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what reason for modulation involves modulating low frequency signals for transmission over long distances? |
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Ease of Radiation |
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What are the three general catergories used to produce modulation in radion frequency (RF) transmission today? |
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Amplitdue, frequency, and phase |
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When the modulating signal and carrier signal are combined within a modulator, the output signal contains a/ an |
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carrier, upper sideband, and lower sideband |
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If a carrier frequency of 1 MHz and a modulating tone of 10 kHz goes to the modulator the output signal include |
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1.01 MHz, 1 MHz, and 0.99 MHz |
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If the modulating audio signal is 10 kHz wide, what is the bandwidth of the transmitted amplitude modulated signal? |
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20 kHz |
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The bandwidth of an amplitude modulated signal is |
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two times the modulating signal. |
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The amount of effect or change that the intelligence has on the carrier in an amplitude modulated signal is expressed as the |
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percent of modulation. |
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Which statement concerning bandwidth is true? |
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Overmodulating increases bandwidth due to the production of harmonics |
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Reducing modulation to less than 100 percent gives |
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no reduction in carrier power |
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In frequency modulation (FM), the amount of oscillator frequency change is |
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directly proportional to the amplitude of the modulating signal |
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In frequency modulation (FM), what is considered a significant sideband? |
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Sidebands containing at least 1 percent of the total transmitted power. |
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What is the formula to find the modulating index? |
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Deviation divided by frequency of the modulation. |
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In phase modulation (PM), the carrier's |
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phase is shifted at the rate of the modulating signal. |
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What is the advantage of adding more phase shifts? |
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Higher data rates with in a given bandwidth. |
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What is the first step in the pulse code modulation (PCM) process? |
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The analog signal is band-limited. |
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What part of the pulse code modulation (PCM) process converts a continuous time signal into a discrete time signal? |
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Sampling |
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A type of pulse modulation (PM) that changes the amplitude of the pulse train to vary according to the amplitude of the input signal is called. |
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pulse amplitude modulation |
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If an error should occur, what data transmission is lost in a synchronous transmission? |
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Block of data. |
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When using vertical redundancy check (VRX), what significance does the amount of ones have in a data bit pattern? |
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Determines parity. |
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What two error detection methods, when used together, are 98 percent effective in detecting errors? |
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Vertical redundancy check and longitudinal redundancy check. |
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What error detection method adds stacked characters, divides it by 255, and disregards the answer except for the remainder? |
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Checksum |
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What error-correction techniques sends a retransmittal request by the receiver to the sender if it finds an error in a received frame? |
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Automatic retransmit on request. |
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When using forward error control as a method of error correction, where does error correction take place? |
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Receiving end. |
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What does an optical source do? |
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Converts electrical energy into optical energy. |
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Light sources that are applicable to fiber optic waverguide are light-emitting diodes (LED) and |
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semiconductor laser diodes. |
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What type of light is emitted from a laser? |
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Coherent |
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Laser diode power coupling is measured in which range |
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milliwatt. |
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A device that accepts optical signals from an optical fiber and coverts them into electrical signals is called an optical |
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receiver. |
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Small current that flows from a photodiode even with no light is called |
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dark current. |
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The responsivity of a photo detector is dependent on the
|
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wavelength of light.
|
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What are the two main types of photodetectors?
|
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Positive intrinsic negative and avalanche photodiode.
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What photo detector converts one photon to one electron?
|
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Positive intrinsic negative (PIN) diode.
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What is used to extend the distance of a fiber optic communication systems link?
|
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Repeater. |
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Which repeater amplifies optical signal without converting to and from the electrical domain?
|
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Optical amplifiers.
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Short sections of single fiber cables that has a connector at each end is called a
|
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patch cord.
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Which fiber-optic connector uses quick release, keyed bayonet couplings that are preferred in situations where severe vibrations are not expected?
|
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Straight tip (ST)
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Which fiber optic connector uses a push-pull engagement for mating?
|
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Subscriber (SC)
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What initial nuclear radiation elements generate electromagnetic pulses?
|
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Gamma rays and neutrons.
