CDC 3D153 Volume 1 V1 (April 2013)

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CDC 3D153 01 1206, Edit Code 02 (April 2013) Volume 1 Units 1-5 Unit 1: Communication Principles Unit 2: Protecting Electronic Equipment Unit 3: General Purpose Instruments Unit 4: Radio Frequency Test Equipment Unit 5: Standard Practices

• 1.

What is one reason for modulation that involves modulating low frequency signals for transmission over long distances?

• A.

Spectrum conservation.

• B.

Channel allocation

• C.

• D.

Companding

Explanation
Modulating low frequency signals for transmission over long distances allows for ease of radiation. This is because low frequency signals have longer wavelengths, which makes them less susceptible to interference and attenuation. By modulating these signals, they can be efficiently transmitted and received over long distances without significant loss or degradation. This ease of radiation is beneficial in ensuring reliable and effective communication over extended ranges.

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• 2.

What are the three general categories used to produce modulation in radio frequency (RF) transmission today?

• A.

Binary amplitude shift keying, frequency shift keying, and phase shift keying.

• B.

Pulse amplitude, pulse width, and pulse position.

• C.

Amplitude, frequency, and phase.

• D.

Analog, digital, and shift keying.

C. Amplitude, frequency, and phase.
Explanation
The correct answer is amplitude, frequency, and phase. These three categories are commonly used in radio frequency transmission today. Amplitude modulation (AM) involves varying the amplitude of the carrier signal to transmit information. Frequency modulation (FM) involves varying the frequency of the carrier signal. Phase modulation (PM) involves varying the phase of the carrier signal. These modulation techniques allow for the encoding and transmission of information through radio waves.

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• 3.

When the modulating signal and carrier signal are combined within a modulator, the output signal contains

• A.

Modulating signal, upper sideband, and lower sideband.

• B.

Carrier, upper sideband, and lower sideband.

• C.

Upper sideband and modulating signal.

• D.

Carrier and modulating signal.

B. Carrier, upper sideband, and lower sideband.
Explanation
When the modulating signal and carrier signal are combined within a modulator, the output signal contains the carrier signal along with the upper sideband and lower sideband. The upper sideband is the portion of the signal that is above the carrier frequency, while the lower sideband is the portion below the carrier frequency. The modulating signal is also present in the output signal as it is used to modulate the carrier signal. Therefore, the correct answer is that the output signal contains the carrier, upper sideband, and lower sideband.

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• 4.

If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator, the output signal include

• A.

1.01 MHz, 1 MHz, and 0.99 MHz.

• B.

1.1 MHz, 1 MHz, and 0.9 MHz.

• C.

1.11 MHz, 1 MHz, and 0.99 MHz.

• D.

1.111 MHz, 1 MHz, 0.999 MHz.

A. 1.01 MHz, 1 MHz, and 0.99 MHz.
Explanation
When a carrier frequency of 1 MHz and a modulating tone of 10 kHz are input to the modulator, the output signal will include the carrier frequency (1 MHz), the sum of the carrier and modulating frequencies (1.01 MHz), and the difference between the carrier and modulating frequencies (0.99 MHz). This is due to the process of modulation, where the modulating tone is used to vary the amplitude, frequency, or phase of the carrier signal. In this case, the modulating tone affects the frequency of the carrier signal, resulting in the additional frequencies in the output signal.

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• 5.

The bandwidth of an amplitude modulated signal is

• A.

Two times the modulating signal.

• B.

The same as the modulating signal.

• C.

Determined by the modulation index.

• D.

Defined in terms of maximum amount of modulation.

A. Two times the modulating signal.
Explanation
The bandwidth of an amplitude modulated signal is two times the modulating signal because in amplitude modulation, the carrier signal is modulated by varying its amplitude according to the modulating signal. This modulation process results in the creation of two sidebands, one above and one below the carrier frequency. These sidebands contain the information of the modulating signal. Since the modulating signal is mirrored in both sidebands, the bandwidth necessary to transmit the modulating signal is twice the frequency range of the modulating signal.

