(ii) Each radial is marked, at a point exactly 16
kilometers from
the transmitter and, at greater distances, at successive 3 kilometer
intervals. Where measurements are to be conducted over extremely rugged
terrain, shorter intervals may be used, but all such intervals must
be
of equal length. Accessible roads intersecting each radial as nearly
as
possible at each 3 kilometer marker are selected. These intersections
are the points on the radial at which measurements are to be made,
and
are referred to subsequently as measuring locations. The elevation
of
each measuring location should approach the elevation at the
corresponding 3 kilometer marker as nearly as possible.
(2) Measurement procedure. All measurements must
be made utilizing a
receiving antenna designed for reception of the horizontally polarized
signal component, elevated 9 meters above the roadbed. At each measuring
location, the following procedure must be used:
(i) The instrument calibration is checked.
(ii) The antenna is elevated to a height of 9 meters.
(iii) The receiving antenna is rotated to determine
if the strongest
signal is arriving from the direction of the transmitter.
(iv) The antenna is oriented so that the sector
of its response
pattern over which maximum gain is realized is in the direction of
the
transmitter.
(v) A mobile run of at least 30 meters is made,
that is centered on
the intersection of the radial and the road, and the measured field
strength is continuously recorded on a chart recorder over the length
of
the run.
(vi) The actual measuring location is marked exactly
on the
topographic map, and a written record, keyed to the specific location,
is made of all factors which may affect the recorded field, such as
topography, height and types of vegetation, buildings, obstacles,
weather, and other local features.
(vii) If, during the test conducted as described
in paragraph
(b)(2)(iii) of this section, the strongest signal is found to come
from
a direction other than from the transmitter, after the mobile run
prescribed in paragraph (b)(2)(v) of this section is concluded,
additional measurements must be made in a ``cluster'' of at least five
fixed points. At each such point, the field strengths with the antenna
oriented toward the transmitter, and with the antenna oriented so as
to
receive the strongest field, are measured and recorded. Generally,
all
points should be within 60 meters of the center point of the mobile
run.
(viii) If overhead obstacles preclude a mobile run
of at least 30
meters, a ``cluster'' of five spot measurements may be made in lieu
of
this run. The first measurement in the cluster is identified. Generally,
the locations for other measurements must be within 60 meters of the
location of the first.
(3) Method of reporting measurements. A report of
measurements to
the Commission shall be submitted in affidavit form, in triplicate,
and
should contain the following information:
(i) Tables of field strength measurements, which,
for each measuring
location, set forth the following data:
(A) Distance from the transmitting antenna.
(B) Ground elevation at measuring location.
(C) Date, time of day, and weather.
(D) Median field in dBu for 0 dBk, for mobile run
or for cluster, as
well as maximum and minimum measured field strengths.
(E) Notes describing each measuring location.
(ii) U.S. Geological Survey topographic maps, on
which is shown the
exact location at which each measurement was made. The original plots
shall be made on maps of the largest available scale. Copies may be
reduced in size for convenient submission to the Commission, but not
to
the extent that important detail is lost. The original maps shall be
made available, if requested. If a large number of maps is involved,
an
index map should be submitted.
(iii) All information necessary to determine the
pertinent
characteristics of the transmitting installation, including frequency,
geographical coordinates of antenna site, rated and actual power output
of transmitter, measured transmission line loss, antenna power gain,
height of antenna above ground,
above mean sea level, and above average terrain. The effective radiated
power should be computed, and horizontal and vertical plane patterns
of
the transmitting antenna should be submitted.
(iv) A list of calibrated equipment used in the
field strength
survey, which, for each instrument, specifies its manufacturer, type,
serial number and rated accuracy, and the date of its most recent
calibration by the manufacturer, or by a laboratory. Complete details
of
any instrument not of standard manufacture shall be submitted.
(v) A detailed description of the calibration of
the measuring
equipment, including field strength meters, measuring antenna, and
connecting cable.
(vi) Terrain profiles in each direction in which
measurements were
made, drawn on curved earth paper for equivalent 4/3 earth radius,
of
the largest available scale.
(c) Collection of field strength data to determine
FM broadcast
service in specific communities.
(1) Preparation for measurement. (i) The population
(P) of the
community, and its suburbs, if any, is determined by reference to an
appropriate source, e.g., the 1970 U.S. Census tables of population
of
cities and urbanized areas.
