Service Tech
Which type of rectifier circuit uses two alternating current (AC) waveforms on the transformer secondary?
A full-wave rectifier with a center-tapped transformer secondary.
DFB laser diode
Can be direct or externally modulated. Operates at 1,310 and 1,550 nm. Has diffraction grating. Puts out light in narrow spectrum.
Shorting bars and shunts
Can be used in place of fuses, but without protection against excessive current flow.
F-P laser diode
Can only be direct modulated. Generates several light modes and wavelengths. Operates only at 1,310 nm.
Which type of capacitor is typically small, with low capacitance values that can withstand working voltages up to 30,000 volts?
Ceramic capacitors are typically small, with low capacitance values that can withstand working voltages up to 30,000 volts.
How does a time domain reflectometer (TDR) measure the distance to a reflection from a fault or the end of a cable?
Circuitry within the TDR converts the pulse travel time into distance and displays the information as a waveform with a scale showing the distance to the reflection.
What should be done before measuring any distance with a measuring wheel?
Set the measuring wheel distance counter to zero.
Which power inserter electrical specification is typically high enough to prevent RF from entering the network power supply?
The port-to-port isolation between the power inserter AC input port and either of the two RF/AC ports is designed to be over 40 decibels (dB)—enough to prevent RF from entering the network power supply.
Why is the power consumed by a wall-wart power supply of concern?
There are tens of millions of wall-wart power supplies used world-wide, and they are frequently plugged in 24 hours a day whether in use or not.
How does a distribution amplifier in a fiber node receive the downstream radio frequency (RF) signals?
Through a coaxial cable that is connected to the downstream optical receiver.
What must be in a line extender to transport signals in the RF return path?
To be capable of transporting signals in the RF return path, a line extender must have a set of diplex filters and a path for the signal through a jumper or an amplifier.
Pin-to-pin splice, or in-line splice block
Two different size cables with pin connectors attached.
Why is it a good practice to measure the downstream input signal and compare the measurements to the calculated levels shown on the network maps before attempting to set up the forward amplifier section of a line extender?
Undocumented changes to the network design can affect the designed input to the line extender, or there could be a separate problem that needs to be corrected.
What are the terminals called in a junction field effect transistor (JFET)?
Valve, pitcher, and catcher. Gate, source, and drain.
What happens when a diode is forward-biased?
When a diode is forward-biased, the battery polarity pushes the holes and free electrons toward the junction to combine and allow current to flow through the diode.
Rectifier diodes
When forward-biased, conducts electricity and allows current to flow, and when reverse-biased, stops conducting causing current flow to stop.
Hardline cable-to-F series adapters
are installed directly on the hardline cable.
What is used to identify the location of a buried cable and the cable's underground route?
A cable locator is used along the top of the ground to identify where a cable is buried and its underground route.
When drawn as a resistive alternating current (AC) circuit, most hybrid fiber/coax (HFC) networks are what?
A combination of equipment powered in series and in parallel.
What does a line extender that requires two power jumpers enable?
A line extender that requires two power jumpers enables the device to be powered from either the input or output ports, or turned off when neither jumper has been installed.
What do all hardline splitter, directional coupler, power inserter, and distribution tap housings have on the back?
A threaded mounting tap and strand clamp on the back for attachment to the aerial strand or an underground pedestal.
Housing-to-housing adapters
eliminate the need for jumper cables to connect two pieces of equipment together, such as an amplifier to a directional coupler or distribution tap.
Level of leakage that must be recorded and repaired.
≥ 20 μV/m
Leakage level used in CLI calculations.
≥ 50 μV/m
8 dB directional coupler tap loss
0.75 dB insertion loss
Distance from the source for leakage level measurements.
10 feet (3 meters)
The Federal Communications Commission (FCC) requires that signal leaks of what intensity and greater must be logged and repaired?
20 microvolts per meter (µV/m), 3 meters from the leak.
What is the attenuation through 1,600-feet of 0.750 cable at 600 MHz and 120° F, when at 68° F and 600 MHz the cable attenuation rate is 1.31 decibels (dB)/100 feet? (Be sure to factor in the higher temperature.)
22.05 dB
What is the power loss in coaxial cable when: (1) the current flow through the coaxial cable is 5 amperes; (2) the coaxial cable loop resistance is 0.9345 ohms; and (3) the alternating current (AC) power source has an effective voltage of 60 volts?
23.36 watts.
What is the typical gain of a line extender in decibels (dB)?
28 to 35 decibels (dB).
What is the average value of a 10 volts peak-to-peak sine wave?
3.18 volts. 3.54 volts.
What is the total inductive reactance of this circuit?
35 ohms
How much intermodulation distortion degradation is added when two line extender amplifiers with identical distortion characteristics are in cascade?
6 decibels (dB).
Which leaks are to be included in the annual CLI report?
65 μV/m
What is the voltage into the second amplifier in cascade, if each amplifier draws 1.5 amps of current, the loop resistance of each section of cable is 1.38 ohms, and the alternating current (AC) source is a 90 volts AC (VAC) network power supply?
90 VAC.
Which form of fluctuating direct current (DC) is a symptom of a malfunctioning DC power supply in hybrid fiber/coax (HFC) amplifiers and fiber nodes?
Alternating current (AC) ripple.
Which is a benefit of an aggressive signal leakage policy?
Decreased ingress-related service calls.
Analog TV leakage detector
Detects leakage of analog TV channels
A distribution amplifier in a fiber node receives the downstream RF signals through a coaxial cable that is connected to the downstream optical receiver.
Diplex filters separate the downstream RF from the upstream RF signals, which are combined before being transported through a short coaxial cable to the return laser.
What is the relationship between eddy currents and the skin effect and the frequency of the alternating current (AC) flowing through a conductor?
Eddy currents and skin-effect losses are most significant at very high frequency currents but negligible at low frequency (60 Hz) currents.
Which of the following is true regarding ferrite? Choose all that apply.
Ferrite is a poor electrical conductor, which allows ferrite solid-core transformers to be used in RF applications with less internal power loss than other iron-core transformers. Ferrite rings are often used as the transformer core in the splitters and directional couplers used in HFC networks.
In hardline coaxial cable, what is the most common dielectric material?
Foamed polyethylene produced by gas injection.
Why must the characteristic impedance of hardline coaxial cable, connectors, and equipment interfaces be 75 ohms (±2 ohms)?
For an efficient transfer of signals, the characteristic impedance of hardline coaxial cable, connectors, and equipment interfaces must be 75 ohms (±2 ohms).
In which application would a bipolar junction transistor (BJT) common base configuration be used?
For impedance isolation between a low-impedance device and high-impedance amplifier.
P-type semiconductor
Has a deficiency of one electron Made by adding Group 13 dopant (impurity) Charge carriers are positively charged holes
N-type semiconductor
Has an extra electron in the outer shell Made by adding Group 15 dopant (impurity) Charge carriers are electrons
Blind spot
Hides the reflected signal near the TDR interface. The area near the connection to the TDR that can conceal a nearby cable fault.
What activity consumes most of the power in complementary metal oxide semiconductor (CMOS) circuits?
In CMOS circuits, most of the power is consumed charging and discharging the unavoidable capacitances in each junction.
Which of the following is true about a flyback power supply? Choose all that apply.
In a flyback power supply, neither the primary nor secondary grounds are the same as the power line ground. The flyback power supply can operate on any input voltage from 85 volts to 365 volts, at either 50 or 60 Hz line frequency.
Ingress
Interference from unwanted over-the-air (OTA) signals that enter the network.
What do you call the maximum voltage that a given capacitor can handle?
The working voltage
When splicing equipment into hardline cable that is buried underground, what must be known to attach the cable to the correct input and output side of the equipment?
It is necessary to know the direction that buried cables are laid to attach the cable to the correct input and output side of the equipment
What does a thermal control circuit in a distribution amplifier do?
It maintains the amplifier output levels as the input levels vary with temperature changes.
How does the total capacitive reactance of capacitors in series compare to the capacitor in the string with the lowest reactance?
Like resistors connected in parallel, the total capacitive reactance of capacitors in series is always less than that of the capacitor in the string with the lowest reactance.
What characteristic of ferrite allows its use as core material in radio frequency (RF) applications?
Low electrical conductivity for less internal power loss at RF than other iron-core transformers.
Automatic gain control (AGC)
Maintains the output signal levels automatically when changes to the input signal levels vary within design tolerances.
Many cable operators require which type of leaks to be fixed?
Many cable operators have a policy to immediately repair all detected leaks, even those below 20 microvolts per meter (μV/m), which exceeds the FCC requirements.
What do many feed-through distribution taps include to maintain the RF signal and AC voltage continuity during tap faceplate removal?
Many feed-through distribution taps include an RF/AC bypass mechanism to maintain the RF signal and AC voltage continuity during tap faceplate removal.
Why do most line extenders operate with a sloped output?
Most line extenders operate with a sloped output to improve the amplifier performance and compensate for inherent tilt from the coaxial cable and other elements.
Finite impulse response filter
Most suitable for digital signals
What is the basic amplifier application that increases the amplitude of the radio frequency (RF) signal to compensate for the signal loss of cable and passive devices preceding the amplifier called?
Unity gain.
How do you obtain the simplest form of capacitance?
Using two parallel metal plates separated by an insulator.
In a directional coupler, what is the relationship of the insertion loss between the directional coupler input and through ports, and the amount of signal tapped off from the input?
None, the insertion loss is independent of the signal tapped from the input.
What advantage is realized by increasing the voltage in a broadband cable network from 60 volts alternating current (VAC) to 90 volts?
Operating with 50% more voltage reduces the voltage drop and current drawn in the network for more efficient power utilization.
How much do you know about a leakage program?
Operators that have aggressive leakage policies report decreased ingress-related service calls, improved network performance, customer satisfaction, and faster identity of network point of weakness are benefits credited to aggressive leakage detection and repair.
