Signals and Emissions 1 G8 - SIGNALS AND EMISSIONS [2 exam questions - 2 groups] G8ACarriers and modulation: AM; FM; single and double sideband ; modulation.

Signals and Emissions1

G8 - SIGNALS AND EMISSIONS G8 - SIGNALS AND EMISSIONS [2 exam questions - 2 groups][2 exam questions - 2 groups]

G8AG8A Carriers and modulation: AM; FM; single and Carriers and modulation: AM; FM; single and double sideband ; modulation envelope; double sideband ; modulation envelope; deviation; overmodulation deviation; overmodulation

G8BG8B Frequency mixing; multiplication; HF data Frequency mixing; multiplication; HF data communications; bandwidths of various modescommunications; bandwidths of various modes


Amplitude ModulationAmplitude Modulation

An unmodulated RFAn unmodulated RFcarrier wavecarrier wave

A carrier wave A carrier wave amplitudeamplitudemodulated (AM) modulated (AM) with a simple with a simple audio toneaudio tone


Amplitude ModulationAmplitude Modulation

An unmodulated RFAn unmodulated RFcarrier requires narrowcarrier requires narrowbandwidthbandwidth

Modulation of the Modulation of the carriercarriercreates sidebands. creates sidebands. ThisThisrequires more requires more bandwidth.bandwidth.Transmitter power is Transmitter power is spread across this spread across this bandwidthbandwidth


AM and SSBAM and SSB

The carrier contains noThe carrier contains noaudio information.audio information.

The sidebands containThe sidebands containduplicate audio duplicate audio informationinformation

By filtering out the carrier and one sideband,By filtering out the carrier and one sideband,we save spectrum and concentrate our RFwe save spectrum and concentrate our RFenergy into a narrower bandwidth. SSB isenergy into a narrower bandwidth. SSB istherefore more efficient.therefore more efficient.

G8A Carriers and modulation: AMG8A Carriers and modulation: AM

• Amplitude modulation Amplitude modulation is the name of the is the name of the process that changes the envelope of an RF wave process that changes the envelope of an RF wave to convey informationto convey information

• Amplitude modulation type of transmission Amplitude modulation type of transmission varies the instantaneous power level of the RF varies the instantaneous power level of the RF signal to convey informationsignal to convey information


G8A Carriers and modulation: FM/PhaseG8A Carriers and modulation: FM/Phase

• Frequency modulation Frequency modulation is the name of the processis the name of the process, , which changes the frequency of an RF wave to covey which changes the frequency of an RF wave to covey informationinformation

• When a modulating audio signal is applied to an When a modulating audio signal is applied to an FM transmitter FM transmitter the carrier frequency changes the carrier frequency changes proportionally to the instantaneous amplitude of the proportionally to the instantaneous amplitude of the modulating signalmodulating signal

• Phase modulationPhase modulation is the name of the process that is the name of the process that changes the phase angle of an RF wave to convey changes the phase angle of an RF wave to convey informationinformation

• Phase modulation emission Phase modulation emission is produced by a is produced by a reactance modulator connected to an RF power reactance modulator connected to an RF power amplifieramplifier


G8A Carrier and modulation: Single and G8A Carrier and modulation: Single and double sidebanddouble sideband

• One advantage of carrier suppression in a One advantage of carrier suppression in a single-sideband phone transmission single-sideband phone transmission is more is more transmitted power can be put into the remaining transmitted power can be put into the remaining sidebandsideband

• Single sideband phone emissions Single sideband phone emissions use the use the narrowest frequency bandwidthnarrowest frequency bandwidth

• Both upper and lower sideband signals Both upper and lower sideband signals would would be found at the output of a properly adjusted be found at the output of a properly adjusted balanced modulator balanced modulator


G8A Modulating envelope; Deviation; G8A Modulating envelope; Deviation; OvermodulationOvermodulation