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• 6.

Use the formula on page 1-3. If an oscilloscope displays a modulation envelope having an E(max) of 200 volts and an E(min) of 20 volts, what is the modulation percentage?

• A.

81.8.

• B.

85.5.

• C.

88.

• D.

122.

A. 81.8.
Explanation
The modulation percentage can be calculated using the formula: (E(max) - E(min)) / (E(max) + E(min)) * 100. Plugging in the given values, we get (200 - 20) / (200 + 20) * 100 = 180 / 220 * 100 = 81.8.

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• 7.

Which statement concerning bandwidth is true?

• A.

Overmodulating increases bandwidth because the distortion produces harmonics.

• B.

Undermodulating increases bandwidth because the distortion produces harmonics.

• C.

Overmodulating increases bandwidth because the output's increased amplitude.

• D.

Undermodulating increases bandwidth because the output's decreased amplitude.

A. Overmodulating increases bandwidth because the distortion produces harmonics.
Explanation
Overmodulating increases bandwidth because the distortion produces harmonics. When a signal is overmodulated, it means that the amplitude of the carrier wave is being increased beyond its normal range. This causes the signal to become distorted, resulting in the generation of harmonics. Harmonics are additional frequencies that are produced by the distortion. These harmonics increase the overall bandwidth of the signal, as they occupy additional frequency space. Therefore, overmodulating a signal will increase its bandwidth due to the production of harmonics.

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• 8.

The output of the oscillator in a frequency modulation (FM) modulator increases in frequency with each...

• A.

Positive half cycle of the carrier.

• B.

Negative half cycle of the carrier.

• C.

Positive half cycle of the modulating signal.

• D.

Negative half cycle of the modulating signal.

C. Positive half cycle of the modulating signal.
Explanation
In frequency modulation (FM), the output of the oscillator increases in frequency with each positive half cycle of the modulating signal. This means that as the amplitude of the modulating signal increases during the positive half cycle, the frequency of the output signal also increases. This relationship between the modulating signal and the output frequency is what allows for the encoding of information in FM modulation.

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• 9.

In frequency modulation, a significant sideband contains at least what percentage of the total transmitted power?

• A.

1.

• B.

3.

• C.

10.

• D.

0.1.

A. 1.
Explanation
In frequency modulation, a significant sideband contains at least 1% of the total transmitted power. This means that when a signal is modulated using frequency modulation, at least 1% of the total power is allocated to the sidebands. Sidebands are the additional frequency components that are created during modulation and contain the information being transmitted. Therefore, it is important to ensure that a significant portion of the power is allocated to the sidebands to ensure the integrity and clarity of the transmitted signal.

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• 10.

What is the formula to find the modulating index?

• A.

Deviation divided by frequency of modulation.

• B.

Deviation times frequency of modulation.

• C.

Sideband divide by carrier frequency.

• D.

Sideband times carrier frequency.

A. Deviation divided by frequency of modulation.
Explanation
The formula to find the modulating index is deviation divided by frequency of modulation. The modulating index represents the ratio between the maximum deviation of the carrier frequency and the frequency of the modulating signal. By dividing the deviation by the frequency of modulation, we can determine the modulating index, which is a crucial parameter in understanding the extent of modulation occurring in a signal.

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• 11.

A 5 kHz modulating signal has enough peak voltage to cause a deviation of 15 kHz. What is the modulation index?

• A.

5.

• B.

0.5.

• C.

0.3.

• D.

3.

D. 3.
Explanation
The modulation index is a measure of the extent of frequency deviation in a frequency modulation (FM) signal. It is calculated by dividing the peak frequency deviation by the modulating frequency. In this case, the modulating signal has a frequency of 5 kHz and causes a deviation of 15 kHz. Therefore, the modulation index is 15 kHz divided by 5 kHz, which equals 3.

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• 12.

What is it called when a narrow frequency band between adjacent stations prevent frequency modulated sidebands from overlapping?

