Radio and Signals Fundamentals

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Chapter 2

• Radio and Signals Fundamentals

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Radio and Signal Fundamentals Radio Signals and
Waves

• Signals travel back and forth between radios
  carrying voices, data and Morse code.
• Radio waves that travel at the speed of light.
• Radio waves start as an electrical signal in an
  antenna that constantly changes direction.
• The rate of change determines the signals
  frequency.
• The radio wave travels away from the antenna
  into space, vibrating or oscillating at the same
  frequency as the electrical signal.

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Radio and Signal Fundamentals Radio Signals and
Waves

• As the radio wave passes other antennas, it
  creates replicas of the original electrical
  signal.
• A radio converts the signal back into a voice,
  digital data or even Morse code.
• The process of turning the transmitter output
  signal into radio waves that leave the antenna is
  called radiation or radiating.
• The radio wave travels away from the antenna into
  space, vibrating or oscillating at the same
  frequency as the electrical signal.

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Radio and Signal Fundamentals Radio Signals and
Waves

• All radio equipment is designed to generate or
  manipulate radio signals.
• No matter how you communicate by ham radio ---
  with voice, Morse code or computer --- those
  resulting radio signals are usually referred to
  as just signals.

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Radio and Signal Fundamentals Radio Signals and
Waves
Prefix Symbol Multiplication Factor Multiplication Factor
Tera T 1010 1,000,000,000,000.0
Giga G 109 1,000,000,000.0 (One billion)
Mega M 106 1,000,000.0 (One million)
Kilo k 103 1,000.0 (One thousand)
Hecto h 102 100
Deca (Basic unit) da 101 10.0
Deci d 10-1 0.1
Centi c 10-2 0.01 (One hundredth)
Milli m 10-3 0.001 (One thousandth)
Micro u 10-6 0.000001 (One millionth)
Nano n 10-9 0.000000001 (One billionth)
Pico p 10-12 0.000000000001 (One trillionth)
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Radio and Signal Fundamentals Radio Signals and
Waves

• As frequency increases, it becomes easier to use
  units of---
• kilohertz (1kHz 1,000 Hz)
• megahertz (1 MHz 1,000 kHz or 1,000,000 Hz)
  and
• gigahertz (1 GHz 1,000 MHz or 1,000,000,000
  Hz)

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Radio and Signal Fundamentals Radio Signals and
Waves

• Metric conversions within the Metric System
• 1.5 amperes How many Milliamperes?
• 1,500 milliamperes
• 1.5 x 1,000 1,500

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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric
System 1,500,000 hertz can be specified in what
other ways? 1,500 kilohertz or 1.5 Megahertz
1,500,000 divided by 1,000 1500 kHz 1,500,000
divided by 1,000,000 1.5 MHz
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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric System How
many volts equal a kilovolt? 1,000 volts Kilo
1000 --- 1 volt x 1,000 a kilovolt
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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric System How
many volts equal a microvolt? A millionth of a
volt Micro 1,000,000 --- 1 volt 1,000,000
a millionth of a volt
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Radio and Signal Fundamentals Radio Signals and
Waves

• Metric conversions within the Metric System
• 500 milliwatts is equal to what?
• 0.5 Watts or one-half watt
• milli equals one thousandth
• 500 milliwatts 1000 0.5 watts

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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric System If
an ammeter calibrated in amperes is used to
measure a 3000-milliampere circuit what would be
the reading? 3 amperes Milli 1000 3000 mA
1000 3 amperes or amps or 0.003 A x 1000 3
amps
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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric
System 3.525 MHz How many kilohertz? 3525
kilohertz Kilo 1000 3.525 x 1000 3525 kHz
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Radio and Signal Fundamentals Radio Signals and
Waves
Metric conversions within the Metric System How
many microfarads equal 1,000,000 picofarads? 1
microfarad A microfarad one millionth of a
farad 1,000,000 picofarads 1,000,000 1
microfarad
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Radio and Signal Fundamentals Radio Signals and
Waves
As the signal oscillates, each back-and-forth
sequence is called a cycle. The number of cycles
per second is the signals frequency and is
represented by the lower case f. The unit of
measure for frequency is hertz, which is
abbreviated as Hz. One cycle per second is one
hertz or 1 Hz.
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Radio and Signal Fundamentals Radio Signals and
Waves
The strength or amplitude of a radio signal
oscillates like a sine wave.
One Cycle