How much do you know about bipolar junction transistors (BJT)?
P-type silicon has an absence of free electrons that are called holes and the N-type silicon has an excess of free electrons.
Why is signal leakage interference at long term evolution (LTE) telephone frequencies difficult to prevent?
Preventing leakage interference at LTE frequencies is especially challenging as almost everyone has an LTE phone that can pick up interference from a nearby TV, set-top box (STB), or cable modem connection.
Zener diode
Regulates voltage when reverse-biased Used for surge protection
What causes the condition known as resonance?
Resonance is a condition that occurs at the frequency when a capacitor and inductor have the same magnitude of reactance, causing energy to move back and forth between the inductor and capacitor.
What type of center conductor is used in most hardline coaxial cable for most broadband cable applications?
The center conductor of hardline coaxial cable can be either solid copper, but for most broadband cable applications, copper-clad aluminum (CCA) is used for the center conductor.
What limits the number of colors from light emitting diodes (LED)?
The elements that can be used for LED dopants and their energy levels.
What is a consequence of cutting hardline coaxial cable with conventional side cutters?
The end of the cable is crushed and deformed, which makes coring the dielectric and sliding connector parts onto the cable difficult.
What should be created to gather materials for a splicing project?
When a splicing project resides within a portion of a network map, a small bill of material (BOM) list can be created to gather materials for the project.
Which of the following is true about LEDs? Choose all that apply.
When forward-biased, the LED emits light. Dopants can be varied to get different wavelengths and colors of visible light emitted by the LED. Emitted light is from excess energy in an electron's valance band.
What is the primary difference between alternating current (AC) and direct current (DC) waveforms?
The primary difference between AC and DC waveforms is that the magnitude and polarity of an AC waveform changes, whereas the magnitude and polarity of a DC waveform is static.
In a resonant circuit, what property is adjusted to achieve the desired bandwidth?
The quality factor (Q).
How are directional couplers identified?
Directional couplers are identified by their tap value, such as an 8 dB directional coupler that has a tap value that is approximately 8 dB lower than the input signal.
Intended to reduce disruption of service to customers, what area should be the priority for preventive maintenance?
Headend equipment and signals originating in the headend that go to all customers are considered the most critical.
Straight splice connector
Repair a cracked cable when there is minimal water migration into the cable.
How does a measuring wheel record distance?
The wheel is calibrated so that each complete revolution triggers a counter that represents the distance that the wheel travels along the ground.
What is indicated by a time domain reflectometer (TDR) connected to coaxial cable that displays a waveform showing a single upward or positive spike?
A TDR connected to coaxial cable that displays a waveform showing a single upward or positive spike indicates an open cable end without any faults.
In what applications can a Zener diode be used?
A Zener diode can be used to regulate the voltage from a rectifier.
Where is a standby network power supply likely to be located?
A large standby network power supply cabinet can only be mounted on a pole or set and anchored onto a concrete pad.
Straight splice connector
Aerial cable tails.
Why is it unnecessary to measure the unregulated direct current (DC) voltage on a line extender that has a switching mode power supply (SMPS)?
An SMPS provides DC voltage regulation over a wider alternating current (AC) voltage range than a linear power supply.
What are two uses of positive, intrinsic, negative (PIN) diodes?
As variable radio frequency (RF) resistors and fast RF switches.
How far beyond a pin connector should the shrink tubing overlap the coaxial cable?
At least two inches after shrinking.
In addition to fines for noncompliance with leakage rules, what band of frequencies used by broadband cable operators can be shut down until the signal leakage is repaired?
108-137 MHz.
To transport electric power efficiently, what power line voltage-current combination would deliver the same amount of power as 10 amps and 10,000 volts, but with the least conductor loss?
2 amperes and 50,000 volts.
Which leaks must be repaired according to the FCC? Choose all that apply.
20 μV/m 65 μV/m 35 μV/m
In a silicon bipolar junction transistor (BJT) common emitter amplifier circuit, what should the base voltage be when the amplifier is forward biased?
3.7 volts above or below the emitter voltage, depending on whether it is an NPN or PNP transistor. 0.7 volt above or below the emitter voltage, depending on whether it is an NPN or PNP transistor.
Which sine wave frequency has the shortest wavelength?
750 megahertz (MHz).
How many doped semiconductor layers are in a junction field effect transistor (J-FET) compared to a bipolar junction transistor?
A J-FET is comprised of only two layers of doped semiconductor material in contrast to that of three doped layers in a BJT.
Why is a distribution amplifier integrated within a fiber node?
A distribution amplifier is integrated within a fiber node since the low-amplitude RF must be amplified before being split and distributed via hardline coaxial cable throughout the network.
Shorts in the coaxial cable and excessive amounts of current can damage the distribution amplifier. Several devices can be used to protect the distribution amplifier from these problems. Which device shorts to ground when an overvoltage situation occurs?
A fast transfer electronic crowbar (FTEC).
What is a pronounced increase in attenuation over a narrow frequency range called?
A frequency suckout is the pronounced increase in attenuation over a narrow frequency range caused by the periodic, regularly spaced defects in hardline coaxial cable.
What two components are used together to build an opto-isolator for applications where it is undesirable to have electrical conduction (continuity) between an input and an output?
A light emitting diode (LED) and a photodiode can be used together to build an opto-isolator for applications where it is undesirable to have electrical conduction (continuity) between an input and an output.
How can a network key map, which provides a view of the network's footprint, be used?
A network key map can be useful for tracking the progress of a network upgrade, or the expanse of a network condition, such as an outage.
What type of map can be useful for tracking the progress of a network upgrade, or the expanse of a network condition, such as an outage?
A network key map.
What causes current to flow through a reverse-biased photodiode?
A photon of light striking an orbiting electron causes the electron-hole pair to conduct current through the reverse-biased photodiode.
Bridger amplifier
A portion of the downstream signal is boosted before being split and routed to as many as four separate coaxial cables—the branches in the architecture.
At temperatures above absolute zero in silicon, what fills the location of electrons knocked out of their stable orbit by thermal effects?
A positive charge called a hole.
What is meant by pressure testing a drop system to check for leakage?
A pressure test of the drop system involves the injection of 40 to 60 dBmV test signals at various frequencies into the tap end of the drop system, then scanning the entire drop system with a leakage detector to check for signal leakage and immediately find and repair the leakage source.
What is different about setting up a return amplifier's output level compared to setting up a forward amplifier's output level?
A return amplifier's output differs from that of a forward amplifier in that the return signal destination is the headend instead of the customer premises, which makes the headend the point of reference for providing optimum return signal levels.
How does encrypting all the digital TV (DTV) channels and service tiers defend against passive pirates?
A set-top box (STB) or TV with an authorized CableCard assigned to the customer account is required for reception.
Why must a technician be able to recognize the appropriate time domain reflectometers (TDR) settings for testing a cable?
A technician must recognize the appropriate TDR settings for testing a cable since the default settings occasionally get changed, or the situation requires the settings be changed for a more accurate measurement or to better scrutinize a fault.
The standard and most common DMM displays the calculated root mean square (RMS) voltage of the AC, by multiplying 0.707 times the peak AC measurement.
A true RMS DMM takes several measurement samples during a wave cycle and uses complex formulas to display an accurate AC measurement.
Why is a digital multimeter (DMM) that takes a true root mean square (RMS) measurement of alternating current (AC) more accurate when measuring the quasi-square wave output of a ferroresonant power supply?
A true RMS DMM takes several measurement samples during a wave cycle and uses complex formulas to display an accurate measurement of the quasi-square wave output of a ferroresonant power supply.
Why are there attenuator pads in each upstream path within a distribution amplifier?
An attenuator pad in each path enables adjustment of upstream levels before the paths are combined and amplified.
GPS leakage system
Can be used with either analog TV or QAM channels transported on the network Can be used to check for leakage near the LTE band Automates the leakage monitoring, recording, and reporting process Detects leakage of analog TV channels
Leakage detection system with tagging
Can be used with either analog TV or QAM channels transported on the network Can be used to check for leakage near the LTE band Detects leakage of analog TV channels Intended to avoid false detection of leaks
What does allowing current to flow in only one direction enable the diode to do?
Change alternating current (AC) to direct current (DC).
Pulse width
Determines how far the signal travels on the coaxial cable.
What should be used in place of short coaxial cable jumpers to provide a compact and solid mechanical and electrical connection between the equipment housings?
Housing-to-housing adapters.
When can a single straight splice connector be used to repair a crack in aerial hardline coaxial cable?
If the crack is small, water migration is minimal, and the crack is in a straight section of cable.
In which full-wave rectifier circuit is the entire transformer secondary active on each half cycle?
In a full-wave bridge rectifier, the entire transformer secondary is active on each half cycle, whereas in a full-wave rectifier with a power transformer that has a center-tapped secondary and two rectifier diodes, one half of the secondary is inactive on each half cycle.
What component in a half-wave rectifier supplies current to the load when the rectifier diode is reversed-biased and stops conducting?
In a half-wave rectifier, when the rectifier diode is reversed-biased and stops conducting, the voltage charged in the filter capacitor during the positive alternation is discharged through the load.
In a standby network power supply, what switches the power supply into standby operation and converts the battery direct current (DC) to alternating current (AC)?
In a standby network power supply, an inverter switches the power supply into standby operation and converts the battery DC to AC when it senses a power outage or when the incoming voltage drops or rises significantly.
What does the term "cumulative" mean in the context of the Cumulative Leakage Index (CLI) reported to the Federal Communications Commission (FCC)?
In the CLI reported to the FCC, the term "cumulative" is used because the calculation is designed to present the overall effect of the leakage in the network
What is inductive reactance?
Inductive reactance is the opposition to alternating current (AC) above the resistance of the inductor to direct current (DC).
What is the counter electromotive force (cemf) reaction that opposes a change in current flow through an inductor is called?
Inductive reactance.
Which practices minimize water migration along the center conductor and dielectric of hardline coaxial cable?
