system technician conventional Exam guide 2023 with
complete solution
Discussing modulation
In a hybrid fiber/coax (HFC) network what type of crude amplitude modulation
(AM) detector causes common path distortion (CPD)?
envelope detector
What are the peaks and minima of the amplitude modulation (AM) waveform
envelope related to
The amplitude of the modulation signal.
What geometric shape is a sine wave based upon?
A right degree triangle
What are the three elements of a carrier wave that can be manipulated
amplitude, frequency, phase
In a conventional amplitude modulation (AM) transmission, how much power is in
the sidebands and how much is in the carrier?
Two-thirds of the power is in the carrier with one-third in the sidebands.
Why can Carson's Rule be used to determine the bandwidth of a frequency
modulation (FM) carrier?
In most cases, the amplitude of the sidebands furthest from the carrier frequency are so
low that they can be ignored.
Applying Carson's Rule to determine the bandwidth of a narrowband frequency
modulation (FM) carrier, what is the most significant factor?
The maximum modulation signal frequency.
Under what principle do frequency modulation (FM) detector circuit designs
operate?
That voltage is created when the signal frequency moves from the center frequency.
What prevents the subcarriers in orthogonal frequency division multiplexing
(OFDM) from interfering with each other?
The peak power of each subcarrier aligns with the minimum power of the adjacent
subcarrier.
How many symbols are available at the output of a quadrature phase shift keying
(QPSK) modulator
4 symbols, each containing 2 bits of data.
Exploring communications circuit blocks
What information remains after the intermediate frequency (IF) signal is detected,
or demodulated?
Analog or digital baseband information.
In a radio receiver, what is almost universally used to conduct the energy
between the antenna and the receiver tuner?
Coaxial cable
What two significant signals go into the mixer to create the intermediate
frequency (IF)
The RF signal frequency at the output of the front end filter and the local oscillator (LO)
signal.
, What part of a receiver has several functions that include limiting the number of
signals that reach the amplifier and mixer?
The front end filter.
What is used in set-top boxes (STB) to strike a balance between image rejection,
the bandwidth of the intermediate frequency (IF) filter, and the frequency which
modulation is done?
Double IF conversion
What type of bandpass filters offer the precision, stability, and bandwidth most
suitable for TV and set-top box (STB) intermediate frequency (IF) sections?
Surface acoustic wave (SAW) filters
What is used in some receivers to remove all attenuation before the amplifier until
the received signal level reaches a designed threshold?
Delayed automatic gain control (AGC).
Which class of amplifier utilizes a push-pull amplifier configuration in which each
transistor conducts current during opposite cycles of the input signal?
Class B amplifier.
Which class of amplifier has an output that is very high in harmonics and must be
attenuated by a filter network?
Class C amplifier.
Which class of amplifier efficiency approaches, but never achieves, 100%?
Class D amplifier.
Discussing discrete amplifier components
What characterizes N-doped silicon that is used in bipolar junction transistors
(BJT)?
N-doped silicon has an excess of free electrons compared to P-doped silicon.
What is another name for the bipolar junction transistor (BJT) common collector
configuration? O Signal amplifier.
Emitter follower
In what application would a bipolar junction transistor (BJT) common base
configuration be used?
For impedance isolation between a low impedance device and high impedance amplifier
Calculating the signal voltage and current range on the output of a bipolar
junction transistor (BJT) involve repeated applications of what?
Ohm's law.
In a basic N-channel junction field effect transistor (J-FET), what when negative
bias is applied to the gate?
The J-FET depletion region is expanded, decreasing the current that is transported
between the source and the drain
Why do metal oxide semiconductor field effect transistors (MOSFET) have
internal zener diodes from the gate to the source or substrate?
To prevent damage from static electricity
In an N-channel enhancement mode metal oxide semiconductor field effect
transistor (MOSFET), what effectively turns the P substrate between the two wells
into an induced N-channel?
