Chapters 1,2&4-6 and Additional Information

8/3/2019 Chapters 1,2&4-6 and Additional Information

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CHAPTER I: Intoduction to Communication Systems

QUESTIONS: ANSWERS:

Practical Electrical communication began in _______ with 1837

Samuel Morse's Telegraph System.

Noise communication by electrical means began with the inven-tion of telephone by Alexander Graham Bell in _____. 1876

The time which tr5ansmitters and receivers used vacuum-tube

technology.

The diode tube had been invented by a) ______ in b) _____. a. Sir John Fleming

1904

The triode which could work as amplifier has invented by _____ Lee Deforest

in 1906.Analog voice signals contains frequency from about _____? 300 Hz to 3 KHz

Analog high fidelity music needs a frequency range of

approximately _______? 20 Hz to 20KHz

Analog video signal of television - broadcast quality needs a

frequency range from dc to about ______? 4.2 MHz

What are the elements of communication systems? 1. Source

2. Transmitter

3. Channel

4. Receiver

5. Destination

The carrier wave will be altered, or _____, by the information modulated

signal in such a way that the information can be recovered at the

destination.Information signal is also known as ______? modulating signal

The frequency spectrum of information signal is often referred to baseband

as _____?

What states that the amount of information that can be

transmitted in a given time is proportional to bandwidth for a given Hartley Law

modulation scheme.

1920


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1.Equipment Noise

What are the types of external noise? 2. Atmospheric Noise

3. Space Noise

What noise is generated by the equipmnet that produces sparks? Equipment Noise

This noise is also known as "static noise" because lightning

which is a static electricity discharges, is a principal source of Atmospheric Noise

this noise. This noise is less severe in less than 30 MHz.What technique is use to improve communication by simply noise blanking

disabling the receiver for the duration of burst?

Space Noise

What are the other names for Extraterrestrial Noise? Cosmic

Stellar

Sky Noise

What do you call of the noise that is produced by the randommotion of electrons in a cnoductor due to heat? Thermal Noise

What term is often used alone to refer to thermal noise, which

is found everywhere in electronic circuitry? noise

What is the other term for thermal noise? White noise

What are the two technique to reduce noise? 1. cyrogenics

2. bandwidth reduction

What do you call of the technique to reduce noise that involves

in cooling the first stage of a receiver for radio astronomy by cyrogenics

emerging it in a liquid nitrogen?

What do you mean by RMS? root-mean-square

What noise is due to random variations in current flow in active

devices such as tubes, transistors, and semiconductors diode? Shot Noise

The name ________ describes the random arrival of electronsat the anode of a vacuum tubes. Like individual pellets or shot Shot Noise

from shot gun.

What do you call of a time a charge carrier spends in the device? transit time

What noise can be used as a substitute for _____ whenever a

known level of noise is required? thermal noise

What noise occur only in devices where a single current separates


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QUESTIONS: ANSWERS:

_____ is relatively new form of radio. Satellite Communications

What was the first atificial satellite? Spuntnik I

Sputnik I was launched by Sovient Union in what year? 1957

Reliable communications via satellite really began with the a. Intelsat

launched of a) _____ b) _____ b. 1965

What was the first geostationary satellite? Anik A-IThe Anik A-I was launched by Canada in what year? 1972

Summary

QUESTIONS: ANSWERS:

What are the 3 essential elements of any communication system? 1. tranmitter

2. receiver

3. channel

What are the characteristics of channel? 1. noisy

2. distorted

3. with limited bandwidth

modulationWhat is necessary with many types of communication channel? modulation

In modulation some characteristics of a carrier waveforn is a. amplitude

changed in accordance with amplitude of a lower frequency b. frequency

signals knows as the a) _____ , b) _____ or c) _____. c. phase

What are the two systems for sharing a channel among several 1. time division

information signals? 2.frequency- division

multiplexingThe amount of information can be transmitted is _____ to the

time taken the channel bandwidth employed. proportional

What do you call of the change in information signal during

transmission? distortion

How are signals can be represented? 1. time domain

2. frequency domain


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2. electrical

3. random

4. mutilates the desired signals

What are the 2 subdivision of noise? 1. internal

2. external

What is the noise created with in the receiver? internal noise

What is the noise created outside the receiver? external noiseWhat are the examples of external noise? 1. Atmospheric Noise

2. Extraterrestrial Noise

3. Industrial Noise

What is a noise caused by lightning discharges in thunderstorms

and other natural electrinc distrubances occuring in the atmosphe- Atmospheric Noise

re. I becomes less severe at frequency of 30 MHz?

