Middleton W.M. (ed.) Reference Data for Engineers: Radio, Electronics, Computer and Communications
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35-2
REFERENCE
DATA
FOR ENGINEERS
Component Coding
of
Signals: SMPTE
125
and CCIR
601
Synchronization and Blanking Interval Considerations
Ancillary Data Signal Format
Advanced Television Systems
References
International Standards for Broadcasting
35-46
CCIR Documents
Selected CCIR Reports and Recommendations
IEC Publications
IS0 Recommendations
Selected
EBU
Publications
Acknowledgements
In this age
of
rapid technical change, it is no longer
accurate to assume that communications services di-
rected to the public at large
are
“broadcasting” in
the traditional sense. More and more of the general
public is served by cable television and by transmis-
sions from satellites. In addition, the video cassette
recorder is an integral part of millions of home
entertainment systems, and in this case the signals
reaching the viewer are distributed by lengths of mag-
netic tape. In consideration of these facts, this chapter
will not only describe conventional over-the-air broad-
casting of radio and television programs, and cable and
satellite television, but also will focus on the elements
that enter into program recording for other media that
serve the public.
The various transmission systems, and the signals
that they convey to the public, must meet certain
technical specifications. Much of this chapter will
consist of summaries and lists of such specifications.
Sources for current versions of relevant specifications
are also identified.
In the United States, broadcasting is regulated by the
Federal Communications Commission (FCC), which
assigns frequencies and establishes technical standards.
Three general classes of broadcast stations have tradi-
tionally been identified. These are standard broadcast
stations (amplitude modulation in the band 535-1605
kHz), FM broadcast stations (frequency modulation in
the band 88-108 MHz), and television broadcast sta-
tions (operating in the bands 54-72, 76-88, 174-216
and 470-806 MHz with vestigial-sideband amplitude
modulation of the visual carrier and frequency modula-
tion of the aural carrier). Technical specifications for
these broadcast services
are
summarized in this chapter.
Cable television systems also have channel assignment
and other specifications; they are also summarized in
this chapter.
Certain technical aspects of international broadcast-
ing
are
described. International broadcasting
(‘
‘short
wave”) uses frequencies between 5950 and 26 100 kHz
in accordance with international agreements.
Other technical information related to broadcasting is
covered under auxiliary services, intercity relay trans-
mission, and terminal facilities.
This chapter provides a comprehensive reference for
standards applicable to audio recording and video
recording. North American standards are listed, and
reference is made to comparable international stan-
dards. Lists of standards are provided.
The rapidly evolving field of advanced television
systems using digital technologies is described in sepa-
rate sections. Both national and international specifica-
tions are listed. A listing of relevant standards promul-
gated by CCIR,
ISO,
and IEC concludes the chapter.
TABLE 1. CLASSIFICATION
OF
STANDARD-BROADCAST STATIONS
Signal-Intensity Contour
of
Area Permissible
Protected from Objectionable Interfering Signal
Interference on Same Channel
Permissible (microvolts/meter) (microvolts/meter)
Class of Class of Power
Channel Station
(kW
Day
I
Night Day’ Night3
Clear I-A
50
sc
=
100
SC
=
500’
5
AC
=
500
AC
=
500’
25
I-B
10-50
sc
=
100
SC
=
500’
5 25
AC
=
500
AC
=
500’
11-A
0.25-50
day
500 500’ 25 25
10-50
night
(:;::)
0.25-50
500
2500’
25
125
0.25-1 500
IO
000
25 500
Regional
111-A
1-5 500 2500’ 25 125
111-B
0.5-5
day
500
4000’
25 200
0.5-1
night
0.25
night
Local
IV
0.25-1
day
500
not prescribed
25
not prescribed
Notes:
SC-same channel, AC-adjacent channel.
’
Ground wave.
250%
skv
wave.
310%
ski
wave.
4A~~lies to those Class 11-B and 11-D stations described in Part
73
of FCC
Rules
and Regulations.
35-4
REFERENCE DATA FOR ENGINEERS
interference criteria in 1992, and a current version
of
the FCC Rules and Regulations should be consulted.)