• A.

Space.

• B.

Guard band.

• C.

Buffer zone.

• D.

Prevention field.

B. Guard band.
Explanation
A guard band refers to a narrow frequency band that is intentionally left unused between adjacent stations. It acts as a buffer zone or prevention field to prevent the frequency modulated sidebands from overlapping. This ensures that there is no interference or distortion between the signals of neighboring stations, allowing for clear and separate reception of each station's broadcast.

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• 13.

In phase modulation, what part of the carrier signal is varied?

• A.

Frequency.

• B.

Amplitude.

• C.

Height.

• D.

Phase.

D. Phase.
Explanation
In phase modulation, the part of the carrier signal that is varied is the phase. Phase modulation involves changing the phase of the carrier signal in order to encode information. By altering the phase, the signal can be modulated to represent different data or signals. This modulation technique is commonly used in telecommunications and is known for its ability to provide good signal quality and resistance to noise.

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• 14.

In phase modulation, the carrier's

• A.

Phase is shifted at the rate of the modulating signal.

• B.

Phase shifted with the phase of the modulating signal.

• C.

Amplitude is shifted at the rate of the modulating signal.

• D.

Amplitude is shifted with the phase of the modulating signal.

A. Phase is shifted at the rate of the modulating signal.
Explanation
In phase modulation, the phase of the carrier signal is shifted at the same rate as the modulating signal. This means that as the modulating signal changes, the phase of the carrier signal also changes accordingly. This allows for the encoding of information in the phase of the carrier signal, which can then be decoded at the receiver end by comparing the phase of the received signal with a reference signal. By shifting the phase of the carrier signal, phase modulation allows for the transmission of data without directly changing the amplitude of the signal, which can be beneficial in certain applications.

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• 15.

What is the first step in the pulse code modulation process?

• A.

Discrete amplitudes are assigned to the sampling pulses.

• B.

A binary code number is assigned to the sample.

• C.

The quantizer limits the amplitude of the pulses.

• D.

The analog signal is band limited.

D. The analog signal is band limited.
Explanation
The first step in the pulse code modulation process is to band limit the analog signal. Band limiting refers to the process of restricting the frequency range of the analog signal to a specific range. This is done to ensure that the signal does not contain any frequencies that are higher than the Nyquist frequency, which is half the sampling frequency. By band limiting the signal, it becomes suitable for sampling and subsequent digital processing.

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• 16.

What part of the pulse code modulation process converts a continuous time signal into a discrete time signal?

• A.

Sampling.

• B.

Rectifying.

• C.

Oscillating.

• D.

Band limiting.

A. Sampling.
Explanation
Sampling is the process in pulse code modulation that converts a continuous time signal into a discrete time signal. It involves taking samples of the continuous signal at regular intervals and representing each sample with a binary code. This allows for the digital representation and transmission of the signal. Rectifying, oscillating, and band limiting are not directly involved in the conversion of continuous time to discrete time signals in pulse code modulation.

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• 17.

In asynchronous transmissions, what bit is used by the receiving device to verify that the transmission was received correctly?

• A.

Control.

• B.

Parity.

• C.

Start.

• D.

Stop.

B. Parity.
Explanation
Parity bit is used by the receiving device in asynchronous transmissions to verify that the transmission was received correctly. It is a simple error-checking method where an extra bit is added to the data being transmitted. The value of the parity bit is determined based on the number of 1s in the data. If the number of 1s is even, the parity bit is set to 0, and if the number of 1s is odd, the parity bit is set to 1. The receiving device checks the parity bit to ensure that the number of 1s in the received data matches the expected parity.

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• 18.

If an error should occur, what transmission is lost in a synchronous transmission?

• A.

One character.

• B.

Block of data.

• C.

A parity bit.

• D.

A stop bit.

B. Block of data.
Explanation
In synchronous transmission, data is sent in blocks rather than one character at a time. Each block of data typically includes multiple characters. Therefore, if an error occurs in a synchronous transmission, it is likely that an entire block of data will be lost, rather than just one character.