(ii) The number of locations at which measurements
are to be made
shall be at least 15, and shall be approximately equal to 0.1(P)<SUP>1/
2</SUP>, if this product is a number greater than 15.
(iii) A rectangular grid, of such size and shape
as to encompass the
boundaries of the community is drawn on an accurate map of the
community. The number of line intersections on the grid included within
the boundaries of the community shall be at least equal to the required
number of measuring locations. The position of each intersection on
the
community map determines the location at which a measurement shall
be
made.
(2) Measurement procedure. All measurements must
be made using a
receiving antenna designed for reception of the horizontally polarized
signal component, elevated 9 meters above ground level.
(i) Each measuring location shall be chosen as close
as feasible to
a point indicated on the map, as previously prepared, and at as nearly
the same elevation as that point as possible.
(ii) At each measuring location, after equipment
calibration and
elevation of the antenna, a check is made to determine whether the
strongest signal arrives from a direction other than from the
transmitter.
(iii) At 20 percent or more of the measuring locations,
mobile runs,
as described in paragraph (b)(2) of this section shall be made, with
no
less than three such mobile runs in any case. The points at which mobile
measurements are made shall be well separated. Spot measurements may
be
made at other measuring points.
(iv) Each actual measuring location is marked exactly
on the map of
the community, and suitably keyed. A written record shall be maintained,
describing, for each location, factors which may affect the recorded
field, such as the approximate time of measurement, weather, topography,
overhead wiring, heights and types of vegetation, buildings and other
structures. The orientation, with respect to the measuring location
shall be indicated of objects of such shape and size as to be capable
of
causing shadows or reflections. If the strongest signal received was
found to arrive from a direction other than that of the transmitter,
this fact shall be recorded.
(3) Method of reporting measurements. A report of
measurements to
the Commission shall be submitted in affidavit form, in triplicate,
and
should contain the following information:
(i) A map of the community showing each actual measuring
location,
specifically identifying the points at which mobile runs were made.
(ii) A table keyed to the above map, showing the
field strength at
each measuring point, reduced to dBu for the actual effective radiated
power of the station. Weather, date, and time of each measurement shall
be indicated.
(iii) Notes describing each measuring location.
(iv) A topographic map of the largest available
scale on which are
marked the community and the transmitter site of the station whose
signals have been measured, which includes all areas on or near the
direct path of signal propagation.
(v) Computations of the mean and standard deviation of
all measured
field strengths, or a graph on which the distribution of measured field
strength values is plotted.
(vi) A list of calibrated equipment used for the
measurements, which
for each instrument, specifies its manufacturer, type, serial number
and
rated accuracy, and the date of its most recent calibration by the
manufacturer, or by a laboratory. Complete details of any instrument
not
of standard manufacture shall be submitted.
(vii) A detailed description of the procedure employed
in the
calibration of the measuring equipment, including field strength meters,
measuring antenna, and connecting cable.
attenuated in accordance with the requirements specified in paragraph
(b) of this section. Emissions shall be measured using a properly
operated and suitable swept-frequency RF spectrum analyzer using a
peak hold duration of 10 minutes, no video filtering, and a 300 Hz
resolution bandwidth, except that a wider resolution bandwidth may be
employed above 11.5 kHz to detect transient emissions. Alternatively,
other specialized receivers or monitors with appropriate characteristics
may be used to determine compliance with the provisions of this section,
provided that any disputes over measurement accuracy are resolved in
favor of measurements obtained by using a calibrated spectrum analyzer
adjusted as set forth above.
(b) Emissions 10.2 kHz to 20 kHz removed from the carrier must
be attenuated at least 25 dB below the unmodulated carrier level,
emissions 20 kHz to 30 kHz removed from the carrier must be attenuated
at least 35 dB below the unmodulated carrier level, emissions 30 kHz to
60 kHz removed from the carrier must be attenuated at least
[5 + 1 dB/kHz] below the unmodulated carrier level, and emissions between
60 kHz and 75 kHz of the carrier frequency must be attenuated at least
65 dB below the unmodulated carrier level. Emissions removed by more
than 75 kHz must be attenuated at least 43 + 10 Log (Power in watts) or
80 dB below the unmodulated carrier level, whichever is the lesser
attenuation, except for transmitters having power less than 158 watts,
where the attenuation must be at least 65 dB below carrier level.