Installing coaxial cable and connectors according to manufacturer recommended procedures. Capping or taping the ends of cable stored outside and installed, waiting to be spliced. Using heat shrink tubing at the cable connections. Using a flooded coaxial cable. Using a coaxial cable that has its dielectric bonded to the center conductor.
Why is a line extender used in a multiple dwelling unit (MDU)?
It is common to find line extenders used as distribution amplifiers to feed the different units in MDUs such as apartments, hotels, and dormitories.
A line extender "extends" the downstream signal deeper into the hybrid fiber/coax (HFC) network.
It is common to find line extenders used as distribution amplifiers to feed the different units in multiple dwelling units (MDU) such as apartments, hotels, and dormitories.
Splice block
Join two different types or sizes of hardline coaxial cable together.
How are silicon crystals grown to satisfy the requirement for eight electrons in the outer shell?
Silicon crystals of pure silicon are grown to where the individual silicon molecules are in a tetrahedron to satisfy the requirement for eight electrons in the outer shell.
How do the leakage regulations for quadrature amplitude modulation (QAM) channels differ from analog modulation channels?
Since the QAM channel power levels are required to be below the level of the leakage test signal, the FCC ruled that enacting QAM channel specific leakage monitoring and measurement regulations and methodology is unnecessary.
For efficiency, manufacturers use the same 8-port housing for their splitters, directional couplers, and power inserters, with the unused ports capped.
Some 8-port housings are square which enables the housing to be used in any orientation, regardless of the direction of signal flow.
What are straight splice connectors designed to do?
Straight splice connectors attach two sections of the same size and type of coaxial cable together.
Compared to a solid copper center conductor, which property about a copper clad aluminum (CCA) center conductor is correct?
The CCA center conductor has almost equal attenuation at high frequencies.
What is the coaxial cable voltage loss between the power supply and the power inserter when: the cable length is 150 feet; the cable's DC loop resistance is 1.07 Ω/1,000 feet; and the total current requirement for amplifiers supplied by that power inserter is 11 A?
The DC loop resistance of the coaxial cable causes some voltage to be lost between the power supply and the power inserter, which can be calculated using ohms law, E = I x R: 1) Obtain the DC loop resistance value (1.07 ohms/1,000 feet), 2) Divide the cable length (in feet) by 1,000, and multiply that resultant by the specified DC loop resistance to obtain the total DC loop resistance (R); 150/1,000 = 0.15 x 1.07 = 0.16 ohms, 3) Multiply the total current (I) which is 11.0A by the total DC loop resistance (0.16 ohms) to obtain the voltage loss; 11.0 x 0.16 = 1.76 volts.
What is the difference between a digital multimeter (DMM) that measures and displays average alternating current voltage (ACV) and true root mean square (RMS) DMM?
The DMM that measures and displays average ACV that is approximately 10% lower than what is present and displayed by a true RMS DMM.
What inserts alternating current (AC) into the network with a direct connection to an amplifier rather than using a power inserter?
The amplifier AC circuitry.
What is the bandwidth of a resonant circuit?
The band of frequencies between the 70.7% points of the voltage curve for parallel resonant circuits or the current curve for series resonant circuits.
What does a simple diode consist of?
The basic semiconductor diode is made by diffusing acceptor (P-type) impurities into one side and donor (N-type) impurities into the opposite side.
In a standby network power supply, what comes online to convert the battery voltage to alternating current (AC), which then goes to the ferroresonant transformer?
The battery-powered inverter.
How can the capacitance of variable capacitors be adjusted?
The capacitance values in some variable capacitors are varied by changing the physical distance, or separation, between the two plates. In another type of variable capacitor, each plate is a half-circle with one stationary plate and one rotating plate separated by mica. Rotating the plate changes the amount of parallel surface between the plates, varying the capacitance.
What does the decibel return loss (dBRL) measurement on a time domain reflectometer (TDR) express?
The dBRL displayed on most TDRs expresses the amplitude of a reflected signal relative to the transmitted signal.
When using the triangulation technique to find the source of a leak, why is a dipole antenna used?
The dipole antenna is directional and picks up the strongest signal that is at a right angle, or perpendicular to the antenna elements.
What is on the interior side of the faceplate in a hardline splitter, directional coupler, power inserter, and distribution tap?
The electronic circuitry and male or female faceplate/housing interconnect pins.
What controls the output signal level from a line extender?
The line extender output signal level is controlled by adjusting the losses through two loss blocks in front of each gain block.
What is the alternating current (AC) frequency?
The number of cycle rotations or complete sine waves, which can be voltage or current, within one second is called the AC frequency.
What can be done when installing hardline splitters, directional couplers, power inserters, and distribution taps in tight quarters, such as in a pedestal?
The seizure screw can be removed, and the hardline connecter attached to the side of the housing.
Why are the signals from cable modems and set top boxes (STB) not used to align the return section of a distribution amplifier?
The short duration upstream signals that originate from cable modems and STB at various locations are impractical for verifying and aligning a distribution amplifier return section.
What is the total opposition to alternating current (AC) in a circuit from resistance and reactance called?
The total opposition to AC in a circuit from resistance and reactance is called circuit impedance and represented by the letter Z.
What is the purpose of the two gaskets in hardline splitters, directional couplers, power inserters, and distribution taps?
The two gaskets installed in hardline splitters, directional couplers, power inserters, and distribution tap protect against environmental contamination and RF signal ingress/egress.
Which statement about a forward-biased silicon diode is true?
The voltage drop across the diode is approximately 0.7 volt.
What is the approximate loss between the input port and each tap port in any 8-port terminating tap?
There is approximately 3.5 dB of loss through each of the three levels of signal division in the 8-port tap for a total tap loss of 10.5 dB (3 × 3.5 dB) between the input port and each tap port.
What is a desirable feature of Schottky barrier diodes?
They have a lower voltage drop than silicon diodes.
In aerial installations, why do cable manufacturers recommend that expansion loops be formed in hardline coaxial cable?
To allow movement of the cable when lashed to the strand.
Why can hardline splitters and directional couplers be configured to either pass or block the flow of AC between the device input and output ports?
To avoid power domain conflicts which can cause equipment failure, hardline splitters and directional couplers can be configured to either pass or block the flow of AC between the device input and output ports.
Why are many network design maps drawn on a scale in which 1 inch represents 100 feet, a ratio of 1:1,200?
To comply with the standard scale of road maps.
How is a time domain reflectometer (TDR) used during a tap audit or when investigating a suspicious network connection?
To confirm an illegal connection of customer premises equipment (CPE) based on the signature of the TDR waveform.
Why would a technician be asked to measure the signal levels on the highest and lowest downstream channels from a specific location when performing a cost payback analysis?
To help the design group determine where to add distribution taps, or to tap into the network for a network extension.
When would a splice block be a better choice than a straight splice to join two hardline coaxial cables together?
To join two hardline coaxial cables together when the ends of the underground cable are left exposed above the ground, the better choice is a splice block because it allows the cables to be joined later and the finished splice is protected inside a pedestal.
How is the loop resistance of a coaxial cable measured?
To measure the loop resistance of a coaxial cable, the center conductor and shield at one end are shorted together with a jumper. At the opposite end, the ohmmeter function of a digital multimeter (DMM) provides the direct current (DC) and measures the loop resistance.
What do many standby power supplies have to optimize the lifespan of the batteries?
To optimize the lifespan of the batteries, most standby power supplies have multiple battery charging modes.
Why is it necessary that feed-through distribution taps pass alternating current (AC)?
To pass AC along to power other amplifiers downstream.
In a power inserter with three filtering networks, what is the purpose of the high-pass filter?
To prevent the 60 hertz (Hz) alternating current (AC) from passing between the two radio frequency (RF)/AC ports.
When splicing equipment into aerial hardline coaxial cable, why is it best to first survey what needs to be done and make all preparation while still on the ground?
To reduce time up the pole, it is best to survey what needs to be done from the ground first and then prepare as much as possible while still on the ground.
What is the purpose of a back-facet diode in an optical transmitter?
To sense the light level being put out by the diode.
What application would you suspect may be causing radio frequency interference (RFI) of a silicon controlled rectifier (SCR) in a customer premises?
Unfiltered switching of an SCR in a light dimmer could be the source of RFI in the customer premises.
Varactor diode
Used for voltage-controlled oscillator circuits Capacitance varies with the applied voltage
Bridge rectifier
Uses four diodes. The entire transformer secondary is active during each half cycle. Charges the filter capacitor once per half cycle.
When using a return path sweep-and-alignment system, how is the field device able to provide the technician with the information to adjust the output of a return amplifier?
Using a return path sweep-and-alignment system, a headend control unit (HCU) receives and analyzes the injected test carriers and sends the data on a telemetry data signal, which is combined onto the forward signal that is received with the forward signal by the field unit.
What applications use varactor diodes?
Varactor diodes are used in frequency modulators, voltage controlled variable frequency oscillators, and other valuable circuit applications.
PIN diode
Voltage-controlled attenuator Fast switching time
How are eddy currents created?
When alternating current (AC) flows through a conductor, a changing magnetic field is created, which in turn induces voltages inside the conductor that create small random currents, called eddy currents.
When monitoring the network for leaks, the leakage detector squelch or gain control settings should be at what setting?
When monitoring the network for leaks, the leakage detector squelch or gain control settings should be at the highest, most sensitive settings.
When performing preventive maintenance on a network power supply, why should the electrical connections be checked?
When performing preventive maintenance on a network power supply, check the electrical connections, which become loose over time due to vibration or temperature changes.
When selecting the input equalizer for a line extender, what adjustment should be made if the output has too much slope?
When selecting the input equalizer for a line extender, too much slope requires a lower value equalizer and too little slope requires an equalizer of higher value.
When splicing hardline coaxial cable into an amplifier, what can be used to allow the amplifier lid to open without obstruction?