• The Audio of microphone gain control The Audio of microphone gain control is is typically adjusted for proper ALC setting on an typically adjusted for proper ALC setting on an amateur single sideband transceiveramateur single sideband transceiver

• The signal of an over-modulated single-The signal of an over-modulated single-sideband phone transmitter sideband phone transmitter becomes distorted becomes distorted and occupies more bandwidthand occupies more bandwidth

• Flat-topping of a single-sideband phone Flat-topping of a single-sideband phone transmission transmission is signal distortion caused by is signal distortion caused by excessive driveexcessive drive



G8A01 What is the name of the process G8A01 What is the name of the process that changes the envelope of an RF that changes the envelope of an RF wave to convey information?wave to convey information?

A.A. Phase modulationPhase modulation

B.B. Frequency modulationFrequency modulation

C.C. Spread Spectrum modulationSpread Spectrum modulation

D.D. Amplitude modulationAmplitude modulation


G8A01 What is the name of the process G8A01 What is the name of the process that changes the envelope of an RF that changes the envelope of an RF wave to convey information?wave to convey information?

A.A. Phase modulationPhase modulation

B.B. Frequency modulationFrequency modulation

C.C. Spread Spectrum modulationSpread Spectrum modulation



G8A02 What is the name of the process G8A02 What is the name of the process that changes the phase angle of an RF that changes the phase angle of an RF wave to convey information?wave to convey information?

A.A. Phase convolutionPhase convolution

B.B. Phase modulationPhase modulation

C.C. Angle convolutionAngle convolution

D.D. Radian InversionRadian Inversion


G8A02 What is the name of the process G8A02 What is the name of the process that changes the phase angle of an RF that changes the phase angle of an RF wave to convey information?wave to convey information?

A.A. Phase convolutionPhase convolution

B.B. Phase modulationPhase modulationC.C. Angle convolutionAngle convolution

D.D. Radian InversionRadian Inversion


Frequency ModulationFrequency Modulation

Unmodulated carrier, full Unmodulated carrier, full power at all timespower at all times

Waveform of modulating Waveform of modulating signalsignal

Modulated carrier with Modulated carrier with frequency deviation and frequency deviation and constant amplitudeconstant amplitude

“Over modulation” called “over deviation” on FM, causes the signal to become wider and potentially cause adjacent channel interference


G8A03 What is the name of the process G8A03 What is the name of the process which changes the frequency of an RF which changes the frequency of an RF wave to convey information?wave to convey information?

A.A. Frequency convolutionFrequency convolution

B.B. Frequency transformationFrequency transformation

C.C. Frequency conversionFrequency conversion

D.D. Frequency modulationFrequency modulation


G8A03 What is the name of the process G8A03 What is the name of the process which changes the frequency of an RF which changes the frequency of an RF wave to convey information?wave to convey information?

A.A. Frequency convolutionFrequency convolution

B.B. Frequency transformationFrequency transformation

C.C. Frequency conversionFrequency conversion



G8A04 What emission is produced by a G8A04 What emission is produced by a reactance modulator connected to an reactance modulator connected to an RF power amplifier?RF power amplifier?

A.A. Multiplex modulationMultiplex modulation

B.B. Phase modulationPhase modulation

C.C. Amplitude modulationAmplitude modulation

D.D. Pulse modulationPulse modulation


G8A04 What emission is produced by a G8A04 What emission is produced by a reactance modulator connected to an reactance modulator connected to an RF power amplifier?RF power amplifier?

A.A. Multiplex modulationMultiplex modulation

B.B. Phase modulationPhase modulationC.C. Amplitude modulationAmplitude modulation

D.D. Pulse modulationPulse modulation


G8A05 What type of transmission G8A05 What type of transmission varies the instantaneous power level of varies the instantaneous power level of the RF signal to convey information?the RF signal to convey information?