(c) Should harmful interference be caused to the reception of
other broadcast or non-broadcast stations by out of band emissions,
the licensee may be directed to achieve a greater degree of attenuation
than specified in paragraphs (a) and (b) of this section.
(d) Measurements to determine compliance with this section for
transmitter type acceptance are to be made using signals sampled at the
output terminals of the transmitter when operating into an artificial
antenna of substantially zero reactance. Measurements made of the
emissions of an operating station are to be made at ground level
approximately 1kilometer from the center of the antenna system. When a
directional antenna is used, the carrier frequency reference field
strengthto be used in order of preference shall be:
(1) The measure non-directional field strength.
(2) The RMS field strength determined from the measured
directional radiation pattern.
(3) The calculated expected field strength that would be radiated
by a non-directional antenna at the station authorized power.
(e) Licensees of stations complying with the ANSI/EIA-549-1988,
NRSC-1 AM Preemphasis/Deemphasis and Broadcast Transmission
Bandwidth Specifications (NRSC-1), prior to June 30, 1990 or from the
original commencement of operation will, until June 30, 1994, be
considered to comply with paragraphs (a) and (b) of this section, absent
any reason for the Commission to believe otherwise. Such stations are
waived from having to make the periodic measurements required in
¦ 73.1590(a)(6) until June 30, 1994. However, licensees must make
measurements to determine compliance with paragraphs (a) and (b) of
this section upon receipt of an Official Notice of Violation or a Notice
of Apparent Liability alleging noncompliance with those provisions, or
upon specific request by the Commission.
section, the operating power shall be determined by the direct method.
The direct method consists of either:
(1) using a suitable instrument for determining the antenna's input
power directly from the RF voltage, RF current, and phase angle; or
(2) calculating the product of the licensed antenna or common point
resistance at the operating frequency (see Sec. 73.54), and the square
of the indicated unmodulated antenna current at that frequency, measured
at the point where the resistance has been determined.
(b) The authorized antenna input power for each station shall be
equal to the nominal power for such station, with the following
exceptions:
(1) For stations with nominal powers of 5 kW, or less, the
authorized antenna input power to directional antennas shall exceed the
nominal power by 8 percent.
(2) For stations with nominal powers in excess of 5 kW, the
authorized antenna input power to directional antennas shall exceed the
nominal power by 5.3 percent.
(3) In specific cases, it may be necessary to limit the radiated
field to a level below that which would result if normal power were
delivered to the antenna. In such cases, excess power may be dissipated
in the antenna feed circuit, the transmitter may be operated with power
output at a level which is less than the rated carrier power, or a
combination of the two methods may be used, subject to the conditions
given in paragraph (c) of this section.
(i) Where a dissipative network is employed, the authorized antenna
current and resistance, and the authorized antenna input power shall be
determined at the input terminals of the dissipative network.
(ii) Where the authorized antenna input power is less than the
nominal power, subject to the conditions set forth in paragraph (c) of
this section, the transmitter may be operated at the reduced power level
necessary to supply the authorized antenna input power.
(c) Applications for authority to operate with antenna input power
which is less than nominal power and/or to employ a dissipative network
in the antenna system shall be made on FCC Form 302. The technical
information supplied on section II-A of this form shall be that applying
to the proposed conditions of operation. In addition, the following
information shall be furnished, as pertinent:
(1) Full details of any network employed for the purpose of
dissipating radio frequency energy otherwise delivered to the antenna
(see Sec. 73.54).
(2) A showing that the transmitter has been type accepted or
notified for operation at the proposed power output level, or, in lieu
thereof:
(i) A full description of the means by which transmitter output
power will be reduced.
(ii) Where the proposed transmitter power output level(s) is less
than 90% of the rated power of the transmitter, equipment performance
measurements must be made to confirm that the station transmissions
conform to the emission limitation specified in Sec. 73.44, under all
conditions of program operation.
(iii) A showing that, at the proposed power output level, means are
provided for varying the transmitter output within a tolerance of
<SUP>plus-minus</SUP>10 percent, to compensate for variations in line
voltage or other factors which may affect the power output level.