BROADCAST AND CABLE
TRANSMISSION SYSTEMS
Standard Broadcasting”
Standard-broadcast stations are licensed for opera-
tion on channels spaced by 10 kHzt and occupy the
band from 535 to
1700
kHz. The major station classifi-
cations prior to 1992 are shown in Table 1.
Field-Strength Requirements-Field strength re-
quirements have been established by the FCC to provide
specified minimum signal levels in various types of
locations. These vary somewhat with the class of station
but more specifically with the anticipated man-made
noise levels in a particular area.
As
of 1991 these levels
generally are as follows.
(As
noted above, the FCC
Rules were undergoing major changes in service and
Primaiy Service:
City business, factory areas-10 to 50
millivolts/meter, ground wave.
City residential areas-2 to 10 millivoltsimeter,
ground wave.
Rural, all areas during winter or northern areas
during summer-0.1 to 0.5 millivoWmeter,
ground wave.
Rural, southern areas during summer-0.25 to 1.0
millivolt/meter, ground wave.
Secondary Service: All areas having sky-wave field
strength equal to or greater than
500
microvolts/
meter for 50% or more
of
the time.
*
FCC
Rules
and
Regulations, Part
73,
Subpart
A.
These
rules
were undergoing
substantial
changes
in
early
1992,
and
a
current version
of
the Rules should
be
consulted
for
latest
classifications
and
requirements.
t
IO-kHz
spacing
is
used
only
in
ITU
Region
2.
Regions
1
and
3
employ
9-kHz
spacing.
For a station employing a directional antenna, all
and
interference
are
based
On
the inverse field of a “standard pattern” for that station.
When applied to nighttime operation, this includes the
radiation pattern in the horizontal plane as well as
Of
MILES
FROM
ANTENNA
200
100
50
20
g
10
SEA
W
E5
cc
30
10
5
3
2
8
v)2
51
i!
2
E
01
fi
002
g
001
3
05
1
5
02
6
005
re
v)
0 005
0
002
0
001
0
000s
0 0002
0
0001
5000
WA1
TER
MILES
FROM
ANTENNA
Fig.
1.
Ground-wave
field
strength
plotted
against
distance.
Computed
for
550
kilohertz.
Dielectric
constant
=
15.
Ground-conductivity
values
are
in
millimhosimeter.
BROADCAST1
NG
STANDARDS
35-5
MILES
FROM
ANTENNA
/
1'
i
I
.
..
..
.,
Ill13
I I I I
I
I1111
I
200
Illll
I
I I
I I
I1111
I
Fig.
2.
Ground
-,
-.
-
L
I
MIL1:S
FROM
ANTt.Nh.4
-~il\c'
tic'ld
wcncth
plotted
against
tlictance.
Cwnputcd
for
1000
kiloherti.
Dirlecrric
conctant
=
-
--
-
Ground-conductivity
values
are
in
millinhosimeter.
radiation at angles above the horizontal plane (vertical
radiation pattern).
Table
1
outlines generally the protected contours and
permissible interference for the various classes of sta-
tions. There are additional details and some exceptions
in Sections 73.21-73.29 and73.181-73.190of Part 73
of the FCC Rules and Regulations.
(See previous
footnote regarding changes to these rules. The new rules
will require stations to employ new interference criteria
and to reduce existing interference for a site change.)
Coverage Data-Figs.
1,
2, and 3 show computed
values of ground-wave field strength as a function of
the
distance from the transmitting antenna. These are used
to determine coverage and interference. They were
computed for the frequencies indicated, for a dielectric
constant equal to 15 for land and
80
for sea water
(referred to air as unity), and for the surface conductivi-
ties noted. The curves are for radiation from a short
vertical antenna at the surface of a uniformly conductive
spherical earth with an antenna efficiency and input
power such that the inverse-distance field is 100 milli-
voltsimeter at one mile. Fig.
4
shows the estimated
effective field for vertical omnidirectional antennas of
15.
various heights. Figs.
5
and
6
show the effective ground
conductivity for various parts
of
the
US
and Canada,
and Fig. 7 shows the sky-wave fields for
10%
and 50%
of the time.