A.A. Frequency shift keyingFrequency shift keying

B.B. Pulse modulationPulse modulation

C.C. Frequency modulationFrequency modulation



G8A05 What type of transmission G8A05 What type of transmission varies the instantaneous power level of varies the instantaneous power level of the RF signal to convey information?the RF signal to convey information?

A.A. Frequency shift keyingFrequency shift keying

B.B. Pulse modulationPulse modulation

C.C. Frequency modulationFrequency modulation



G8A06 What is one advantage of carrier G8A06 What is one advantage of carrier suppression in a single-sideband phone suppression in a single-sideband phone transmission?transmission?

A.A. Audio fidelity is improvedAudio fidelity is improved

B.B. Greater modulation percentage is obtainable with Greater modulation percentage is obtainable with lower distortionlower distortion

C.C. More transmitter power can be put into the More transmitter power can be put into the remaining sidebandremaining sideband

D.D. Simpler receiving equipment can be usedSimpler receiving equipment can be used


G8A06 What is one advantage of carrier G8A06 What is one advantage of carrier suppression in a single-sideband phone suppression in a single-sideband phone transmission?transmission?

A.A. Audio fidelity is improvedAudio fidelity is improved

B.B. Greater modulation percentage is obtainable with Greater modulation percentage is obtainable with lower distortionlower distortion

C.C. More transmitter power can be put into More transmitter power can be put into the remaining sidebandthe remaining sideband

D.D. Simpler receiving equipment can be usedSimpler receiving equipment can be used


G8A07 Which of the following phone G8A07 Which of the following phone emissions uses the narrowest emissions uses the narrowest frequency bandwidth?frequency bandwidth?

A.A. Single sidebandSingle sideband

B.B. Double sidebandDouble sideband

C.C. Phase modulationPhase modulation



G8A07 Which of the following phone G8A07 Which of the following phone emissions uses the narrowest emissions uses the narrowest frequency bandwidth?frequency bandwidth?

A.A. Single sidebandSingle sidebandB.B. Double sidebandDouble sideband

C.C. Phase modulationPhase modulation



G8A08 What happens to the signal of G8A08 What happens to the signal of an over-modulated single-sideband an over-modulated single-sideband phone transmitter?phone transmitter?

A.A. It becomes louder with no other effectsIt becomes louder with no other effects

B.B. It occupies less bandwidth with poor high frequency It occupies less bandwidth with poor high frequency responseresponse

C.C. It has higher fidelity and improved signal to noise It has higher fidelity and improved signal to noise ratioratio

D.D. It becomes distorted and occupies more bandwidthIt becomes distorted and occupies more bandwidth


G8A08 What happens to the signal of G8A08 What happens to the signal of an over-modulated single-sideband an over-modulated single-sideband phone transmitter?phone transmitter?

A.A. It becomes louder with no other effectsIt becomes louder with no other effects

B.B. It occupies less bandwidth with poor high frequency It occupies less bandwidth with poor high frequency responseresponse

C.C. It has higher fidelity and improved signal to noise It has higher fidelity and improved signal to noise ratioratio

D.D. It becomes distorted and occupies more It becomes distorted and occupies more bandwidthbandwidth


G8A09 What control is typically G8A09 What control is typically adjusted for proper ALC setting on an adjusted for proper ALC setting on an amateur single sideband transceiver?amateur single sideband transceiver?

A.A. The RF Clipping LevelThe RF Clipping Level

B.B. Audio or microphone gainAudio or microphone gain

C.C. Antenna inductance or capacitanceAntenna inductance or capacitance

D.D. Attenuator LevelAttenuator Level


G8A09 What control is typically G8A09 What control is typically adjusted for proper ALC setting on an adjusted for proper ALC setting on an amateur single sideband transceiver?amateur single sideband transceiver?

A.A. The RF Clipping LevelThe RF Clipping Level

B.B. Audio or microphone gainAudio or microphone gainC.C. Antenna inductance or capacitanceAntenna inductance or capacitance

D.D. Attenuator LevelAttenuator Level


G8A10 What is meant by flat-topping of G8A10 What is meant by flat-topping of a single-sideband phone transmission?a single-sideband phone transmission?

