Question 1

The worst case signal-to-noise ratio at the output of an FM detector occurs when:

Accepted Answer

A)  the desired signal is 90 degrees out of phase with the intelligence signal. 
B)  the desired signal is 90 degrees out of phase with the resultant signal of adding the signal to the noise. 
C)  the noise signal is 90 degrees out of phase with the resultant signal of adding the signal to the noise. 
D)  the desired signal is 90 degrees out of phase with the noise signal. 
A)  the desired signal is 90 degrees out of phase with the intelligence signal. 
B)  the desired signal is 90 degrees out of phase with the resultant signal of adding the signal to the noise. 
C)  the noise signal is 90 degrees out of phase with the resultant signal of adding the signal to the noise. 
D)  the desired signal is 90 degrees out of phase with the noise signal. C

Question 2

Phase modulation is an indirect form of:

Accepted Answer

A)  frequency modulation 
B)  angle modulation 
C)  amplitude modulation 
D)  pulse modulation 
A)  frequency modulation 
B)  angle modulation 
C)  amplitude modulation 
D)  pulse modulation A

Question 3

Why are stereo FM broadcasts more prone to noise than are monophonic FM broadcasts?

Accepted Answer

A)  Stereo has two separate channels that can become covered by noise rather than the single channel of the monophonic broadcast. 
B)  The L-R signal is weaker than the L+R signal. 
C)  The L-R signal is at higher modulating frequencies than the L+R signal. 
D)  all of the above 
A)  Stereo has two separate channels that can become covered by noise rather than the single channel of the monophonic broadcast. 
B)  The L-R signal is weaker than the L+R signal. 
C)  The L-R signal is at higher modulating frequencies than the L+R signal. 
D)  all of the above D

Question 4

A de-emphasis network has:

Accepted Answer

A)  an upper cutoff frequency of 2.120 kHz. 
B)  a high-frequency roll-off rate of -20 db per decade. 
C)  a time constant of 75 microseconds. 
D)  all of the above 
A)  an upper cutoff frequency of 2.120 kHz. 
B)  a high-frequency roll-off rate of -20 db per decade. 
C)  a time constant of 75 microseconds. 
D)  all of the above

Question 5

The deviation return for NTSC broadcast television is

Accepted Answer

A)  .5 
B)  2.5 
C)  6.71 
D)  1.67 
E)  5 
A)  .5 
B)  2.5 
C)  6.71 
D)  1.67 
E)  5

Question 6

FM systems that utilize an indirect FM modulator consisting of a phase modulator stage are known as:

Accepted Answer

A)  Crosby systems 
B)  Hartley systems 
C)  Armstrong systems 
D)  PLL systems 
A)  Crosby systems 
B)  Hartley systems 
C)  Armstrong systems 
D)  PLL systems

Question 7

Which best describes how a varactor diode modulator creates FM?

Accepted Answer

A)  The intelligence signal causes the diode to create phase shift which indirectly creates FM 
B)  The intelligence signal alters the capacitance of the diode to shift the resonant frequency of a tank circuit. 
C)  The intelligence signal creates mixing action in the nonlinear varactor diode to create an FM signal. 
D)  The intelligence signal alters the amount of forward bias of the varactor diode to create an FM signal. 
A)  The intelligence signal causes the diode to create phase shift which indirectly creates FM 
B)  The intelligence signal alters the capacitance of the diode to shift the resonant frequency of a tank circuit. 
C)  The intelligence signal creates mixing action in the nonlinear varactor diode to create an FM signal. 
D)  The intelligence signal alters the amount of forward bias of the varactor diode to create an FM signal.

Question 8

An indirect FM wideband transmitter can have its output signal be at the proper carrier frequency and at the same time have the required deviation by:

Accepted Answer

A)  using a balanced modulator and a 90 degree phase shifter 
B)  using a reactance modulator 
C)  using combinations of mixers and multiplier stages 
D)  using a frequency correcting network 
A)  using a balanced modulator and a 90 degree phase shifter 
B)  using a reactance modulator 
C)  using combinations of mixers and multiplier stages 
D)  using a frequency correcting network

Question 9

Standard FM broadcast stations use a maximum frequency deviation of:

Accepted Answer

A)  75 kHz 
B)  5 kHz 
C)  200 kHz 
D)  150 kHz 
A)  75 kHz 
B)  5 kHz 
C)  200 kHz 
D)  150 kHz