When splicing hardline coaxial cable into an amplifier, a 180-degree adapter with a swiveling shaft can be used to allow the amplifier lid to open without obstruction.
What is the term for when the signal loss preceding an amplifier and the gain of the amplifier are equal?
When the amplifier gain equals the signal loss, there is unity gain, which is ideal for minimal distortion.
When troubleshooting downstream RF issues, what can be determined by measuring the downstream input levels to a distribution amplifier?
When troubleshooting downstream RF issues, the downstream input levels to a distribution amplifier should be measured to see if the problem is upstream or downstream from the distribution amplifier.
What is the inductive reactance formula for this circuit?
XLtotal = 1/(1/XL1 + 1/XL2 + 1/XL3)
Review the circuit. What is the inductive reactance formula for this circuit?
XLtotal = XL1 + XL2 + XL3
90° and 180° adapters
are used to eliminate tight cable bends when placing equipment in a smaller enclosure.
Egress
The leaking of radio frequency (RF) signals into the open air through a crack in the coaxial cable, a defective connector, or component.
Pedestal splice block
Join cables rising from ground next to each other.
How is the voltage drop across the cable loop resistance derived?
The voltage drop across the cable loop resistance is derived from Ohm's law, E = I x R, in which E is the voltage drop, I is the current through the cable, and R is the cable loop resistance.
How does capacitive reactance oppose a changing applied voltage?
With energy that is temporarily stored in an electric field.
Which type of diode utilizes the junction capacitance across a reverse-biased diode?
A rectifier diode.
Customer premises
Connected to the network through distribution taps spliced into the coaxial cable.
Plug-in attenuator pads
Sets the output signals to a fixed level; the stability of the output signal levels is dependent upon the stability of the input signal levels.
What happens when you apply the direct current (DC) voltage of a battery to the conductive plates of a capacitor?
The plate connected to the positive battery terminal receives a negative charge.
Why is there a diplex filter at each downstream output port in a distribution amplifier?
To separate the downstream radio frequency (RF) from the upstream RF signals.
Back-facet diode
Adjusts the laser drive current to maintain the light level despite temperature changes and over the life of the diode. Puts out a current proportional to the light it receives.
When splicing equipment into underground hardline coaxial cable, if the construction crew forgets to identify the direction of the cable, what can be done to find which cable attaches to the input and output side of the equipment?
Attach a cable locator to each cable to identify the route that each buried cable follows.
Of the three basic transistor designs, why is the common emitter the most common configuration?
Because it is a practical amplifier design, the common emitter is the most common transistor design configuration.
Why is the circuit impedance dependent on the alternating current (AC) frequency?
Because the capacitive and inductive reactance vary with the AC frequency.
What is cable attenuation?
Cable attenuation is the electrical property of coaxial cable that reduces the amplitude of transported signals over a given distance.
What is another name for the bipolar junction transistor (BJT) common collector configuration?
Emitter follower.
What should be worn when cutting and preparing hardline coaxial cable for connector attachment?
Leather work gloves
Which of the following is true about semiconductors? Choose all that apply.
Semiconductors are used to build everything from diodes to transistors to complex integrated circuits that make all modern electronics possible. A semiconductor is neither a good conductor, nor insulator of electricity. A semiconductor is made conductive by a process called doping.
Fast transfer electronic crowbar (FTEC)
Shorts harmful over voltages to ground.
Which time domain reflectometer (TDR) setting must be correct for accurate distance measurements?
The TDR velocity of propagation (VOP) setting must be correct to obtain accurate distance measurements for the cable being tested.
How is a back-facet diode used?
The current from a back-facet diode is used to sense the amount of light the laser diode is putting out, closing the loop that holds the light output constant over time and temperature.
Filter capacitor
Used in most circuits to block DC and pass AC.
What is generated when the magnetic field around an inductor collapses?
+An opposing voltage called counter electromagnetic force (cemf) that is proportional to the rate of the changing current. Complete flux loops around the whole coil and a flux pattern like a bar magnet.
What does a filter with enhanced flatness across the top, and sharpness at the edge of the bandwidth passed by the filter contain?
+Multiple resonant circuits.
When a circuit has several inductors, how is the total inductive reactance calculated?
+The same way the total resistance of resistors in a circuit is determined. By multiplying the inductive reactance of each inductor.
Where does a distribution amplifier module receive the direct current (DC) required for operation?
-From a coaxial cable that transports DC voltage from a network power supply. -From a rechargeable 12-volt battery in the station housing lid.
16 dB directional coupler tap loss
0.11 dB insertion loss
What is the secondary current when the primary current is 1 ampere?
0.125 amperes or 125 milliamps (mA) 1 ampere/8 = 0.125 amperes or 125 milliamps (mA)
How else can a capacitance of 243 nanofarads (nF) be expressed?
0.243 microfarads (µF).
12 dB directional coupler tap loss
0.28 dB insertion loss
What is the secondary current when the primary current is 0.05 amperes or 50 milliamperes?
0.5 amperes or 500 milliamperes (mA) 0.05 ampere x 10 = 0.5 amperes or 500 milliamperes (mA)
Velocity of propagation (VOP) is the speed of the radio frequency (RF) signals traveling in a coaxial cable relative to the speed of light. What is the range of VOP factors for broadband coaxial cable?
0.78 to 0.93
If the leakage detector indicates there is a leak and displays a reading of 14 microvolts per meter (uV/m) measured at 80 feet from a possible leak source, what is the approximate calculated level of the leak from 10 feet?
112 uV/m.
What is the secondary voltage when 120 volts is the primary voltage on a 10:1 step-down transformer?
12 volts 120 volts/10 = 12 volts
To comply with FCC leakage rules, which leaks must be repaired?
12.5 μV/m, 40 feet from the network. 5 μV/m, 40 feet from the network. 1.875 μV/m, 160 feet from the network.
If the attenuation through a span of coaxial cable at 75 MHz is 2.5 dB, what will be the approximate attenuation at 300 MHz?
2 x 2.5 dB, or 5.0 dB. 3 x 2.5 dB, or 7.5 dB. 5 x 2.5 dB, or 12.5 dB.
In a network design map, the squares with the number inside are symbols for what devices?
4-port distribution taps.
Approximately how much cable remains on a reel of PIII, 0.625 cable with a specified loop resistance of 1.07 ohms per 1,000 feet, and the measured loop resistance is 0.73 ohms?
682 feet
What is the secondary voltage when 12 volts is the primary voltage on a 1:8 step-up transformer?
96 volts. 8 x 12 volts = 96 volts.
A Schottky barrier diode exhibits what?
A Schottky barrier diode exhibits extremely fast switching time and a lower forward voltage drop than do silicon diodes.
What does a time domain reflectometer (TDR) measure?
A TDR measures the time it takes for an injected signal pulse to travel down the cable, and for the reflection to return.
What device is used to compensate for unequal cable loss and provides a flat input to the pre-amplifier of a line extender?
A cable equalizer, or a cable simulator, compensates for unequal cable loss and provides a flat input to the pre-amplifier of a line extender.
Which type of capacitor is constructed like a paper capacitor but with a different dielectric, and is available with either axial or radial leads?
A ceramic capacitor. plastic-film capacitor
What is a desirable characteristic of a ferroresonant network power supply?
A desirable characteristic of a ferroresonant network power supply is a steady output voltage over a wide range of input voltages.
Under what conditions does a diode become forward-biased?
A diode is forward-biased when its anode is more positive than the cathode.
Which type of capacitor is likely used in a low frequency alternating current (AC) circuit where the maximum breakdown voltage is from 200 volts to 1,600 volts?
A paper capacitor.
Power transformer
A passive device that changes or "transforms" the AC voltage to a lower voltage that the DC circuits require.
Which type of capacitor is constructed like a paper capacitor but with a different dielectric, and is available with either axial or radial leads?
A plastic-film capacitor
What forces alternating current (AC) to flow through a circuit?
A polarity changing voltage.
Describe the ports of a typical power inserter.
A power inserter has three ports: one port for alternating current (AC) voltage from the power supply and two ports for the combined AC voltage and RF signals.
How much does a power inserter impact the radio frequency (RF) in a network?
A power inserter should have minimal impact on the RF in both directions.
What is a property of inductor/capacitor (LC) filter circuits that occurs near their cut-off frequency?
A property of LC filter circuits is that near the cut-off frequency of the filter, signal components take longer to get through the filter, creating what is called group delay.
What can be done to enable semiconductors to conduct electricity?
A semiconductor can be made conductive by a process called doping that adds certain impurities.
What is a metallic time domain reflectometer (MTDR)?
A test instrument that measures reflected voltage at discrete moments in time to evaluate the electrical characteristics of metallic cables.
What are the most basic parts of a transformer?
A transformer consists of two or more inductors that transfer electrical energy from one circuit to another by mutual inductance.
What happens if a utility power outage shuts off a network power supply that sends alternating current (AC) to several amplifiers?
A utility power outage that shuts off a network power supply that sends (AC) to several amplifiers causes a service interruption to all customers served by those amplifiers.
How is alternating current (AC) inserted into the network through a direct hardline coaxial cable connection to an amplifier housing?
AC from a network power supply with a direct hardline coaxial cable connection to an amplifier housing is inserted into the network using the amplifier AC circuitry.
In an aerial installation, the faceplate should always face the street for easier access if it needs to be changed, and to identify the device from the ground.
All the housings have a threaded mounting tap and strand clamp on the back for attachment to the aerial strand, or an underground pedestal or vault installation.
What is the advantage for supplying alternating current (AC) to multiple amplifiers from one network power supply?
Allows the designer to place amplifiers without concern about access to electrical utility power.
What can happen when adjustable joint pliers, rather than a second wrench, are used to tighten and loosen the connector nuts?
Although many technicians will use adjustable joint pliers rather than a second wrench, the pliers can round off the connector nuts or body.
Which of the following is true about taking safety precautions when using a TDR? Choose all that apply.