A.A. Signal distortion caused by insufficient collector Signal distortion caused by insufficient collector currentcurrent

B.B. The transmitter's automatic level control is properly The transmitter's automatic level control is properly adjustedadjusted

C.C. Signal distortion caused by excessive driveSignal distortion caused by excessive drive

D.D. The transmitter's carrier is properly suppressedThe transmitter's carrier is properly suppressed


G8A10 What is meant by flat-topping of G8A10 What is meant by flat-topping of a single-sideband phone transmission?a single-sideband phone transmission?

A.A. Signal distortion caused by insufficient collector Signal distortion caused by insufficient collector currentcurrent

B.B. The transmitter's automatic level control is properly The transmitter's automatic level control is properly adjustedadjusted

C.C. Signal distortion caused by excessive Signal distortion caused by excessive drivedrive

D.D. The transmitter's carrier is properly suppressedThe transmitter's carrier is properly suppressed


G8A11 What happens to the RF carrier G8A11 What happens to the RF carrier signal when a modulating audio signal signal when a modulating audio signal is applied to an FM transmitter?is applied to an FM transmitter?

A.A. The carrier frequency changes proportionally to the The carrier frequency changes proportionally to the instantaneous amplitude of the modulating signalinstantaneous amplitude of the modulating signal

B.B. The carrier frequency changes proportionally to the The carrier frequency changes proportionally to the amplitude and frequency of the modulating signalamplitude and frequency of the modulating signal

C.C. The carrier amplitude changes proportionally to the The carrier amplitude changes proportionally to the instantaneous frequency of the modulating signalinstantaneous frequency of the modulating signal

D.D. The carrier phase changes proportionally to the The carrier phase changes proportionally to the instantaneous amplitude of the modulating signalinstantaneous amplitude of the modulating signal


G8A11 What happens to the RF carrier G8A11 What happens to the RF carrier signal when a modulating audio signal signal when a modulating audio signal is applied to an FM transmitter?is applied to an FM transmitter?

A.A. The carrier frequency changes The carrier frequency changes proportionally to the instantaneous amplitude proportionally to the instantaneous amplitude of the modulating signalof the modulating signal

B.B. The carrier frequency changes proportionally to the The carrier frequency changes proportionally to the amplitude and frequency of the modulating signalamplitude and frequency of the modulating signal

C.C. The carrier amplitude changes proportionally to the The carrier amplitude changes proportionally to the instantaneous frequency of the modulating signalinstantaneous frequency of the modulating signal

D.D. The carrier phase changes proportionally to the The carrier phase changes proportionally to the instantaneous amplitude of the modulating signalinstantaneous amplitude of the modulating signal


G8A12 What signal(s) would be found G8A12 What signal(s) would be found at the output of a properly adjusted at the output of a properly adjusted balanced modulator?balanced modulator?

A.A. Both upper and lower sidebandsBoth upper and lower sidebands

B.B. Either upper or lower sideband, but not bothEither upper or lower sideband, but not both

C.C. Both upper and lower sidebands and the carrierBoth upper and lower sidebands and the carrier

D.D. The modulating signal and the unmodulated carrierThe modulating signal and the unmodulated carrier


G8A12 What signal(s) would be found G8A12 What signal(s) would be found at the output of a properly adjusted at the output of a properly adjusted balanced modulator?balanced modulator?

