Angle Modulation I

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Modulation that results whenever the phase angle of a sinusoidal wave is varied with respect to time.

Angle Modulation

The original unmodulated carrier frequency in the resultant angle-modulated waveform.

Carrier Rest Frequency

These are the output versus input transfer functions for the modulators, which give the relationship between what output parameter changes in respect to specified changes in the input signal.

Deviation Sensitivities

What is emission designation for Frequency Modulation?

F3E

What is the emission designation for Phase Modulation?

G3E

It varies the frequency of a constant-amplitude carrier directly proportional to the amplitude of the modulating signal at a rate equal to the frequency of the modulating signal.

Direct Frequency Modulation

The change in frequency that occurs in the carrier when it is acted on by a modulating-signal frequency.

Frequency Deviation

Maximum FM Deviation occurs at

both negative and positive amplitudes of modulating signal.

What is the maximum deviation for Monoaural TV Sound?

25 kHz.

What is the maximum deviation for Stereo TV Sound?

50 kHz

What is the highest deviation frequency?

75 kHz or 220 kHz

What is the maximum deviation for Two Way transmitter?

5 kHz

What is the maximum modulating frequency for Two Way transmitter?

3 kHz

The precise frequency of the carrier at a given instant of time and is defined as the first time derivative of the instantaneous phase.

Instantaneous Frequency

The instantaneous change in frequency of the carrier and is defined as the first time derivative of the instantaneous phase deviation.

Instantaneous Frequency Deviation

The peak-to-peak frequency deviation.

Carrier Swing

When there is received signal but the carrier signal has no change in its frequency characteristics. The frequency of carrier is ______

Center Frequency

The ratio of the frequency deviation actually produced to the maximum frequency deviation

Modulation Index

What is the percent modulation of Stereo FM in Main Channel?

45%

What is the percent modulation of Stereo FM in Carrier?

45%

What is the percent modulation of Stereo FM in Sub Channel?

10%

What is the percent modulation of Stereo FM in Subcarrier?

10%

What determines the number of sidebands are the following except:

Center Frequency

The following statements are false except:

A louder sound when generating modulating waveform for FM cause frequency deviation.

Instrument that displays the carrier and sidebands amplitude with frequency to frequency.

Spectrum Analyzer

Circuit which the carrier is varied in such a way that its instantaneous phase is proportional to the integral of the modulating signal.

Frequency Deviator

Frequency Modulator is preceded by a _____ generates a PM waveform.

differentiator

Frequency Modulation is more efficient because their power is increased by ______

Class C Amplifier

________ FM are low index FM systems while _____ FM are high index FM systems

narrowband, wideband

In a narrowband FM, deviation ratio is commonly _____, and highest audio frequency is limited to ______.

1, 3 kHz

It defines a bandwidth that includes approximately 98% of the total power in the modulated wave.

Carson's Rule

Carson's Rule states that bandwidth is equal to twice the sum of ________ and _______.

modulating frequency, frequency deviation

The following are the advantage of FM except:

excessive use of spectrum space

It refers to worst case modulation index.

Deviation Ratio

What is the maximum deviation for Narrowband FM?

1.67

The FCC has assigned the commercial FM broadcast service a 20 MegaHertz band of frequencies that extends from __ MegaHertz to ____ MegaHertz.

88, 108

The 20 MHz commercial FM band is divided into ____ 200 kHz wide channels beginning at 88.1 MegaHertz.

100

To provide high-quality, reliable music, the maximum frequency deviation allowed is ____ with a maximum modulating frequency of _____.

75 kHz, 15 kHz

What is the lowest modulating frequency?

50 kHz

A ____ wide guard band is usually on either side of each assigned channel.

200 kHz

The highest side frequencies from one channel are allowed to spill over into adjacent channels, producing an interference.

Adjacent Channel Interference

The noise voltage at the output of an FM demodulator increases linearly with frequency.

Noise Triangle

_____ occurs when carrier frequency is modulated.

Direct FM

In order for Direct Frequency Modulation to maintain its freqeucny, it requires for the need of ______

AFC

Three common methods for producing direct FM are following except:

Diode Modulator

Direct frequency modulator used for low-index applications, such as two-way mobile radio.

Varactor Diode Modulator

Device whose capacitance is a function of applied voltage.

Varactor

Varactor Diode has equivalent circuit of _______.

capacitor in series with resistor.

