1
| ECE 7: Broadcast and Acoustic
Engineering
PREFACE
This learning material is for instructional delivery purposes of the faculty
members of Samar State University only. This is intended solely for the consumption
of officially enrolled students of the course and this should not be sold, reproduced,
shared nor copied by other individuals.
The entire course is divided into four packets which will be delivered to your
respective LGU links where you belong. The packets must be withdrawn from the
LGU links as scheduled. You are to undergo a self-directed learning using this
module and a link to the references used. If by any means you have an access to
internet, it is encouraged that you visit your accounts in the SSU Learning
Management System for additional resources. After you studied you are to answer
the questions and the individual activities asked from you which is found in the
assessment section of the module. You can take the assessment and submit the
class requirements online or through hard copies to the LGU links. Be aware of the
deadline of submissions of the said documents, online or not. Late submissions will
affect your grade.
More than the ratings, it is our hope that you learn for your future. It’s okay
to ask help from anyone but do not compromise the chance to learn the lessons. By
copying without learning, it is you who will be affected. According to Brian Herbert,
the capacity to learn is a gift, the ability to learn is a skill, and the willingness to
learn is a choice. With our current situation, your indulgence in making sure that
you learn is what we are hoping for.
i
1
| ECE 7: Broadcast and Acoustic
Engineering
UNIT 1:
Introduction to AM Broadcasting System and Standards
1.0. Intended Learning Outcomes
After reading this material, students are expected to:
•
•
•
•
Recognize, identify and analyze the AM broadcast communications system
concepts, elements and applications
Differentiate AM broadcasting technique from FM and TV
Use the AM standards in the design of AM broadcasting network which
includes coverage mapping and interference
Use the AM standards in the design of AM station which includes the design
of studio system, Technical Operation Center (TOC), Transmission System,
Coverage Mapping and prediction and interference study.
1.1. Introduction
When we talk about Broadcasting, we may probably think about radio and
television. For radio broadcasting, we have AM Radio Broadcasting, which is the
main topic of this material and of course the FM Radio Broadcasting. Every home
in our current community must have encountered and experienced to use a radio
with probably less emphasis whether it is AM or FM. What matters is that we are
able to use the radio for various purposes such as hearing the news, listening to
music, entertainment thru ads, radio drama, and etc. Before going to the discussion
on AM Broadcasting System and Standards, let us first define the term
broadcasting.
According to RA 9292 or the Electronics Engineering Law of 2004, broadcast or
broadcasting is an undertaking the object of which is to transmit audio, video, text,
images or other signals or messages for reception of a broad audience in a
geographical area via wired or wireless means. This means that broadcasting
allows us to send or receive information in the form of audio such as the case in
radio, while information in the form of video, text, and images such as in television
on top of audio signals. From the broadcast stations, listeners or audiences all over
the world are able to receive the signals provided that provisions in the reception
of signals are properly met. In this learning material, we will study the AM
Broadcasting System and the standards that we need to follow to successfully
transmit a signal through Amplitude Modulation. Additionally, we are also going
to study about FM Broadcasting System, TV systems and Acoustic Engineering
which is the study of sound. For now, let us focus on Am Broadcasting System and
Standards.
C. M. D. Hamo-ay
1
1
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2. Topics/Discussion (with Assessment/Activities)
Ever since the advent of radio, there have been progressive efforts in regulating this
medium of communication. At the turn of the 20th century, international
conferences were convened to discuss problems in radio communications –
primarily, to minimize mutual interferences among the growing number of stations.
The use of radio in mass communications, or broadcasting, eventually compelled
governments of nations to take over the regulation of radio in their respective
nations in response to the people’s needs. Thus, controlling agencies, organized by
governments, took the avowed task of formulating rules, regulations and technical
standards which are mostly so designed for the benefit of the listening public.
In the formulation of Technical Standards for domestic broadcasting, the more
important considerations must include:
•
•
•
The prevention of harmful signal interferences;
The provision for better signal quality, so that the listener may enjoy a clear
and more realistic sound reproduction, and
The proper utilization of the broadcast spectrum. The Kapisanan ng mga
Brodkaster sa Pilipinas and the National Telecommunications Commission,
cognizant of these criteria, have designated professionals directly involved
with the broadcast industry and representatives of the government to revise
existing local standards, or formulate new standards, which shall be
applicable to the country’s broadcast industry.
1.2.1 Definition of Terms for AM Broadcasting System
Antenna Current
"Antenna current" is the radio-frequency current in the antenna with no
modulation.
Antenna Input Power
"Antenna input power" is the product of the square of the antenna current and
the antenna resistance at the point where the current is measured.
Antenna Resistance
"Antenna resistance" means the total resistance of the transmitting antenna
system at the operating frequency and at the point at which the antenna current
is measured.
Attended Transmitter
Attended transmitter means a transmitter where a qualified technician is in
attendance during all periods of its operation.
Audio- Frequency (af) Signal -to - Interference Ratio
C. M. D. Hamo-ay
2
2
1
| ECE 7: Broadcast and Acoustic
Engineering
Is the ratio (expressed in dB) between the values of the voltage of the wanted
signal and the voltage of the interference, measured under specified conditions,
at the audio-frequency output of the receiver.
Audio-Frequency (AF) Protection Ratio
Is the agreed minimum value of the audio-frequency signal-to-interference
ratio considered necessary to achieve a subjectively defined reception quality.
Authority
The National Telecommunications Commission.
Authorized Frequency
The carrier frequency authorized by the Authority.
Authorized Operating Power
"Authorized operating power" is the power authorized by the Authority.
Carrier Shift
The variation of the mean carrier amplitude resulting from the process of
amplitude modulation; carrier shift is expressed in terms of variations
produced at a given percentage modulation by a sinusoidal test signal, the
variation being expressed as a percentage of the unmodulated carrier
amplitude.
Carrier Frequency
The frequency of the carrier wave. 2.6 Operating Frequency The carrier
frequency at any particular time.