0
time
-
One Wavelength
One Second
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Radio and Signal Fundamentals Radio Signals and
Waves
The period of the cycle (represented by T) is
its duration. The reciprocal of the period, 1/T,
is the signals frequency, f. A harmonic is a
signal with a frequency that is some integer
multiple (2,3,4 and so on) of a fundamental
frequency. 7.006 MHz fundamental
frequency 14.012 MHz second harmonic 21.018 MHz
third harmonic 28.024 MHz fourth harmonic
There is no First Harmonic
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Radio and Signal Fundamentals Radio Signals and
Waves
Harmonic are used to shift signal frequencies and
create new signals by radio designers. These
unwanted signals can also cause problems such as
interference and can potentially result in
signals being transmitted outside the amateur
frequency bands as spurious emissions.
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Radio and Signal Fundamentals Radio Signals and
Waves

• Every cycle of the signal has the same basic
  shape
• Rising and falling and returning to where it
  started.
• Position within a cycle is called phase.
• Phase is used to compare how sine wave signals
  are aligned in time.
• Phase is measured in degrees and there are 360
  degrees in one cycle of a sine wave.

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Radio and Signal Fundamentals Radio Signals and
Waves
Two sine waves with a phase difference of 180
degrees so that one wave is increasing while the
other is decreasing, they are out of phase.
Waves with no phase difference (e.g.,
increasing and decreasing at the same time) are
in phase.
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Radio and Signal Fundamentals Radio Signals and
Waves
Heinrich Hertz was the first to send and receive
radio waves in 1886.
James Clerk Maxwell predicted the existence of
radio waves in 1864.
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Radio and Signal Fundamentals Radio Signals and
Waves
Signals below 20 kHz produce sound waves that
humans can hear when connected to a speaker or
headset. We call them audio frequency or AF
signals. Signals whose frequency is greater than
20,000 Hz or 20 kHz are called radio frequency or
RF signals. The range of frequencies of RF
signals is called the radio spectrum. It starts
at 20 kHz and goes through several hundred GHz or
a thousand million times higher.
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Radio and Signal Fundamentals Radio Signals and
Waves
For convenience, the radio spectrum is divided
into ranges of frequencies that have similar
characteristics. Frequencies above 1 GHz are
generally considered to be microwaves. Microwave
ov ens operate at 2.4 GHz Hams primarily use
frequencies in the Middle Frequency (MF) through
Ultra High Frequency (UHF) and microwave ranges.
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Radio and Signal Fundamentals Radio Signals and
Waves
RF Spectrum Ranges RF Spectrum Ranges RF Spectrum Ranges
Range Name Abbreviation Frequency Range
Very Low Frequency VLF 3 kHz-30 kHz
Low Frequency LF 30 kHz 300 kHz
Medium Frequency MF 300 kHz 3 MHz
High Frequency HF 3 MHz 30 MHz
Very High Frequency VHF 30 MHz 300 MHz
Ultra High Frequency UHF 300 MHz 3 GHz
Super High Frequency SHF 3 GHz 30 GHz
Extremely High Frequency EHF 30 GHz 300 GHz
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Radio and Signal Fundamentals Radio Signals and
Waves
Specific ranges of frequencies in which signals
are used for a common purpose or share similar
characteristics are called bands. The AM
broadcast band covers 550-1700 kHz The FM
broadcast band covers 88-108 MHZ Frequency bands
used by radio amateurs are called amateur bands
or ham bands.
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Radio and Signal Fundamentals Radio Signals and
Waves
FM
Mobile Phones
VHF TV
UHF TV
Shortwave
AM
VLF LF MF HF VHF UHF SHF EHF
3 kHz
30 kHz
300 kHz
3 MHz
30 MHz
300 MHz
3 GHz
30 GHz
300 GHz
audio
radio
Some amateur portions of the RF spectrum
Low Frequencies Long Wavelengths
High Frequencies Short Wavelengths
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Radio and Signal Fundamentals Radio Signals and
Waves
The wavelength of a signal is the distance that
it travels in during one complete cycle. It is
represented by the Greek letter lambda All
radio waves travel at the speed of light which is
represented by a lower-case c. The speed of
light in space and air is 300 million meters per
second or 3 x 108 meters per second.
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Radio and Signal Fundamentals Radio Signals and
Waves
Radio waves are often referred to by their
wavelength or frequency because the two are
related by the speed of light. You can determine
the wavelength or frequency using these
formulas Wavelength speed of light divided by
frequency Frequency speed of light divided by
wavelength
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Radio and Signal Fundamentals Radio Signals and
Waves