Always wear safety glasses when preparing coaxial drop or hardline cable. Wear proper personal protection equipment (PPE) when working in underground or aerial networks. Minimize the possibility of electrical shocks by removing power from the cable tested. Secure all dismantled active and passive devices.
Which of the following is true about choosing reference carriers? Choose all that apply.
Amplitude levels are the same as the legacy analog TV channels. Frequencies are at the edges or just outside the forward frequency spectrum. Must be an analog TV channel or an unmodulated carrier.
What enables electrolytic capacitors to achieve a larger capacitance than other capacitor types?
An electrolytic capacitor uses a liquid or gel containing a high concentration of ions, called electrolyte, to achieve a larger capacitance than other capacitor types.
What can cause a resistive type of test to deliver false information?
An impedance mismatch.
What must be added to a light emitting diode (LED) to make it a Fabry-Perot (F-P) laser?
An interferometer, consisting of a mirror on one side of the laser diode and a partially-reflecting mirror on the other side.
How much do you know about opto-isolators?
An opto-isolator is comprised of an LED and photodiode. An opto-isolator provides total electrical and mechanical isolation between the controlling circuit and the controlled circuit.
For an application where it is undesirable to have electrical conduction (continuity) between an input and an output, what component would be used?
An opto-isolator.
Half-wave dipole
Antenna type used for leakage measurement.
What is 1 time constant (1T) of a capacitor?
Approximately 63% of the source voltage, the product of the of circuit resistance (R) and the capacitance (C) of the capacitor (R x C).
What enabled the power limitation for network power supplies in broadband cable networks to be increased from 60 volts alternating current (VAC) to 90 VAC?
As cable TV networks evolved into broadband cable networks, National Electrical Code (NEC) Article 830, which defines power limitations for network-powered broadband communications systems, raised the maximum voltage from low-power sources to 100 VAC.
Why was the impedance for the broadband cable industry standardized at 75 ohms (Ω)?
At 75 Ω characteristic impedance, the coaxial cable has minimal attenuation, with adequate breakdown voltage and power carrying capacity.
What happens to the circuit impedance at the resonant frequency?
At the resonant frequency, the circuit impedance is purely resistive without either inductive or capacitive reactance.
To attach a connector to hardline coaxial cable, what tool is used to remove a small portion of the dielectric?
Attaching a connector to hardline coaxial cable requires removing a small portion of the cable's dielectric with a coring tool that fits within the aluminum outer shield and over the center conductor.
What type of filter is used in channel to traps to block some frequencies from arriving at the customer premises?
Band-stop filters.
What type of filter enables the selection of a single channel out of hundreds for reception and processing?
Bandpass filters enable the selection of a single channel out of hundreds for reception and processing. In addition to being used to tune channels, bandpass filters are in signal processors, modulators, and set-top boxes (STB).
What is a priority in any standby power supply maintenance program?
Battery care.
When the base of a bipolar junction transistor (BJT) is forward biased, why does most of the charge from the emitter wind up replenishing depleted charges in the collector region?
Because the base region is very thin, when the base is forward biased, only a little of the charge that crosses from the emitter becomes base current. Most of the charge from the emitter winds up replenishing depleted charges in the collector region.
What must be remembered when using a coaxial cable jumper to connect the time domain reflectometer (TDR) to a coaxial cable for testing?
Because the coaxial cable jumper cable is included in the TDR measurements, the TDR user must remember to account for the jumper length in all measurements.
If a signal leak measured at 120 MHz is 35 microvolts per meter (uV/m), what is the leakage level at 400 MHz?
Because the leakage signal level at different frequencies is unpredictable, it is impossible to know the leakage level at 400 MHz based on a 35 uV/m leak at 120 MHz.
When using a cable locator, why is it unnecessary to disconnect the cable from any connections?
Because the locating signal is carried on the cable shield.
What is the purpose for distribution amplifiers in a hybrid fiber/coax (HFC) network?
Boost the downstream signals before being divided and circulated throughout neighborhoods in the coaxial cable portion of the network.
Why are signal levels through buried, underground cable unaffected by temperature changes?
Buried, underground cable is insulated by the ground and is usually unaffected by temperature changes.
How can a time domain reflectometer (TDR) confirm an illegal connection of equipment, which is a form of cable signal theft?
By connecting a TDR to the customer drop at the tap, the signature of the TDR waveform indicates if any equipment is connected within the customer premises, indicating an illegal connection.
How does surge protection at the input and output of a ferroresonant power supply defend against voltage surges?
By passing voltage surges (within the surge device rating) to ground without damage.
What is the ratio of the charge transferred between the capacitor plates to the potential difference between the plates?
Capacitance
Why is the total capacitive reactance of a network of capacitors connected in parallel calculated by adding their reactance together like a series of resistors?
Capacitors in parallel act like one large capacitor whose plate area is equal to the sum of the conductive plate areas of the individual capacitors.
Where is a clamp-on ammeter attached to measure the output current from a network power supply?
Clamped around one of the conductors going to cabinet indicator lamp.
If the hardline coaxial cable center conductor is too short after coring the dielectric with a combination coring tool, what should be done?
Clean out any dielectric and aluminum trimmings from the cable and the tool and continue coring to the correct depth.
Which element likely has distributed capacitance?
Coaxial cable
Changes in impedance
Displayed by a waveform TDR.
What happens to the power loss caused by conductor resistance when electricity is transported to the load at the end of the conductors?
Even though the conductor diameter is large, there is some resistance that wastes power in the form of heat, before the electric current reaches the load at the end of the conductors.
Extension adapters
Extension adapters are typically used where old equipment is replaced by new equipment with a smaller footprint.
Why do hardline splitter, directional coupler, and power inserter housings typically have eight ports?
For efficiency, manufacturers use the same 8-port housing for their splitters, directional couplers, and power inserters, with the unused ports capped. The 8-port housing also enables the equipment to be rotated in any direction during installation, allowing the housing to be used in any orientation, regardless of the direction of signal flow.
When setting up the forward amplifier of a line extender, why must the manual gain control be at a mid-range position at the desired operating level?
For the automatic/thermal control to work effectively.
What property of a filter with inductors (L) and capacitors (C) can stretch and distort digital TV data pulses, making it difficult for the receiver to recover the signal?
Group delay.
Step-signal TDR
Has no blind spot.
Why is a dipole antenna used for Federal Communications Commission (FCC) leakage measurements?
Having well known performance characteristics, the half-wave dipole antenna, and the length of its elements, is designed to operate at a specific frequency. At the design frequency and a specific field strength, the half-wave dipole antenna provides a known output signal.
What do housing-to-housing adapters eliminate when connecting two pieces of equipment together?
Housing-to-housing adapters eliminate the need for jumper cables to connect two pieces of equipment together.
In a distributed feedback laser (DFB), what restricts the reinforced wavelengths to a very narrow range?
In a DFB laser, diffraction grating is incorporated into the active region of the laser, to restrict the reinforced wavelengths to a very narrow range.
What are the reflecting surfaces on each side of the intrinsic layer in a Fabry-Perot laser called?
In a Fabry-Perot laser, the two reflecting surfaces on each side of the intrinsic layer, form a Fabry-Perot interferometer, which reinforces the reflection of photons at the desired wavelength.
In a Zener diode regulator circuit, how should the Zener diode be biased?
In a Zener diode regulator circuit, the Zener diode should be reverse-biased.
How does the direct current (DC) power supply module in a distribution amplifier receive alternating current (AC) voltage?
In a distribution amplifier, the AC voltage is delivered from the amplifier module to the DC power supply module via a cable, through which the DC voltage is also delivered to the amplifier module over a separate wire.
The RF signal distribution of a feed-through distribution tap can be divided into which two sections?
In a feed-through distribution tap the directional coupler portion of the tap efficiently routes most of the signal to the output port, while routing a lesser amount of the signal to the splitter network.
A power inserter utilizes what type of filter to prevent RF from entering the network power supply?
In a power inserter, a low-pass filter network passes the 60-Hz AC from the power supply to downstream and/or upstream amplifiers on the coaxial cable and prevents RF signals from passing through the AC input port to the power supply.
What is the phase relationship of the voltage and current sine waves in a resistive alternating current (AC) circuit?
In a resistive AC circuit, the current and voltage sine waves are in-phase, reaching their maximum and minimum value at the same time.
What is the relationship between power, voltage, and current in a resistive AC circuit?
In a resistive AC circuit, the relationship between power (P), voltage (E), and current (I) is expressed in the equation: P = IE.
Why do cable manufacturers recommend that expansion loops be formed in aerial installations of hardline coaxial cable?
In aerial installations, the aluminum hardline coaxial cable expands and contracts at almost twice the rate of the steel strand that the cable is lashed to for support. As a solution, cable manufacturers recommend that expansion loops be formed in hardline coaxial cable to allow additional movement of the cable when lashed to the strand.
What is the purpose of the seizure screw in hardline splitters, directional couplers, power inserters, and distribution taps?
In hardline splitters, directional couplers, power inserters, and distribution taps, the seizure screw makes a mechanical and an electrical connection between the device and the hardline coaxial cable connector pin.
What is typically done before adding a new distribution tap or network extension to serve potential new customers?
In most broadband cable networks, there is a design group that performs a cost payback analysis before incorporating new distribution taps or extensions into the network design.
In many areas, the utility company requires an electrical power meter to measure how much electricity is used and the cable operator is billed accordingly.
In some areas, the utility company charges a bulk rate per power supply, which makes a power meter unnecessary, and only requires the primary disconnect box interface with the network power supply.
For a quick view of how widespread an outage is, the network key map should be consulted.
In the two views of a network key map, the first segment of the map number represents the vertical plane with the lowest number being the furthest south. The second segment of the map number represents the horizontal plane with the lowest number being the furthest west.
dBRL
Indicates the severity of a cable fault.
What is the opposition to alternating current above the resistance of the inductor to direct current (DC) called?
Inductive reactance.