Carrier Wave
A sinusoidal voltage or current generated in a transmitter and subsequently
modulated by a modulating wave.
Daytime
The term "daytime" refers to that period of time between 2200 Universal Time
Coordinates (UTC) to 1000 Universal Time Coordinates (UTC) (6:00 AM-6:00
PM local standard time).
Effective Field
The term "effective field" or "effective field intensity" is the root-mean square
(RMS) value of the inverse distance field at 1.6 km. from the antenna in all
directions in the horizontal plane.
Experimental Period
The term "experimental period" means that time between 12 midnight to 5:00
AM local standard time (1600-2100 Universal Time Coordinates). (UTC). This
period may be used for experimental purposes in testing and maintaining
apparatus by the licensee of any medium frequency broadcast station on its
C. M. D. Hamo-ay
3
3
1
| ECE 7: Broadcast and Acoustic
Engineering
assigned frequency and with its authorized power, provided no interference is
caused to other stations maintaining a regular operating schedule within such
period.
Field Strength
The root-mean-square (RMS) value of the voltage stress produced in space by
the electric field or a radio wave, and is ex-pressed in volts per meter or in
decibels (dB) relative to it.
Frequency Response
The variation, over a specified audio frequency range of the transmission
efficiency of the equipment under test; the variation is expressed in decibels
relative to the transmission efficiency at a specific frequency, such as 1,000
Hertz.
Gain of an Audio Frequency Amplifier
The gain of an audio-frequency amplifier or a chain of audio frequency
equipment incorporating one or more such amplifiers, means the ratio,
expressed in decibels of the power delivered to the load at a specific frequency
(usually 1,000 Hertz) to The power which would be delivered to the same load
if the amplifier or chain of equipment were replaced by an ideal transformer
matching the nominal load and source impedances.
Hertz
The term "Hertz" abbreviated "Hz", is used as a unit of frequency, supplanting
the term "cycle per second" (cps).
High-Level Modulation
"High-level modulation°" is modulation produced in the last radio stage of the
system.
Input Power
"Input power" is the product of the voltage and current at the output of the last
radio stage, measured without modulation.
Licensee
The holder of a license for a broadcasting station issued by the Authority.
Low-Level Modulation
"Low-level modulation" is modulation produced in an earlier stage than the
final.
Maximum Percentage of Modulation
"Maximum percentage of modulation" means the greatest percentage of
modulation that may be obtained by a transmitter without producing, in its
output, harmonics of the modulating frequency in excess of those permitted by
these regulations.
C. M. D. Hamo-ay
4
4
1
| ECE 7: Broadcast and Acoustic
Engineering
Maximum Rated Carrier Power
"Maximum rated carrier power" is the maximum power at which the
transmitter can be operated satisfactorily and is deter-mined by the design of
the transmitter.
Medium Frequency Broadcast Band
The band of frequencies from 526.5 to 1705 kilohertz.
Medium Frequency Broadcast Channel
The band of frequencies occupied by the carrier and two (2) sidebands of an
AM Broadcast signal with the carrier frequency at the center. Channels shall be
designated by the assigned carrier frequencies starting from 531 kHz in
increments of 9 kHz. (A total of 131 AM broadcast channels)
Medium Frequency Broadcast Station
An AM Broadcast Station licensed for aural or sound transmissions intended
for direct reception by the general public and operated on a channel in the
Medium Frequency band.
Modulator Stage
"Modulator stage" means the last audio amplifier stage of the modulating wave
which modulates a radio-frequency stage.
Modulated Stage
"Modulated stage" means the radio-frequency stage to which the modulator is
coupled and in which the continuous wave (carrier wave) is modulated in
accordance with the system of modulation and the characteristics of the
modulating wave.
Nighttime
The term "nighttime" refers to that period of time between 1000 Universal Time
Coordinates (UTC) to 2200 Universal Time Coordinates (UTC) (6:00 PM-6:00
AM local standard time).
Noise Level
• "Noise level" means the rootmean-square (RMS) value of the voltage of
spurious origin present in the audio frequency output of the equipment
under test, ex-pressed in decibels relative to a specified root-meansquare (RMS) value of sinusoidal audio frequency voltage.
• "Unweighted noise level" in a specified band means the noise level in
that band measured by an instrument, the frequency response which is
uniform over that band.
Operating Power
"Operating power" is the transmitter output power.
Percentage Modulation (Amplitude)
In a positive direction:
In a negative direction:
C. M. D. Hamo-ay
5
5
1
| ECE 7: Broadcast and Acoustic
M=(MAX - C)100/C
Engineering
M=(MIN - C)100/C
Where:
M = modulation level in percent
MAX = instantaneous maximum level of the modulated radio frequency envelope
MIN = instantaneous minimum level of the modulated radio frequency envelope
C = carrier level of radio frequency envelope without modulation
Qualified Technician
A person who is a holder of a radio operator's license or its equivalent, as
required by these regulations, issued by the Authority.
Radio-Frequency (RF) Protection Ratio
The value of the radio-frequency wan to-interference signal ratio that enables,
under specified conditions, the audio-frequency protection ratio to be obtained
at the output of a receiver.
Radio- Frequency (RF) Wanted -to- Interference Signal Ratio
Is the ratio (expressed in dB), between the values of the radiofrequency voltage
of the wanted signal and the interfering signal, measured at the input of the
receiver under specified conditions.
Service Areas
• The term "primary service area" of a broadcast station means the area in
which the groundwave field of 1 mV/m (60 dBu) is not subject to
objectionable interference or objectionable fading.
• The term "secondary service area" of a broadcast station means the area
served by the save and not subject to objectionable interference. The
signal is subject to intermittent variations in intensity.
• The term "intermittent service area" of a broadcast station means the area
receiving service from the groundwave but beyond the primary service
area and subject to some interference and fading.