Transmission System Requirements
Modulation:
85%
on peaks of frequent recurrence at
authorized operating power. Not greater than
100% on negative peaks or 125%
on
positive
peaks.
Audio-Frequency Response:
In
accordance with
NRSC
recommendations.
Carrier AmplitudeiCarrier Shift: Less than
5%
at any
level of modulation percentage.
Out-of-Band Emissions: Per
FCCiNRSC
require-
ments, see FCC Rules.
AM
Stereo Transmission-Three basic transmis-
sion methods were proposed for adding stereo to the
standard AM broadcast system. The three methods
were:
Mixed Mode: The carrier is amplitude modulated
with the
(L+R)
signal and phase or frequency
modulated with the
(L-R)
signal.
35-6
REFERENCE
DATA
FOR ENGINEERS
MILES FROM ANTENNA
.:
02
I15
lU
L
5
in
20
1
IL?
530
200
100
50
20
10
5
2
1
05
02
g
01
3
005
K
c
v,
002
fi
001
0 005
0
002
0
001
o
ono:
0
0002
0
0001
10
20 50
100
200
500
1000 2000
MILES FROM ANTENNA
Fig.
3.
Ground-wave field strength plotted against distance. Computed
for 1600
kilohertz. Dielectric constant
=
15.
Ground-conductivity values are
in
millimhos/meter.
Independent Sideband: The upper and lower side-
bands of the carrier are modulated with the
L
and
R
signals, respectively (Kahn system).
Quadrature: Two phase-locked carriers are amplitude
modulated and combined at a fixed phase angle
(Motorola system).
A
“marketplace approach” has been employed in the
US
to select the best system, and that manufacturer’s
technique will become the
de
facto
standard. In Canada
and Japan, the Motorola system has been standardized,
and most
US
stations also employ this system.
Frequency- Modulation
Broadcasting”
Frequency-modulation (FM) broadcast stations are
authorized for operation on 101 allocated channels,
each
200
kHz
wide, extending consecutively from
channel
200
on 87.9 MHz to channel
300
on
107.9
*
FCC Rules and Regulations,
Part
73,
Subparts
B
and C.
-
280
260
240
‘
c
220
K
2
s
-
2000
a
1800
>
K
5
1600
E
L
z
200
’s
5
1200
U
1x0
j
2
1000
E
z
W
2
1400
v)
0
2
160
W
3
3
800
140
600
w
0
01
02
03
04
05
06
07
ANTENNA HEIGHT IN WAVELENGTH (CURVE A)
U
bo0
660
860
ld00
I&
1400
l&O
2040
3
2
FREQUENCY
IN
KILOHERTZ (CURVE
6)
Fig.
4.
Effective field at
1
mile
for
1
kilowatt (curve
A).
Use
for
simple omnidirectional vertical antenna with ground
system
of
at least
120
radials
A14
long.
From
FCC
Rules and
Regulations.
BROADCAST1
NG
STANDARDS
35-7
35-8
REFERENCE
DATA
FOR ENGINEERS
Fig.
6.
Estimated effective ground conductivity
in
Canada.
MHz. Commercial broadcasting is authorized on chan-
nels 221 (92.1 MHz) through
300.
Noncommercial
educational broadcasting is permitted on any channel,
but channels 200 through 220 are reserved for such use
(see Part
73
of the FCC Rules and Regulations).
Station Classification-An FM station is classi-
fied by type in accordance with its authorized maxi-
mum operating power and antenna height (Table 2). A
‘‘reference distance” has been established for each
class
to
denote the distance to the theoretical limit of its
service area (the 1 mV/m contour-see “Coverage”
below).
A
station operating with an antenna height
in
excess of the maximum for its class must reduce its
effective radiated power (ERP)
so
that its
1
mV/m
contour does not exceed the reference distance.
Channel Availability-Channels 221 through 300
are assigned to specific communities in accordance with
the Table
of
Assignments (see Section 73.202 of FCC
Rules). The number (and type) of channels assigned to a
community is based on population, the limits imposed
by cochannel and adjacent-channel interference consid-
erations, and the zone in which the community lies.