What is typical capacitance of Varactor?

picoFarad

There is only ______ frequency change in crystal oscillator produced by varactor diode and can be increased by mixer.

small

Direct FM modulator using a JFET as the active device.

Crosby Modulator

If small inductance were used in place of capacitor in reactance tube modulator, it become _______.

inductive reactive

This is first and indirect method of generating FM.

Armstrong System

It is used by broadcasting station.

Indirect FM

Which generate a stable and accurate direct FM output and proportional to input modulating signal.

Vacuum Tube

Increasing or decreasing input frequency to be locked, VCO will jump to

free running frequency.

It produce an output waveform in which the frequency deviation is directly proportional to the modulating signal.

Direct FM Transmitter

It produce an output waveform in which phase deviation is directly proportional to the modulating signal.

Indirect FM Transmitter

Circuit that compares the frequency of the noncrystal carrier oscillator to a crystal reference oscillator and then produces a correction voltage proportional to the difference between the frequencies.

AFC

The following statements are true except:

AFC produces a correction voltage proportional to the sum of the frequencies.

Frequency selective device whose output voltage is proportional to the difference between the input frequency and its resonant frequency.

FM Discriminator

Discriminator has input ______ signal and output ______ signal.

Intermediate Frequency, Audio Frequency

Which device that feeds the FM Discriminator?

Final IF Amplifier

Pulse Averaging Discriminator is implemented on ______ multivibrator.

Any of these

Voltage added to the modulating signal to adjust the oscillator’s center frequency to compensate for the low-frequency drift.

DC Correction Voltage

Noise interferes mainly with _____ modulating frequencies.

high

A properly designed FM has relative immunity to _______

atmospheric noise.

In order for FM to produce a stable signal, the local oscillator must be ________

crystal controlled

The local oscillator is tuned to frequency ______ incoming frequency to allow adequate frequency coverage without switching.

higher than

Controlled oscillator synthesizer is preferred to the direct one because it is _____

it is free of spurious frequencies

Which of the following statement about Capture Effect is false?

It captures any signal.

Receiver with good block performance is unaffected by

AGC derived from nearby transmission.

It is constant-amplitude output for all input signals above a prescribed minimum input level.

Any of these

The improvement in the S/N ratio when the peaks of the signal have the limiter so far into saturation that the weaker noise is totally eliminated.

None of these

_____ is the minimum dB difference in signal strength between two received signals for capture effect.

Capture Ratio

FM Receiver has the voltage at the output of the audio detector is ______ the frequency deviation at its input.

directly proportional to

A good FM receiver has a sensitivity of _____

1 microVolt

FM Receiver consists of the following except:

Preemphasis

A beat frequency oscillator has output differs by a frequency of _____.

1 kHz

Method used to remove amplitude variations caused by noise from the composite waveform simply by clipping the peaks of the envelope prior to detection

Limiting

Noise Floor of Receiver is the _____ for receiver sensitivity.

limiting condition

It rejects the image frequency in FM receivers.

Preselector

It establishes the signal to noise ratio and noise figure in FM receivers.

RF Amplifier

Which of the following is false?

None of these

What determines the sensitivity of the receiver?

Any of these

It refers to reduction of receiver gain caused by nearby signal of same frequency.

Desentizing

Which of the following is true?

Any of these

Modulation system system used for telegraphy.

Frequency Shift Keying

The envelope peak detector common to AM receivers is replaced in FM receivers by ______.

Limiter, Frequency Discriminator and De-emphasis Network

What do limiters prevents?

Any of these

It extracts the information from the modulated wave.

Discriminator

It convert FM to AM and then demodulate the AM envelope with conventional peak detectors.

Tuned Circuit Frequency Discriminator

Which of the following is false?

None of these

The cutoff frequency of Preemphasis and Deemphasis is _____

2.122 kHz

What is added at matrix of stereo FM receiver.

De-emphasis

It refers to the complete stages for FM production with desired carrier and deviation.

Exciter

These are frequency-dependent circuits designed to produce an output voltage that is proportional to the instantaneous frequency at its input.

Frequency Demodulator

The following are FM Demodulators except:

Diode Detector

The simplest form of tuned circuit frequency discriminator.

Ratio Detector

100

Slope Detector use shape of ______ of IF Filter.

frequency response roll off versus frequency

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