• There are two important relationships between
  frequency and wavelength
• As frequency increases, wavelength decreases
• As wavelength increases, frequency decreases
• It is very common to refer to frequencies in the
  amateur bands by their wavelength as well as
  their frequency.
• Ill call you on 2 meters. Lets try 146.52 MHz

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Radio and Signal Fundamentals Radio Signals and
Waves
Ill call you on 2 meters. Lets try 146.52
MHz In the example above, the frequency band is
referred to as 2 meters because that is
approximately how long the radio waves are in
that band.
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Radio and Signal Fundamentals Radio Signals and
Waves
Ill call you on 2 meters. Lets try 146.52 MHz
Determine the approximate wavelength
Determine the approximate frequency
300
150 MHz
2 meters
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Radio and Signal Fundamentals Radio Signals and
Waves
Determine the approximate wavelength
300 14.300 MHz
20.98 meters
Determine the approximate frequency
300
15.0 MHz
20 meters
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Radio and Signal Fundamentals Modulation
Understanding the basic concept of modulation is
very important to understanding the various
techniques that radio amateurs use to
communicate. A simple radio signal in and of
itself isnt very useful and doesnt do much
communicating. Information must be added or
contained in the radio signal. The simplest
radio signal at one frequency whose strength
never changes is called a continuous wave which
we abbreviate as CW.
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Radio and Signal Fundamentals Modulation
Adding information to a signal by modifying in
some manner is called modulation Recovering
information from a signal is called
demodulation. The simplest type of modulation
is a continuous wave that is turned on and off in
a specified and distinct pattern such as Morse
code. Morse code radio signals are often
referred to as CW for that reason.
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Radio and Signal Fundamentals Modulation
If we add speech to the radio signal, the result
is a phone or voice mode signal. If data is
added to the radio signal, the result is a data
mode or digital mode signal. Analog modes
carry information that can be understood directly
by a human such as speech or Morse code. Digital
or data modes carry information as data
characters between two computers. Software in
the computers converts the information into a
readable form as text or pictures.
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Radio and Signal Fundamentals Modulation

• Three characteristics of a signal can be
  modulated
• Its amplitude or strength
• Its frequency
• Its phase
• All three types of modulation are used in ham
  radio.

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Radio and Signal Fundamentals Modulation

• Youre probably familiar with two types of
  modulation
• Amplitude modulation or AM
• Frequency modulation or FM
• You probably never gave it any thought about it
  but are familiar with these to modulations from
  you car radio or home stereo system.
• Hams use variations of AM and FM plus many more
  types of modulation.