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High-altitude electromagnetic pulse is what type of frequency phenomenon, and involves which frequency range?
|
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Wideband; 1 hertz to 1 gigahertz
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A system-generated electromagnetic pulse is a problem for satellites and reentry vehicles that are
|
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directly exposed to nuclear radiations from a high-altitude burst.
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Which distinct region of the source region electromagnetic pulse is produced by the interactions between the weapon products and the earth's atmosphere?
|
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Source |
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What electromagnetic pulse region is the principal threat to electronic systems by cable?
|
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Radiated.
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How does scintillation effects communications?
|
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Transmitted signal fading caused by multiple path propagation through the structured plasma field.
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Atmospheric disturbances from initial nuclear radiation on higher frequencies affect communications by which types of effects?
|
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Scintillation |
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Which one of the following statements are true concerning shielding?
|
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Sensitive equipment will be located within the shielded barrier.
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What is the purpose of bonding?
|
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To ensure a mechanically strong, low impedance interconnection between metal objects.
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Which types of filters are always used in combination with surge arresters?
|
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Linear |
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If the interference can be eliminated by disconnecting the receiving antenna, the source of the disturbance is most likely
|
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external to the radio.
|
| |
What is an example of intentionally induced electromagnetic interference (EMI)?
|
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Jamming |
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What type of electromagnetic interference (EMI) occurs when a receiver responds to off-frequency signals?
|
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Spurious responses
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What type of equipment often generates many spurious emissions?
|
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Rapid tuning transmitter.
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What man-made noise results from voltage surges, arcing, or corona discharges?
|
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Power line.
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How can you normally eliminate electromagnetic interference (EMI) noise bursts caused by sodium and mercury vapor lights that have stopped working while the power is still applied?
|
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Change the bulb.
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| |
What Air Force program is used to resolve an electromagnetic interference (EMI) incident?
|
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Spectrum interference resolution (SIR)
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At what level does the Air Force want electromagnetic interference (EMI) problems resolved?
|
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Affected unit.
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What is the first step in the Air Force spectrum interference resolution (SIR) program?
|
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Identify the source.
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What do you do when you are reasonably sure electromagnetic interference (EMI) exists?
|
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Systematically gather data for analysis.
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Who is initially responsible for reporting an electromagnetic interference (EMI)?
|
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The operator.
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| |
Which Air Force service provides on-site direction finding and interference problem analysis?
|
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Quick Fix Interference Reduction Capability.
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| |
What program addresses persistent and recurring interferences problems in joint operations?
|
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Joint Spectrum Interference Resolution (SIR)
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| |
Who is tasked to provide interference resolution support to the unified commanders?
|
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Joint Spectrum Center (JSC)
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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?
|
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Touch-hold push button.
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Which current range on the Fluke 8025A do you selct to measure 250 milliamps alternating current (AC)?
|
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Milliamps/amp AC
|
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When testing a diode with the 8025A, the leads across a "good" diode produces an "OL" (open) on the display in one direction while reversing the leads produces
|
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a continuous audible tone.
|
| |
How are voltage, time , and depth represented on the oscilloscope display?
|
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Voltage = vertical axis, time = horizontal axis, and depth = intensity.
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Which mode of triggering an oscilloscope causes a trace to be drawn on the screen at all times, whether there is an input signal or not?
|
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Auto |
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Which probe does not need to actually make contact with the circuit under test?
|
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Current probe
|
| |
What digital storage oscilloscope circuit compensates for high sampling rates of high frequency signals?
|
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Charged coupled device.
|
| |
Sampled data points are stored in the memory of a digital storage oscilloscope as
|
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waveform points
|
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What area of a digital storage oscilloscope takes digitized samples and performs numerous manipulations on the data including measuring rise and fall time, periods, time intervals, and math computations?