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• 19.

When using vertical redundancy check, what significance does the amount of ones have in a data bit pattern?

• A.

Determines parity.

• B.

Determines transmission rate.

• C.

Determines whether transmission is in ASCII format.

• D.

Determines whether transmission is synchronous or asynchronous.

A. Determines parity.
Explanation
The amount of ones in a data bit pattern determines parity when using vertical redundancy check. Parity is a technique used to detect errors in data transmission. In this case, the number of ones in the data bit pattern is used to determine whether the total number of ones is even or odd. This information is then used to detect if any errors have occurred during transmission.

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• 20.

What error detection method is used for checking a data block greater than 512 and is about 99 percent effective in most applications?

• A.

Checksum.

• B.

Cyclic redundancy check.

• C.

Vertical redundancy check.

• D.

Longitudinal redundancy check.

B. Cyclic redundancy check.
Explanation
Cyclic redundancy check (CRC) is an error detection method that is used for checking a data block greater than 512 and is about 99 percent effective in most applications. CRC involves generating a checksum for the data block by performing mathematical calculations on the data. This checksum is then compared with the received checksum to determine if any errors have occurred during transmission. If the two checksums do not match, it indicates that an error has occurred. CRC is widely used in various communication protocols and storage systems to ensure data integrity.

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• 21.

When using forward error control as a method of error correction, where does error correction take place?

• A.

Receiving end.

• B.

In the oscillator.

• C.

Transmitting end.

• D.

In the primary buffers.

A. Receiving end.
Explanation
When using forward error control as a method of error correction, error correction takes place at the receiving end. This means that the receiver of the transmitted data is responsible for detecting and correcting any errors that may have occurred during transmission. By implementing error correction techniques at the receiving end, the receiver can identify and fix errors, ensuring that the received data is accurate and reliable.

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• 22.

Light sources that are applicable to fiber optic waveguide are light-emitting diodes and

• A.

Photo transistors.

• B.

Hybrid photodiodes.

• C.

Semiconductor laser diodes.

• D.

Integrated photodiode/preamplifiers.

C. Semiconductor laser diodes.
Explanation
Semiconductor laser diodes are suitable light sources for fiber optic waveguides because they can emit a highly focused and intense beam of light. This makes them ideal for transmitting data over long distances through the fiber optic cables. Light-emitting diodes (LEDs) are not as focused or intense as laser diodes, and photo transistors are used for detecting light rather than emitting it. Hybrid photodiodes and integrated photodiode/preamplifiers are not specifically designed for emitting light, but rather for detecting and amplifying the signals received from the fiber optic waveguide.

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• 23.

What type of light is emitted from a laser?

• A.

Incoherent.

• B.

Coherent.

• C.

Ordinary.

• D.

Invisible.

B. Coherent.
Explanation
A laser emits coherent light. Coherent light is characterized by its synchronized waves that have a fixed phase relationship. This means that all the light waves are in step with each other, resulting in a single, concentrated beam of light. In contrast, incoherent light is random and lacks this synchronization. Ordinary light refers to natural light sources like the sun or a light bulb, which emit incoherent light. Invisible light, on the other hand, refers to wavelengths that are outside the visible spectrum, such as ultraviolet or infrared light.

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• 24.

What are the two main types of photodetectors?

• A.

Positive intrinsic negative and avalanche photodiode.

• B.

Light-emitting diode and avalanche photodiode.

• C.

Light emitting diode and semiconductor laser.

• D.

Tunnel and zener diodes.

A. Positive intrinsic negative and avalanche photodiode.
Explanation
The correct answer is positive intrinsic negative and avalanche photodiode. These are the two main types of photodetectors used in various applications. Positive intrinsic negative (PIN) diode is a type of photodiode that operates based on the principle of the internal photoelectric effect. It has a wide depletion region, allowing it to capture more light and generate a larger photocurrent. Avalanche photodiode (APD), on the other hand, utilizes the avalanche effect to amplify the photocurrent. It has a higher sensitivity and faster response compared to PIN diodes.