What can be added to a leakage test signal to avoid false detection of leaks?
Intended to avoid false detection of leaks, a tagging signal on the leakage test carrier causes a distinct audio tone from the compatible leakage detectors when a leak is detected.
Which of the following problem(s) are caused by egress from a hybrid fiber/coax (HFC) network?
Interference with aeronautical navigation and communication, amateur radio, public service, and cellular communications.
What occurs when a Group 13 (acceptor) impurity such as boron, gallium, or indium is introduced to the semiconductor crystal?
Introducing a Group 13 (acceptor) impurity such as boron, gallium, and indium into the semiconductor crystal creates a deficiency of one electron, called a hole, in the semiconductor lattice structure.
Which of the following describes a power inserter?
It contains a high-pass filter network that passes radio frequency (RF) signals between the two RF/alternating current (AC) ports and blocks the 60-hertz (Hz) AC voltage between the same two ports.
Which characterizes a feed-through distribution tap?
It has a directional coupler that efficiently routes most of the signal to the output port while removing a small amount of the signal and passing it to the splitter network.
Why is it a good practice to take a time domain reflectometer (TDR) measurement of a cable where a fence was recently installed and likely damaged the cable?
It is a good practice to take a TDR measurement of a cable where a fence was recently installed to find out if the cable is damaged at the first or second fence post, or further along the row of fence posts.
Why is it a best practice to remove power from cables being tested with a time domain reflectometer (TDR)?
It is best practice to remove power from any cable being tested with a TDR to prevent electrical shock which could cause a fall or additional personal injury.
What can be said about a straight splice connector?
It is essentially two hardline connectors with a common interface.
When looking at a design map, what do the small circles with an X connected with a solid line represent?
Joint use poles.
What properties of electrons and protons prevent a charge on the atom?
Keeping the number of electrons equal to the number of protons prevents an electrical charge on the atom.
What information does the circuit designer need to know to calculate the signal voltage and current range on the output of a bipolar junction transistor (BJT)?
Knowing the resistance of the circuit following the amplifier stage (the load resistance), the circuit designer can calculate the signal voltage and current range on the output of the BJT.
What leakage level must be entered in the leakage log?
Leaks 20 microvolts per meter (μV/m) or higher measured 10 feet from the cable.
Line extenders can be powered from the network or from a 120- volts alternating current (VAC) source. Which of the following statements about line extender power sources is true?
Line extenders powered by the network can pass current to other devices.
Schotky barrier diode
Low forward voltage drop Fast switching time
Which is an air dielectric hardline coaxial cable?
MC2
Thermal control circuit
Maintains the output levels as the input levels vary with temperature changes.
What are the three categories that most hardline cable splicing projects can be grouped into?
Most hardline cable splicing projects can be grouped into one of three categories: repair and/or maintenance, equipment replacement, and network extensions.
What is the induction of electromotive force (emf) into an inductor from the changing magnetic field lines around another inductor that encircle, or link, the turns of the inductors called?
Mutual inductance.
How much do you know about the P-N junction?
Near the junction of the P-type and N-type regions, the free holes on the N side move to the P side, and the electrons on the P side cross over to the N side, placing a negative charge on the P side and a positive charge on the N side. The opposite polarity charges on both sides creates the depletion region, which prevents the flow of free electrons and holes.
What is one of the most basic applications for solid-state diodes?
Of the numerous applications for solid-state diodes, one of the most basic applications is to change the alternating current (AC) used in power distribution to homes and businesses to direct current (DC).
What type of network architecture design did the original broadband cable networks use to transport television and audio signals to customer premises?
Originally, broadband cable networks were designed using copper/aluminum coaxial cable in a tree-and-branch architecture to transport television and audio signals to customer premises.
Why are pin-type hardline connectors the preferred type of connector for attaching hardline coaxial cable to equipment housings in today's networks?
Over the years, intermittent operation, low-frequency roll-off, and common path distortion (CPD) issues have been attributed to feed-through connectors.
Pedestal splice block
Pedestal with cable tails sticking up.
What is the preferred type of connector for attaching hardline coaxial cable to equipment housings?
Pin-type hardline connectors are the preferred type of connector for attaching hardline coaxial cable to equipment housings.
What element in a splitter and directional coupler serves, among other functions, to determine to which ports 60/90 alternating current voltage (VAC) is sent?
Plug-in fuses.
What is used to select which distribution amplifier secondary downstream output ports are active and whether they have equal or unequal output levels?
Plug-in modules or jumpers.
As the RF signal travels on the coaxial cable, one portion of the signal may be attenuated more than the others. What term is used to describe a situation where cable attenuation is low, causing signal levels to remain greater at the higher frequencies than at the lower frequencies?
Positive tilt
What is a consequence of high-speed charging and discharging of the capacitance in a complementary metal oxide semiconductor (CMOS)?
Power is dissipated as heat.
Fuses and circuit breakers
Protects distribution amplifier circuitry against damage by opening when an excessive amount of current is drawn within the amplifier module.
When trying to find the source of a very strong leakage signal, what should be done?
Reduce the sensitivity of the leakage detector or even remove the antenna and allow the connector alone to pick up the leakage signal.
Full-wave rectifier
Requires a center-tapped transformer secondary. Charges the filter capacitor once per half cycle. On the alternate half cycles, one half of the secondary is inactive.
Which of the following is true about a return path sweep-and-alignment system? Choose all that apply.
Sends a telemetry signal on the forward path. Places a device in the headend that communicates with a device or devices in the network. Enables a single technician in the network to check the operation and alignment of return amplifiers.
When setting the line extender's output slope, what would be the effect of using Channel 68 (487.45 MHz) instead of Channel 78 (547.25 MHz) as the reference carrier on a 550 MHz system?
Setting the line extender's output slope using Channel 68 instead of Channel 78 as the reference carrier on a 550 MHz system creates more slope than what is specified.
Trunk amplifiers
Several are typically cascaded in series to maintain channel amplitude at useable levels at customer premises farthest from the headend.
To detect and measure egress, why is a dedicated leakage detector preferred rather than a signal level meter?
Signal leaks can be very low amplitude, and difficult to detect with an SLM. Instead, dedicated leakage detectors are capable of measuring leaks with an amplitude as low as 2 microvolts/meter (µV/m).
A return path sweep-and-alignment system is used to adjust which of the following?
Signals from a line extender to the headend.
Why are the output levels from a line extender sloped from the highest to the lowest output frequency?
Sloping the output of a line extender from the highest to the lowest output frequency closes the signal differential between the frequencies and reduces the distortion from the line extender by approximately 0.5 dB for every 1 dB of slope.
What is the purpose of the optional housing port on some distribution amplifier housings?
Some amplifier station housings provide an optional port for AC power directly from a hardline coaxial cable connected to a network power supply.
What happens when there is an impedance mismatch between the coaxial cable and the load?
Some signal energy is transferred to the load, with the remainder reflected along the coaxial cable back to the source.
When troubleshooting signal leakage in the drop system, what does it mean if all signs of signal leakage disappear when the ground block is disconnected and terminated on the side connected to the customer premises?
Something in the customer premises is the leakage source.
Which hardline coaxial cable splicing project would be in the repair and/or maintenance category?
Splicing in a short replacement cable with a straight splice connector.
What must be done when measuring the port-to-port isolation between the output ports of a splitter or directional coupler?
Terminate the common input port.
How does the power waveform of a resistive alternating current (AC) circuit compare to the voltage and current sine waves?
The AC power waveform has two positive half-cycles and two positive peaks.
In a hybrid fiber/coax (HFC) network, what term defines the maximum number of cascaded amplifiers in a network design?
The Node +N term defines the maximum number of cascaded amplifiers in a network design. For example, a network designed for a maximum of six cascaded amplifiers is called a Node +6 network, for one fiber node plus six amplifiers.
How much do you know about key forward characteristics of the diode?
The Schottky diode the has a forward voltage drop of about 0.3 volt. The reverse capacitance characteristic is utilized in varactor diodes in circuits to adjust frequencies. For forward-biased silicon diodes, which are most common, forward voltage drop is about 0.7 volt at useful currents. For germanium diodes, forward voltage drop is about 0.2 volt, but this diode has other characteristics that make it less suitable for most applications.
How much do you know about connecting the TDR to coaxial cable?
The TDR user must account for the jumper cable length in all measurements. A hardline cable-to-F female (or BAFF) adapter provides a clean transition from the hardline coaxial cable to an F-connector for TDR testing. A coaxial cable jumper with an F-connector on one end and alligator clips attached the center conductor and shield at the opposite end enables a quick connection to test hardline coaxial cable with the TDR without compromising measurement accuracy.
According to the Federal Communications Commission (FCC) leakage regulations, what distance must an antenna be from the network for leakage level measurements?
The antenna must be 3 meters (10 feet) from the network elements and 3 meters (10 feet) above the ground.
When using a single-purpose coring tool, what is done before the coring tool can be used to cut and remove the dielectric?
The appropriate length of aluminum shield and dielectric must be removed, to expose the cable center conductor.
How are the equal outputs from a balanced 3-way splitter achieved?
The balanced 3-way splitter consists of a 5.5 dB directional coupler with the low-loss (2 dB) leg feeding a 2-way splitter. Assuming that the 2-way splitter loss is 3.5 dB, the loss through all three legs is 5.5 dB, for equal levels from each output port, a balanced output.
In a half-wave power supply, what enables voltage to be provided to despite current flow through the diode stopping?
The capacitor across the load.
What happens when alternating current (AC) is applied to an inductor?
The changing polarity AC source current is continually opposed by the inductor counter electromotive force (cemf) current.
What is the time constant of a capacitor?
The charging rate of a capacitor, or the time constant, is t = R x C, where t is one time constant; R is the circuit resistance; and C is the capacitance. The product of the of circuit resistance and the capacitance of the capacitor (R x C) is approximately 63% of the source voltage, or 1 time constant (1T).