The Table of Assignments may be amended to add
channels upon approval
of
a petition for rulemaking
which includes a showing
of
need and conformity with
the separation standards shown in Table 3. Noncom-
mercial stations operating on channels 217-220 must
conform with Table 2 with respect
to
stations operating
on
channels 22 1-223. Stations operating on channels
200 through
216
are authorized based on mutual
interference standards in lieu of a Table of Assign-
ments. These standards are expressed in terms of the
following interference ratios
of
desired
to
undesired
signals,
Cochannel:
1st Adjacent Channel:
2nd Adjacent Channel:
3rd Adjacent Channel:
10:
1,
or 20 dB
2:1, or
6
dB
l:lO, or -20 dB
1:100, or
-40
dB
The ratios are the magnitude of the field strength from
the undesired station determined from the F50,lO
curves* at the limit
of
the protected contour? of the
desired station (see “Coverage” below).
Channel 200
is
available only for Class
D
(maximum
transmitter output of 10 watts) use in areas not served by
a television broadcast station operating on channel
6.
Stations
on
channels 201 through 220 are also subject to
*
The
protected
contour
is
normally
the
1
mVlm
or
60
dBu
service
contour
as
determined
by
the
F50,50 propagation
curves. However,
class
B
stations
receive
slightly
greater
protection. Refer
to
FCC
Rules.
?-
Refer
to
Fig.
11
in
the
section
on television broadcasting.
1000
w
i?
5
100
2
10
2
Q.
m
t;
0 400 800 1200 1600 2000 2400
:1
MILES
Fig.
7.
Sky-wave
signals
for
10%
and
50%
of
the
time. The
sky-wave range
for
frequencies
from
540
to
1600
kilohertz
is
based
on
a
radiated
field
of
100
millivolts/meter
at
1
mile
at
the
pertinent
vertical
angle.
TABLE
2.
CLASSES
OF
FM STATIONS
Station
Class'
A
B1
B
c3
c2
c1
C
Maximum ERP
6
kW
(7.8
dBk)
25
kW
(14.0
dBk)
50
kW
(17.0
dBk)
25
kW
(14.0
dBk)
50
kW
(17.0
dBk)
100
kW
(20.0
dBk)
100
kW
(20.0
dBk)
Reference
HA AT^
in
Meters (ft.)
100 (328)
100 (328)
150 (492)
100 (328)
150 (492)
299 (981)
600 (1968)
Class
Contour
Distance
in
Kilometers
28
39
52
39
52
72
92
1.
Class B stations are available in
Zone
1
and Class
C
stations in
Zone
11.
See
FCC
Rules for
zone
boundaries
2.
HAAT is height
of
the antenna radiation center above average terrain elevation. Average terrain is determined by a procedure
set forth in the
FCC
Rules.
maximum power restrictions if located in or near areas
served by a television station operating on channel
6.
Coverage-The
estimated
'Overage Of
an
FM
sta-
tion can be determined from the FCC
F50,50
curves
shown in Fig.
8.*
These curves permit the prediction of
-
*
These curves
are
approximate only, Official
FCC
data
should be used for engineering designs.
the field strength that will be exceeded for
50%
of the
time at
50%
of the locations within the contour distance
from the transmitter for various combinations of effec-
tive radiated power and antenna height above average
Station Performance-The performance of an FM
broadcast station is required to be maintained in accord-
ance with the following general specifications (see FCC
TABLE
3.