A.A. Both upper and lower sidebandsBoth upper and lower sidebandsB.B. Either upper or lower sideband, but not bothEither upper or lower sideband, but not both

C.C. Both upper and lower sidebands and the carrierBoth upper and lower sidebands and the carrier

D.D. The modulating signal and the unmodulated carrierThe modulating signal and the unmodulated carrier

G8B Frequency mixingG8B Frequency mixing

• Heterodyning Heterodyning is another term for mixing of two is another term for mixing of two RF signalsRF signals

• A mixer stage in a transmitter A mixer stage in a transmitter would change a would change a 5.3 MHz input signal to 14.3 MHz5.3 MHz input signal to 14.3 MHz

• The Mixer stage in a receiver The Mixer stage in a receiver combines a combines a 14.250 MHz input signal with a 13.795 MHz 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 kHz intermediate oscillator signal to produce a 455 kHz intermediate frequency (IF) signal frequency (IF) signal

Sum -> 14.250 MHz + 13.795 MHz = 28.045 Sum -> 14.250 MHz + 13.795 MHz = 28.045 MHzMHz

Difference->Difference->

14.250 MHz – 13.794 MHz = 0.455 MH 14.250 MHz – 13.794 MHz = 0.455 MH (455kHz)(455kHz)


G8B Frequency mixing cont’dG8B Frequency mixing cont’d

If a receiver mixes a 13.800 MHz VFO with a If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal to produce a 455 14.255 MHz received signal to produce a 455 kHz intermediate frequency (IF) signal, kHz intermediate frequency (IF) signal, a a 13.345 MHz signal will produce 13.345 MHz signal will produce image response image response interferenceinterference in the receiver in the receiver


G8B MultiplicationG8B Multiplication

The Multiplier stage in a VHF FM transmitter The Multiplier stage in a VHF FM transmitter selects a harmonic of an HF signal to reach the selects a harmonic of an HF signal to reach the desired operating frequencydesired operating frequency


G8B HF data communicationsG8B HF data communications

• The frequency shift The frequency shift is related to keying speed in is related to keying speed in an signal in that greater keying speeds require an signal in that greater keying speeds require greater frequency shiftsgreater frequency shifts

• RTTY, Morse code, PSK31 and packet RTTY, Morse code, PSK31 and packet communications communications are all digital modesare all digital modes

• When transmitting a data mode signal, When transmitting a data mode signal, it is it is important to know the duty cycle of the mode you important to know the duty cycle of the mode you are using to prevent damage to your transmitter’s are using to prevent damage to your transmitter’s final stagefinal stage

• The part of the 20 meter band most The part of the 20 meter band most commonly used for PSK 31 operation commonly used for PSK 31 operation is below is below the RTTY segment , near 14.070 MHzthe RTTY segment , near 14.070 MHz


G8B Bandwidths of various modesG8B Bandwidths of various modes

• Frequency modulated (FM) phone Frequency modulated (FM) phone isn’t used isn’t used below 29.5 MHz because the bandwidth would below 29.5 MHz because the bandwidth would exceed FCC limitsexceed FCC limits

• The total bandwidth of an FM-phone The total bandwidth of an FM-phone transmission having a 5 kHz deviation and a transmission having a 5 kHz deviation and a 3 kHz modulating frequency 3 kHz modulating frequency is 16 kHzis 16 kHz

Total Bandwidth = 2 * (Deviation + Modulating Total Bandwidth = 2 * (Deviation + Modulating Fx)Fx)

Total Bandwidth = 2 *(5 kHz + 3 kHz) = 16 kHzTotal Bandwidth = 2 *(5 kHz + 3 kHz) = 16 kHz


G8B Bandwidth cont’dG8B Bandwidth cont’d

For a 12.21-MHz reactance-modulated oscillator For a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52-MHz FM-phone in a 5-kHz deviation, 146.52-MHz FM-phone transmitter, transmitter, the frequency deviation is 416.7 Hzthe frequency deviation is 416.7 Hz

transmitter Fx transmitter Fx 146.52 MHz146.52 MHz

Multiplication factor =HF Oscillator Fx =12.21 MHz = 12Multiplication factor =HF Oscillator Fx =12.21 MHz = 12

Transmitter Deviation Transmitter Deviation 5000Hz 5000Hz

Desired oscillator Fx= Multiplication Factor = 12Desired oscillator Fx= Multiplication Factor = 12

= 416.7 Hz= 416.7 Hz



G8B01 What receiver stage combines a G8B01 What receiver stage combines a 14.250 MHz input signal with a 13.795 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 MHz oscillator signal to produce a 455 kHz intermediate frequency (IF) signal?kHz intermediate frequency (IF) signal?