What is the other name for Atmospheric Noise? Static NoiseWhat are the 2 examples of Extraterrestrial Noise? 1. Solar Noise

2. Cosmic Noise

What is the other name for Atmospheric Noise? Space Noise

What is the noise coming from the sun? Solar Noise

At what frequency does the Extraterrestrial Noise present? 8 MHz - 1.43 GHz

What do you call of a noise from distant stars, from our own

galaxy, the milky way, from other galaxy and other virtual point Cosmic Noise

sources such as quasars and pulsars?

What is the other name for Cosmic Noise? Thermal Noise or Blackbody

QUESTIONS: ANSWERS:

What is the noise coming from man - made sources such as

aoutomobile and aircraft ignition, electric motors and switching

equipment; leakages from high voltage line and multitude of other Industrial Noise

heavy electric machine?

What is the other name for Industrial Noise? Man- made Noise

CHAPTER II: Radio Frequency Circuits


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CHAPTER II: Radio Frequency Circuits

Electronics. Rewind

Alternatorsas Oscillators

QUESTIONS: ANSWERS:

What do you call of a high power radio-frequency signals thatcould be generated using specialized mechanical ac Alternators

generators?

When was the first practical alternator transmitter designed? 1906

Who designed in 1906 the first practivcal alternators? Ernst Alexanderson

QUESTIONS: ANSWERS:What do we consider in order to find low-frequency response of

a simple audio amplifier? consider capacitive reactance

What circuits seem to bear a very little physical resemblance

to those at lower frequency? Microwave frequency

What do you call of a point where the two reactances are equal

and the capacitor becomes series-resonant circuit? self-resonant frequency

What is the time when it takes a charge carrier to cross a

device? transit time

What do we do to reduce the transit time? Make the devices physically

small

How do we keep the componets from interaction between

each other in a circuit board? by shielding

What is the other name for shielding? "cheap and dirty"What can provide a useful shielding? ground plane

What provides a small capacitance to ground that is adjusted

during circuit alignment by bending the wire slightly in one "gimmick"

direction or another?

How do we prevent RF current from travelling from one part

of the circuit to another? "bypassing"

f d t l tt t h i d th i t i it


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fundamental requency attenuates harmonics and other spurious resonant circuit

signals?

What should be the biased of a Class C amplifier? beyond cutoff

What is accomplished by deliberately feeding back a portion of

the output signal to the input in such a way that it has the same neutralization

amplitude as the unwanted feedback but the opposite phase?

What do you call of the circuit that operate at lower frequenciesthan straightforward through amplifier,and they are used at low frequency multipliers

power level?

What do you call of the multipliers that operate at the second, frequency doublers

or third, harmonic of the input frequency? or triplers

What circuits are more common at radio frequency? LC circuits

1. The gain aroun the loop

must be equal to one.2. The phase shift around

What are the Barkhausen criteria? the loop must total either

0 or some interger multiple

of 360 at the operating

frequency

What type of oscillator can be recognized by its use

of a tapped inductor, part of a resonant circuit, to provide Hartley Oscillator

feedback?

What do you call ot the oscillator that uses a capacitive voltage

divider instead of a tapped inductor provide feedback? Colpitts oscillator

What do you call of the oscillator that is designed to swamp

device capacitance for greater stability? Clapp Oscillator

It is typically tuned by moving a ferrite core into or out of the coil? inductor When inductor is tuned it is called? slug tuning

What should be the biased of a varactor silicon-diode? reversed-biased

What do you call of the circuit where the junction capacitance is VCO

made part of the resonant circuit that can be tuned simply by (voltage-controlled oscillator

by varying the dc voltage on the varactor?