How much does the cable attenuation change with each 10°F change in cable temperature?
The coaxial cable attenuation typically varies between 0.1% and 0.12% per degree Fahrenheit (˚F) change, which is approximately equal to a 1% change in cable attenuation for every 10°F change in cable temperature.
For the power in the primary and secondary windings of a transformer to remain equal, what must the current in the secondary windings do when the voltage is stepped up?
The current in the secondary windings must step down in proportion to the voltage increase.
Near the junction of the P-type and N-type regions, the free electrons on the N-side move across the junction to the P-side, and the holes on the P-side cross over to the N-side. What prevents any further flow of free electrons and holes?
The depletion region.
What three factors combined, provide coaxial cable its characteristic impedance?
The dielectric constant of the material between the center and outer conductors, the size of the center conductor, and the inside diameter and thickness of the outer conductor/aluminum of coaxial cable combined, provide coaxial cable its characteristic impedance.
What is the return loss in coaxial cable?
The difference in decibels (dB) between the signal power applied to a terminated cable and the reflected signal power.
What are the terminals of a diode called?
The diode terminals are called the anode and the cathode. When the voltage applied to the anode is more positive than the cathode, the diode is forward-biased and conducts current.
What is done to light emitting diodes (LED) to get them to produce different colors of visible light?
The dopants used on the two sides of the diode can be varied to get the LED to emit energy at different wavelengths and colors of visible light.
Branches in the architecture
The downstream signal is distributed within nearby neighborhoods using 0.412-inch to 0.625-inch diameter coaxial cable, splitters, and directional couplers.
What does the semi-circle big contact on a North American power plug connect?
The earth ground is frequently made through the third wire of the power connector, the semi-circle big contact on a North American power plug.
How do the electrical properties of hardline coaxial cable compare to that of coaxial cable used in drop systems?
The electrical properties of hardline coaxial cable and coaxial cable used in the drop system are identical, except for the attenuation.
Anomalies, such as echoes and blind spots, can hide cable faults or cause a technician to misinterpret the signature of a time domain reflectometer (TDR) waveform. What causes an echo on a waveform TDR?
The extra distance that the TDR pulse travels after initially reflecting off the end of the cable span.
What type of adapter provides a clean transition from the hardline coaxial cable to an F-connector when testing hardline coaxial cable with a time domain reflectometer (TDR)?
The hardline cable-to-F female (or BAFF) adapter.
What units are used to express inductance?
The henry (H).
When studying a network map for an upcoming splicing project, how can you identify the high-output port of an unbalanced 3-way splitter ?
The high-output port of an unbalanced 3-way splitter is indicated by a dot on the map symbol.
When opening a distribution amplifier station housing, why is it usually unnecessary to loosen the bolts at the bottom of the housing?
The housing lid is usually attached to the base of the housing with hinges.
Where should a technician look to identify an unfamiliar symbol on a network design map?
The identity of the symbols on network design maps can be found in the legend at the bottom of most design maps.
Why are insulating-core inductors also called air-core inductors?
The insulating-core inductor is also considered an air-core inductor because the insulating core is only for supporting the coiled conductor, without magnetic properties.
What is done for leak measuring 1.25 microvolts per meter (μV/m) from about 160 feet away from the coaxial cable network?
The leak level is likely 20 μV/m or higher when measured 10 feet from the cable and must be fixed and recorded in the leakage log.
When calculating the network cumulative leakage index (CLI), what is done with leaks that are equal to or greater than 50 microvolts per meter (µVm) measured 10 feet from the network?
The leakage values are added together, then multiplied times a factor based on how much of the network was tested in 90 days.
What presents the biggest electrical shock hazard when operating a time domain reflectometer (TDR) in the network?
The low-frequency alternating current (AC) voltage on the coaxial cable.
Which part of a ferroresonant transformer regulates the load on the secondary winding?
The magnetic shunt.
What is the most basic method used to adjust distribution amplifier output levels?
The most basic method to adjust distribution amplifier output levels uses plug-in attenuator pads that set the output signals to a fixed level.
What are the most common types of inductor/capacitor (LC) filters?
The most common LC filter types are the low-pass filter (LPF), high-pass filter (HPF), band-pass filter (BPF), and band-stop filter (BSF).
How much do you know about the composition of an atom?
The most important shell for electricity is the valence shell. The valence shell is the outside ring. There are eight electrons in the valence shell of most inert and stable atoms.
What is the output voltage from a power transformer dependent upon?
The output voltage from a power transformer depends on the input voltage and the turns ratio of the primary and secondary of the transformer.
Which of the following determines the inductance of an inductor? Choose all that apply.
The permeability of the core. The spacing between the turns. The number of turns in the inductor windings. The cross-sectional area of the core.
What is the port-to-port isolation of splitters and directional couplers?
The port-to-port isolation of splitters and directional couplers is the measure of the attenuation between the two output ports at a specified frequency, with the common port terminated.
What is the coaxial cable velocity of propagation (VoP)?
The rate that radio frequency (RF) signals travel through the coaxial cable versus the speed that RF signals travel in a vacuum or free space.
What is the expected B+ voltage from the line extender power supply?
The regulated DC or B+ voltage, for most line extenders is +24 volts direct current (DC), ±.5 volt.
What does the decibel return loss (dBRL) displayed on most time domain reflectometers (TDR) indicate?
The relative severity of a cable fault.
What is a characteristic of a positive, intrinsic, negative (PIN) diode?
The resistance at RF being a function of the DC applied to the PIN diode, is a characteristic that makes a good variable RF resistor controlled by the amount of DC applied.
What features of other network architectures appear to be major advantages over the hybrid fiber/coax (HFC) network architecture?
The seemingly infinite bandwidth of passive optical networks (PON) and the wireless accessibility of 5G networks appear to be major advantages over the HFC network architecture.
Velocity of propagation (VOP)
The speed of RF signals in a coaxial cable relative to the speed of RF in a vacuum. Setting for the TDR to measure distances to the end of the cable and coaxial cable faults or impedance mismatches.
What are three advantages of using a switching mode power supply (SMPS) in a line extender versus a linear power supply?
The switching components in an SMPS are smaller, lighter, and at lower cost than the linear power supply components. The SMPS operates within a wider AC input voltage range with a tightly regulated output voltage, while using less energy and generating less heat than the linear power supply.
Why must the test point value be known when measuring input signal levels at a line extender?
The test point value must be known by the technician to take accurate measurements and inject test signals at the correct levels.
When a network design map shows a distribution amplifier with a black dot at one of the downstream output ports, what does the black dot indicate?
The three-output distribution amplifier map symbol has a black dot that identifies the output port that has the highest output of the three ports.
What defines the period of a sine wave?
The time that it takes for completion of one cycle of the signal.
How is the total capacitive reactance of capacitors in a series circuit calculated?
The total capacitive reactance of capacitors in a series circuit is calculated like resistors in a series/parallel circuit.
Describe a typical distribution amplifier.
The typical distribution amplifier has one fixed and nonconfigurable, primary downstream output port and two or more configurable secondary downstream output ports.
As cable TV networks evolved into broadband cable networks, NEC Article 830, which defines the power limitations for network-powered broadband communications systems apply.
The voltage from the network power supplies in broadband cable networks can be increased from the 60 VAC to 90 VAC. Operating with 50% more voltage, reduces the voltage drop and current drawn in the network for more efficient power utilization.
Which well-understood technology has been adapted in time domain reflectometers (TDR) to test and troubleshoot metallic conductors separated by an insulator?
The well-understood radar technique has been adapted in TDRs to test and troubleshoot metallic conductors separated by an insulator.
What characteristics about upstream signals from cable modems and set-top boxes (STB) make them impractical for verifying and aligning a distribution amplifier return section?
They are of short duration and originate from various locations.
How can signal leaks (egress) from hardline coaxial cable occur?
Through cracks in the shield where the cable is bent, or tiny holes in the shield.
How is the alternating current (AC) voltage from a generator accessed?
Through slip rings that maintain physical contact with stationary brushes that can be connected directly to a circuit.
What test instrument sends out a test signal and displays any reflections caused by impedance mismatches in the cable that are characteristic of cable faults?
Time domain reflectometer (TDR)
How should a knife be used when preparing hardline coaxial cable for connector attachment?
To carefully cut the dielectric away before coring the cable.
List the three principles that a time domain reflectometer (TDR) uses to measure the distance to the end of the cable and any faults in between.
To measure the distance between the TDR the end of the cable, and any faults in between, involves the principles of cable radar, velocity of propagation (VOP), and the signal pulse width.
When aligning amplifiers in the return path, what must be achieved and maintained from the customer premises to the headend, or node?
Unity gain.
Saw filter
Uses vibrations that propagate across the surface of a crystal to an output transducer, where the vibrations are converted back to electrical energy.
Which of the following is true regarding thermal level control (TLC)? Choose all that apply.
Utilizes passive circuitry. Adjusts the internal attenuation in the line extender as the temperature changes.
TDR
Waveform TDRs feature automatic measurement capability, keypad operation, variable markers, color LCD waveform displays, as well as storage to compare previous waveforms. The digital TDRs are less expensive of the two types of TDRs and are just as accurate and capable of locating major cable faults. Detection of minor cable faults and splices are more likely to be found with the more expensive waveform TDR, which is also more suitable for testing longer cables.
What is the relationship of wavelength to waveform frequency?
When the frequency increases, the wavelength of one cycle of a waveform decreases, and when the frequency decreases, the wavelength increases inversely proportional to the frequency.
What is the input voltage at an amplifier when the source voltage is 90 volts alternating current (VAC) and the voltage across the loop resistance in front of the amplifier is 2.5 V?
When the source voltage is 90 VAC and the voltage across the loop resistance in front of an amplifier is 2.5 V, the amplifier input voltage is 90 - 2.5 = 87.5 VAC.
How can alternating current (AC) flow from a distribution amplifier port be verified when unable to see the fuse or circuit breaker?
