Goto Section: 2.201 | 2.301 | Table of Contents

FCC 2.202
Revised as of November 27, 2020
Goto Year:2020 | 2022
  §  2.202   Bandwidths.

   (a) Occupied bandwidth. The frequency bandwidth such that, below its
   lower and above its upper frequency limits, the mean powers radiated
   are each equal to 0.5 percent of the total mean power radiated by a
   given emission. In some cases, for example multichannel
   frequency-division systems, the percentage of 0.5 percent may lead to
   certain difficulties in the practical application of the definitions of
   occupied and necessary bandwidth; in such cases a different percentage
   may prove useful.

   (b) Necessary bandwidth. For a given class of emission, the minimum
   value of the occupied bandwidth sufficient to ensure the transmission
   of information at the rate and with the quality required for the system
   employed, under specified conditions. Emissions useful for the good
   functioning of the receiving equipment as, for example, the emission
   corresponding to the carrier of reduced carrier systems, shall be
   included in the necessary bandwidth.

   (1) The necessary bandwidth shall be expressed by three numerals and
   one letter. The letter occupies the position of the decimal point and
   represents the unit of bandwidth. The first character shall be neither
   zero nor K, M or G.

   (2) Necessary bandwidths:

   between 0.001 and 999 Hz shall be expressed in Hz (letter H);

   between 1.00 and 999 kHz shall be expressed in kHz (letter K);

   between 1.00 and 999 MHz shall be expressed in MHz (letter M);

   between 1.00 and 999 GHz shall be expressed in GHz (letter G).

   (3) Examples:
   0.002 Hz—H002     180.5 kHz—181K
   0.1 Hz—H100       180.7 kHz—181K
   25.3 Hz—25H3      1.25 MHz—1M25
   400 Hz—400H       2 MHz—2M00
   2.4 kHz—2K40      10 MHz—10M0
   6 kHz—6K00        202 MHz—202M
   12.5 kHz—12K5     5.65 GHz—5G65
   180.4 kHz—180K

   (c) The necessary bandwidth may be determined by one of the following
   methods:

   (1) Use of the formulas included in the table, in paragraph (g) of this
   section, which also gives examples of necessary bandwidths and
   designation of corresponding emissions;

   (2) For frequency modulated radio systems which have a substantially
   linear relationship between the value of input voltage to the modulator
   and the resulting frequency deviation of the carrier and which carry
   either single sideband suppressed carrier frequency division multiplex
   speech channels or television, computation in accordance with
   provisions of paragraph (f) of this section and formulas and methods
   indicated in the table, in paragraph (g) of this section;

   (3) Computation in accordance with Recommendations of the International
   Radio Consultative Committee (C.C.I.R.);

   (4) Measurement in cases not covered by paragraph (c) (1), (2), or (3)
   of this section.

   (d) The value so determined should be used when the full designation of
   an emission is required. However, the necessary bandwidth so determined
   is not the only characteristic of an emission to be considered in
   evaluating the interference that may be caused by that emission.

   (e) In the formulation of the table in paragraph (g) of this section,
   the following terms are employed:

   Bn = Necessary bandwidth in hertz

   B = Modulation rate in bauds

   N = Maximum possible number of black plus white elements to be
   transmitted per second, in facsimile

   M = Maximum modulation frequency in hertz

   C = Sub-carrier frequency in hertz

   D = Peak frequency deviation, i.e., half the difference between the
   maximum and minimum values of the instantaneous frequency. The
   instantaneous frequency in hertz is the time rate of change in phase in
   radians divided by 2

   t = Pulse duration in seconds at half-amplitude

   tr = Pulse rise time in seconds between 10% and 90% of maximum
   amplitude

   K = An overall numerical factor which varies according to the emission
   and which depends upon the allowable signal distortion.

   Nc = Number of baseband telephone channels in radio systems employing
   multichannel multiplexing

   P = Continuity pilot sub-carrier frequency (Hz) (continuous signal
   utilized to verify performance of frequency-division multiplex
   systems).

