(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--H0020.1 Hz--H10025.3 Hz--25H3400 Hz--400H2.4 kHz--2K406 kHz--6K0012.5 kHz--12K5180.4 kHz--180K180.5 kHz--181K180.7 kHz--181K1.25 MHz--1M252 MHz--2M0010 MHz--10M0202 MHz--202M5.65 GHz--5G65
(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 hertzB = Modulation rate in baudsN = Maximum possible number of black plus white elements to be transmitted per second, in facsimileM = Maximum modulation frequency in hertzC = Sub-carrier frequency in hertzD = 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 2t = Pulse duration in seconds at half-amplitudetr = Pulse rise time in seconds between 10% and 90% of maximum amplitudeK = 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 multiplexingP = 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 x [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: -5.6 to -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: --------------------------------------------------------------------------------------------------------------------------------------------------------
Necessary bandwidth
Description of emission ------------------------------------------------------------------------------------------ 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 25 words per minute; B = 20, K = 5, Bandwidth: 100HA1A
= 3 for non-fading circuits 100 Hz
Telegraphy by on-off keying of a tone Bn = BK + 2M, K = 5 for fading 25 words per minute; B = 20, M = 1000, K = 5, 2K10A2A
modulated carrier. circuits, K = 3 for non-fading Bandwidth: 2100 Hz = 2.1 kHz
circuits
Selective calling signal, single- Bn = M Maximum code frequency is: 2110 Hz, M = 2110, 2K11H2B
sideband full carrier. Bandwidth: 2110 Hz = 2.11 kHz
Direct-printing telegraphy using a Bn = 2M + 2DK, M = B / 2 B = 50, D = 35 Hz (70 Hz shift), K = 1.2, 134HJ2B
frequency shifted modulating sub- Bandwidth: 134 Hz
carrier single-sideband suppressed
carrier.
Telegraphy, single sideband reduced Bn = central frequency + M + DK, M = B 15 channels; highest central frequency is: 2805 2K89R7B
carrier. / 2 Hz, B = 100, D = 42.5 Hz (85 Hz shift), K = 0.7
Bandwidth: 2.885 Hz = 2.885 kHz--------------------------------------------------------------------------------------------------------------------------------------------------------
2. Telephony (Commercial Quality)--------------------------------------------------------------------------------------------------------------------------------------------------------Telephony double-sideband............ Bn = 2M M = 3000, Bandwidth = 6000 Hz = 6 kHz 6K00A3E
Telephony, single-sideband, full Bn = 2M M = 3000, Bandwidth: 3000 Hz = 3 kHz 3K00H3E
carrier.
Telephony, single-sideband suppressed Bn = M-lowest modulation frequency M = 3000, lowest modulation frequency is 3000 2K70J3E
carrier. Hz, 2700 Hz Bandwidth: 2700Hz = 2.7 kHz
Telephony with separate frequency Bn = M Maximum control frequency is 2990 Hz, M = 2990, 2K99R3E
modulated signal to control the Bandwidth: 2990 Hz = 2.99 kHz
level of demodulated speech signal,
single-sideband, reduced carrier.
Telephony with privacy, single- Bn = Nc M-lowest modulation frequency Nc = 2, M = 3000 lowest modulation frequency is 5K75J8E
sideband, suppressed carrier (two or in the lowest channel 250 Hz, Bandwidth: 5750 Hz = 5.75 kHz
more channels).
