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2016-E8B: Modulation and demodulation: modulation methods; modulation index and deviation ratio; frequency and time division multiplexing; Orthogonal Frequency Division Multiplexing

2016-E8B01: What is the term for the ratio between the frequency deviation of an RF carrier wave and the modulating frequency of its corresponding FM-phone signal?

Modulation index

FM compressibility

Quieting index

Percentage of modulation



2016-E8B02: How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)?

It does not depend on the RF carrier frequency

It increases as the RF carrier frequency increases

It decreases as the RF carrier frequency increases

It varies with the square root of the RF carrier frequency



2016-E8B03: What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency when the modulating frequency is 1000 Hz?

3

0.3

3000

1000



2016-E8B04: What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2 kHz modulating frequency?

3

6000

2000

1/3



2016-E8B05: What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

1.67

60

0.167

0.6



2016-E8B06: What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

2.14

0.214

0.47

47



2016-E8B07: Orthogonal Frequency Division Multiplexing is a technique used for which type of amateur communication?

High speed digital modes

Extremely low-power contacts

EME

OFDM signals are not allowed on amateur bands



2016-E8B08: What describes Orthogonal Frequency Division Multiplexing?

A digital modulation technique using subcarriers at frequencies chosen to avoid intersymbol interference

A frequency modulation technique which uses non-harmonically related frequencies

A bandwidth compression technique using Fourier transforms

A digital mode for narrow band, slow speed transmissions



2016-E8B09: What is meant by deviation ratio?

The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency

The ratio of the audio modulating frequency to the center carrier frequency

The ratio of the carrier center frequency to the audio modulating frequency

The ratio of the highest audio modulating frequency to the average audio modulating frequency



2016-E8B10: What describes frequency division multiplexing?

Two or more information streams are merged into a baseband, which then modulates the transmitter

The transmitted signal jumps from band to band at a predetermined rate

The transmitted signal is divided into packets of information

Two or more information streams are merged into a digital combiner, which then pulse position modulates the transmitter



2016-E8B11: What is digital time division multiplexing?

Two or more signals are arranged to share discrete time slots of a data transmission

Two or more data streams are assigned to discrete sub-carriers on an FM transmitter

Two or more data streams share the same channel by transmitting time of transmission as the sub-carrier

Two or more signals are quadrature modulated to increase bandwidth efficiency





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2016-E8A: AC waveforms: sine, square, sawtooth and irregular waveforms; AC measurements; average and PEP of RF signals; Fourier analysis; Analog to digital conversion: Digital to Analog conversion
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