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• 25.

What photo detector converts one photon to one electron?

• A.

Light emitting diode.

• B.

Avalanche photodiode.

• C.

Positive intrinsic negative diode.

• D.

Integrated photodiode/preamplifier.

C. Positive intrinsic negative diode.
Explanation
The correct answer is Positive intrinsic negative diode. This is because a positive intrinsic negative (PIN) diode is a type of photo detector that is capable of converting one photon of light into one electron. The PIN diode consists of an intrinsic (undoped) region sandwiched between a P-type and an N-type region, allowing it to efficiently convert light into an electrical signal.

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• 26.

Which repeater amplifies optical signal without converting to and from the electrical domain?

• A.

• B.

Repeaters.

• C.

Regenerators.

• D.

Optical amplifiers.

D. Optical amplifiers.
Explanation
Optical amplifiers are devices that amplify optical signals without converting them to and from the electrical domain. They work by using a doped fiber or a semiconductor to amplify the signal directly in the optical domain. This allows for the signal to be amplified without the need for conversion to electrical signals, making optical amplifiers more efficient and faster than other options such as repeaters or regenerators.

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• 27.

A short section of single fiber cable that has a connector at each end is called a

• A.

Pigtail.

• B.

Jumper.

• C.

Patch cord.

• D.

Breakout cables.

C. Patch cord.
Explanation
A short section of single fiber cable that has a connector at each end is called a patch cord. A patch cord is commonly used to connect devices such as computers, routers, and switches to a network or to connect different components within a network. It is a flexible and convenient solution for quickly establishing connections and can be easily plugged and unplugged.

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• 28.

Which fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected?

• A.

Biconic.

• B.

Field (FC).

• C.

Straight tip (ST).

• D.

Sub-miniature, type A (SMA).

C. Straight tip (ST).
Explanation
The straight tip (ST) fiber-optic connector uses quick-release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected. This type of connector provides a secure and reliable connection while allowing for easy and quick installation and removal. The straight tip design ensures proper alignment and minimizes signal loss, making it suitable for applications where stability is important. The other options, such as Biconic, FC, and SMA connectors, may have different coupling mechanisms or may not be as suitable for situations with vibrations.

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• 29.

Whoever made the CDC's skipped over question 29. This slot pending for potential future revision. The Hadron Collider in Switzerland has the ability to 'make' atoms. For instance, it can make 2,000,000 gold atoms every second. Question: If the Hadron Collider were producing 2 million atoms of gold every second, how long would it take to produce 1 gram of gold?

• A.

100 years.

• B.

20 minutes. It's science.

• C.

24.6 years.

• D.

50 million years.

D. 50 million years.
Explanation
The Hadron Collider has the ability to produce 2 million atoms of gold every second. To find out how long it would take to produce 1 gram of gold, we need to calculate the total number of atoms in 1 gram of gold. Since 1 mole of gold contains 6.022 x 10^23 atoms, and the molar mass of gold is approximately 197 grams per mole, we can calculate that 1 gram of gold contains approximately 3.02 x 10^21 atoms. Dividing this number by 2 million (the number of atoms produced per second), we get approximately 1.51 x 10^15 seconds. Converting this to years, we get approximately 50 million years.

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• 30.

High-altitude electromagnetic pulse is a wideband phenomenon that involves which frequency range?

• A.

1 hertz to 1 kilohertz.

• B.

1 hertz to 1 gigahertz.

• C.

10 hertz to 10 kilohertz.

• D.

10 hertz to 10 gigahertz.

B. 1 hertz to 1 gigahertz.
Explanation
High-altitude electromagnetic pulse (HEMP) is a phenomenon that occurs when a nuclear explosion happens at high altitudes, causing a burst of electromagnetic radiation. This pulse covers a wide range of frequencies, from 1 hertz to 1 gigahertz. This range includes both extremely low frequencies (ELF) and radio frequencies (RF), which are commonly used in communication systems. Therefore, the correct answer is 1 hertz to 1 gigahertz.

