Sec. 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
0.1 Hz--H100
25.3 Hz--25H3
400 Hz--400H
2.4 kHz--2K40
6 kHz--6K00
12.5 kHz--12K5
180.4 kHz--180K
180.5 kHz--181K
180.7 kHz--181K
1.25 MHz--1M25
2 MHz--2M00
10 MHz--10M0
202 MHz--202M
5.65 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 hertz
B = Modulation rate in bauds
[[Page 497]]
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:
------------------------------------------------------------------------
Limits
of X
Number of message circuits Multiplying factors (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:
[[Page 498]]
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Neces
sary bandwidth
Description of emission -----------------------------------------
------------------------------------------------- Designation of emission
Formula
Sample calculation
-------------------------------------------------------------------------------
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I. NO MODULATI
NG SIGNAL
Continuous wave emission............. ......................................
................................................ N0N (zero)
II. AMPLITUDE M
ODULATION
1. Signal With Quantized or Digital
Information
Continuous wave telegraphy........... Bn=BK, K=5 for fading circuits, K=3
25 words per minute; B=20, K=5, Bandwidth: 100 100HA1A
for non-fading circuits
Hz
Telegraphy by on-off keying of a tone Bn=BK+2M, K=5 for fading circuits,
K=3 25 words per minute; B=20, M=1000, K=5, 2K10A2A
modulated carrier. for non-fading circuits
Bandwidth: 2100 Hz=2.1 kHz
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=B2
B=50, D=35 Hz (70 Hz shift), K=1.2, Bandwidth: 134HJ2B
frequency shifted modulating sub-
134 Hz
carrier single-sideband suppressed
carrier.
Telegraphy, single sideband reduced Bn=central frequency+M+DK,
15 channels; highest central frequency is: 2805 2K89R7B
carrier. M=B2
Hz, B=100, D=42.5 Hz (85 Hz shift), K=0.7
Bandwidth: 2.885 Hz=2.885 kHz
2. Telephony (Comme
rcial 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 Hz, 2K70J3E
carrier.
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 freq
uency in Nc=2, M=3000 lowest modulation frequency is 250 5K75J8E
sideband, suppressed carrier (two or the lowest channel
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 Broa
dcasting
Sound broadcasting, double-sideband.. Bn=2M, M may vary between 4000 and
Speech and music, M=4000, Bandwidth: 8000 Hz= 8 8K00A3E
10000 depending on the quality
kHz
desired
Sound broadcasting, single-sideband Bn=M, M may vary between 4000 and
Speech and music, M=4000, Bandwidth: 4000 Hz= 4 4K00R3E
reduced carrier (single channel). 10000 depending on the quality
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
[[Page 499]]
4. Televi
sion
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. Facsim
ile
Analogue facsimile by sub-carrier Bn=C-N2+DK, K=1.1 (typicall
y) N=1100, corresponding to an index of cooperation 2K89R3C
frequency modulation of a single-
of 352 and a cycler rotation speed of 60 rpm.
sideband emission with reduced
Index of cooperation is the product of the drum
carrier.
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 (typic
ally) N=1100, D=400 Hz, Bandwidth: 1980 Hz=1.98 kHz 1K98J3C
modulation of an audio frequency sub-
carrier which modulates the main
carrier, single-sideband suppressed
carrier.
6. Composite E
missions
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 106 D=50 x 103 Hz, M=15,000,
Bandwidth: 13.13 x 106 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 (typicall
y) The main carrier is modulated by: --a 30 Hz sub- 20K9A9W
voice (VOR=VHF omnidirectional radio
carrier--a carrier resulting from a 9960 Hz
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=B2, K=1.2
B=100, D=85 Hz (170 Hz shift), Bandwidth: 304 Hz 304HF1B
(single channel). (typically)
Four-frequency duplex telegraphy..... Bn2M+2DK, B=Modulation rate in band
s Spacing between adjacent frequencies=400 Hz; 1K42F7B
of the faster channel. If the
Synchronized channels; B=100, M=50, D=600 Hz,
channels are synchronized:
Bandwidth: 1420 Hz=1.42 kHz
M=B2, otherwise M=2B, K=1.1
(typically)
[[Page 500]]
2. Telephony (Comme
rcial Quality)
Commercial telephony................. Bn=2M+2DK, K=1 (typically, but unde
r For an average case of commercial telephony, 16K0F3E
conditions a higher value may be
M=3,000, Bandwidth: 16,000 Hz=16 kHz
necessary
3. Sound Broa
dcasting
Sound broadcasting................... Bn=2M+2DK, K=1 (typically)
Monaural, D=75,000 Hz, M=15,000, Bandwidth: 180KF3E
18,000 Hz=180 kHz
4. Facsim
ile
Facsimile by direct frequency Bn=2M+2DK, M=N2, K=1.1
N=1100 elements/sec; D=400 Hz, Bandwidth: 1980 1K98F1C
modulation of the carrier; black and (typically)
Hz=1.98 kHZ
white.
Analogue facsimile................... Bn=2M+2DK, M=N2, K=1.1
N=1100 elements/sec; D=400 Hz, Bandwidth: 1980 1K98F3C
(typically)
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 1033 x 3.76 x 1.19), Hz=0.895 x 106,
P=0.331 x 106 Hz; Bandwidth: 2.452 x 106 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=(200 x 103 x 3.76 x 3.63)=2.73 x 106; M=5.64
x 106 Hz; P=6.2 x 106 Hz; (2M+2DK<2P; Bandwidth
16.59 x 106 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 103 x 3.76 x 2.565)=1.93 x 106 Hz;
M=2.54 x 106 Hz; 2DK)2P Bandwidth: 17 x 106 Hz
Unmodulated pulse emission........... Bn=2Kt, K depends upon the
Primary Radar Range resolution: 150 m, K=1.5 3M00P0N
ratio of pulse rise time. Its value
(triangular pulse where t tr, only components
usually falls between 1 and 10 and in
down to 27 dB from the strongest are
many cases it does not need to exceed
considered) Then t=2 x range
6
resolutionvelocity of light=2 x
1503 x 108=1 x 10-6 seconds, Bandwidth:
3 x 106 Hz=3 MHz
6. Composite E
missions
Radio-relay system................... Bn=2Kt, K=1.6
Pulse position modulated by 36 voice 8M00M7E
channel baseband; pulse width at half
amplitude=0.4 us, Bandwidth: 8 x 106 Hz=8 MHz
(Bandwidth independent of the number of voice
channels)
[[Page 501]]
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[ 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]
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.