Spurious Emission
The emission on any frequency outside of the assigned channel or authorized
band of frequencies and tolerances allowed by these regulations. Emissions
outside of the assigned channel, as a result of the modulation process, is not
considered spurious, unless it is due to over-modulation.
Total Harmonic Distortion
The effective value of the harmonic voltages present in the audio frequency
output of the equipment under test. It is expressed as a percentage of the
effective value of the fundamental audio frequency voltage and the harmonic
voltages present in the output.
C. M. D. Hamo-ay
6
6
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2.2 Technical Requirements
1.2.2.1 General Technical Requirements
Equipment shall be constructed according to good engineering practice, such
as mechanical soundness, neatness of wiring and accessibility for maintenance.
Ad-equate testing and monitoring points shall be provided to permit the
isolation and testing of individual items of the equipment.
1.2.2.1.a. Adequacy of Components
The quality of all component parts shall be in accordance with good
engineering practice. Where appropriate, the specifications of these
components shall comply with standards set by the Authority, or, in the
absence of such standards, the components shall comply with CCIR standards.
1.2.2.1.b. Compliance with Electrical Wiring Rules
All equipment using electrical power shall comply with the rules of the
Philippine Electronics Code and the Philippine Electrical Code.
1.2.2.1.c. Regulation of Supply Voltage
Adequate voltage regulation shall be provided, where necessary, to ensure that
equipment performance is not affected by variations in supply voltage.
1.2.2.1.d. Protection
•
Protection of Persons. Having regard for the high voltage employed in
transmitting apparatus, adequate provision shall be made in the
construction of all equipment and in the protective enclosure. Warning
signs and safety switches shall be provided, in accordance with good
engineering practice, to ensure, as far as practicable, the safety of all
persons.
It shall be the responsibility of the management or the licensee operating
a broadcasting station, to ensure that protective devices are installed and
appropriate safety rules are observed.
•
Protection of equipment. Equipment shall be protected, in accordance
with good engineering practice, against unsafe conditions and damage
that may otherwise result under faulty conditions.
C. M. D. Hamo-ay
7
7
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2.3 Detailed Technical Requirements
1.2.3.1 Consideration of the Antenna System
The chief purpose of the medium-wave radio broadcasting antenna is to
radiate efficiently the energy supplied by the transmitter, more so, towards the
horizon or along the ground and least to-wards the sky. It is usually the vertical
tower radiator that meets these requirements successfully over most other
models because of its superior groundwave propagation characteristics and
simplicity of antenna design. The antenna, being the take-off point of radio
waves, is the last element of the system under the control of the radio
broadcasting station. Radio waves radiated from the transmitting antenna are
propagated through space to the receiving antenna. The only control over these
propagated waves is in the selection of the antenna site, the polarization, and
the strength of the signal leaving the transmitting antenna. Further
consideration must be given to directional antenna systems which concentrate
the amount of radiation in the direction(s) where it is wanted and restricts the
radiation in the direction(s) where it is not wanted. Since both the intensity and
direction of all electromagnetic transmissions are regulated by the Authority
for all classes of stations, due consideration must also be given to:
1.2.3.1a Location of Antenna Site
The main considerations in the selection of an antenna site are:
a) Location in relation to the population to be served and to other
communication installations and airports;
b) Conductivity of the soil at and immediately adjacent to the site;
c) Conductivity of the path between the site and the target area.
Before the approval is given for any site, the Authority shall refer to
existing local and national regulations governing antenna construction.
Restrictions may be imposed on the height and location of masts in
certain areas and obstruction painting and/or lighting may be necessary.
Except in the area now officially designated as an antenna farm, masts
or towers less than 150 feet from the ground in height may be erected
and are exempted from this provision. Masts or towers with heights
above 150 feet from the ground are normally required to put up the
standard obstruction lighting and painting.
C. M. D. Hamo-ay
8
8
| ECE 7: Broadcast and Acoustic
1
Engineering
1.2.3.1b Antenna Design
•
The transmitting antenna system shall be vertically polarized and
shall radiate an effective field of not less than that of a 60-degree
vertical radiator.
•
For economic reasons, a single vertical tower radiator as mentioned
above may be employed to serve as a common antenna (multiple
frequency antennas) for two or more stations.
•
In the case of a directional antenna system, its composition shall be
of the same vertical tower radiators as mentioned above, arranged
to conform to a design configuration that would emit the desired
radiation pattern.
•
The antenna, antenna lead-in, and counter-poise (if used), shall be
installed so as not to present a hazard. The antenna may be located
close by or at a distance from the transmitter building. A properly
designed and terminated transmission line should be used between
the transmitter and the antenna.
•
The antenna radio frequency current meters (both regular and remote or any other radio frequency instrument which is necessary for
the operator to read) shall be so installed permanently as to be easily
and accurately read without the opera-tor having to risk contact with
circuits carrying high potential radio frequency energy.
•
It is not necessary to protect the equipment in the antenna tuning
house and the base of the antenna with screens and interlocks,
provided, the door to the tuning house and antenna base are fenced
and locked at all times, to ensure that no unauthorized person can
gain access; thus, providing maximum safety to lives. Ungrounded
fencing or wires must be effectively grounded, either directly or
through proper static leaks. Lightning protection for the antenna
system must be installed.
1.2.4 Transmitting Equipment
The transmitting equipment and facilities shall be laid out in accordance with
good engineering practice, thereby providing ease of maintenance and
operation, and safety to personnel.
a) Location and Layout
C. M. D. Hamo-ay
9
9
1
| ECE 7: Broadcast and Acoustic
Engineering
The building shall be of a design and type of construction suitable to the
area in which it is located and it shall comply with relevant building
regulations.
1) Adequate space shall be provided in the building to facilitate access to
all equipment for operation and maintenance purposes. Adequate
space for staff facilities shall also be provided.
2) Adequate ventilation and, where necessary, air conditioning shall be
provided to ensure satisfactory working conditions for staff and
equipment.
3) Adequate lighting shall be provided in all equipment rooms to
facilitate operation and maintenance of the equipment.