What oscillator achieved greater stability by using a small slab

What is the other name for LPF lowpass filter? "loop filter"


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What is the other name for LPF lowpass filter? "loop filter"

What do you call of the external reference signal that is

compared with the VCO signal? phase detector

What is the purpose of the PLL? to lock the VCO to the

reference dignal

What do you call of the frequency at which it opwerates when the

control voltage is zero? free-running frequencyWhat do you call when the phase detector generate a control

voltage which will cause the VCO frequency to change until acquisition of phase lock

it is exactly that of the externalinput signal?

What determines how far apart the external and internal

frequencies canh initially be for the loop to achieve lock? capture range

What do you call when its frequency is change to follow the

external signal? trackWhat do youi call when you achieve and maintain the total

frequency range? lock range

What can be change by altering the voltage on some of the

pins of the divider chip? modulus

What do you call of the minimum freequency step of the

synthesizer? resolution

What is the simplest way to get a synthesizer work at frequencies add a fixed-modulus

beyond those at which programmable divider operate? divider in the front of the

programmable divider

What is a digital technology that can be used at frequencies ECL

above 1 GHz? (emitter-coupled logic)

What do you call of the divider that can be programmed to divide

by either two consecutive integer? two-modulus prescaler What should be the interval of FM broadcast stations? 200KHz

What is the frequency range of FM broadcast stations? 88.1-107.9 MHz

What is used to remove the difference components as well as the

VCO and crystal oscillators frequencies from the mixer output? bandpass filter

What do you call of the movement of a block of the frequency? frequency translation

What is a small slab of quartz with attached electrodes; used as


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What is a small slab of quartz with attached electrodes; used as

resonant circuit? crystal

What do you do to prevent the undesired passage of signals

between circuits? decouple

What do you call of a multiplier where the output frequency is

twice that of the input signal? doubler

The frequency at which a VCO operates when its control voltageis zero? free-running frequency

What do you call of the device that can produce large number

of output frequencies from a smaller number of fixed-frequency frequency synthesizer

oscillators?

What do you call of the movement of signal from one frequency

to another using a mixer-oscillator combination? frequency translation

What do yopu call of a small length of wire, connected at only oneend and used as a cfapacitance to ground? gimmick

What do you call of an artificial ground, often consisting of an area

of foil left on one side of a cicuit board? ground plane

What do you call ot the total frequency range over which a PLL

once locked, can remain locked? lock range

What do you call of the internal capacitance of the active device

that can cause feedback that produces the same effect on the Miller effect

input as a much larger capacitance across the amplifier input?

What do you call of a nonlinear circuit designed to generate sum

and difference frequencies when two or more frequencies are mixer

present at its input(s).

What do you call ot a number by which a digital divider chain

divides? modulusWhat do you call of a circuit whose output is proportional to the

product of the instantaneous amplitudes of two input signals? multiplier

What is a menas of avoiding istability in amplifier by using

negative feedback? neutralization

CHAPTER IV: Angle Modulation


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CHAPTER IV: Angle Modulation

QUESTIONS: ANSWERS:

What do you call of the general term that includes frequency

and phase modulation? Angle Modulation

1. radio broadcasting

2. sound signal in televisionWhat are the applications of FM? 3. two-way fixed and mobile

radio systems

4. satellite communications

5. cellular telephone system

1. data communication

What are the apllications of PM? 2. used in some FM transmitter

as an intermediate step ingeneration of FM

What is the most important advantage of FM of PM over AM? The possibility of greatly

improved signal-to-noise ratio

In FM, the _____ of the modulated signal varies with the frequency

amplitude of the modulating signal.

In PM, the _____ varies directly with the modulating-signal phase

amplitude.What is the most important thing to remember in all types of It is the amplitude of the

modulation? modulating signal that varies

the carrier wave.

The FM transmitter can use as Class _____ amlipfiers throughout

since amplitude linearity is not important. C

What can be accomplished at low power levels? Modulation

When the frequency is greater than the _____, the phase angle

gradually moves ahead, and when the frequency is lower than carrier frequency

the carrier frequency, the phase begins to lag.