A.A. MixerMixer

B.B. BFOBFO

C.C. VFOVFO

D.D. MultiplierMultiplier


G8B01 What receiver stage combines a G8B01 What receiver stage combines a 14.250 MHz input signal with a 13.795 14.250 MHz input signal with a 13.795 MHz oscillator signal to produce a 455 MHz oscillator signal to produce a 455 kHz intermediate frequency (IF) signal?kHz intermediate frequency (IF) signal?

A.A. MixerMixerB.B. BFOBFO

C.C. VFOVFO



G8B02 If a receiver mixes a 13.800 MHz G8B02 If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal VFO with a 14.255 MHz received signal to produce a 455 kHz intermediate to produce a 455 kHz intermediate frequency (IF) signal, what type of frequency (IF) signal, what type of interference will a 13.345 MHz signal interference will a 13.345 MHz signal produce in the receiver?produce in the receiver?

A.A. Local oscillatorLocal oscillator

B.B. Image responseImage response

C.C. Mixer interferenceMixer interference

D.D. Intermediate interferenceIntermediate interference


G8B02 If a receiver mixes a 13.800 MHz G8B02 If a receiver mixes a 13.800 MHz VFO with a 14.255 MHz received signal VFO with a 14.255 MHz received signal to produce a 455 kHz intermediate to produce a 455 kHz intermediate frequency (IF) signal, what type of frequency (IF) signal, what type of interference will a 13.345 MHz signal interference will a 13.345 MHz signal produce in the receiver?produce in the receiver?

A.A. Local oscillatorLocal oscillator

B.B. Image responseImage responseC.C. Mixer interferenceMixer interference

D.D. Intermediate interferenceIntermediate interference


G8B03 What stage in a transmitter G8B03 What stage in a transmitter would change a 5.3 MHz input signal to would change a 5.3 MHz input signal to 14.3 MHz?14.3 MHz?

A.A. A mixerA mixer

B.B. A beat frequency oscillatorA beat frequency oscillator

C.C. A frequency multiplierA frequency multiplier

D.D. A linear translatorA linear translator


G8B03 What stage in a transmitter G8B03 What stage in a transmitter would change a 5.3 MHz input signal to would change a 5.3 MHz input signal to 14.3 MHz?14.3 MHz?

A.A. A mixerA mixerB.B. A beat frequency oscillatorA beat frequency oscillator

C.C. A frequency multiplierA frequency multiplier

D.D. A linear translatorA linear translator


G8B04 What is the name of the stage in G8B04 What is the name of the stage in a VHF FM transmitter that selects a a VHF FM transmitter that selects a harmonic of an HF signal to reach the harmonic of an HF signal to reach the desired operating frequency?desired operating frequency?

A.A. MixerMixer

B.B. Reactance modulatorReactance modulator

C.C. Pre-emphasis networkPre-emphasis network



G8B04 What is the name of the stage in G8B04 What is the name of the stage in a VHF FM transmitter that selects a a VHF FM transmitter that selects a harmonic of an HF signal to reach the harmonic of an HF signal to reach the desired operating frequency?desired operating frequency?

A.A. MixerMixer

B.B. Reactance modulatorReactance modulator

C.C. Pre-emphasis networkPre-emphasis network



G8B05 Why isn't frequency modulated G8B05 Why isn't frequency modulated (FM) phone used below 29.5 MHz?(FM) phone used below 29.5 MHz?