1.2.4.1 Design, Construction and Safety to Life
1) The transmitter must be capable of delivering its rated carrier power, with
the provision for varying the same to compensate for variations in line
voltage and other factors which may affect the power output.
2) The transmitter must be capable of delivering and maintaining its carrier
power within the required limits of + 10 percent, whether to be at full
power daytime mode or at reduced power nighttime mode. The power
shall be determined by the direct methods, i.e., the square of the
transmission line current measured at the input of the antenna matching
network multiplied by the resistance at this same point. [The indirect
method (Ep x Ip x Efficiency of the last radio frequency stage) may also be
used.]
3) The transmitter must be capable of satisfactory operation at the
authorized operating power with modulation of at least 90 percent with
no more distortion than given in Sub-section 3.2.2.b (7).
4) The transmitter must be capable of maintaining the operating frequency
within the limits of ± 10 Hertz of the assigned frequency.
5) The carrier shift (current) at any percentage of modulation shall not
exceed 5 percent.
6) The carrier hum and extraneous noise level, (unweighted r.s.s.) exclusive
of microphone and studio noises over the frequency band 30 to 20,000 Hz
is, at least, 45 dB below the level of a sinusoidal tone of a 400 Hz,
producing 90 percent modulation of the carrier.
7) The total audio frequency distortion from microphone terminals,
including micro-phone amplifier, to antenna output, must not exceed 5
percent harmonics (voltage measurements of arithmetical sum or r.s.s.)
when modulated from 0 to 84 percent, and not over 7.5 percent harmonics
when modulating from 85 percent to 95 percent. Distortion shall be
measured with modulating frequencies of 50, 100, 400, 1000, 5000, and
7,500 Hertz up to the tenth harmonic or 16,000 Hz or any intermediate
frequency that readings on these frequencies indicate is desirable.
8) The audio frequency transmitting characteristics of the equipment from
the microphone terminals (including microphone amplifier, unless
C. M. D. Hamo-ay
10
10
1
9)
10)
11)
12)
13)
14)
15)
16)
17)
18)
19)
20)
21)
| ECE 7: Broadcast and Acoustic
Engineering
microphone frequency correction is included, in which event proper
allowance shall be made accordingly) to the antenna output, does not
depart more than 2 decibels (dB) from that at 1, 000 Hertz between 80 and
7,500 Hz.
The transmitter must be equipped with indicating instruments to
continuously measure the DC plate cur-rent and voltage and any other
indicating instruments necessary for proper operation.
The transmitter shall be equipped with an adequate control system for the
application and removal of power.
Adequate allowances shall be provided for all component parts to avoid
over-heating at the maximum rated power output.
Any emission appearing on a frequency removed from the carrier by
between 15 kHz and 30 kHz inclusive, shall be attenuated at least 35
decibels below the level of the unmodulated carrier.
Any emission appearing on a frequency removed from the carrier by more
than 30 kHz and up to and including 75 kHz, inclusive, shall be attenuated
at least 35 decibels below the level of the unmodulated carrier.
Any emission appearing on a frequency removed from the carrier by more
than 75 kHz shall be attenuated at least 43 ± 10 log10 (Power in watts)
decibels below the level of the unmodulated carrier or 80 decibels whichever is the lesser attenuation.
The transmitter shall be operated, tuned, and adjusted so that emissions
outside of the authorized channel do not cause harmful interference to the
reception of other stations. In any case, should harmful interference to the
reception of other radio stations occur, the licensee may be required to
take further steps as may be necessary in accordance with Sec. 3.2.2.b) (14).
In general, the transmitter shall be constructed either on racks and panels
or in totally enclosed frames protected as required by the Philippine
Electronics Code.
Means shall be provided for making all tuning adjustments of any circuit
involving the application of voltages in excess of 110 volts AC or DC from
the front panel with all access doors closed.
Bleeder resistors or such other automatic means shall be installed across
all the condenser banks to re-move any charge which may remain after
the high volt-age circuit is opened.
Plate supply and other high voltage devices, including transformers,
filters, rectifiers, and motor generators, shall be provided with protective
circuits so as to prevent injury to operating personnel.
In case the voltmeter is located on the low potential side of the multiplier
resistor with one terminal of the instrument at or less than 1,000 volts
above ground, no protective case is required. However, it is a good
practice to protect voltmeters that are subject to more than 5,000 volts with
suitable protective de-vice across the instrument terminals in case the
winding opens.
Wiring between units of the transmitter shall be in-stalled in conduits or
approved fiber or metal raceways to protect it from mechanical injury.
C. M. D. Hamo-ay
11
11
1
| ECE 7: Broadcast and Acoustic
Engineering
22) Circuits carrying low level radio frequency energy between units of the
transmitter shall be properly wired and shielded to prevent the pick-up of
modulated radio frequency energy from the output circuits.
23) Each stage (including the oscillator) preceding the modulated stage shall
be properly shielded and filtered to prevent feedback from any circuit
following the modulated stage.
24) An oscilloscope or a type approved meter indicator type modulation
monitor is required for monitoring transmitter modulation.
25) A frequency monitor or a type approved frequency meter indicator is
required for monitoring transmitter carrier frequency.
1.2.5 Metering Equipment
a) Linear scale instruments indicating the plate current or plate voltage of the last
radio stage shall meet the following specifications:
1) Length of scale shall not be less than 6 cm.
2) Accuracy shall be at least 2 percent of the full reading.
3) The maximum rating of the meter shall be such that it does not read off
scale during normal operation.
4) Full scale reading shall not be greater than five times the minimum
normal indication.
b) Instruments indicating antenna current, common point current, and base
currents shall meet the following specifications:
1) Instruments having logarithmic or square law scales:
(a) Shall meet the requirements of paragraph 3.2.3.1 a(1), a(2), and a(3)
of this section for linear scale instruments.
(b) Full scale reading shall not be greater than three times the minimum
normal indication.
