficient showing of need. However, The occupied bandwidth, that is the any tones so chosen must not be har- frequency bandwidth such that, below monically related, the third and fifth its lower and above its upper frequency order intermodulation products which limits, the mean powers radiated are occur must fall within the ¥25 dB step each equal to 0.5 percent of the total of the emission bandwidth limitation mean power radiated by a given emis- curve, the seventh and ninth order sion shall be measured under the fol- products must fall within the ¥35 dB lowing conditions as applicable: step of the referenced curve and the (a) Radiotelegraph transmitters for eleventh and all higher order products manual operation when keyed at 16 must fall beyond the ¥35 dB step of the dots per second. referenced curve. (b) Other keyed transmitters—when (5) Independent sideband transmit- keyed at the maximum machine speed. ters having two channels—when modu- (c) Radiotelephone transmitters lated by 1700 Hz tones applied simulta- equipped with a device to limit modu- neously to both channels. The input lation or peak envelope power shall be levels of the tones shall be so adjusted modulated as follows. For single side- that the two principal frequency com- band and independent sideband trans- ponents of the radio frequency signal mitters, the input level of the modu- produced are equal in magnitude. lating signal shall be 10 dB greater (d) Radiotelephone transmitters than that necessary to produce rated without a device to limit modulation peak envelope power. or peak envelope power shall be modu- (1) Other than single sideband or lated as follows. For single sideband independent sideband transmitters— and independent sideband transmitters, when modulated by a 2500 Hz tone at an the input level of the modulating sig- input level 16 dB greater than that nec- nal should be that necessary to produce essary to produce 50 percent modula- rated peak envelope power. tion. The input level shall be estab- (1) Other than single sideband or lished at the frequency of maximum re- independent sideband transmitters— sponse of the audio modulating circuit. when modulated by a 2500 Hz tone of (2) Single sideband transmitters in sufficient level to produce at least 85 A3A or A3J emission modes—when modulated by two tones at frequencies percent modulation. If 85 percent mod- of 400 Hz and 1800 Hz (for 3.0 kHz au- ulation is unattainable, the highest thorized bandwidth), or 500 Hz and 2100 percentage modulation shall be used. Hz (for 3.5 kHz authorized bandwidth), (2) Single sideband transmitters in or 500 Hz and 2400 Hz (for 4.0 kHz au- A3A or A3J emission modes—when thorized bandwidth), applied simulta- modulated by two tones at frequencies neously. The input levels of the tones of 400 Hz and 1800 Hz (for 3.0 kHz au- shall be so adjusted that the two prin- thorized bandwidth), or 500 Hz and 2100 cipal frequency components of the Hz (for 3.5 kHz authorized bandwidth), radio frequency signal produced are or 500 Hz and 2400 Hz (for 4.0 kHz au- equal in magnitude. thorized bandwidth), applied simulta- (3) Single sideband transmitters in neously. The input levels of the tones the A3H emission mode—when modu- shall be so adjusted that the two prin- lated by one tone at a frequency of 1500 cipal frequency components of the Hz (for 3.0 kHz authorized bandwidth), radio frequency signal produced are or 1700 Hz (for 3.5 kHz authorized band- equal in magnitude. width), or 1900 Hz (for 4.0 kHz author- (3) Single sideband transmitters in ized bandwidth), the level of which is the A3H emission mode—when modu- adjusted to produce a radio frequency lated by one tone at a frequency of 1500 signal component equal in magnitude Hz (for 3.0 kHz authorized bandwidth), to the magnitude of the carrier in this or 1700 Hz (for 3.5 kHz authorized band- mode. width), or 1900 Hz (for 4.0 kHz author- (4) As an alternative to paragraphs ized bandwidth), the level of which is (c) (2) and (3) of this section, other adjusted to produce a radio frequency tones besides those specified may be signal component equal in magnitude