A.A. The transmitter efficiency for this mode is lowThe transmitter efficiency for this mode is low

B.B. Harmonics could not be attenuated to practical Harmonics could not be attenuated to practical levelslevels

C.C. The bandwidth would exceed FCC limitsThe bandwidth would exceed FCC limits

D.D. The frequency stability would not be adequateThe frequency stability would not be adequate


G8B05 Why isn't frequency modulated G8B05 Why isn't frequency modulated (FM) phone used below 29.5 MHz?(FM) phone used below 29.5 MHz?

A.A. The transmitter efficiency for this mode is lowThe transmitter efficiency for this mode is low

B.B. Harmonics could not be attenuated to practical Harmonics could not be attenuated to practical levelslevels

C.C. The bandwidth would exceed FCC limitsThe bandwidth would exceed FCC limitsD.D. The frequency stability would not be adequateThe frequency stability would not be adequate


G8B06 What is the total bandwidth of G8B06 What is the total bandwidth of an FM-phone transmission having a 5 an FM-phone transmission having a 5 kHz deviation and a 3 kHz modulating kHz deviation and a 3 kHz modulating frequency?frequency?

A.A. 3 kHz3 kHz

B.B. 5 kHz5 kHz

C.C. 8 kHz8 kHz

D.D. 16 kHz16 kHz


G8B06 What is the total bandwidth of G8B06 What is the total bandwidth of an FM-phone transmission having a 5 an FM-phone transmission having a 5 kHz deviation and a 3 kHz modulating kHz deviation and a 3 kHz modulating frequency?frequency?

A.A. 3 kHz3 kHz

B.B. 5 kHz5 kHz

C.C. 8 kHz8 kHz

D.D. 16 kHz16 kHz


G8B07 What is the frequency deviation G8B07 What is the frequency deviation for a 12.21-MHz reactance-modulated for a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52-oscillator in a 5-kHz deviation, 146.52-MHz FM-phone transmitter?MHz FM-phone transmitter?

A.A. 101.75 Hz101.75 Hz

B.B. 416.7 Hz416.7 Hz

C.C. 5 kHz5 kHz

D.D. 60 kHz60 kHz


G8B07 What is the frequency deviation G8B07 What is the frequency deviation for a 12.21-MHz reactance-modulated for a 12.21-MHz reactance-modulated oscillator in a 5-kHz deviation, 146.52-oscillator in a 5-kHz deviation, 146.52-MHz FM-phone transmitter?MHz FM-phone transmitter?

A.A. 101.75 Hz101.75 Hz

B.B. 416.7 Hz416.7 HzC.C. 5 kHz5 kHz

D.D. 60 kHz60 kHz


G8B08 How is frequency shift related to G8B08 How is frequency shift related to keying speed in an FSK signal?keying speed in an FSK signal?

A.A. The frequency shift in hertz must be at least four The frequency shift in hertz must be at least four times the keying speed in WPMtimes the keying speed in WPM

B.B. The frequency shift must not exceed 15 Hz per WPM The frequency shift must not exceed 15 Hz per WPM of keying speedof keying speed

C.C. Greater keying speeds require greater frequency Greater keying speeds require greater frequency shiftsshifts

D.D. Greater keying speeds require smaller frequency Greater keying speeds require smaller frequency shiftsshifts


G8B08 How is frequency shift related to G8B08 How is frequency shift related to keying speed in an FSK signal?keying speed in an FSK signal?

A.A. The frequency shift in hertz must be at least four The frequency shift in hertz must be at least four times the keying speed in WPMtimes the keying speed in WPM

B.B. The frequency shift must not exceed 15 Hz per WPM The frequency shift must not exceed 15 Hz per WPM of keying speedof keying speed

C.C. Greater keying speeds require greater Greater keying speeds require greater frequency shiftsfrequency shifts

D.D. Greater keying speeds require smaller frequency Greater keying speeds require smaller frequency shiftsshifts


G8B09 What do RTTY, Morse code, G8B09 What do RTTY, Morse code, PSK31 and packet communications PSK31 and packet communications have in common?have in common?