(c) No scale division above one-fifth scale reading (in amperes) shall be
greater than one-fiftieth of the full-scale reading. (Ex: An ammeter
meeting requirement (1) is acceptable for indicating currents from 1
to 5 amperes, provided no division between 1 and 5 amperes is
greater than one-fiftieth of 5 amperes, 0.1 ampere).
c) A radio frequency ammeter meeting the requirements of paragraph (b) of this
section shall be permanently installed in the antenna circuit and a suitable
arrangement may be made to protect it from damage by lightning. Where this
arrangement is used, contacts shall be protected against corrosion. Since the
meter is permanently connected in the antenna circuit, provision may be made
to short the meter when it is not being used. Such switching shall be
accomplished without interrupting the transmission of the station.
C. M. D. Hamo-ay
12
12
1
| ECE 7: Broadcast and Acoustic
Engineering
d) Remote reading antenna ammeter(s) may be employed and the indications
logged as the antenna current, or in the case of a directional antenna, the
common point current and base currents, in accordance win the following:
1) Remote reading antenna common point or base am-meters maybe
provided by:
(a) A factory-calibrated cur-rent transformer connected to a metering
instrument for RF antenna current indication.
(b) Using indications of phase monitor for deter-mining the antenna
base currents or their ratio in the case of directional antennas,
provided:
1. the base current readings are logged in accordance with the
pro vision of the station license;
2. that the indicating instruments in the unit are connected
directly in the current sampling circuit with no other shunt
circuits of any nature.
3. all sampling fines have equal total lengths and identical
electrical characteristics. Portions of sampling lines between
towers and transmitter building, prefer-ably, should be
buried, if run above ground, the lines should be rigidly
supported and positioned with the outer conductors
grounded, where necessary, to ensure that fields from the
array will not induce error currents in the line.
(c) Using indications of re-mote control instruments, provided that such
indicating instruments are capable of being connected directly into
the antenna circuit at the same point as the antenna ammeter.
2) Remote ammeters shall be connected into the antenna circuit at the same
point as, but below (transmitter side) the antenna ammeter(s), and shall
be calibrated to indicate within 2 percent of the regular meter over the
entire range above one-third or one-fifth full-scale.
3) All remote meters shall meet the same requirement as the regular antenna
ammeter with respect to scale accuracy, etc.
4) Calibration shall be checked against the regular meter at least once a
week.
5) All remote meters shall be provided with shielding or filters as necessary
to pre-vent any feed-back from the antenna to the transmitter.
6) In the case of shunt-excited antenna, the transmission line current meter
at the transmitter may be considered as the remote antenna ammeter,
C. M. D. Hamo-ay
13
13
1
| ECE 7: Broadcast and Acoustic
Engineering
provided the transmission line is terminated directly into the excitation
circuit feed-line, which shall employ series tuning only (no shunt circuits
of any type shall be employed) and, inasmuch as is practicable, the type
and scale of the transmission line meter shall be the same as those of the
excitation circuit feed-line meter (meter in slant wire feed line or its
equivalent).
7) In the event that there is any question as to the method of providing the
re-mote indication, or the ac-curacy of the remote meter, the burden of
proof of satisfactory performance shall be upon the licensee and the
manufacturer of the equipment.
e) The function of each instrument shall be clearly and permanently shown on the
instrument itself or on the panel immediately adjacent thereto.
f) Digital meters, printers, or other numerical read-out devices may be used in
addition to or in lieu of indicating instruments meeting the specifications of
paragraphs (a) and (b) of this section. If a single digital device is used at the
transmitter for reading and logging of operating parameters, either (1)
indicating instruments meeting the above-mentioned specifications shall be
installed in the transmitter and antenna circuit, or (2) a spare digital device shall
be maintained at the transmitter with the provision for its rapid substitution
for the main device, should that device malfunction. The readout of the device
shall include at least three digits and shall indicate the value or a decimal
multiple of the value of the parameter being read to an accuracy of at least 2
percent. The multiplier to be applied to the reading of each parameter shall be
indicated at the operating position of a switch used to select the parameter for
display, or on the face of an automatically printed log at least once for each
calendar day.
g) The antenna ammeters (both regular and remote) and any other radio
frequency instrument which are necessary for the operator to read shall be so
installed as to be easily and accurately read without the operator having to risk
contact with circuits carrying high potential radio frequency energy.
h) Frequency Monitor Specifications:
1) The unit shall have an accuracy of at least 5 parts per million under
ordinary conditions of temperature and humidity encountered in
standard broadcast stations throughout the Philip-pines.
2) The range of the indicating device shall be, at least, from 20 Hertz below
to 20 Hertz above the assigned frequency.
3) The scale of the indicating device shall be so calibrated as to be
accurately read within at least 1 Hertz.
C. M. D. Hamo-ay
14
14
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2.6 Monitoring Equipment
a. Frequency Monitor
1) The licensee of each station shall have in operation, either at the transmitter
or at the place where the transmitter is controlled, a frequency monitor of a
type approved by the Authority which shall be independent of the
frequency control of the transmitter.
2) In the event that the frequency monitor becomes defective, the station may
be operated without such equipment pending its repair or replacement for
a period not in excess of 60 days without further permission of the
Authority: Provided, That:
a) Appropriate entries shall be made in the operation log of the station
to show the date and time the monitor was removed from and
restored to service.
b) The Engineer in Charge of the Region in which the station is located
shall be notified both immediately after the monitor is found to be
defective and immediately after the repaired or re-placement
monitor has been installed and is functioning properly.
c) The frequency of the station shall be compared with an external
frequency source of known accuracy at sufficiently frequent intervals
to insure that the frequency is maintained within the tolerance. An
entry shall be made in the station log as to the method used and the
results thereof.
3) If conditions beyond the control of the licensee or permittee prevent the
restoration of the monitor to service within the above allowed period,
informal request may be filed with the Engineer in Charge of the Region in
which the station is located for such additional time as may be required to
complete re-pairs of the defective instrument or equipment.
b. Modulation Monitor
1) The licensee of each station shall have in operation, either at the transmitter
or at the place where the transmitter is control-led, an oscilloscope or a
modulation monitor of a type approved by the Authority.