   (f) Determination of values of D and Bn for systems specified in
   paragraph (c)(2) of this section:

   (1) Determination of D in systems for multichannel telephony:

   (i) The rms value of the per-channel deviation for the system shall be
   specified. (In the case of systems employing preemphasis or phase
   modulation, this value of per-channel deviation shall be specified at
   the characteristic baseband frequency.)

   (ii) The value of D is then calculated by multiplying the rms value of
   the per-channel deviation by the appropriate factors, as follows:
   Number of message circuits Multiplying factors Limits of X (Pavg
   (dBmO))
   More than 3, but less than 12 4.47 × [a factor specified by the
   equipment manufacturer or station licensee, subject to Commission
   approval]
       3.76 antilog (X + 2 log10 Nc)
   At least 12, but less than 60 ————————————— X: −2 to + 2.6.
       20
       3.76 antilog (X + 4 log10 Nc)
   At least 60, but less than 240 ————————————— X: −5.6to −1.0.
       20
       3.76 antilog (X + 10 log10 Nc)
   240 or more ————————————— X: −19.6 to −15.0.
       20

   Where X represents the average power in a message circuit in dBmO; Nc
   is the number of circuits in the multiplexed message load; 3.76
   corresponds to a peak load factor of 11.5 dB.

   (2) The necessary bandwidth (Bn) normally is considered to be
   numerically equal to:

   (i) 2M + 2DK, for systems having no continuity pilot subcarrier or
   having a continuity pilot subcarrier whose frequency is not the highest
   modulating the main carrier;

   (ii) 2P + 2DK, for systems having a continuity pilot subcarrier whose
   frequency exceeds that of any other signal modulating the main carrier,
   unless the conditions set forth in paragraph (f)(3) of this section are
   met.

   (3) As an exception to paragraph (f)(2)(ii) of this section, the
   necessary bandwidth (Bn) for such systems is numerically equal to 2P or
   2M + 2DK, whichever is greater, provided the following conditions are
   met:

   (i) The modulation index of the main carrier due to the continuity
   pilot subcarrier does not exceed 0.25, and

   (ii) In a radio system of multichannel telephony, the rms frequency
   deviation of the main carrier due to the continuity pilot subcarrier
   does not exceed 70 percent of the rms value of the per-channel
   deviation, or, in a radio system for television, the rms deviation of
   the main carrier due to the pilot does not exceed 3.55 percent of the
   peak deviation of the main carrier.