Question 10

Determine the worst case output signal-to-noise ratio for a broadcast FM receiver with a maximum deviation of 75 kHz and a maximum intelligence frequency of 10 kHz if the input signal-to-noise ratio is 2:1

Accepted Answer

A)  30:1 
B)  15:1 
C)  2:1 
D)  10:1 
A)  30:1 
B)  15:1 
C)  2:1 
D)  10:1

Question 11

The disadvantage of indirect FM modulators is

Accepted Answer

A)  they can only work at low intelligence frequencies 
B)  they have insufficient frequency deviation 
C)  they only work with large signal amplitudes 
D)  they have very limited frequency stability 
A)  they can only work at low intelligence frequencies 
B)  they have insufficient frequency deviation 
C)  they only work with large signal amplitudes 
D)  they have very limited frequency stability

Question 12

The deviation ratio for broadcast FM radio is

Accepted Answer

A)  5 
B)  1.67 
C)  6.71 
D)  2.5 
E)  .5 
A)  5 
B)  1.67 
C)  6.71 
D)  2.5 
E)  .5

Question 13

In an FM modulator, the intelligence frequency determines the:

Accepted Answer

A)  amount of carrier frequency deviation 
B)  phase angle of the carrier frequency component 
C)  rate of carrier frequency deviation 
D)  power level of the FM signal 
A)  amount of carrier frequency deviation 
B)  phase angle of the carrier frequency component 
C)  rate of carrier frequency deviation 
D)  power level of the FM signal

Question 14

An FM stereo broadcast is an example of

Accepted Answer

A)  frequency-division multiplexing 
B)  amplitude-division multiplexing 
C)  time-division multiplexing 
D)  phase-division multiplexing 
A)  frequency-division multiplexing 
B)  amplitude-division multiplexing 
C)  time-division multiplexing 
D)  phase-division multiplexing

Question 15

The two types of angle modulation are:

Accepted Answer

A)  amplitude and frequency modulation 
B)  phase and amplitude modulation 
C)  phase and frequency modulation 
D)  pulse and frequency modulation 
A)  amplitude and frequency modulation 
B)  phase and amplitude modulation 
C)  phase and frequency modulation 
D)  pulse and frequency modulation

Question 16

In FM stereo broadcasts, why are the left and right audio signals first converted to L+R and L-R signals before being frequency modulated?

Accepted Answer

A)  This permits higher intelligence frequencies to be used 
B)  This permits compatibility between monaural and stereo systems 
C)  This is necessary to be able to be multiplexed properly 
D)  This produces higher signal-to-noise ratios 
A)  This permits higher intelligence frequencies to be used 
B)  This permits compatibility between monaural and stereo systems 
C)  This is necessary to be able to be multiplexed properly 
D)  This produces higher signal-to-noise ratios

Question 17

Multiplex transmission is:

Accepted Answer

A)  using two transmitters to transmit two separate channels of information 
B)  the technique of separating the L and R signals into L+R and L-R in a stereo FM transmitter. 
C)  the simultaneous transmission of two or more signals on one carrier 
D)  using two carriers to transmit two separate channels of information 
A)  using two transmitters to transmit two separate channels of information 
B)  the technique of separating the L and R signals into L+R and L-R in a stereo FM transmitter. 
C)  the simultaneous transmission of two or more signals on one carrier 
D)  using two carriers to transmit two separate channels of information

Question 18

The advantage of indirect FM modulation over direct FM modulation is:

Accepted Answer

A)  in their ability to work at higher intelligence frequencies 
B)  in their increased frequency deviation 
C)  in their ability to work with small signal amplitudes 
D)  in their improved frequency stability 
A)  in their ability to work at higher intelligence frequencies 
B)  in their increased frequency deviation 
C)  in their ability to work with small signal amplitudes 
D)  in their improved frequency stability

Question 19

The main disadvantage of direct FM modulators is:

Accepted Answer

A)  they can only work at low radio frequencies 
B)  they have very limited frequency stability 
C)  they have insufficient frequency deviation 
D)  they work reliably only with low-level intelligence signals 
A)  they can only work at low radio frequencies 
B)  they have very limited frequency stability 
C)  they have insufficient frequency deviation 
D)  they work reliably only with low-level intelligence signals

Question 20

Why can low-level modulated FM signals be amplified by class C power amplifier stages without distorting unlike AM or SSB signals?