What is generated when changing the amplitude of a sine wave? side frequencies or sidebands

What is the simpliest method that can be use in generation use VCO

of FM signal? (voltage-controlled oscillator)

QUESTIONS: ANSWERS:


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QUESTIONS: ANSWERS:

What effect can be observed by simply driving away from an

FM broadcast transmitter while listening to it on a car radio? threshold effect

What do you call of the effect of the strong signal that captures

the receiver, and in fact this property of FM? capture effect

What do you call of the noise power that is evenly distributed

across the channel at the receiver bandwidth? white noiseAn improvement in S/N can be made by boosting or _____ these

high frequencies before modulation, with a corresponding cut in pre-emphasizing

the receiver after demodulation.

When was FM stereo introduced? 1961

What is used such as background music stores and offices? Subsidiary Carrier Association

What is the maximum audio frequency of SCA signal? 7 KHz

What instrument allows the power in the carrier and each sidebandto be measured, and it allows the modulation frequency to be Spectrum analyzer

found by measuring the separation between sidebands?

What do you call of the method of measuring deviation that is

elegant and simple, but requires an expensive spectrum analyzer Bessel zero method

and complete control over the modulating frequency?

Summary

QUESTIONS: ANSWERS:

What includes the angle modulation? frequency modulation

phase modulation

What is widely used for analog communications? frequency modulation

What is used for data communications? phase modulationThe _____ of an angle modulation signal does not change with

modulation, but the _____ ioncreases due to generation of power, bandwidth

multiple side of sidebands.

What can be used to calculate the voltage and power of each

sidebands? Bessel Function

What rule is an approximation of bandwidth? Carson's Rule

What do you call of the frequency of signal before modulation


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What do you call of the frequency of signal before modulation

is applied? carrier frequency

What is used of low-pass filter in a receiver to remove the effect

of pre-emphasis on the frequency response? de-emphasis

What do you call of the amout by which the frequecny of an FM

signal shifts to each side of the carrier frequency? frequency deviation

In FM and PM, what do you call of the peak amount in radiansby which the phase of the signals deviates from its resting value? modulation index

What do you call of an FM with a relatively low modulation index? (NBFM)

Narrow band FM

What is use of a high-pass filter in an FM transmitter to improve

the signal-to-noise ratio; and always used with de-emphasis at pre-emphasis

the receiver?

What do you call of the frequency of the unmodulated carrierof an FM signal? rest frequency

What is the synonyms for rest frequency? carrier frequency

What do you call of the secondary carrier that can carry an

additional modulating signal and is itself modulated onto the subcarrier

main carrier?

What do you call of the noise rduction effect that occurs with

strong FM signals? threshold effect

What do you call of an FM with relatively large modulation index? (WBFM)

wideband FM

exclusive for power handling stages? exciter


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p g g

What stage calls for the power amplifier, probably operating (IPA)

Class C to drive the final stage? Intermediate Power amplifier

What circuit is required to amplify the very small signal from a

microphone to a sufficient level to modulate the transmitter? audio circuitry

What do you call of electrically, the process of really

summation? mixingWhat network can be used to transform impedance either from

up or down but it is best suited to active device that requires a pie network

fairly high load impedance such as tubes?

What two networks acts like a low-pass filters, aiding in the

reduction of harmonic levels? pie and T network

It is a noninductive resistor of the correct value (usually 50)

that is capable of dissipating the transmitter's rated power? dummy loadIt is always found as part of the tranceiver. CB radio

It is actually a frequency synthesizer, to maintain cystal-

controlled frequency accuracy and stability. oscillator

What provides the power to the large speaker when the tranceiver

is in the receive mode? integrated-circuit amplifier

What is designed to keep the modulation index as high as

possible without permitting overmodulation? automatic level control

What do you call of an amlifier that amplify audio linearity and

yet efficient? Class D amplifier

What is the other name for Class D amplifier? switching amplification

The pulses are produce by switching to the ampltude of the (PDM)

sample? Pulse Duration Modulation

What is the other name for PDM? pulse width modulationWhat do you call of the technique that is patent by Harris

corporation, uses multiple solid state power amplifer? Digital Amplitude Modulation

What do you call of the cancellation of the input frequency of

itself? balanced

An ideal balance modulator is mathematically equivalent to____? multiplier

What is the far most common device for suppressing the

A typical AM transmitter has a or oscillator followed crystal-controlled,


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yp _____ _____ y ,

by several stages of amplification. frequency synthesizer

Usually the final amplifier stages, called the _____, modulated. power amplifier

this allows all stages to operate at Class C.