   (g) Table of necessary bandwidths:
   Description of emission Necessary bandwidth Designation of emission
   Formula Sample calculation
   I. NO MODULATING SIGNAL
   Continuous wave emission N0N (zero)
   II. AMPLITUDE MODULATION
   1. Signal With Quantized or Digital Information
   Continuous wave telegraphy Bn = BK, K = 5 for fading circuits, K = 3
   for non-fading circuits 25 words per minute; B = 20, K = 5, Bandwidth:
   100 Hz 100HA1A
   Telegraphy by on-off keying of a tone modulated carrier Bn = BK + 2M, K
   = 5 for fading circuits, K = 3 for non-fading circuits 25 words per
   minute; B = 20, M = 1000, K = 5, Bandwidth: 2100 Hz = 2.1 kHz 2K10A2A
   Selective calling signal, single-sideband full carrier Bn = M Maximum
   code frequency is: 2110 Hz, M = 2110, Bandwidth: 2110 Hz = 2.11 kHz
   2K11H2B
   Direct-printing telegraphy using a frequency shifted modulating
   sub-carrier single-sideband suppressed carrier Bn = 2M + 2DK, M = B ÷ 2
   B = 50, D = 35 Hz (70 Hz shift), K = 1.2, Bandwidth: 134 Hz 134HJ2B
   Telegraphy, single sideband reduced carrier Bn = central frequency + M
   + DK, M = B ÷ 2 15 channels; highest central frequency is: 2805 Hz, B =
   100, D = 42.5 Hz (85 Hz shift), K = 0.7 Bandwidth: 2.885 Hz = 2.885 kHz
   2K89R7B
   2. Telephony (Commercial Quality)
   Telephony double-sideband Bn = 2M M = 3000, Bandwidth = 6000 Hz = 6 kHz
   6K00A3E
   Telephony, single-sideband, full carrier Bn = 2M M = 3000, Bandwidth:
   3000 Hz = 3 kHz 3K00H3E
   Telephony, single-sideband suppressed carrier Bn = M−lowest modulation
   frequency M = 3000, lowest modulation frequency is 3000 Hz, 2700 Hz
   Bandwidth: 2700Hz = 2.7 kHz 2K70J3E
   Telephony with separate frequency modulated signal to control the level
   of demodulated speech signal, single-sideband, reduced carrier Bn = M
   Maximum control frequency is 2990 Hz, M = 2990, Bandwidth: 2990 Hz =
   2.99 kHz 2K99R3E
   Telephony with privacy, single-sideband, suppressed carrier (two or
   more channels) Bn = Nc M−lowest modulation frequency in the lowest
   channel Nc = 2, M = 3000 lowest modulation frequency is 250 Hz,
   Bandwidth: 5750 Hz = 5.75 kHz 5K75J8E
   Telephony, independent sideband (two or more channels) Bn = sum of M
   for each sideband 2 channels, M = 3000, Bandwidth: 6000 Hz = 6 kHz
   6K00B8E
   3. Sound Broadcasting
   Sound broadcasting, double-sideband Bn = 2M, M may vary between 4000
   and 10000 depending on the quality desired Speech and music, M = 4000,
   Bandwidth: 8000 Hz= 8 kHz 8K00A3E
   Sound broadcasting, single-sideband reduced carrier (single channel) Bn
   = M, M may vary between 4000 and 10000 depending on the quality desired
   Speech and music, M = 4000, Bandwidth: 4000 Hz= 4 kHz 4K00R3E
   Sound broadcasting, single-sideband, suppressed carrier Bn = M−lowest
   modulation frequency Speech and music, M = 4500, lowest modulation
   frequency = 50 Hz, Bandwidth: 4450 Hz = 4.45 kHz 4K45J3E
   4. Television
   Television, vision and sound Refer to CCIR documents for the bandwidths
   of the commonly used television systems Number of lines = 525; Nominal
   video bandwidth: 4.2 MHz, Sound carrier relative to video carrier = 4.5
   MHz 5M75C3F
           Total vision bandwidth: 5.75 MHz; FM aural bandwidth including
   guardbands: 250,000 Hz 250KF3E
           Total bandwidth: 6 MHz 6M25C3F
   5. Facsimile
   Analogue facsimile by sub-carrier frequency modulation of a
   single-sideband emission with reduced carrier Bn = C−N ÷ 2 + DK, K =
   1.1 (typically) N = 1100, corresponding to an index of cooperation of
   352 and a cycler rotation speed of 60 rpm. Index of cooperation is the