(d) When it is not possible or appropriate to use the direct method
of power determination due to technical reasons, the indirect method of
determining operating power (see paragraphs (e) and (f) of this section)
may be used on a temporary basis. A notation must be made in the station
log indicating the dates of commencement and termination of measurement
using the indirect method of power determination.
(e) The antenna input power is determined indirectly by applying an
appropriate factor to the input power to the last radio-frequency power
amplifier stage of the transmitter, using the following formula:
Where:
Antenna input power=Ep x Ip x F
Ep=DC input voltage of final radio stage.
Ip=Total DC input current of final radio stage.
F= Efficiency factor.
(1) If the above formula is not appropriate for the design of the
transmitter final amplifier, use a formula specified by the transmitter
manufacturer with other appropriate operating parameters.
(2) The value of F applicable to each mode of operation must be
determined and a record kept thereof with a notation as to its
derivation. This factor is to be established by one of the methods
described in paragraph (f) of this section and retained in the station
records.
(f) The value of F is to be determined by one of the following
procedures listed in order of preference:
(1) If the station had previously been authorized and operating by
determining the antenna input power by the direct method, the factor F
is the ratio of the antenna input power (determined by the direct
method) to the corresponding final radio frequency power amplifier input
power.
(2) If a station has not been previously in regular operation with
the power authorized for the period of indirect power determination, if
a new transmitter has been installed, or if, for any other reason, the
determination of the factor F by the method described in paragraph
(f)(1) of this section is impracticable:
(i) The factor F as shown in the transmitter manufacturer's test
report, if such a test report specifies a unique value of F for the
power level and frequently used; or
(ii) The value determined by reference to the following table:
------------------------------------------------------------------------
Method of Maximum rated carrier Class of
Factor(F) modulation power amplifier
------------------------------------------------------------------------
0.70..... Plate.............. 1 kW or less.......... ................
.80...... Plate.............. 2.5 kW and over....... ................
.35...... Low level.......... 0.25 kW and over...... B.
.65...... Low level.......... 0.25 kW and over...... BC\1\.
.35...... Grid............... 0.25 kW and over...... ................
------------------------------------------------------------------------
\1\All linear amplifier operation where efficiency approaches that of
class C operation.
measured at either the base of the antenna without intervening coupling
or tuning networks, or at the point the transmission line connects to
the output terminals of the transmitter. The resistance of a shunt
excited antenna may be measured at the point the radio frequency energy
is transferred to the feed wire circuit or at the output terminals of
the transmitter.
(b) The resistance and reactance of a directional antenna shall be
measured at the point of common radiofrequency input to the directional
antenna system. The following conditions shall obtain:
(1) The antenna shall be finally adjusted for the required radiation
pattern.
(2) The reactance at the operating frequency and at the point of
measurement shall be adjusted to zero, or as near thereto as
practicable.
(c)(1) The resistance of an antenna shall be determined by the
following procedure: A series of discrete measurements shall be made
over a band of frequencies extending from approximately 25 kHz below the
operating frequency to approximately 25 kHz above that frequency, at
intervals of approximately 5 kHz. The measured values shall be plotted
on a linear graph, with frequency as the abscissa and resistance as the
ordinate. A smooth curve shall be drawn through the plotted values. The
resistance value corresponding to the point of intersection of the curve
and the ordinate representing the operating frequency of the station
shall be the resistance of the antenna.
(2) For a directional antenna, the reactance of the antenna shall be
determined by a procedure similar to that described in paragraph (c)(1)
of this section.
(d) A letter of notification must be filed with the FCC in
Washington, DC, Attention: Audio Services Division, Mass Media Bureau,
when determining power by the direct method pursuant to Sec. 73.51 and must specify the
antenna or common point resistance at the operating frequency. The
following information must also be kept on file at the station:
(1) A full description of the method used to make measurements.
(2) A schematic diagram showing clearly all components of coupling
circuits, the point of resistance measurement, the location of the
antenna ammeter, connections to and characteristics of all tower
lighting isolation circuits, static drains, and any other fixtures
connected to and supported by the antenna, including other antennas and
associated networks. Any network or circuit component used to dissipate
radio frequency power shall be specifically identified, and the
impedances of all components which control the level of power
dissipation, and the effective input resistance of the network must be
indicated.