What is used in most AM transmitter for greater efficiency? high-level modulation

What can be generated by means of a balanced modulator to

which a baseband and carrier-frequency signals are applied? DSBSC AMWhat do you call of a transmitter that is usally work by filtering

a DSBSC signal to remove the unwanted sidebands? SSB transmitter

Transmitter requires an _____ circuit between the outout of the impedance-matching

power amplifier and the antenna. circuit

What are the basic ways to genrate FM? 1. direct FM

2. indirect FM

It requires that the carrier oscillator be frequency modulated? direct FMThe baseband signal is integrated and then applied to a phase

modulator indirect FM

What can be use to uncrease the frequency deviation in an FM

transmitter? Frequency multiplier

Most FM transmitters use _____ . PLL modulator

What can be use to amplify FM signal? Nonlinear amplifier

What are the technique in measuring output power of transmitter? 1. calori-meter wattmeter2. directional couplers

3. RF ammeters

CHAPTER VI: Receivers


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QUESTIONS: ANSWERS:

A _____ must separate the desired signal from other signals and receiver

noise and then demodulate the signals.

What is the most common type os receiver? superheterodyne

What do you call of a receiver where it uses a mixer/local

oscillator combination to transfer all incoming signal superheterodyne

frequencies to a common IF?

It is responsible for setting the noise figureof the reciever. RF amplifier

When a receiver can receive signal at frequency other than that

to which the receiver is tuned? image frequency

The _____ must be high enough to provide good image rejectionbut low enough to allow the required selectivity to be obtained IF

with the type of filter in used.

What depend of a superheterodyne receiver directly on that of

the locar oscillator? stability

It is responsible fot the selectivity of the receiver and it also

provide most of the predetection gain? IF amplifier

Most AM Receiver use _____ which have the advantage ofrelatively high levels of distortion. envelope detectors

It requires a beat-frequency oscillator to reinsert the carrier single-sideband suppressed

and generally used product detectors carrier

What can be use to remove AM before the detector? Limiters

Receivers require some form of _____ to componsate for the very

great range in signal strenght at antenna. AGC

What refers to the signal strenght require for a satisfactory signal

to noise ratio? sensitivity

What refers to the ability of the receiver to reject interference

and out-of-channel noise? selectivity

_____ and _____ are useful for troubleshooting technique for signal injectio,

receiver and for many other typesof electronic system signal tracing

that operates at a frequency below that of the incoming signal. low-side injection


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QUESTIONS: ANSWERS:

What do you call of a bandpass filter that uses mechanical

resonators? mechanical filter

It is a low level carrier signal transmitted to facilitate regeneration

of the carrier at the receiver. pilotcarrier

What is a detector for suppressed-carrier AM signals that works

by multiplying the signal with a regenerated carrier? product detector

What do you call of the strenght of an unmodulated carrierthat reduces the noise output of an FM receiver by a specified quieting sensitivity

amout?

It is an FM detector that is based on a 90- degree pahse shift

network. quadrature detector

it is a type of FM detector. radio detector

What is the ratio of signal-plus-noise and distortion to noise-plus-

distortion (closely related to signal to noise ratio) SINADWhat do you call of a meter in a receiver that indicates the

strenght of the receivedsignal? S-meter

What do you call of the ability of the receiver to reject signals

of frequencies other than the frequency to which the receiver selectivity

is tuned?