   product of the drum diameter and number of lines per unit length C =
   1900, D = 400 Hz, Bandwidth = 2.890 Hz = 2.89 kHz 2K89R3C
   Analogue facsimile; frequency modulation of an audio frequency
   sub-carrier which modulates the main carrier, single-sideband
   suppressed carrier Bn = 2M + 2DK, M = N/2, K = 1.1 (typically) N =
   1100, D = 400 Hz, Bandwidth: 1980 Hz = 1.98 kHz 1K98J3C
   6. Composite Emissions
   Double-sideband, television relay Bn = 2C + 2M + 2D Video limited to 5
   MHz, audio on 6.5 MHz frequency modulated subcarrier deviation = 50
   kHz: C = 6.5 × 10^6 D = 50 × 10^3 Hz, M = 15,000, Bandwidth: 13.13 ×
   10^6 Hz = 13.13 MHz 13M2A8W
   Double-sideband radio relay system Bn = 2M 10 voice channels occupying
   baseband between 1 kHz and 164 kHz; M = 164,000 bandwith = 328,000 Hz =
   328 kHz 328KA8E
   Double-sideband emission of VOR with voice (VOR = VHF omnidirectional
   radio range) Bn = 2Cmax + 2M + 2DK, K = 1 (typically) The main carrier
   is modulated by: —a 30 Hz sub-carrier—a carrier resulting from a 9960
   Hz tone frequency modulated by a 30 Hz tone—a telephone channel—a 1020
   Hz keyed tone for continual Morse identification. Cmax = 9960, M = 30,
   D = 480 Hz, Bandwidth: 20,940 Hz = 20.94 kHz 20K9A9W
   Independent sidebands; several telegraph channels together with several
   telephone channels Bn = sum of M for each sideband Normally composite
   systems are operated in accordance with standardized channel
   arrangements, (e.g. CCIR Rec. 348-2) 3 telephone channels and 15
   telegraphy channels require the bandwidth 12,000 Hz = 12 kHz 12K0B9W
   III-A. FREQUENCY MODULATION
   1. Signal With Quantized or Digital Information
   Telegraphy without error-correction (single channel) Bn = 2M + 2DK, M =
   B ÷ 2, K = 1.2 (typically) B = 100, D = 85 Hz (170 Hz shift),
   Bandwidth: 304 Hz 304HF1B
   Four-frequency duplex telegraphy Bn2M + 2DK, B = Modulation rate in
   bands of the faster channel. If the channels are synchronized: M = B ÷
   2, otherwise M = 2B, K = 1.1 (typically) Spacing between adjacent
   frequencies = 400 Hz; Synchronized channels; B = 100, M = 50, D = 600
   Hz, Bandwidth: 1420 Hz = 1.42 kHz 1K42F7B
   2. Telephony (Commercial Quality)
   Commercial telephony Bn = 2M + 2DK, K = 1 (typically, but under
   conditions a higher value may be necessary For an average case of
   commercial telephony, M = 3,000, Bandwidth: 16,000 Hz = 16 kHz 16K0F3E
   3. Sound Broadcasting
   Sound broadcasting Bn = 2M + 2DK, K = 1 (typically) Monaural, D =
   75,000 Hz, M = 15,000, Bandwidth: 18,000 Hz = 180 kHz 180KF3E
   4. Facsimile
   Facsimile by direct frequency modulation of the carrier; black and
   white Bn = 2M + 2DK, M = N ÷ 2, K = 1.1 (typically) N = 1100
   elements/sec; D = 400 Hz, Bandwidth: 1980 Hz = 1.98 kHZ 1K98F1C
   Analogue facsimile Bn = 2M + 2DK, M = N ÷ 2, K = 1.1 (typically) N =
   1100 elements/sec; D = 400 Hz, Bandwidth: 1980 Hz = 1.98 kHz 1K98F3C
   5. Composite Emissions (See Table III-B)
   Radio-relay system, frequency division multiplex Bn = 2P + 2DK, K = 1
   Microwave radio relay system specifications: 60 telephone channels
   occupying baseband between 60 and 300 kHz; rms per-channel deviation
   200 kHz; pilot at 331 kHz produces 200 kHz rms deviation of main
   carrier. Computation of Bn:D = (200 × 10^33 × 3.76 × 1.19), Hz = 0.895
   × 10^6, P = 0.331 × 10^6 Hz; Bandwidth: 2.452 × 10^6 Hz 2M45F8E
   Radio-relay system frequency division multiple Bn = 2M + 2DK, K = 1
   Microwave radio relay relay systems specifications: 1200 telephone
   channels occupying baseband between 60 and 5564 kHz; rms per channel