Telephony, independent sideband (two Bn = sum of M for each sideband 2 channels, M = 3000, Bandwidth: 6000 Hz = 6 kHz 6K00B8E
or more channels).--------------------------------------------------------------------------------------------------------------------------------------------------------
3. Sound Broadcasting--------------------------------------------------------------------------------------------------------------------------------------------------------Sound broadcasting, double-sideband.. Bn = 2M, M may vary between 4000 and Speech and music, M = 4000, Bandwidth: 8000 Hz= 8K00A3E
10000 depending on the quality 8 kHz
desired
Sound broadcasting, single-sideband Bn = M, M may vary between 4000 and Speech and music, M = 4000, Bandwidth: 4000 Hz= 4K00R3E
reduced carrier (single channel). 10000 depending on the quality 4 kHz
desired
Sound broadcasting, single-sideband, Bn = M-lowest modulation frequency Speech and music, M = 4500, lowest modulation 4K45J3E
suppressed carrier. frequency = 50 Hz, Bandwidth: 4450 Hz = 4.45
kHz--------------------------------------------------------------------------------------------------------------------------------------------------------
4. Television--------------------------------------------------------------------------------------------------------------------------------------------------------Television, vision and sound......... Refer to CCIR documents for the Number of lines = 525; Nominal video bandwidth: 5M75C3F
bandwidths of the commonly used 4.2 MHz, Sound carrier relative to video
television systems carrier = 4.5 MHz
...................................... Total vision bandwidth: 5.75 MHz; FM aural 250KF3E
bandwidth including guardbands: 250,000 Hz
...................................... Total bandwidth: 6 MHz 6M25C3F--------------------------------------------------------------------------------------------------------------------------------------------------------
5. Facsimile--------------------------------------------------------------------------------------------------------------------------------------------------------Analogue facsimile by sub-carrier Bn = C-N / 2 + DK, K = 1.1 (typically) N = 1100, corresponding to an index of 2K89R3C
frequency modulation of a single- cooperation of 352 and a cycler rotation speed
sideband emission with reduced of 60 rpm. Index of cooperation is the product
carrier. of the drum diameter and number of lines per
unit length C = 1900, D = 400 Hz, Bandwidth =
2.890 Hz = 2.89 kHz
Analogue facsimile; frequency Bn = 2M + 2DK, M = N/2, K = 1.1 N = 1100, D = 400 Hz, Bandwidth: 1980 Hz = 1.98 1K98J3C
modulation of an audio frequency sub- (typically) kHz
carrier which modulates the main
carrier, single-sideband suppressed
carrier.--------------------------------------------------------------------------------------------------------------------------------------------------------
6. Composite Emissions--------------------------------------------------------------------------------------------------------------------------------------------------------Double-sideband, television relay.... Bn = 2C + 2M + 2D Video limited to 5 MHz, audio on 6.5 MHz 13M2A8W
frequency modulated subcarrier deviation = 50
kHz: C = 6.5 x 10\6\ D = 50 x 10\3\ Hz, M =
15,000, Bandwidth: 13.13 x 10\6\ Hz = 13.13 MHz
Double-sideband radio relay system... Bn = 2M 10 voice channels occupying baseband between 1 328KA8E
kHz and 164 kHz; M = 164,000 bandwith = 328,000
Hz = 328 kHz
Double-sideband emission of VOR with Bn = 2Cmax + 2M + 2DK, K = 1 The main carrier is modulated by: --a 30 Hz sub- 20K9A9W
voice (VOR = VHF omnidirectional (typically) carrier--a carrier resulting from a 9960 Hz
radio range). 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
Independent sidebands; several Bn = sum of M for each sideband Normally composite systems are operated in 12K0B9W
telegraph channels together with accordance with standardized channel
several telephone channels. arrangements, (e.g. CCIR Rec. 348-2) 3
telephone channels and 15 telegraphy channels
require the bandwidth 12,000 Hz = 12 kHz--------------------------------------------------------------------------------------------------------------------------------------------------------
III-A. FREQUENCY MODULATION
1. Signal With Quantized or Digital Information--------------------------------------------------------------------------------------------------------------------------------------------------------Telegraphy without error-correction Bn = 2M + 2DK, M = B / 2, K = 1.2 B = 100, D = 85 Hz (170 Hz shift), Bandwidth: 304HF1B
(single channel). (typically) 304 Hz
Four-frequency duplex telegraphy..... Bn2M + 2DK, B = Modulation rate in Spacing between adjacent frequencies = 400 Hz; 1K42F7B
bands of the faster channel. If the Synchronized channels; B = 100, M = 50, D = 600
channels are synchronized: M = B / 2, Hz, Bandwidth: 1420 Hz = 1.42 kHz
otherwise M = 2B, K = 1.1 (typically)--------------------------------------------------------------------------------------------------------------------------------------------------------
2. Telephony (Commercial Quality)--------------------------------------------------------------------------------------------------------------------------------------------------------Commercial telephony................. Bn = 2M + 2DK, K = 1 (typically, but For an average case of commercial telephony, M = 16K0F3E
under conditions a higher value may 3,000, Bandwidth: 16,000 Hz = 16 kHz
be necessary--------------------------------------------------------------------------------------------------------------------------------------------------------
3. Sound Broadcasting--------------------------------------------------------------------------------------------------------------------------------------------------------Sound broadcasting................... Bn = 2M + 2DK, K = 1 (typically) Monaural, D = 75,000 Hz, M = 15,000, Bandwidth: 180KF3E
18,000 Hz = 180 kHz--------------------------------------------------------------------------------------------------------------------------------------------------------
4. Facsimile--------------------------------------------------------------------------------------------------------------------------------------------------------Facsimile by direct frequency Bn = 2M + 2DK, M = N / 2, K = 1.1 N = 1100 elements/sec; D = 400 Hz, Bandwidth: 1K98F1C
modulation of the carrier; black and (typically) 1980 Hz = 1.98 kHZ
white.