Accepted Answer

A)  These FM signals have only one upper and lower sideband frequency components. 
B)  These FM signals do not vary in amplitude. 
C)  The FM signals do not have a carrier frequency component. 
D)  These FM signals have larger bandwidths than do AM or SSB signals. 
A)  These FM signals have only one upper and lower sideband frequency components. 
B)  These FM signals do not vary in amplitude. 
C)  The FM signals do not have a carrier frequency component. 
D)  These FM signals have larger bandwidths than do AM or SSB signals.

The worst case signal-to-noise ratio at the output of an FM detector occurs when:

Phase modulation is an indirect form of:

Why are stereo FM broadcasts more prone to noise than are monophonic FM broadcasts?

A de-emphasis network has:

The deviation return for NTSC broadcast television is

FM systems that utilize an indirect FM modulator consisting of a phase modulator stage are known as:

Which best describes how a varactor diode modulator creates FM?

An indirect FM wideband transmitter can have its output signal be at the proper carrier frequency and at the same time have the required deviation by:

Standard FM broadcast stations use a maximum frequency deviation of:

Determine the worst case output signal-to-noise ratio for a broadcast FM receiver with a maximum deviation of 75 kHz and a maximum intelligence frequency of 10 kHz if the input signal-to-noise ratio is 2:1

The disadvantage of indirect FM modulators is

The deviation ratio for broadcast FM radio is

In an FM modulator, the intelligence frequency determines the:

An FM stereo broadcast is an example of

The two types of angle modulation are:

In FM stereo broadcasts, why are the left and right audio signals first converted to L+R and L-R signals before being frequency modulated?

Multiplex transmission is:

The advantage of indirect FM modulation over direct FM modulation is:

The main disadvantage of direct FM modulators is:

Why can low-level modulated FM signals be amplified by class C power amplifier stages without distorting unlike AM or SSB signals?

Introductory Topics

Amplitude Modulation: Transmission

Amplitude Modulation: Reception

Single-Sideband Communications

Frequency Modulation: Reception

Communications Techniques

Digital Communications: Coding Techniques

Wired Digital Communications

Wireless Digital Communications

Network Communications

Transmission Lines

Wave Propagation

Antennas

Waveguides and Radar

Microwaves and Lasers

Television

Fiber Optics

Filters

Exam 5: Frequency Modulation: Transmission

The worst case signal-to-noise ratio at the output of an FM detector occurs when:

Phase modulation is an indirect form of:

Why are stereo FM broadcasts more prone to noise than are monophonic FM broadcasts?

A de-emphasis network has:

The deviation return for NTSC broadcast television is

FM systems that utilize an indirect FM modulator consisting of a phase modulator stage are known as:

Which best describes how a varactor diode modulator creates FM?

An indirect FM wideband transmitter can have its output signal be at the proper carrier frequency and at the same time have the required deviation by:

Standard FM broadcast stations use a maximum frequency deviation of:

Determine the worst case output signal-to-noise ratio for a broadcast FM receiver with a maximum deviation of 75 kHz and a maximum intelligence frequency of 10 kHz if the input signal-to-noise ratio is 2:1

The disadvantage of indirect FM modulators is

The deviation ratio for broadcast FM radio is

In an FM modulator, the intelligence frequency determines the:

An FM stereo broadcast is an example of

The two types of angle modulation are:

In FM stereo broadcasts, why are the left and right audio signals first converted to L+R and L-R signals before being frequency modulated?

Multiplex transmission is:

The advantage of indirect FM modulation over direct FM modulation is:

The main disadvantage of direct FM modulators is:

Why can low-level modulated FM signals be amplified by class C power amplifier stages without distorting unlike AM or SSB signals?

Introductory Topics

Amplitude Modulation: Transmission

Amplitude Modulation: Reception

Single-Sideband Communications

Frequency Modulation: Reception

Communications Techniques

Digital Communications: Coding Techniques

Wired Digital Communications

Wireless Digital Communications

Network Communications

Transmission Lines

Wave Propagation

Antennas

Waveguides and Radar

Microwaves and Lasers

Television

Fiber Optics

Filters