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• 31.

High-altitude electromagnetic pulse environment protection is important for critical, time urgent mission systems because it

• A.

Is a problem for electronic components in satellites and reentry vehicles.

• B.

Has a vertical amplitude that decreases inversely with distance, but remains significant for many kilometers.

• C.

Has very intense radial electrical fields, azimuthal magnetic fields, and time-varying air conductivity.

• D.

Is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons.

D. Is the only nuclear environment that may be imposed on many systems simultaneously with the expenditure of very few weapons.
Explanation
High-altitude electromagnetic pulse (HEMP) refers to the electromagnetic radiation that is generated by a nuclear explosion at high altitudes. This radiation can cause significant damage to electronic components in satellites and reentry vehicles. The given answer states that HEMP is the only nuclear environment that can affect multiple systems simultaneously with the use of only a few weapons. This highlights the importance of protecting critical, time urgent mission systems from HEMP, as it can have widespread and devastating effects on various electronic systems.

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• 32.

A system-generated electromagnetic pulse is a problem for satellites and reentry vehicles that are

• A.

Susceptible to the wideband frequency phenomenon.

• B.

Directly exposed to nuclear radiations from a high-altitude burst.

• C.

Affected by the azimuthal magnetic fields and time-varying air conductivity.

• D.

Influenced by the signal fading or waveform distortion caused by the structured plasma field.

B. Directly exposed to nuclear radiations from a high-altitude burst.
Explanation
Satellites and reentry vehicles are susceptible to the wideband frequency phenomenon caused by a system-generated electromagnetic pulse. This phenomenon occurs when the electromagnetic pulse affects a wide range of frequencies, potentially disrupting the functioning of these vehicles. However, the correct answer states that these vehicles are directly exposed to nuclear radiations from a high-altitude burst. This suggests that the main problem for these vehicles is the direct exposure to the intense nuclear radiations released during a high-altitude burst, which can cause significant damage to their systems.

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• 33.

Which distinct region of the source region electromagnetic pulse is produced by the interactions between the weapon products and the earth’s atmosphere?

• A.

Secondary.

• B.

• C.

Plasma.

• D.

Source.

D. Source.
Explanation
The correct answer is "Source." In this context, the source region refers to the area where the electromagnetic pulse (EMP) is initially produced. It is the region where the weapon products interact with the earth's atmosphere, leading to the generation of the EMP. The other options, such as secondary, radiated, and plasma, do not specifically refer to the distinct region where the interaction occurs.

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• 34.

Atmospheric disturbances from initial nuclear radiation on higher frequencies affect communications by

• A.

Blackout effects.

• B.

Absorption effects.

• C.

Scintillation effects.

• D.

Attenuation effects.

C. Scintillation effects.
Explanation
Scintillation effects refer to the rapid fluctuations in the intensity and phase of radio waves caused by atmospheric disturbances. These disturbances, which are a result of initial nuclear radiation, can cause the signal to become distorted and difficult to decipher. This can lead to disruptions and interruptions in communication, commonly known as scintillation effects.

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• 35.

Currents and voltages induced on power lines, cable links, and pipelines by electromagnetic pulse are called

• A.

Scintillation.

• B.

Local effects.

• C.

Source region.

• D.

Long-line effects.

D. Long-line effects.
Explanation
The currents and voltages induced on power lines, cable links, and pipelines by electromagnetic pulse are referred to as long-line effects. This term is used to describe the phenomenon where the electromagnetic pulse causes disturbances and fluctuations in the electrical systems and infrastructure over long distances. These effects can lead to disruptions and damage to the power grid and other connected systems.

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• 36.

Which type of filters are always used in combination with surge arresters?

• A.

Linear.

• B.

AC line.

• C.

DC line.

• D.

Power line.