2) In the event that the modulation monitor becomes defective, the station may
be operated without such equipment pending its re-pair or replacement for
a period not in excess of 60 days without further authority of the
Commission: Provided that:
C. M. D. Hamo-ay
15
15
1
| ECE 7: Broadcast and Acoustic
Engineering
a) Appropriate entries shall be made in the operation log of the station
to show the date and time the monitor was removed from and
restored to service.
b) The Engineer in Charge of the Region in which the station is located
shall be notified both immediately after the monitor is found to be
defective and immediately after the repaired or replacement monitor
has been installed and is functioning properly.
c) The degree of modulation of the station shall be monitored with a
cathode ray oscilloscope or other means.
3) If conditions beyond the control of the licensee or permittee prevent the
restoration of the monitor to service within the above allowed period,
informal request may be filed with the Engineer in Charge of the region in
which the station is located for such additional time as may be required to
complete repairs of the defective instrument or equipment.
1.2.7 Studio, Equipment, and Allied Facilities
The studio, being the source of programs, must be provided with such
control room, equipment and other accommodation as are necessary to ensure
the provision of a satisfactory service by the station.
a) Studio and Layout Location
1) The building that will contain the studio shall satisfy the
provisions given in Section 3.2.2.a. of these standards.
2) Each studio shall be associated with a control room from which
the operational area of the studio may be viewed with ease. The
Authority may, however, approve an operation whereby the
studio and control rooms are integrated into one and that
responsible personnel shall perform simple front panel type
functions like level adjustments and switchings during his/her
board hours, provided, a licensed radio technician with a 1st, 2nd,
or 3rd Crass radiotelephone license is employed to perform all
the more complicated pre-and post-sign-on adjustments of a
more technical nature including maintenance jobs which are
necessary for the proper operation of technical studio equipment.
Provided further, that for this kind of operation, an automatic
program level control is employed to ensure that a proper
program level is fed to the transmitter.
3) Studios and control rooms shall be so constructed that they are
adequately insulated from sources of extraneous noise and
vibration, and the acoustic treatment of such studios and control
rooms shall be in accordance with good engineering practice.
C. M. D. Hamo-ay
16
16
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2.8 Emergency Equipment and Facilities
a) Alternate Main Transmitter
1) The regular and the optional main transmitter are co-located in a single
place.
2) The external effects from both regular and alternate main transmitters
shall substantially be the same as to frequency stability.
b) Auxiliary Transmitter
1) An auxiliary transmitter may be provided and may be installed in the
same location as the regular main transmitter or in an-other location.
2) Its operating power shall not be less than 10% or never greater than the
authorized operating power of the main transmitter.
3) A licensed operator shall be in control whenever an auxiliary transmitter
is placed in operation.
4) When installed in a location different from that of the regular main
transmitter, a type-approved modulation monitor and a frequency
monitor are required to be installed along with it.
c) Emergency Electric Power Generating Unit
An electric power generating unit with sufficient electrical capability to
sustain the station's emergency or regular operations shall be maintained to
ensure an uninterrupted operation. Should this generating unit, however, in
the course of its operation, cause or emit radio frequency energy and/or
harmonics that may prove harmful to the purity of the station's signal, such
interference shall be contained sufficiently as to satisfy the provisions of
sections 3.2.2.b) 12) through 3.2.2.b) 15) of these standards.
d) Emergency Announce Equipment Complement
Where the need exists, an emergency announce equipment complement
shall be maintained in the transmitter side for emergencies, to ensure
uninterrupted programming during the station's authorized hours of
operations.
e) Spare Component Parts
In order to cut down-times during scheduled on-air operations, a
reasonable variety and number of spare components appropriate to the
equipment installed at the site, shall be kept on hand at each studio and
transmitter sites in the most convenient location therein.
f) Fire Fighting Facilities
Appropriate and adequate fire-fighting facilities shall be maintained
within the establishment, especially in fire-prone areas therein.
C. M. D. Hamo-ay
17
17
1
| ECE 7: Broadcast and Acoustic
Engineering
g) All stations, whether operating by remote control or direct control, shall be
so equipped as to be able to follow the prescribed EBS alerting procedures
set forth in the EBS Manual for Broadcast Stations.
1.2.9 Broadcast Auxiliary Services
Broadcast transmission auxiliary services fall under these three categories:
• Studio-to-Transmitter Link (STL)
• Remote Pick-Up Broadcast Station
• Communications, Coordination and Control Link
A. The frequency band allocation for STUDIO-TO-TRANSMITTER LINK/REMOTE
CONTROL SYTEM shall be:
• Band A 300-315 MHz
• Band B 734-752 MHz
• Band C 942-952 MHz
The maximum power allowable for STL's shall be 15 watts.
B. The frequency band allocation for REMOTE PICK-UP STATION shall be:
• Band A: 315-325 MHz
• Band B: 450-451 MHz
• Band C: 455-456 MHz
The maximum power allowable for Remote Pick-up Stations shall be 35 watts.
C. The frequency band allocation for COMMUNICATIONS, COORDINATION AND
CONTROL LINK shall be:
• Band A: 412 MHz (non-exclusive)
• Band B: 25.67 – 26.1 MHz
• Band C: 162.235 – 162.615 MHz
166.250 and 170.150 MHz
• Band D: 432.5 - 433 MHz
437.5 -438 MHz
The maximum power allowable for Communications, Coordination and
Control Link shall be:
Band A - 100 watts (SBS)
B - 160 watts (ERP)
C - 160 watts (ERP)
D - 200 watts (for repeater)
The Authority shall authorize the employment of any one or all of these broadcast
transmission services to a station depending on the necessity and availability of
frequencies for the purpose. Any AM or FM station authorized to operate is entitled to
use any broad cast transmission service relevant to the efficient operation of the station
where the use of physical lines arcades is not feasible.