   deviation 200 kHz; continunity pilot at 6199 kHz produces 140 kHz rms
   deviation of main carrier. Computation of Bn:D = (20^0 × 10^3 × 3.76 ×
   3.63) = 2.73 × 10^6; M = 5.64 × 10^6 Hz; P = 6.2 × 10^6 Hz; (2M +
   2DK<2P; Bandwidth 16.59 × 10^6 Hz 16M6F8E
   Radio-relay system, frequency division multiplex Bn = 2P Microwave
   radio relay system specifications: Multiplex 600 telephone channels
   occupying baseband between 60 and 2540 kHz; continuity pilot at 8500
   kHz produces 140 kHz rms deviation of main carrier. Computation of Bn:D
   = (200 × 10^3 × 3.76 × 2.565) = 1.93 × 10^6 Hz; M = 2.54 × 10^6 Hz;
   2DK)≤2P Bandwidth: 17 × 10^6 Hz 17M0F8E
   Unmodulated pulse emission Bn = 2K ÷ t, K depends upon the ratio of
   pulse rise time. Its value usually falls between 1 and 10 and in many
   cases it does not need to exceed 6 Primary Radar Range resolution: 150
   m, K = 1.5 (triangular pulse where t≃tr, only components down to 27 dB
   from the strongest are considered) Then t = 2 × range resolution ÷
   velocity of light = 2 × 150 ÷ 3 × 10^8 = 1 × 10−6 seconds, Bandwidth: 3
   × 10^6 Hz = 3 MHz 3M00P0N
   6. Composite Emissions
   Radio-relay system Bn = 2K ÷ t, K = 1.6 Pulse position modulated by 36
   voice channel baseband; pulse width at half amplitude = 0.4 us,
   Bandwidth: 8 × 10^6 Hz = 8 MHz (Bandwidth independent of the number of
   voice channels) 8M00M7E
   Radio-relay system Bn = 2K/t
   K = 1.6 Pulse position modulated by 36 voice channel baseband: pulse
   width at half amplitude 0.4 μS; Bn = 8 × 10^6 Hz = 8 MHz (Bandwidth
   independent of the number of voice channels) 8M00M7E
   Composite transmission digital modulation using DSB-AM (Microwave radio
   relay system) Bn = 2RK/log2S Digital modulation used to send 5 megabits
   per second by use of amplitude modulation of the main carrier with 4
   signaling states
   R = 5 × 10^6 bits per second; K = 1; S = 4; Bn = 5 MHz 5M00K7
   Binary Frequency Shift Keying (0.03 <2D/R <1.0);
   Bn = 3.86D + 0.27R
   (1.0 <2D/R <2)
   Bn = 2.4D + 1.0R Digital modulation used to send 1 megabit per second
   by frequency shift keying with 2 signaling states and 0.75 MHz peak
   deviation of the carrier
   R = 1 × 10^6 bps; D = 0.75 × 10^6 Hz; Bn = 2.8 MHz 2M80F1D
   Multilevel Frequency Shift Keying Bn = (R/log2S) + 2DK Digital
   modulation to send 10 megabits per second by use of frequency shift
   keying with four signaling states and 2 MHz peak deviation of the main
   carrier
   R = 10 × 10^6 bps; D = 2 MHz; K = 1; S = 4; Bn = 9 MHz 9M00F7D
   Phase Shift Keying Bn = 2RK/log2S Digital modulation used to send 10
   megabits per second by use of phase shift keying with 4 signaling
   states
   R = 10 × 10^6 bps; K = 1; S = 4; Bn = 10 MHz 10M0G7D
   Quadrature Amplitude Modulation (QAM) Bn = 2R/log2S 64 QAM used to send
   135 Mbps has the same necessary bandwidth as 64-PSK used to send 135
   Mbps;
   R = 135 × 10^6 bps; S = 64; Bn = 45 MHz 45M0W
   Minimum Shift Keying 2-ary:
   Bn = R(1.18)
   4-ary:
   Bn = R(2.34) Digital modulation used to send 2 megabits per second
   using 2-ary minimum shift keying
   R = 2.36 × 10^6 bps; Bn = 2.36 MHz 2M36G1D

   [ 28 FR 12465 , Nov. 22, 1963, as amended at  37 FR 8883 , May 2, 1972;  37 FR 9996 , May 18, 1972;  48 FR 16492 , Apr. 18, 1983;  49 FR 48698 , Dec.
   14, 1984;  68 FR 68543 , Dec. 9, 2003]

   

Subpart D—Call Signs and Other Forms of Identifying Radio Transmissions

   Authority: Secs. 4, 5, 303, 48 Stat., as amended, 1066, 1068, 1082; 47
   U.S.C. 154, 155, 303.

   


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