|
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Microprocessors. |
| |
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What type of sampling does a digital storage oscilloscope normally use on single-shot or seldom-occurring signals? |
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Real-time |
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In real-time sampling, what type of interpolation is used when measuring pulse waves?
|
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Linear |
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Which are the three types of digital storage oscilloscope acquisition modes, and which is the standard operating mode?
|
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Sample, peak detect, averaging; sample
|
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In acquiring a 4K record length on a digital storage oscilloscope, how many samples can you view at one time?
|
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1,000 |
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What test equipment provides a bit error detection system that can determine the received data quality after traveling over a communications link?
|
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Bit error rate (BER)
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| |
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What pattern simulator section of the bit error rate test set accepts a 48-bit parallel word and generates a serial pattern? |
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48-bit transmitter only |
| |
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What pattern simulator section of the bit error rate test set converts the non-return zero-level (NRZ-L) data into the desired coding, such as non-return zero-mark (NRZ-M)? |
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Code converter. |
| |
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What pattern synchronizer and error counter section of the bit error rate test set internally generates its own pattern to compare with the received data from the data/clock receivers? |
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Pseudo random noise (PRN) synchronizer/ comparator. |
| |
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Which of these bit rates do you use for a bit error rate test on a 64 Kbps data circuit? |
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64 Kbps |
| |
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On the bit error rate test (BER) set, the 25-pin connectors are designed to operate with the data modems to |
|
simplify connection of test equipment to the modem under test and to carry the necessary signaling and handshake signals for modem operations. |
| |
|
System grounds must continually be tested? |
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periodically |
| |
|
A known current is generated by the earth ground tester between the earth ground electrode and the |
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auxiliary current probe |
| |
|
Where is voltage potential measured in the fall of potential ground testing method? |
|
Between the auxiliary potential electrode and the earth ground electrode. |
| |
|
The Institute of Electrical and Electronics Engineers (IEEE) have recommended a ground resistance value of |
|
5 ohms or less |
| |
|
What components on a protocol analyzer process the frames based on the selected test and user configuration inputs? |
|
Central processing unit (CPU) |
| |
|
What protocol analyzer teat window provides information concerning the network utilization and frame error that are related to a specific protocol? |
|
Protocol statistics |
| |
|
What protocol analyzer test window reports errors that occur at the physical layer such as bad frame check sequence (FSC), short frames, and jabbers? |
|
Media access control (MAC) node statistics. |
| |
|
What active test is selected to see the path that the packets are traveling and the time it takes the packets to compete the trip. |
|
Trace Route. |
| |
|
Which one of these is not an application of a radio frequency (RF) generator? |
|
Verifying transmitter frequencies. |
| |
|
A power reading that uses the abbreviation dBm indicates the |
|
ratio of decibels relative to a 1-milliwatt standard |
| |
|
During what operation is the radio frequency blanking output used on the HP 436A power meter? |
|
During the automatic zeroing operation |
| |
|
Plug-in elements of the wattmeter are selected based on the |
|
frequency and power to be measured. |
| |
|
The two switches on the front panel of the wattmeter is to correspond to the |
|
power range of the forward element. |
| |
|
When reading forward power on a wattmeter, what does two right facing arrow head mean ? |
|
Power exceeds 120 percent of the range. |
| |
|
What feature is useful for making adjustments to optimize any of the parameters which the wattmeter measures? |
|
peaking aid |
| |
|
Which measurements are not made with a spectrum analyzer? |
|
peak-peak voltage. |
| |
|
Which are the correct four classes of electronic counters? |
|
Frequency counters, universal counters, microwave counters, and reciprocals counters. (FUMR) |
| |
|
What test equipment combines the operations of many test instruments into a single compact unit? |
|
Communication service monitor |
| |
|
What function is not part of the communication service monitor? |
|
Analog multimeter |
| |
|
What operational capability of the communication service monitor produces sine, square , and triangle waveforms? |
|
Function generator |
| |