MINIMUM DISTANCE SEPARATION REQUIREMENTS
IN
KILOMETERS (MILES)
10.61
Relation
co- 200
kHz
4001600 10.8
channel kHz MHz
-
A to A
115 (71)
72 (45) 31 (19) 10 (6)
A to
B1
143 (89)
96 (60) 48 (30) 12 (7)
A
to
C3
142 (88)
89 (55)
42 (26)
12
(7)
A
to
C2
166 (103)
106 (66)
55 (34) 15 (9)
A to
C1
200 (1 24)
133 (83)
75 (47) 22 (14)
A to
C
226 (140)
165 (103)
95 (59) 29 (18)
B1
to
B1
175 (109)
114 (71)
50 (31) 14
(9)
B1 toB
211 (131)
145 (90)
71 (44) 17 (11)
B1
to
C2
200 (124)
134 (83)
56 (35) 17 (11)
B1
to
C1
233 (145)
161 (100)
77 (48) 24 (15)
B1 toC
259 (161)
193 (120)
105 (65) 31 (19)
B to
C3
211 (131)
145 (90)
71 (44) 17 (11)
B
to
C1
270 (168)
195 (121)
79 (49) 21 (17)
A to B
178 (111) 113 (70) 69 (43) 15 (9)
B1
to
C3 175 (109) 114 (71) 50 (31) 14 (9)
B
to
B
241 (150)
169 (105)
74 (46) 20 (12)
B to
C2
241 (150)
169 (105)
74 (46) 20 (12)
B to
C
274 (170)
217 (135)
105 (65) 35 (22)
c3
to
c3 153 (95)
99
(62) 43 (27) 14
(9)
c3
to
c2
177 (110)
117 (73)
56 (35) 17 (11)
c3
to
c1
211 (131)
144 (90)
76 (47) 24 (15)
c3
to
c
237 (147)
176 (109)
96 (60) 31 (19)
c2
to
c1 224 (139) 158 (98) 79 (49) 27 (17)
c2
to
c2
190 (118)
130 (81)
58 (36) 20 (12)
c2
to
c
249 (155)
188 (117)
105 (65) 35 (22)
c1
to
c1
245 (152)
177 (1 10)
82 (51) 34 (21)
c1
toc
270 (168)
209 (130)
105 (65) 41 (25)
c
to
c
290 (180)
241 (150)
105 (65) 48 (30)
Note: Different criteria apply
to
stations within
320
km
of US-Canadian and US-Mexican borders. Consult
FCC
Rules
and
Regulations, section
73.207.
35-10
REFERENCE
DATA
FOR ENGINEERS
Fig.
8.
Estimated field strength exceeded at
50
percent
of
the potential receiver locations for at least
50
percent
of
the time (FM
channels, receiving antenna height
9
meters).
After
FCC
Rules
and
Regulations.
Rules Section 73.3 17 for additional details). Key sys- with monophonic receivers. The stereophonic signal
tem criteria include: consists of a main channel and a subchannel. The
main channel
is
modulated by the sum
of
the left
(L)
and right (R) stereo signals. The subchannel consists
of sidebands
of
a 38-kHz suppressed carrier that is
modulated with
an
L
minus R (difference) signal.
Since the modulating frequencies can be as high as
kHz,
the
sidebands
occupy
the
baseband
spectrum
from
23
kHz
to
53
kHz
(Fig,
9).
A
pilot carrier
of
19
kHz is also transmitted to allow the receiver to generate
a phase-locked 38-kHz carrier in order
to
demodulate
the L-R signal.
A
matrix in the stereo receiver recovers
L-plus-R and L-minus-R signals.
A
monophonic re-
ceiver demodulates only the L-plus-R (main channel)
signal.
Modulation Capability: t75
kHz
deviation of carrier
for
100%
modulation.
Audio-Frequency Response: Within limits shown
in
FCC Rules for 75 microseconds pre-emphasis.
Polarization: Typically right-hand circular; elliptical
or other modes acceptable provided horizontal
polarization is dominant.?:
Stereophonic Transmission-Most
FM
stations
broadcast in a stereophonic mode that is compatible
ti
An exception to this requirement permits noncommer-
cia1 stations operating on channels
201-220
to
use
vertical
polarization to reduce interference to television channel
6.
-
the
L
and R signals by algebraic operation
on
the
SUPPRESSED
STEREO
SUBCARRIER
DIFFERENCE
SIDEBANDS
SUBSIDIARY
COMMUNICATION
I
(IF USED)
I
-I
I I
I
11‘
I
I
I
I,
I
III
I
I
I
I
0
15
19
23
30
38
45
53
60
99
FREQUENCY
IN
KILOHERTZ
Fig.
9.