(e) AM stations using direct reading power meters in accordance with
Sec. 73.51, can either submit the information required by paragraph (d)
of this section or submit a statement indicating that such a meter is
being used. Subsequent station licenses will indicate the use of a
direct reading power meter in lieu of the antenna resistance value in
such a situation.
either the direct or indirect method.
(b) Direct method. The direct method of power determination for an
FM station uses the indications of a calibrated transmission line meter
(responsive to relative voltage, current, or power) located at the RF
output terminals of the transmitter. This meter must be calibrated
whenever there is any indication that the calibration is inaccurate or
whenever any component of the metering circuit is repaired or replaced.
The calibration must cover, as a minimum, the range from 90% to 105% of
authorized power. The meter calibration may be checked by measuring the
power at the transmitter terminals while either:
(1) Operating the transmitter into the transmitting antenna, and
determining actual operating power by the indirect method described in
Sec. 73.267(c); or
(2) Operating the transmitter into a load (of substantially zero
reactance and a resistance equal to the transmission line characteristic
impedance) and using an electrical device (within <plus-minus>5%
accuracy) or temperature and coolant flow indicator (within
<plus-minus>4% accuracy) to determine the power.
(3) The calibration must cover, as a minimum, the range from 90% to
105% of authorized power and the meter must provide clear indications
which will permit maintaining the operating power within the prescribed
tolerance or the meter shall be calibrated to read directly in power
units.
(c) Indirect method. The operating power is determined by the
indirect method by applying an appropriate factor to the input power to
the last radio-frequency power amplifier stage of the transmitter, using
the following formula:
Transmitter output power=Ep x Ip x F
Where:
Ep=DC input voltage of final radio stage.
Ip=Total DC input current of final radio stage.
F=Efficiency factor.
(1) If the above formula is not appropriate for the design of the
transmitter final amplifier, use a formula specified by the transmitter
manufacturer with other appropriate operating parameters.
(2) The value of the efficiency factor, F, established for the
authorized transmitter output power is to be used for maintaining the
operating power, even though there may be some variation in F over the
power operating range of the transmitter.
(3) The value of F is to be determined and a record kept thereof by
one of the following procedures listed in order of preference:
(i) Using the most recent measurement data for calibration of the
transmission line meter according to the procedures described in
paragraph (b) of this section or the most recent measurements made by
the licensee establishing the value of F. In the case of composite
transmitters or those in which the final amplifier stages have
been modified pursuant to FCC approval, the licensee must furnish the
FCC and also retain with the station records the measurement data used
as a basis for determining the value of F.
(ii) Using measurement data shown on the transmitter manufacturer's
test data supplied to the licensee; Provided, That measurements were
made at the authorized frequency and transmitter output power.
(iii) Using the transmitter manufacturer's measurement data
submitted to the FCC for type acceptance and as shown in the instruction
book supplied to the licensee.
transmissions of FM multiplex subcarriers except those used for
stereophonic sound broadcasts under the provisions of Sec. 73.322.
(b) Modulation. Any form of modulation may be used for subcarrier
operation.
(c) Subcarrier baseband. (1) During monophonic program
transmissions, multiplex subcarriers and their significant sidebands
must be within the range of 20 kHz to 99 kHz.
(2) During stereophonic sound program transmissions (see
Sec. 73.322), multiplex subcarriers and their significant sidebands must
be within the range of 53 kHz to 99 kHz.
(3) During periods when broadcast programs are not being
transmitted, multiplex subcarriers and their significant sidebands must
be within the range of 20 kHz to 99 kHz.
(d) Subcarrier injection.
(1) During monophonic program transmissions, modulation of the
carrier by the arithmetic sum of all subcarriers may not exceed 30%
referenced to 75 kHz modulation deviation. However, the modulation of
the carrier by the arithmetic sum of all subcarriers above 75 kHz may
not modulate the carrier by more than 10%.
(2) During stereophonic program transmissions, modulation of the
carrier by the arithmetic sum of all subcarriers may not exceed 20%
referenced to 75 kHz modulation deviation. However, the modulation of
the carrier by the arithmetic sum of all subcarriers above 75 kHz may
not modulate the carrier by more than 10%.
(3) During periods when no broadcast program service is transmitted,
modulation of the carrier by the arithmetic sum of all subcarriers may
not exceed 30% referenced to 75 kHz modulation deviation. However, the modulation
of the carrier by the arithmetic sum of all subcarriers above 75 kHz may not modulate the
carrier by more than 10%.