A.A. They require the same bandwidthThey require the same bandwidth

B.B. They are digital modesThey are digital modes

C.C. They use on/off keyingThey use on/off keying

D.D. They use phase shift modulationThey use phase shift modulation


G8B09 What do RTTY, Morse code, G8B09 What do RTTY, Morse code, PSK31 and packet communications PSK31 and packet communications have in common?have in common?

A.A. They require the same bandwidthThey require the same bandwidth

B.B. They are digital modesThey are digital modesC.C. They use on/off keyingThey use on/off keying

D.D. They use phase shift modulationThey use phase shift modulation


G8B10 When transmitting a data mode G8B10 When transmitting a data mode signal, why is it important to know the signal, why is it important to know the duty cycle of the mode you are using?duty cycle of the mode you are using?

A.A. To aid in tuning your transmitterTo aid in tuning your transmitter

B.B. To prevent damage to your transmitter's final To prevent damage to your transmitter's final output stageoutput stage

C.C. To allow time for the other station to break in during To allow time for the other station to break in during a transmissiona transmission

D.D. All of these choices are correctAll of these choices are correct


G8B10 When transmitting a data mode G8B10 When transmitting a data mode signal, why is it important to know the signal, why is it important to know the duty cycle of the mode you are using?duty cycle of the mode you are using?

A.A. To aid in tuning your transmitterTo aid in tuning your transmitter

B.B. To prevent damage to your transmitter's To prevent damage to your transmitter's final output stagefinal output stage

C.C. To allow time for the other station to break in during To allow time for the other station to break in during a transmissiona transmission

D.D. All of these choices are correctAll of these choices are correct


G8B11 What part of the 20 meter band G8B11 What part of the 20 meter band is most commonly used for PSK31 is most commonly used for PSK31 operation?operation?

A.A. At the bottom of the slow-scan TV segment, near At the bottom of the slow-scan TV segment, near 14.230 MHz14.230 MHz

B.B. At the top of the SSB phone segment, near 14.325 At the top of the SSB phone segment, near 14.325 MHzMHz

C.C. In the middle of the CW segment, near 14.100 MHzIn the middle of the CW segment, near 14.100 MHz

D.D. Below the RTTY segment, near 14.070 MHzBelow the RTTY segment, near 14.070 MHz


G8B11 What part of the 20 meter band G8B11 What part of the 20 meter band is most commonly used for PSK31 is most commonly used for PSK31 operation?operation?

A.A. At the bottom of the slow-scan TV segment, near At the bottom of the slow-scan TV segment, near 14.230 MHz14.230 MHz

B.B. At the top of the SSB phone segment, near 14.325 At the top of the SSB phone segment, near 14.325 MHzMHz

C.C. In the middle of the CW segment, near 14.100 MHzIn the middle of the CW segment, near 14.100 MHz

D.D. Below the RTTY segment, near 14.070 MHzBelow the RTTY segment, near 14.070 MHz


G8B12 What is another term for the G8B12 What is another term for the mixing of two RF signals?mixing of two RF signals?

A.A. HeterodyningHeterodyning

B.B. SynthesizingSynthesizing

C.C. CancellationCancellation

D.D. MultiplyingMultiplying


G8B12 What is another term for the G8B12 What is another term for the mixing of two RF signals?mixing of two RF signals?

A.A. HeterodyningHeterodyningB.B. SynthesizingSynthesizing

C.C. CancellationCancellation

D.D. MultiplyingMultiplying


G8 - SIGNALS AND EMISSIONS G8 - SIGNALS AND EMISSIONS [2 exam questions - 2 groups][2 exam questions - 2 groups]

Signals and Emissions 1 G8 - SIGNALS AND EMISSIONS [2 exam questions - 2 groups] G8ACarriers and modulation: AM; FM; single and double sideband ; modulation.

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rf wave

rf signal

information signals

carrier wave amplitude

fmphase frequency modulation

carrier frequency changes

unmodulated rf carrier

narrow bandwidth modulation