C. M. D. Hamo-ay
18
18
| ECE 7: Broadcast and Acoustic
1
Engineering
1.2.10 Operating Requirements
1.2.10.1 Hours of Operation
• Minimum Operating Schedule. The licensee of each medium-frequency
broadcast station shall maintain a minimum operating schedule of twothirds of the total hours that it is authorized to operate except that in
emergencies when, due to causes beyond the control of the licensee, it
becomes impossible to continue operating, the station may cease
operations for a period not exceeding 10 days.
• Broadcast(s) outside of the authorized regular operating schedules (as
before regular sign-on schedules and/or beyond the regular sign-off
schedules) may be aired without prior authorization from the Authority
provided the program falls under an emergency category or of very
important relevance to the station's existence. The information shall be
entered in the program and operating logs at the time the broadcast was
aired.
• If a permanent discontinuance of operations is being contemplated, then
the licensee shall notify in writing the Authority or regional office where
the station is located at least two (2) days before the actual
discontinuance is affected.
1.2.10.2 Other Operating Practices
The percentage of modulation shall be maintained as high as possible,
consistent with good quality transmission and, in no case, more than 125
percent on positive peaks nor more than 100 percent on negative peaks of
frequent recurrence during any selection which is transmitted at the highest
level of the program under consideration.
1.2.10.2a Posting of Station and Operator Licenses
•
The station license and other instruments) of station
authorization shall be posted in a conspicuous place in such a
manner that all terms are visible, at the place the licensee
considers to be the principal control point of the transmitter. At
all other control points listed on the station authorization, a
photocopy of the station license and other instruments of station
authorization shall be posted.
•
The original copy of the operator's license shall be posted at the
place where he is on duty as an operator.
C. M. D. Hamo-ay
19
19
| ECE 7: Broadcast and Acoustic
1
Engineering
1.2.10.3 Operator Requirements
a. Radio operator holding a valid radio telephone first class operator's
license shall be in actual charge of the transmitting apparatus and shall
be on duty either at the transmitter location or remote control point.
b. The licensee of a station shall employ at least one (1) fulltime licensed
first-class radiotelephone operator whose primary duty shall be to effect
and in-sure the proper functioning of the transmitting equipment.
1.2.10.4 Station Identification Announcements
a. A licensee of a medium-frequency broadcast station shall make station
identification announcements (call letters, frequency, and location) at
the beginning and ending of each time of operation and during
operation on the hour and either on the half hour or at the quarter hour
preceding the next hour: Provided,
b. Such identification announcement need not be made on the half hour or
quarter hour when, to make such announcement, would interrupt a
single consecutive speech, play, religious service, symphony concert, or
operatic production. In such cases, an identification announcement shall
be made at the first interruption of the entertainment continuity and at
the conclusion of the program: Provided, that an announcement within
five minutes of either on the half hour or at the quarter hour preceding
the next hour will satisfy the requirements of identification
announcements. In the case of variety show programs, basketball game
broadcasts, or similar programs of longer duration than 30 minutes, the
identification announcement shall be made within 5 minutes of the
times specified.
c. In the case of all other pro-grams, the identification announcement shall
be made within 2 minutes of the times specified.
1.2.10.5 Logs
The licensee or permittee of each medium frequency broadcast station shall
maintain program and operating logs and shall require entries to be made
as follows:
a) In the Program Log:
1) An entry of the time each station identification announcement
(call letters, frequency, and location) is made.
2) An entry briefly describing each program broadcast, such as
"music", "drama", "speech", etc. together with the name or title
thereof, and the sponsor's name, with the time of the be-ginning
C. M. D. Hamo-ay
20
20
1
| ECE 7: Broadcast and Acoustic
Engineering
and ending of the complete program. If a mechanical record is
used, the entry shall show the exact nature thereof, such as
"record", "transcription", etc., and the time it is announced as a
mechanical record. If a speech is made by a political candidate,
the name and political affiliations of such speaker shall be
entered.
3) An entry showing that each sponsored program broadcast has
been announced as sponsored, paid for, or furnished by the
sponsor.
4) An entry showing, for each pro-gram of network origin, the name
of the network originating the program.
5) An entry of the time the program begins and ends.
b) In the Operating Log (Transmitter Log)
1) An entry of the time the station begins to supply power to the
antenna, and the time it stops.
2) An entry of each interruption to the carrier wave, its cause, and
duration.
3) An entry of the following every 30 minutes:
a) Operating constants of the last radio frequency stage plate
current and plate voltage
b) Antenna current
4) Any other entries required by the instrument of authorization.
5) A log of all operations must be kept during the experimental
period. If the entries required above are not applicable thereto,
then the entries shall be made so as to fully describe the operation.
6) Logs of medium frequency broadcast stations shall be retained by
the licensee or permittee for a period of two (2) years: Provided,
however, that logs involving communications incident to a
disaster or which include communications incident to or
involved in an investigation by the Authority and concerning
which the licensee or permittee has been notified, shall be
retained by the licensee or permittee until he is specifically
authorized in writing by the Authority to destroy them:
Provided, further, that log s incident to or involved in any claim
or complaint of which the licensee or permittee has notice shall
be retained by the licensee or permittee until such claim or
complaint has been fully satisfied or until the same has been
barred by the statute limiting the time for filing of suits upon such
claims.
C. M. D. Hamo-ay
21
21
1
| ECE 7: Broadcast and Acoustic
Engineering
7) Each log shall be maintained and signed by the radio operator
during his tour of duty. The logs shall be made available upon
request by an authorized representative of the Authority.
8) The log shall be kept in an orderly manner, in suitable form, and
in such detail that the data required for the particular class of
station concerned are readily available. Key letters or
abbreviations may be used if proper meaning or explanation is
contained elsewhere in the log.
9) No log or portion thereof shall be erased, obliterated, or willfully
destroyed within the period of retention provided by the rules.