Resulting stereophonic frequency spectrum
A recent development in FM stereo modulation
called FMX Stereo* employs a compressed L-R signal
which modulates a 38-kHz suppressed carrier in a
manner similar to the normal stereo difference signal.
This signal is transmitted in quadrature to the main
L- R signal and is, therefore, transparent to ordinary
FM stereo decoders. Receivers equipped with an FMX
decoder can demodulate and expand the compressed
difference signal for an overall signal-to-noise improve-
ment of 12-15 dB. This improvement helps to mitigate
the 17-20 dB signal-to-noise penalty suffered in normal
stereo transmission relative to monophonic FM trans-
mission.
Other
FM
Services-A Subsidiary Communica-
tions Authorization (SCA) permits the addition of one
or more subcarriers on the main channel; these subcar-
riers may be used for the transmission of voice or data
signals related or unrelated to the broadcast-station
operation. The subcarrier is amplitude modulated and is
bandwidth limited. (See FCC Rules Section 73.319).
FM
Translators-The FCC permits the use
of
very
low power
(1
watt east of the Mississippi river and 10
watts west) translators to rebroadcast the signals of FM
stations in areas where no reception is possible. The
translator station receives the main FM signal “off the
air” and rebroadcasts it on a different channel; other
methods of program delivery are permissible. Coverage
range can be from one to five miles depending on
power, antenna height, antenna gain, and terrain.
Channels are assigned on a secondary basis (noninter-
ference with operating stations). (See Subpart
L,
Part
74 of the FCC Rules and Regulations.)
Television Broadcasting
(VHF
and
UHF)
Channel Designations-Television broadcast sta-
tions are authorized for commercial and educational
operation on the channels shown in Table 4. Assign-
ment of channels to specific communities is made by
the FCC, and the channel assignments are designated as
commercial (unreserved) or educational (reserved). Ac-
tual carrier frequencies are assigned by a plan for carrier
offsets to reduce cochannel interference (see “Trans-
mission Standards”).
Coverage Data-The channel assignments have
been made in such a manner as to facilitate maximum
interference-free coverage in the available frequency
bands. The radiated power
of
a particular station is fixed
by several considerations. Minimum power is 100 watts
visual effective radiated power.
No
minimum antenna
height is specified.
Except as limited for stations using antenna heights
in excess
of
300 meters (600 meters for channels
14-69) in Zone
I
and antenna heights in excess of 600
meters in Zones I1 and 111, the maximum visual power
in decibels above 1 kilowatt (dBk) is:
Channels
Maximum
Power
2-6 20 dBk
=
100
kilowatts
7-13 25 dBk
=
316 kilowatts
14-69 37 dBk
=
5000
kilowatts
Zone I is the Northeastern United States. Zone I1
includes Puerto Rico, Alaska, the Hawaiian Islands, the
Virgin Islands, and other parts of the US not in Zones I
or
111.
Zone I11 is essentially a strip along the southeast-
ern border of the
US
from Florida to Texas. Zone I11
cochannel separations reflect the propagation anomalies
experienced in the Gulf Coastal Region. Detailed
descriptions of the zones are in the FCC Rules and
Regulations, Section 73.609. Stations operating with
heights in excess of the classizone maxima must reduce
power in accordance with the requirements of 73.614 of
the FCC Rules and Regulations.
Grades of service are designated
A
and B. The signal
strengths in decibels above 1 microvolt/meter (dBu)
specified for the various channels are:
Channel Grade
A
Grade
B
2-6 68 dBu
47 dBu
7-13
71 dBu 56 dBu
14-69 74 dBu
64 dBu
The transmitter location must be
so
chosen that, with
the effective radiated power and antenna height pro-
posed, the minimum field strength (sometimes referred
to as “city grade”) predicted over the principal com-
munity to be served will be:
Channel Signal
2-6 74 dBu
7-13 77 dBu
14-83
80
dBu
The curves of Figs.
10
through 14* give estimated
50%
and
10%
time-varying field strengths for
VHF
and
*
FMX Stereo
is
a registered trademark of Broadcast
Technology Partners.
*
The curves in Figs.
10
through
14
are approximate
only.
Official FCC data should be used for engineering designs.