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to the magnitude of the carrier in this the stereophonic subchannel, and the mode. pilot subcarrier simultaneously. The (4) As an alternative to paragraphs input signals to the main channel and (d) (2) and (3) of this section, other stereophonic subchannel each shall tones besides those specified may be produce 38 percent modulation of the used as modulating frequencies, upon a carrier. The pilot subcarrier should sufficient showing of need. However produce 9 percent modulation of the any tones so chosen must not be har- carrier. monically related, the third and fifth (6) Television broadcast monaural order intermodulation products which transmitters—when modulated 85% by occur must fall within the ¥25 dB step a 15 kHz input signal. of the emission bandwidth limitation (7) Television broadcast stereophonic curve, the seventh and ninth order sound transmitters—when the trans- products must fall within the ¥35 dB mitter is modulated with a 15 kHz step of the referenced curve and the input signal to the main channel and eleventh and all higher order products the stereophonic subchannel, any pilot must fall beyond the ¥35 dB step of the subcarrier(s) and any unmodulated referenced curve. auxiliary subcarrier(s) which may be (5) Independent sideband transmit- provided. The signals to the main chan- ters having two channels—when modu- nel and the stereophonic subchannel lated by 1700 Hz tones applied simulta- must be representative of the system neously to both channels. The input being tested and when combined with levels of the tones shall be so adjusted any pilot subcarrier(s) or other auxil- that the two principal frequency com- iary subcarriers shall result in 85% de- ponents of the radio frequency signal viation of the maximum specified aural produced are equal in magnitude. carrier deviation. (e) Transmitters for use in the Radio (f) Transmitters for which peak fre- Broadcast Services: quency deviation (D) is determined in (1) AM broadcast transmitters for accordance with § 2.202(f), and in which monaural operation—when amplitude the modulating baseband comprises modulated 85% by a 7,500 Hz input sig- more than 3 independent speech chan- nal. nels—when modulated by a test signal (2) AM broadcast stereophonic oper- determined in accordance with the fol- ation—when the transmitter operated lowing: under any stereophonic modulation (1) A modulation reference level is es- condition not exceeding 100% on nega- tablished for the characteristic tive peaks and tested under the condi- baseband frequency. (Modulation ref- tions specified in § 73.128 in part 73 of erence level is defined as the average the FCC rules for AM broadcast sta- power level of a sinusoidal test signal tions. delivered to the modulator input which (3) FM broadcast transmitter not provides the specified value of per- used for multiplex operation—when channel deviation.) modulated 85 percent by a 15 kHz input (2) Modulation reference level being signal. established, the total rms deviation of (4) FM broadcast transmitters for the transmitter is measured when a multiplex operation under Subsidiary test signal consisting of a band of ran- Communication Authorization (SCA)— dom noise extending from below 20 kHz when carrier is modulated 70 percent to the highest frequency in the by a 15 kHz main channel input signal, baseband, is applied to the modulator and modulated an additional 15 percent input through any preemphasis net- simultaneously by a 67 kHz subcarrier works used in normal service. The av- (unmodulated). erage power level of the test signal (5) FM broadcast transmitter for shall exceed the modulation reference stereophonic operation—when modu- level by the number of decibels deter- lated by a 15 kHz input signal to the mined using the appropriate formula in main channel, a 15 kHz input signal to the following table:

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Number of message circuits that Number of dB by which the average power (Pavg) level test sig- modulate the transmitter nal shall exceed the modulation reference level Limits of Pavg (dBm0)

More than 3, but less than 12 ...... To be specified by the equipment manufacturer subject to FCC approval. At least 12, but less than 60 ...... X+2 log10 Nc ...... X: ¥2 to +2.6 At least 60, but less than 240 ...... X+4 log10 Nc ...... X: ¥5.6 to ¥1.0 240 or more ...... X+10 log10 Nc ...... X: ¥19.6 to ¥15.0

Where X represents the average power in a message circuit in dBm0; Nc is the number of circuits in the multiplexed message load. Pavg shall be selected by the transmitter manufacturer and included with the technical data submitted with the application for type acceptance. (See § 2.202(e) in this chapter.)

(g) Transmitters in which the modu- and appearing on a spurious frequency lating baseband comprises not more shall be checked at the equipment out- than three independent channels— put terminals when properly loaded when modulated by the full com- with a suitable artificial antenna. plement of signals for which the trans- Curves or equivalent data shall show mitter is rated. The level of modula- the magnitude of each harmonic and tion for each channel should be set to other spurious emission that can be de- that prescribed in rule parts applicable tected when the equipment is operated to the services for which the trans- under the conditions specified in mitter is intended. If specific modula- § 2.1049 as appropriate. The magnitude tion levels are not set forth in the of spurious emissions which are attenu- rules, the tests should provide the ated more than 20 dB below the permis- manufacturer’s maximum rated condi- sible value need not be specified. tion. [39 FR 5919, Feb. 15, 1974. Redesignated and (h) Transmitters employing digital amended at 63 FR 36599, July 7, 1998] modulation techniques—when modu- lated by an input signal such that its § 2.1053 Measurements required: Field amplitude and symbol rate represent strength of spurious radiation. the maximum rated conditions under (a) Measurements shall be made to which the equipment will be operated. detect spurious emissions that may be The signal shall be applied through any radiated directly from the cabinet, filter networks, pseudo-random genera- control circuits, power leads, or inter- tors or other devices required in nor- mediate circuit elements under normal mal service. Additionally, the occupied conditions of installation and oper- bandwidth shall be shown for operation ation. Curves or equivalent data shall with any devices used for modifying be supplied showing the magnitude of the spectrum when such devices are op- each harmonic and other spurious tional at the discretion of the user. emission. For this test, single side- (i) Transmitters designed for other band, independent sideband, and con- types of modulation—when modulated trolled carrier transmitters shall be by an appropriate signal of sufficient modulated under the conditions speci- amplitude to be representative of the fied in paragraph (c) of § 2.1049, as ap- type of service in which used. A de- propriate. For equipment operating on scription of the input signal should be frequencies below 890 MHz, an open supplied. field test is normally required, with (Secs. 4, 303, 307, 48 Stat., as amended, 1066, the measuring instrument antenna lo- 1082, 1083; 47 U.S.C. 154, 303, 307) cated in the far-field at all test fre- quencies. In the event it is either im- [39 FR 5919, Feb. 15, 1974, as amended at 39 FR 35664, Oct. 3, 1974; 47 FR 13164, Mar. 29, practical or impossible to make open 1982; 48 FR 16493, Apr. 18, 1983; 49 FR 18105, field measurements (e.g. a broadcast Apr. 27, 1984. Redesignated at 63 FR 36599, transmitter installed in a building) July 7, 1998] measurements will be accepted of the equipment as installed. Such measure- § 2.1051 Measurements required: Spu- ments must be accompanied by a de- rious emissions at antenna termi- scription of the site where the meas- nals. urements were made showing the loca- The radio frequency voltage or pow- tion of any possible source of reflec- ers generated within the equipment tions which might distort the field

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