Any necessary correction may be made only by the person
originating the entry who shall strike out the erroneous portion,
initial the correction made, and indicate the date of correction.
10) Rough log may be transcribed into condensed form, but in such
cases the original rough log or memoranda and all par-dons
thereof shall be preserved and made a part of the complete log.
1.2.10.6 Remote Control Operation
Operation by remote control shall be subject to the following conditions:
a. The equipment at the operating and transmitting positions shall be so
installed and protected that it is not accessible to or capable of operation
by per-sons other than those duly authorized by the licensee.
b. The control circuits from the operating positions to the transmitter shall
provide positive on and off control and shall be such that open circuits,
short circuits, grounds or other line faults will not actuate the transmitter
and any fault causing loss of such control will automatically place the
transmitter in an inoperative position.
c. A malfunction of any part of the remote-control equipment and
associated line circuits resulting in improper control or inaccurate meter
readings shall be cause for the immediate cessation of operation by
remote control
d. Control and monitoring equipment shall be installed so as to allow the
licensed operator at the remote-control point to per-form all the
functions in a manner required by the rules. Control point of the antenna
current meter for directional antenna, the common point current meter
and remote base current meters shall be read and entered in the
operating log each half hour.
C. M. D. Hamo-ay
22
22
1
| ECE 7: Broadcast and Acoustic
Engineering
e. The indications at the remote-control point of the antenna current meter
for directional antenna, the common point current meter and remote
base current meters shall be read and entered in the operating log each
half hour.
f. The indications at the transmitter, if a directional antenna station, of the
common point cur-rent, base currents, phase monitor sample loop
currents and phase indications shall be read and entered in the operating
log once each day for each pattern. These readings must be made within
two hours after the commencement of operation for each pattern.
g. Stations with authorized operating power in excess of 10 kilo-watts
employing directional antenna and operated by remote control, shall
make a skeleton proof of performance each year, consisting of three or
four measurements on each radial used in the original application and
must submit the results of these measurements, plus the monitoring
point readings with the renewal application.
1.2.11 Allocation Rules and Regulation
1.2.11.1 Maximum Power Allocation
AREA
Metro Manila*
All other areas
MAXIMUM POWER IN KW
50 kw
10 kw
* NOTE: Transmitters of Existing Metro Manila Stations may be located outside
of Metro Manila. Provided, Metro Manila remains within the 80 dBu contour
of the transmitter.
a) The station shall not operate more than 5% and not lower than 10% of
its authorized operating power.
b) The Authority may grant a permit to operate a non- commercial AM
broadcast station exceeding these Maximum Power Allocations on a
case-to-case basis; Provided, such proposed station shall conform
with the Frequency Allocation Rules and Regulations.
c) For new stations and increase of power applications, the maximum
power allowed must conform to protection ratios embodied in the
medium-wave band and therefore, shall be acted upon on a case to
case basis.
C. M. D. Hamo-ay
23
23
1
| ECE 7: Broadcast and Acoustic
Engineering
1.2.11.2 Radio Frequency Protection Ratio
a) The following radio frequency protection ratios provide for the minimum
physical separation of AM stations and their protection from interference.
b) Frequency Separation.
The minimum frequency separation in any service area is 36 kHz.
c) Number of AM Radio Stations per Commercial Broadcast Entity in Each
Service Area. Each commercial broadcast entity may be allowed to operate
not more than one AM radio station in any broadcast service area.
1.2.12 AM Stereophonic Standard
The AM stereophonic standard is the C-QUAM AM stereophonic system.
1.2.13 Public Information File
An updated Public information File at each broadcast station shall be made
available to the NTC inspector or to any interested parry. The Public
Information File shall contain the following:
a) A copy of the station license.
b) Documents as to mode of ownership whether partnerships, corporation
or single proprietorship including trade name as registered in the
Department of Trade.
c) A list of changes in transmitting facilities arranged chronologically).
d) Copies of the Program Standards, the Technical Standards, the NTC
compilation of laws, regulations, circulars and memoranda.
e) Evidence of membership in the KBP.
C. M. D. Hamo-ay
24
24
1
| ECE 7: Broadcast and Acoustic
Engineering
Assessment of Learning
Quiz:
1.
What is the local oscillator frequency in commercial AM broadcast if it is equal
to 455 kHz?
2. The maximum power suggested by KBP on 919-1312 AM broadcast station in
Metro Manila is ______.
3. KBP radio code mandates that station must provide a minimum of ___ minutes.
4. The minimum frequency separation between the frequency of AM
broadcasting station is ______.
5. In accordance with existing provision of law and the KBP rules and the
regulations, all stations shall actively promote the growth and the development
of Filipino music by playing _____ OPM every clock hour.
6. Part of broadcast day from midnight to local sunrise.
7. The standard AM radio broadcast belongs to which frequency band?
8. Standard AM broadcasting use _____ for greater and efficient coverage.
9. What is the highest assigned carrier frequency for standard AM broadcast?
10. What refers to the standard frequency band limits of AM broadcast band?
Assignment:
1. What are the different concepts regarding AM Broadcast Communications
System?
2. Identify the elements and applications of AM Broadcast Communication
System.
3. How does AM Broadcasting technique differs from FM and TV Broadcasting
Systems?
4. Come-up with the design of AM broadcasting network including coverage
mapping and interference.
5. Define the following:
a. AM studio system
b. AM Technical Operation Center
c. AM Transmission System
d. AM Coverage Mapping
e. AM Prediction and Interference Study
C. M. D. Hamo-ay
25
25
1
| ECE 7: Broadcast and Acoustic
Engineering
1.3 References
•
Technical Standards and Operating Requirements for Broadcast Stations in the
Philippines (Kapisanan ng mga Brodkaster ng Pilipinas)
1.4 Acknowledgment
The images, tables, figures and information contained in this module were
taken from the reference cited above. These are all based on the standards set by
KBP.
C. M. D. Hamo-ay
26
26