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Radio and Signal Fundamentals Modulation
Amplitude Modulation
Turning an unmodulated signal on and off can
produce Morse code characters. Adding speech to
an unmodulated signal will cause its amplitude
or strength to vary. The information is
contained in the envelope of the resulting
signal.
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Radio and Signal Fundamentals Modulation
The receiver recovers your voice by following the
signals amplitude variations. This process of
recovering speech or music in an AM signal is
called detection and can be performed by very
simple circuits. AM is used because it is simple
to transmit and receive.
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Radio and Signal Fundamentals Modulation
An AM signal is composed of a carrier and two
sidebands. The total power of an AM signal is
divided between the carrier and two sidebands.
The carrier is a continuous wave whose
amplitude does not change and does not contain
any information.
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Radio and Signal Fundamentals Modulation
The upper sideband or USB is higher in
frequency than the carrier tone. The lower
sideband or LSB is lower in frequency than the
carrier.
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Radio and Signal Fundamentals Modulation
If the AM signal had a carrier of 800 KHz
modulated by a single steady tone of 600 Hz,
it would result in two sidebands each of whose
width would be 600 Hz each. Both sidebands
contain the information needed to reproduce the
tone used to modulate the signal.
800 kHz
799.4 kHz
800.6 kHz
600 Hz
600 Hz
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Radio and Signal Fundamentals Modulation
The addition of sidebands during the process of
modulation causes the resulting modulated signal
to be spread over a range of frequencies called
the signals bandwidth. Each signal has some
bandwidth. A simple CW signal requires a
bandwidth of up to 150 Hz.
600 Hz
600 Hz
1200 Hz bandwidth
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Radio and Signal Fundamentals Modulation
Single-Sideband (SSB)
AM signals are inefficient from the standpoint of
power. The carrier doesnt contain information
yet it takes up most of the signal power. Each
sideband contains an exact copy of the modulated
signal. A single-sideband signal is an AM signal
with the carrier and one sideband removed so that
all of the signals power is devoted to the
remaining sideband.
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Radio and Signal Fundamentals Modulation
An AM signal with the carrier and one sideband
removed by electronic circuitry is called a
single sideband (SSB) signal.
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Radio and Signal Fundamentals Modulation
The upper sideband (USB) is used on VHF and
UHF. Both USB and LSB are used on the MF and HF
bands SSB signals require more complex equipment
but the improved performance is worth it. SSB
signals have a superior range because all of the
power is concentrated in a single sideband. The
SSBs bandwidth is less than 3 kHz
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Radio and Signal Fundamentals Modulation
Frequency Phase Modulation
Modes that vary the frequency of a signal to add
speech or data information are called frequency
modulated or FM signals.
Each cycle of the unmodulated carrier is the
same. The signal of a frequency modulated
carrier increases and decreases as the amplitude
of the signal changes.
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Radio and Signal Fundamentals Modulation
The frequency of an FM signal varies with the
amplitude (strength) of the modulating signal.
The amount of variation is called carrier
deviation or just deviation. Speaking louder
into the microphone of an FM transmitter
increases deviation. As deviation increases, so
does the signals bandwidth. Excessive
deviation can cause interference to nearby
signals.
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Radio and Signal Fundamentals Modulation
Your radio displays only the carrier frequency.
You must remember to leave room the signals
sidebands. You do not want to transmit out of
the amateur bands or outside of you frequency
privileges. Thats illegal. If your FM voice
signal is 15kHz wide, that means the sideband is
the center frequency plus 7.5 kHz. Frequency.
Give yourself a 10 kHz margin to be safe.
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Radio and Signal Fundamentals Modulation
Phase Modulation
Phase modulation or PM is similar to FM. Phase
modulation varies the phase instead of the
frequency. These two techniques result in
signals that are approximately the
same. Receivers demodulate the FM and PM signals
with the same circuit.
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Radio and Signal Fundamentals Modulation
Phase Modulation
Most hams refer to either FM or PM signals as
FM FM signals have one carrier and many
sidebands that add together in a 5-15 kHz
bandwidth. The amplitude of a FM signal does not
change
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Radio and Signal Fundamentals Modulation
What are the different types of modulation and
signals available? How do you choose one over
the other? What are the strengths and weaknesses
of each What makes on better than another?
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Radio and Signal Fundamentals Modulation
Fortunately, there has been a lot of
experimenting since ham radio began its sorta
what we do. Why use FM for VHF and UHF voice if
these signals occupy more bandwidth than
SSB? The information in an FM signal is carried
as variations in the signals frequency.
Atmospheric and electrical noises are meaningless
to an FM signal. The limiter circuit in an FM
receiver strips away the noises so they are not
heard in the receivers output.
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Radio and Signal Fundamentals Modulation
Unfortunately, the AM signals are subject to all
the noise while the FM signals are
static-free. For short-range and regional
communications, the lower noise of FM signals
clearly outweigh any considerations about
bandwidth. FM can also be used for data signals,
such as those for packet radio on VHF and UHF.
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Radio and Signal Fundamentals Modulation
Even though FM may proved a better quality
signal, SSB is often used where signals are
weaker and where the spectrum will not support a
large number of FM users. Signals on the HF
bands below 30 MHz are almost exclusively SSB or
CW. SSB signals use much less bandwidth than FM
or digital signals.
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Radio and Signal Fundamentals Modulation
Typical Signal Bandwidths Typical Signal Bandwidths
Type of Signal Typical Bandwidth
AM amateur voice 6 KHz
Amateur television 6 MHz
Commercial television 6-7.5 MHz
SSB voice 2-3 kHz
SSB digital 500 to 3,000 Hz (0.5 to 3 kHz)
CW 100-300 Hz (0.1 to 0.3 kHz)
FM amateur voice 5-15 kHz
Commercial FM 150 kHz
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Radio and Signal Fundamentals Modulation
Because the signals power is concentrated into a
narrow bandwidth, it is possible to communicate
over much longer distances and in poorer
conditions compared to FM or AM, particularly on
the VHF and UHF bands. Thats why the VHF and
UHF Dxers and contest operators use SSB. For
even better range, extremely narrow CW signals
are the easiest for a human operator to send and
receive, especially in noisy or fading
conditions. CW ops rule. Phone ops drool.
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Radio and Signal Fundamentals Modulation

• Upper sideband or lower sideband which to use?
• It doesnt matter as long as both stations are
  using the same sideband. Otherwise it wont
  work.
• Ham radio operators and manufacturers have agreed
  upon a standard
• Above 10 MHz USB is used including all of the
  VHF and UHF bands.
• Below 10 MHz LSB is used EXCEPT on the 60m
  band where you are REQUIRED to use USB.