Analogue facsimile................... Bn = 2M + 2DK, M = N / 2, K = 1.1 N = 1100 elements/sec; D = 400 Hz, Bandwidth: 1K98F3C
(typically) 1980 Hz = 1.98 kHz--------------------------------------------------------------------------------------------------------------------------------------------------------
5. Composite Emissions (See Table III-B)--------------------------------------------------------------------------------------------------------------------------------------------------------Radio-relay system, frequency Bn = 2P + 2DK, K = 1 Microwave radio relay system specifications: 60 2M45F8E
division multiplex. 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 x 10\3\3 x 3.76 x 1.19), Hz = 0.895 x
10\6\, P = 0.331 x 10\6\ Hz; Bandwidth: 2.452 x
10\6\ Hz
Radio-relay system frequency division Bn = 2M + 2DK, K = 1 Microwave radio relay relay systems 16M6F8E
multiple. 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\ x 10\3\ x 3.76 x 3.63) = 2.73 x 10\6\;
M = 5.64 x 10\6\ Hz; P = 6.2 x 10\6\ Hz; (2M +
2DK<2P; Bandwidth 16.59 x 10\6\ Hz
Radio-relay system, frequency Bn = 2P Microwave radio relay system specifications: 17M0F8E
division multiplex. 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 x 10\3\ x 3.76 x 2.565) = 1.93 x 10\6\
Hz; M = 2.54 x 10\6\ Hz; 2DK)<=2P Bandwidth: 17
x 10\6\ Hz--------------------------------------------------------------------------------------------------------------------------------------------------------Unmodulated pulse emission........... Bn = 2K / t, K depends upon the ratio Primary Radar Range resolution: 150 m, K = 1.5 3M00P0N
of pulse rise time. Its value usually (triangular pulse where t[sime]tr, only
falls between 1 and 10 and in many components down to 27 dB from the strongest are
cases it does not need to exceed 6 considered) Then t = 2 x range resolution /
velocity of light = 2 x 150 / 3 x 10\8\ = 1 x
10-6 seconds, Bandwidth: 3 x 10\6\ Hz = 3 MHz--------------------------------------------------------------------------------------------------------------------------------------------------------
6. Composite Emissions--------------------------------------------------------------------------------------------------------------------------------------------------------Radio-relay system................... Bn = 2K / t, K = 1.6 Pulse position modulated by 36 voice channel 8M00M7E
baseband; pulse width at half amplitude = 0.4
us, Bandwidth: 8 x 10\6\ Hz = 8 MHz (Bandwidth
independent of the number of voice channels)Radio-relay system................... Bn = 2K/t Pulse position modulated by 36 voice channel 8M00M7E
K = 1.6 baseband: pulse width at half amplitude 0.4
[mu]S; Bn = 8 x 10 \6\ Hz = 8 MHz (Bandwidth
independent of the number of voice channels)Composite transmission digital Bn = 2RK/log2S Digital modulation used to send 5 megabits per 5M00K7
modulation using DSB-AM (Microwave second by use of amplitude modulation of the
radio relay system). main carrier with 4 signaling states
R = 5 x 10 \6\ bits per second; K = 1; S = 4; Bn
= 5 MHzBinary Frequency Shift Keying........ (0.03 <2D/R <1.0); Digital modulation used to send 1 megabit per 2M80F1D
Bn = 3.86D + 0.27R second by frequency shift keying with 2
(1.0 <2D/R <2) signaling states and 0.75 MHz peak deviation of
Bn = 2.4D + 1.0R the carrier
R = 1 x 10 \6\ bps; D = 0.75 x 10 \6\ Hz; Bn =
2.8 MHzMultilevel Frequency Shift Keying.... Bn = (R/log2S) + 2DK Digital modulation to send 10 megabits per 9M00F7D
second by use of frequency shift keying with
four signaling states and 2 MHz peak deviation
of the main carrier
R = 10 x 10 \6\ bps; D = 2 MHz; K = 1; S = 4; Bn
= 9 MHzPhase Shift Keying................... Bn = 2RK/log2S Digital modulation used to send 10 megabits per 10M0G7D
second by use of phase shift keying with 4
signaling states
R = 10 x 10 \6\ bps; K = 1; S = 4; Bn = 10 MHz
Quadrature Amplitude Modulation (QAM) Bn = 2R/log2S 64 QAM used to send 135 Mbps has the same 45M0W
necessary bandwidth as 64-PSK used to send 135
Mbps;
R = 135 x 10 \6\ bps; S = 64; Bn = 45 MHzMinimum Shift Keying................. 2-ary: Digital modulation used to send 2 megabits per 2M36G1D
Bn = R(1.18) second using 2-ary minimum shift keying
4-ary: R = 2.36 x 10 \6\ bps; Bn = 2.36 MHz
Bn = R(2.34)-------------------------------------------------------------------------------------------------------------------------------------------------------- [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]