What do you call of the receiver to receive weak signals with

a satisfactory signal-to-noise ratio? sensitivity

For a bandpass filter, what is the ratio between the bandwidth

fortwo specified amount of attenuation? shape factor

What is a reception of signal at frequencies other than that to

which a receiver is tuned? skin effect

What is a systems that disables the output of a receiver in the

ADDITIONAL INFORMATION: Frequency Modulation ( FM )


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QUESTIONS: ANSWERS:

What type of angle modulation wherein the frequency is varied

relative to the modulating frequency signal? Frequency Modulation

What do you call of the amount by which the frequency varies

its unmodulated value? Frequency Deviation ( max )

What is the total variation in frequency? Carrier swing

What is the frequency deviation over the modulating

frequency ( fm )? modulation index ( mf )

What is the ratio of the actual deviation to the maximum

deviation multiplied by 100%? Percent of modulation

What are the 2 bands of FM? Wideband and Narrowband

What is the modulation index of Wideband FM? mf > 1 ( 5-2500)

How about the modulation index of the Narrowband FM? mf 1

What is the frequency deviation of Wideband FM? max = 75 kHx

What is the freqeuncy deviation of Narrowband FM? max = 5 kHz

What is the modulating frequency range of Wideband FM? fm range: 30 kHz- 15kHz

What is the maximum modulating frequency on Narrowband FM? fm, max = 3 kHz

What is the application of Wideband FM? for Entertainment andBroadcasting

What is the application of Narrowband FM? Employed in communications

What do you call of the boosting of the higher modulating

frequency at the transmitter, in accordance with a pre-arrange Pre-emphasis

curve to improve noise immunity at FM?

What is the cutting of the higher modulating frequencies at the

receiver? De- emphasisWhat are the 3 forms of Interference in FM? 1. Image frequency

2. Co- channel Interference

3. Adjacent channel interference

What is the effect of two stations being received simultaneously? Image frequency

What do you call of the interference that is true to mobile

receivers because this interference occur when travelling Co-channel interference

remove amplitude variations

d b i


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caused by noise.

3. It is possible to reduce noise

still further by increasing

deviation (unlike AM)

4. There are guardbands

between FM stations

5. FM transmitter operate

in the upper VHF and UHF

1. A much wider channel is

required by FM, 7 to 15

times as large as that needed

by AM

2. FM transmitting and receivingequipment tends to be more

What are the disadvantages of FM? complex, particularly for

modulation and demodulation

therefeore more expensive

3. Since reception is limited to

line of sight, the area of reception

for FM is much smaller thanfor AM.

What do you call of the process by which the modulating signla

is recovered from the modulated carrier and is found in the Demodulation

receiver?

What do you call of the device that has the function of selecting

the desired signal from all the other unwanted signals amplfying receiver

and demodulating it, and dispaying it in the desired manner.What are the 2 types of receiver? 1. Tuned Radio Frequency ( TRF)

2. Superheterodyne receiver

What do tyou call of the type of receiver where its composition

is simple and high sensitive? TRF receiver

What is the other name for TRF receiver? "logical" receiver

What is the alignment broascast frequency of TRF receiver? 535- 1640 kHz e era ommun cat ons omm ss on m ss on ass cat on


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Symbol Letter Type of Modulation

First Unmodulated

N Unmodulated

Amplitude Modulation

A Double-Sideband, Full Carrier ( DSBFC )B Independent Sideband, Full Carrier ( ISBFC )

C Vestigial Sideband, Full Carrier ( VSB )

H Single- Sideband, Full Carrier ( SSBFC )

J Single- Sideband, Suppressed Carrier ( SSBSC )

K Single- Sideband, Reduced Carrier ( SSBRC )

Angle Modulation

K Pulse- Amplitude Modulation ( PAM )

L Pulse- Width Modulation ( PWM )M Pulse- Positive Modulation ( PPM )

P Unmodulated pulse (binary data)

Q Angle Modulated during pulses

V Any combination of pulse-modulation category

W Any combination of two or more of the above forms of modulation

X cases not otherwise covered

Second 0 No modulating signal1 Digitally Keyed Carrier

2 Digitally Keyed Tone

3 Analog (sound or video)

7 Two or more digital channels

8 Two or more analog channels

9 Analog and digital

Third A Telegraphy, manual

B Telegraphy, automatic (teletype)C Facsimile

D Data, telemetry

E Telephony (sound broadcasting)

F Television (video broadcasting)

N No information transmitted

W Any combination of second letter

Documents

Chapters 1,2&4-6 and Additional Information