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Radio and Signal Fundamentals Radio Equipment
Basics

• The basic elements of a radio station
• Transmitter (Xmtr) Generates/converts sounds
  into a signal that carries speech, Morse code or
  data information.
• Receiver (Rcvr) Recovers/converts speech, Morse
  code or data information.

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Radio and Signal Fundamentals Radio Equipment
Basics

• Three basic elements of a radio station
• 3. Antenna (Ant) Turns radio signals into
  energy that travels through space as a radio
  wave. The antenna also captures radio waves and
  turns them into signals for the receiver to work
  with.
• A feed line connects the antenna to the
  transmitter or the receiver.

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Radio and Signal Fundamentals Radio Equipment
Basics
Most amateur equipment combine the transmitter
and receiver into a single piece of equipment
called a transceiver (XCVR). This is normally
what hams mean when they refer to something as a
radio or rig. A transceiver shares a single
antenna between the transmitter and receiver by
using a transmit-receive (TR) switch.
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Radio and Signal Fundamentals Radio Equipment
Basics
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Radio and Signal Fundamentals Radio Equipment
Basics
Antenna
The operator would have to switch the antenna
back and forth between transmitting and receiving.
Antenna T/R Switch
Power Supply
AC Outlet
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Radio and Signal Fundamentals Radio Equipment
Basics
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Radio and Signal Fundamentals Radio Equipment
Basics
Antenna Feed Line 450 Ohm ladder Line
Antenna Tuner
SWR/Power Meters
Speaker
Receiver
Transmitter
Morse Code Key
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Radio and Signal Fundamentals Radio Equipment
Basics
A repeater is a station that transmits a received
signal simultaneously on another frequency or
channel. Repeaters provide local and regional
communications between low-power mobile and
portable stations. The job of the repeater is to
provide a strong, low-noise signal that everyone
can hear and understand well, especially during
emergencies.
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Radio and Signal Fundamentals Radio Equipment
Basics
A repeater consists of a receiver and transmitter
connected together so that the received signal is
retransmitted on a different channel or even
multiple channels. Because a repeater receives
and transmits at the same time, it uses a
duplexer instead of a transmit-receive
switch. The duplexer allows the strong signal
from the transmitter and the weaker signals being
received to share a single antenna.
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Radio and Signal Fundamentals Radio Equipment
Basics
A simple repeater
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Radio and Signal Fundamentals Radio Equipment
Basics
Input Freq 147.705 MHz
Output Freq 147.105 MHz
Offset 600 kHz
50-60 miles
Listen on 147.105 MHz Transmit on 147.705 MHz
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Radio and Signal Fundamentals Radio Equipment
Basics
Accessories
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Radio and Signal Fundamentals Radio Equipment
Basics
Amplifier
Desk Microphone
Headphones with Microphone
Terminal Node Controller
Morse code Paddles
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Radio and Signal Fundamentals Radio Equipment
Basics
Straight Key
Dummy Load
Speaker
Antenna tuner
Computer
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Radio and Signal Fundamentals Radio Equipment
Basics
A microphone or mike converts sound waves into
an electrical audio signal and connects to the
transmitter (or transceiver) A speaker turns an
electrical audio signal into sound
waves. Headphones are often used in place of a
speaker to help you hear in a noisy area or when
dealing with interference.
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Radio and Signal Fundamentals Radio Equipment
Basics
An amplifier are circuits or equipment that
increase the strength of a signal. Preamplifiers
increase the strength of a signal before it is
heard in the receiver. Power amplifiers increase
the strength of a transmitted signal before it is
sent to the antenna. A Morse key is a special
switch used by the operator to turn the
transmitters output signal on and off in the
pattern of Morse code.
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Radio and Signal Fundamentals Radio Equipment
Basics
Questions? Read chapter 3 for next week