(4) Total modulation of the carrier wave during transmission of
multiplex subcarriers used for subsidiary communications services must
comply with the provisions Sec. 73.1570(b).
(e) Subcarrier generators may be installed and used with a type
accepted FM broadcast transmitter without specific authorization from
the FCC provided the generator can be connected to the transmitter
without requiring any mechanical or electrical modifications in the
transmitter FM exciter circuits.
(f) Stations installing multiplex subcarrier transmitting equipment
must ensure the proper suppression of spurious or harmonic radiations.
See Secs. 73.317, 73.1590 and 73.1690. If the subcarrier operation
causes the station's transmissions not to comply with the technical
provisions for FM broadcast stations or causes harmful interference to
other communication services, the licensee or permittee must correct the
problem promptly or cease operation. The licensee may be required to
verify the corrective measures with supporting data. Such data must be
retained at the station and be made available to the FCC upon request.
carrier frequency and the difference between the visual carrier and the
aural carrier or center frequency of each TV station shall be measured
or determined as often as necessary to ensure that they are maintained
within the prescribed tolerances.
(b) In measuring the carrier frequency, the licensee may use any
method or procedure that has sufficient precision to establish that the
carrier frequency is within the prescribed departure limits.
(c) The primary standard of frequency for radio frequency
measurements is the standard frequency maintained by the National Bureau
of Standards or the standard signals of Stations WWV, WWVB, and WWVH of
the National Bureau of Standards.
Class D non-commercial educational FM stations authorized to operate
with 10 watts or less output power, must make equipment performance
measurements for each main transmitter as follows:
(1) Upon initial installation of a new or replacement main
transmitter.
(2) Upon modification of an existing transmitter made under the
provisions of Sec. 73.1690, Modification of transmission systems, and
specified therein.
(3) Installation of AM stereophonic transmission equipment pursuant
to Sec. 73.128.
(4) Installation of FM subcarrier or stereophonic transmission
equipment pursuant to Sec. 73.295, Sec. 73.297, Sec. 73.593 or
Sec. 73.597.
(5) Installation of TV stereophonic or subcarrier transmission
equipment pursuant to Secs. 73.669 and 73.1690.
(6) Annually, for AM stations, with not more than 14 months between
measurements.
(7) When required by other provisions of the rules or the station
license.
(b) Measurements for spurious and harmonic emissions must be made to
show compliance with the transmission system requirements of Sec. 73.44
for AM stations; Sec. 73.317 for FM stations and Sec. 73.687 for TV
stations. Measurements must be made under all conditions of modulation
expected to be encountered by the station whether transmitting
monophonic or stereophonic programs and providing subsidiary
communications services.
(c) TV visual equipment performance measurements must be made with
the equipment adjusted for normal program operation at the transmitter
antenna sampling port to yield the following information:
(1) Field strength or voltage of the lower side-band for a
modulating frequency of 1.25 MHz or greater, (including 3.58 MHz for
color), and of the upper side-band for a modulating frequency of 4.75
MHz or greater.
(2) Data showing that the waveform of the transmitted signal
conforms to that specified by the standards for TV transmissions.
(3) Photographs of a test pattern taken from a receiver or monitor
connected to the transmitter output.
(4) Data showing envelope delay characteristics of the radiated
signal.
(5) Data showing the attenuation of spurious and harmonic radiation,
if, after type acceptance, any changes have been made in the transmitter
or associated equipment (filters, multiplexer, etc.) which could cause
changes in its radiation products.
(d) The data required by paragraphs (b) and (c) of this section,
together with a description of the equipment and procedure used in
making the measurements, signed and dated by the qualified person(s) making the
measurements, must be kept on file at the transmitter or remote control
point for a period of 2 years, and on request must be made available
during that time to duly authorized representatives of the FCC.
Subpart H--Rules Applicable to All Broadcast Stations
that at all times the station operates within tolerances specified by
applicable technical rules contained in this part and in accordance with
the terms of the station authorization. Any method of complying with
applicable tolerances is permissible. The following are typical methods
of transmission system operation:
(a) Attended operation. (1) Attended operation consists of ongoing
supervision of the transmission facilities by a station employee or
other person designated by the licensee. Such supervision may be
accomplished by either:
(i) Direct supervision and control of transmission system parameters
by a person at the transmitter site; or
(ii) Remote control of the transmission system by a person at the
main studio or other location. The remote control system must provide
sufficient transmission system monitoring and control capability so as
to ensure compliance with Sec. 73.1350.