A. Linear.
Explanation
Linear filters are always used in combination with surge arresters because surge arresters are designed to protect electrical systems from sudden voltage spikes or surges. These surges can cause damage to sensitive equipment and disrupt the normal functioning of the system. Linear filters are used to suppress high-frequency noise and transients that can be present in the power supply. By combining surge arresters with linear filters, the electrical system is provided with both surge protection and noise suppression, ensuring the smooth and uninterrupted operation of the system.

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• 37.

If the interference can be eliminated by disconnecting the receiving antenna, the source of the disturbance is most likely

• A.

Line noise.

• B.

• C.

• D.

Explanation
If disconnecting the receiving antenna eliminates the interference, it suggests that the source of the disturbance is external to the radio. This means that the interference is coming from an external source, such as another electronic device or a nearby radio transmitter. If the interference was internal to the radio or a result of radio receiver trouble, disconnecting the antenna would not have resolved the issue. Therefore, the most likely explanation is that the disturbance is external to the radio.

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• 38.

Little or no variations in the strength of the interfering signal when moving the receiving antenna for short distance normally indicates

• A.

Enemy jamming.

• B.

Internal interference.

• C.

• D.

Unintentional interference.

A. Enemy jamming.
Explanation
When there are little or no variations in the strength of the interfering signal when moving the receiving antenna for a short distance, it suggests that the interference is not caused by internal factors or radio receiver trouble. Additionally, unintentional interference would typically exhibit some variations in signal strength. Therefore, the most plausible explanation for this scenario is enemy jamming, where a deliberate attempt is made to disrupt the reception of signals.

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• 39.

What type of electromagnetic interference occurs when a receiver responds to off-frequency signals?

• A.

Rusty bolt.

• B.

Co-channel.

• C.

Brute force.

• D.

Spurious responses.

D. Spurious responses.
Explanation
When a receiver responds to off-frequency signals, it is experiencing spurious responses. Spurious responses refer to the unwanted signals or interference that a receiver picks up, which are not within the desired frequency range. These off-frequency signals can cause disruption or distortion in the receiver's operation, leading to interference with the intended transmission.

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• 40.

Which type of intermodulation interference varies significantly with temperature and weather conditions?

• A.

Transmitter.

• B.

Rusty-bolt.

• C.

Spurious.

• D.

B. Rusty-bolt.
Explanation
Rusty-bolt interference is a type of intermodulation interference that is affected by temperature and weather conditions. When there is a loose or corroded connection in a transmission system, it can create non-linearities that cause intermodulation interference. This interference can vary significantly with changes in temperature and weather conditions, as these factors can affect the conductivity and resistance of the rusty-bolt connection. Therefore, the correct answer is rusty-bolt.

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• 41.

What man-made noise results from voltage surges, arcing, or corona discharges?

• A.

Relays.

• B.

Lighting.

• C.

Power line.

• D.

Switching equipment.

C. Power line.
Explanation
The correct answer is Power line. Voltage surges, arcing, and corona discharges can cause disturbances in power lines, resulting in man-made noise. This noise can interfere with the transmission and reception of signals, causing disruptions in communication and electrical systems.

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• 42.

How can you normally eliminate electromagnetic interference noise bursts caused by sodium and mercury vapor lights that have stopped working while the power is still applied?

• A.

Change the bulb.

• B.

Ground out the light fixture.

• C.

Install a noise reject filter on the light.

• D.

Install a noise reject filter on the receiver.

A. Change the bulb.
Explanation
When sodium and mercury vapor lights stop working while the power is still applied, it can cause electromagnetic interference noise bursts. The best way to eliminate this noise is to change the bulb. By replacing the faulty bulb with a new one, the interference caused by the malfunctioning light will be eliminated.

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• 43.

What Air Force program is used to resolve an electromagnetic interference incident?

• A.

Mishap prevention.

• B.

Frequency management.

• C.

Electrostatic discharge control.

• D.

Spectrum interference resolution.