A suitable positive voltage placed between the gate and source
complete solution
Discussing modulation
In a hybrid fiber/coax (HFC) network what type of crude amplitude modulation
(AM) detector causes common path distortion (CPD)?
envelope detector
What are the peaks and minima of the amplitude modulation (AM) waveform
envelope related to
The amplitude of the modulation signal.
What geometric shape is a sine wave based upon?
A right degree triangle
What are the three elements of a carrier wave that can be manipulated
amplitude, frequency, phase
In a conventional amplitude modulation (AM) transmission, how much power is in
the sidebands and how much is in the carrier?
Two-thirds of the power is in the carrier with one-third in the sidebands.
Why can Carson's Rule be used to determine the bandwidth of a frequency
modulation (FM) carrier?
In most cases, the amplitude of the sidebands furthest from the carrier frequency are so
low that they can be ignored.
Applying Carson's Rule to determine the bandwidth of a narrowband frequency
modulation (FM) carrier, what is the most significant factor?
The maximum modulation signal frequency.
Under what principle do frequency modulation (FM) detector circuit designs
operate?
That voltage is created when the signal frequency moves from the center frequency.
What prevents the subcarriers in orthogonal frequency division multiplexing
(OFDM) from interfering with each other?
The peak power of each subcarrier aligns with the minimum power of the adjacent
subcarrier.
How many symbols are available at the output of a quadrature phase shift keying
(QPSK) modulator
4 symbols, each containing 2 bits of data.
Exploring communications circuit blocks
What information remains after the intermediate frequency (IF) signal is detected,
or demodulated?
Analog or digital baseband information.
In a radio receiver, what is almost universally used to conduct the energy
between the antenna and the receiver tuner?
Coaxial cable
What two significant signals go into the mixer to create the intermediate
frequency (IF)
The RF signal frequency at the output of the front end filter and the local oscillator (LO)
signal.
, What part of a receiver has several functions that include limiting the number of
signals that reach the amplifier and mixer?
The front end filter.
What is used in set-top boxes (STB) to strike a balance between image rejection,
the bandwidth of the intermediate frequency (IF) filter, and the frequency which
modulation is done?
Double IF conversion
What type of bandpass filters offer the precision, stability, and bandwidth most
suitable for TV and set-top box (STB) intermediate frequency (IF) sections?
Surface acoustic wave (SAW) filters
What is used in some receivers to remove all attenuation before the amplifier until
the received signal level reaches a designed threshold?
Delayed automatic gain control (AGC).
Which class of amplifier utilizes a push-pull amplifier configuration in which each
transistor conducts current during opposite cycles of the input signal?
Class B amplifier.
Which class of amplifier has an output that is very high in harmonics and must be
attenuated by a filter network?
Class C amplifier.
Which class of amplifier efficiency approaches, but never achieves, 100%?
Class D amplifier.
Discussing discrete amplifier components
What characterizes N-doped silicon that is used in bipolar junction transistors
(BJT)?
N-doped silicon has an excess of free electrons compared to P-doped silicon.
What is another name for the bipolar junction transistor (BJT) common collector
configuration? O Signal amplifier.
Emitter follower
In what application would a bipolar junction transistor (BJT) common base
configuration be used?
For impedance isolation between a low impedance device and high impedance amplifier
Calculating the signal voltage and current range on the output of a bipolar
junction transistor (BJT) involve repeated applications of what?
Ohm's law.
In a basic N-channel junction field effect transistor (J-FET), what when negative
bias is applied to the gate?
The J-FET depletion region is expanded, decreasing the current that is transported
between the source and the drain
Why do metal oxide semiconductor field effect transistors (MOSFET) have
internal zener diodes from the gate to the source or substrate?
To prevent damage from static electricity
In an N-channel enhancement mode metal oxide semiconductor field effect
transistor (MOSFET), what effectively turns the P substrate between the two wells
into an induced N-channel?
A suitable positive voltage placed between the gate and source
