§ 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]

   return arrow Back to Top

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.

   return arrow Back to Top