D. Spectrum interference resolution.
Explanation
Spectrum interference resolution is the correct answer because it specifically refers to a program used to resolve electromagnetic interference incidents. Mishap prevention, frequency management, and electrostatic discharge control are not directly related to resolving electromagnetic interference incidents.

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• 44.

At what level does the Air Force want electromagnetic interference problems resolved?

• A.

Affected unit.

• B.

Affected major command.

• C.

Electromagnetic environmental effects office.

• D.

Spectrum interference resolution office.

A. Affected unit.
Explanation
The Air Force wants electromagnetic interference problems to be resolved at the affected unit level. This means that the responsibility for resolving these issues lies with the specific unit that is experiencing the interference. This approach allows for a more efficient and targeted resolution process, as the unit experiencing the interference is best equipped to understand and address the specific problems they are facing.

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• 45.

What do you do when you are reasonably sure electromagnetic interference exists?

• A.

Request engineering assistance.

• B.

Contact the base frequency manager.

• C.

Systematically gather data for analysis.

• D.

Contact the spectrum interference resolution office.

C. Systematically gather data for analysis.
Explanation
When you are reasonably sure electromagnetic interference exists, the best course of action is to systematically gather data for analysis. This involves collecting information about the interference, such as its frequency, duration, and location, in order to better understand its characteristics and potential sources. By gathering data in a systematic manner, it becomes easier to identify patterns and make informed decisions about how to mitigate or resolve the interference. Requesting engineering assistance or contacting the base frequency manager or spectrum interference resolution office may be necessary steps after data analysis, but the initial step is to gather data systematically.

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• 46.

Who is initially responsible for reporting an electromagnetic interference?

• A.

The operator.

• B.

Major command.

• C.

The frequency manager.

• D.

Federal Communications Commission.

A. The operator.
Explanation
The operator is initially responsible for reporting an electromagnetic interference because they are the ones who directly observe and experience the interference. They are in the best position to provide immediate information about the nature and extent of the interference, allowing for prompt action to be taken to address and resolve the issue. The other options, such as the major command, frequency manager, and Federal Communications Commission, may also have a role in addressing interference, but the operator is the first point of contact and responsible for reporting it.

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• 47.

Who is tasked to provide interference resolution support to the unified commanders?

• A.

The operator.

• B.

Joint spectrum center.

• C.

Installation spectrum manager.

• D.

Federal Communications Commission.

B. Joint spectrum center.
Explanation
The Joint Spectrum Center is tasked with providing interference resolution support to the unified commanders. They are responsible for managing the electromagnetic spectrum and ensuring its effective and efficient use by military forces. This includes resolving any issues related to interference and coordinating spectrum usage among different military units and operations.

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• 48.

Which feature of the Fluke 8025A multimeter do you use to select various measurement functions?

• A.

Circuit jacks.

• B.

Rotary switch.

• C.

Range push button.

• D.

Touch-hold button.

B. Rotary switch.
Explanation
The rotary switch on the Fluke 8025A multimeter is used to select various measurement functions. This switch allows the user to easily switch between different modes such as voltage, current, resistance, and continuity. By turning the rotary switch, the user can select the desired measurement function and accurately measure the electrical parameters they are interested in.

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• 49.

Which part of the Fluke 8025A’s display section indicates the absolute value of the input?

• A.

Digital.

• B.

Annunciator.

• C.

Range indicator.

• D.

Analog bar graph.

D. Analog bar graph.
Explanation
The analog bar graph on the Fluke 8025A's display section indicates the absolute value of the input.

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• 50.

Which feature of the Fluke 8025A locks the measurement into the display for viewing and automatically updates the display when you take a new measurement?

• A.

Rotary switch.

• B.

Range push button.

• C.

Power-up self-test.

• D.

Touch-hold push button.

D. Touch-hold push button.
Explanation
The touch-hold push button feature of the Fluke 8025A locks the measurement into the display for viewing and automatically updates the display when a new measurement is taken.

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