(2) A station may also be monitored and controlled by an automatic
transmission system (ATS) that is configured to contact a person
designated by the licensee in the event of a technical malfunction. An
automatic transmission system consists of monitoring devices, control
and alarm circuitry, arranged so that they interact automatically to
operate the station's transmitter and maintain technical parameters
within licensed values.
(3) A hybrid system containing some remote control and some ATS
features is also permissible.
(4) In the case of remote control or ATS operation, not every
station parameter need be monitored or controlled if the licensee has
good reason to believe that its stability is so great that its
monitoring and control are unnecessary.
(b) Unattended operation. Unattended operation is either the absence
of human supervision or the substitution of automated supervision of a
station's transmission system for human supervision. In the former case,
equipment is employed which is expected to operate within assigned
tolerances for extended periods of time. The latter consists of the use
of a self-monitoring or ATS-monitored and controlled transmission system
that, in lieu of contacting a person designated by the licensee,
automatically takes the station off the air within three hours of any
technical malfunction which is capable of causing interference.
monophonic transmissions or center frequency for stereophonic
transmissions may not exceed <plus-minus> 20 Hz from the assigned
frequency.
(b) FM stations. (1) The departure of the carrier or center
frequency of an FM station with an authorized transmitter output power
more than 10 watts may not exceed <plus-minus>2000 Hz from the assigned
frequency.
(2) The departure of the carrier or center frequency of an FM
station with an authorized transmitter output power of 10 watts or less
may not exceed <plus-minus>3000 Hz from the assigned frequency.
(c) TV stations. (1) The departure of the visual carrier frequency
of a TV station may not exceed <plus-minus>1000 Hz from the assigned
visual carrier frequency.
(2) The departure of the aural carrier frequency of a TV station may
not exceed <plus-minus>1000 Hz from the actual visual carrier frequency
plus exactly 4.5 MHz.
(d) International broadcast stations. The departure of the carrier
frequency of an International broadcast station may not exceed 0.0015%
of the assigned frequency on which the station is transmitting.
level as is consistent with good quality of transmission and good
broadcast service, with maximum levels not to exceed the values
specified in paragraph (b). Generally, the modulation should not be less
than 85% on peaks of frequent recurrence, but where lower modulation
levels may be required to avoid objectionable loudness or to maintain
the dynamic range of the program material, the degree of modulation may
be reduced to whatever level is necessary for this purpose, even though
under such circumstances, the level may be substantially less than that
which produces peaks of frequent recurrence at a level of 85%.
(b) Maximum modulation levels must meet the following limitations:
(1) AM stations. In no case shall the amplitude modulation of the
carrier wave exceed 100% on negative peaks of frequent recurrence, or
125% on positive peaks at any time.
(i) AM stations transmitting stereophonic programs not exceed the AM
maximum stereophonic transmission signal modulation specifications of
stereophonic system in use.
(ii) For AM stations transmitting telemetry signals for remote
control or automatic transmission system operation, the amplitude of
modulation of the carrier by the use of subaudible tones must not be
higher than necessary to effect reliable and accurate data transmission
and may not, in any case, exceed 6%.
(2) FM stations. The total modulation must not exceed 100 percent on
peaks of frequent reoccurrence referenced to 75 kHz deviation. However,
stations providing subsidiary communications services using subcarriers under provisions
of Sec. 73.319 concurrently with the broadcasting of stereophonic or monophonic programs may
increase the peak modulation deviation as follows:
(i) The total peak modulation may be increased 0.5 percent for each
1.0 percent subcarrier injection modulation.
(ii) In no event may the modulation of the carrier exceed 110
percent (82.5 kHz peak deviation).
(3) TV station. In no case shall the total modulation of the aural
carrier exceed 100% on peaks of frequent recurrence, unless some other
peak modulation level is specified in an instrument of authorization.
For monophonic transmissions, 100% modulation is defined as
<plus-minus>25 kHz.
(c) If a limiting or compression amplifier is employed to maintain
modulation levels, precaution must be taken so as not to substantially
alter the dynamic characteristics of programs.