When unable to see the condition of a fuse or breaker, the AC can be verified using a digital multimeter (DMM) to measure AC voltage at the associated distribution amplifier module port.
When using a return path sweep-and-alignment system, how should the test carriers be adjusted when compared to the stored reference trace?
When using a return path sweep-and-alignment system, the output levels of the return amplifier should be adjusted with the intent to match the reference trace for received level and frequency response.
When working in the network where hardline coaxial cable is installed on poles or buried underground, what basic personal protective equipment (PPE) must be worn avoid injury from an accident?
When working in the network where hardline coaxial cable is installed on poles or buried underground, approved hardhats, footwear, and safety glasses are basic PPE that must be worn to avoid injury from an accident.
What precautions must be observed when working with circuits that contain metal oxide semiconductor field effect transistors (MOSFET)?
When working on circuits that contain MOSFETs, a grounded anti-static mat is recommended, and anyone working with the circuit should also be grounded to the anti-static mat.
When does the shape of the quasi-square waveform from a ferroresonant network power supply resemble a sine wave?
With a full 15-ampere (A) load, the shape of the quasi-square waveform from a ferroresonant network power supply resembles a sine wave.
Why does it appear that a capacitor passes alternating current (AC), but blocks direct current (DC)?
With an AC source, the capacitor continuously charges and discharges for current flow in the same direction, appearing to pass through the capacitor.
Housing terminator
are pin-type devices designed to terminate unused network equipment ports into 75 Ω impedance.
Pin-to-F adapters
are used for permanent or temporary jumper installation in place of damaged hardline coaxial cable or equipment hookup.
What are the three most common components of an atom and where are they located in the atom?
Protons and neutrons are located in the nucleus of the atom and electrons are located in orbit around the nucleus.
What is different about preparing QR hardline coaxial cable for connector installation compared to all other types?
QR cable is first cored and the aluminum shield is stripped before the polyethylene jacket is removed to the proper length, the reverse of other cable types.
What could a light dimmer with a silicon controlled rectifier (SCR) create in a customer premises?
Radio frequency interference (RFI). Efficient dimming of lights during a full power cycle.
What type of adapter is used for permanent or temporary jumper installation in place of damaged hardline coaxial cable or equipment hookup?
Pin-to-F female adapter
What is the value of the current in a resistive alternating current (AC) circuit when: (1) the effective voltage is 120 volts; (2) the resistance of the source is 3 ohms; (3) the resistance of the conductors is 2 ohms; and (4) the resistance of the load is 5 ohms?
12.0 amperes
What is spliced into the hardline coaxial cable to combine the AC power with the transported RF signal in a hybrid fiber/coax (HFC) network?
A power inserter.
Which of the following are attributes of an electrolytic capacitor? Choose all that apply.
Achieves a larger capacitance than other capacitor types. Uses a liquid or gel containing a high concentration of ions. A thin oxide film acts as the insulating material. Direct current (DC) voltage is applied during manufacture.
What is the effective value of an alternating current (AC) sine wave?
Because an AC voltage and current varies over time, more energy is required to have the same effect (such as heat in a resistor) as an equal amount of DC. This effective value, (0.707) is also called the root mean square (RMS) value multiplied times the sine wave peak value.
In a resistive AC circuit, what prevents the power waveform from going below zero?
Because the circuit power is the product of the instantaneous values of the circuit voltage and current, the circuit power is always zero or positive, even during the negative half-cycle of the voltage and current.
What is required for checking the physical network integrity when maintaining the coaxial cable network?
Being observant and performing some minor tasks while engaged in regularly scheduled activities.
What is a cable network best practice that can reduce the damage and danger of lightning to both property and life?
Bonding and grounding of the cable network.
What is capacitance?
Capacitance is the property of conductors and insulators that are configured to enable storage of an electric charge.
How are units of capacitance typically stated?
Capacitances are typically stated in units with the prefixes micro (µ), nano (n), and pico (p) preceding Farad, thus, microfarad (µF), nanofarad (nF), and picofarad (pF).
If all conductors have inductance, why are inductors typically coiled conductors?
Coiled conductors link the magnetic field between the coil loops, increase the inductance, and enable packaging of the conductor into a smaller space.
What are the most common ranges of inductance in alternating current (AC) circuits?
Combining the term henry with the metric prefix, 0.001 henry can be expressed as 1.0 millihenry (mh) and 0.000001 henry as 1.0 microhenry (μh)—the most common ranges of inductance in AC circuits.
What is required for alternating current (AC) to flow through a circuit?
For current to flow through a circuit there must be electromotive force (EMF), which is a difference of voltage potential, applied to the ends of a conductor to complete the circuit.
What technologies are defined in DOCSIS 4.0 to help sustain the hybrid fiber/coax (HFC) network infrastructure for several more years?
Full Duplex DOCSIS (FDX) and Extended Spectrum DOCSIS (ESD).
Where is a capacitor most likely to be found in a hybrid fiber/coax (HFC) network?
In HFC networks, capacitors are used throughout in network power supplies, fiber nodes, amplifiers, splitters, directional couplers, filters, and so on.
What is the total inductive reactance of a circuit containing several inductors connected in series?
Just like the resistive series circuit, the current flow through each inductor connected in series is the same, and the total inductive reactance, is the sum of the inductive reactance of all the inductors.
What type of relationship exists between the sine wave period and frequency?
Like the wavelength, the period is inversely proportional to the sine wave frequency, expressed in the equation: Period = 1 ÷ frequency in Hz
What enables a transformer to transfer electrical energy from circuit to another?
Mutual inductance.
What is a common solution when congestion from modem activity and traffic becomes unacceptable in a hybrid fiber/coax (HFC) network?
Node split
The Occupational Safety & Health Administration (OSHA) requires the cable operator to provide its field workforce regular safety training on which topics?
None, OSHA defers to the cable operator's insurance carrier to determine what training is relevant, necessary, and appropriate for their employees. Topics that reinforce the operator's commitment to employees about safety in the workplace.
Where is the density of eddy currents in a conductor the greatest, causing the skin effect?
Outside the magnetic field rings on the outside of the conductor. Inside the magnetic field rings in the central part of the conductor.
Because field employees are frequently working without supervision, what must cable operators do to remind and help employees make the safest decisions?
Provide safety training regularly.
There are many ways that broadband cable signals can be "pirated," or taken without compensation to the cable operator. Which of the following is an example of passive piracy?
Someone moves into an apartment and broadband service is already active without establishing an account.
What is the name of the alternating current (AC) waveform that represents the variations in output voltage or current with respect to changes in the angular position of a generator armature?
The AC waveform is called a sine wave because the variations in output voltage or current with respect to changes in the angular position of the generator armature is the sine of the angle.
The Proactive Network Maintenance (PNM) specification is defined in what other specification?
The Data Over Cable Service Interface Specification (DOCSIS).
Compared to direct current (DC), what does the skin effect do to the cross-sectional area and alternating current (AC) flow capacity of the conductor?
The cross-sectional area and AC flow capacity of the conductor remain the same. The cross-sectional area and AC flow capacity of the conductor are reduced.
In a resistive alternating current (AC) with all the resistance in series, what is known?
The current through all the resistance is the same.
How is the skin effect related to eddy currents?
The density of eddy currents is greatest inside the magnetic field ring in the central part of the conductor, which forces alternating current to flow on the outside surface of the conductor, creating what is called the skin effect.
What should you be looking for when analyzing the network design maps to troubleshoot a problem?
The device common to those customers affected before traveling to make signal status checks.
What is the sine wave phase angle?
The distance in degrees from the 0° reference point to any other point on the waveform.
How can a distribution amplifier be identified in the network or on a network design map?
The distribution amplifier has multiple downstream outputs.
Unless specified otherwise, what does I = E/R for a resistive alternating current (AC) circuit is assumed to mean?
The effective value of the current (IEFF) equals the effective value of the voltage (EEFF) divided by the resistance (R).
What is the relationship of the inductive reactance of an inductor and frequency?
The higher the frequency, the higher the inductive reactance. The inductive reactance remains the same at all frequencies.
How can a less-experienced technician identify what non-standard symbols on the network design maps represent?
The legend at the bottom of the network design map that defines the map symbols, cable types, and amplifier data.
What characteristic of a ferrite enables its use as the transformer core in the splitters and directional couplers used in HFC networks?
The low electrical conductivity of the ferrite solid-core transformer has less internal power loss at RF than other iron-core transformers, enabling ferrite to be used as the transformer core in the splitters and directional couplers used in HFC networks.
In a resistive alternating current (AC) circuit, what is the magnitude of the current directly proportional to when the resistance remains the same?
The magnitude of the voltage.
What is the peak value of a sine wave?
The most positive or most negative level of each sine wave half cycle.
How does the network designer calculate the voltage at each amplifier in a hybrid fiber/coax (HFC) network?
The network designer calculates the voltage at each amplifier by subtracting the voltage dropped across the resistance value in front of each amplifier from the preceding voltage source.
What are the characteristics that determine the inductance in an inductor?
The number of turns in the inductor windings, the spacing between the turns, the cross-sectional area of the core, and the permeability of the core are the characteristics that determine inductance in an inductor.
What is inductance?
The property by which voltage and current is induced into a circuit by a changing magnetic field.
What is a characteristic of the quasi-square wave produced by the ferroresonant transformer in hybrid fiber/coax (HFC) network power supplies?
The quasi-square wave edges become more rounded as the load increases.
What is the RF distribution tap value indicated on the tap face plate by a sticker or number stamped into the housing?
The signal loss between the tap downstream input port and the tap ports.
How long can a capacitor store an energy charge?
Theoretically, a charged capacitor will store energy indefinitely. In practice, there is a small amount of leakage current through the insulator and the capacitor will slowly discharge, therefore, the discharge time varies from seconds to months depending on the capacitor dielectric and construction.
In addition to being less expensive than cable with a solid copper center conductor, what other benefit does a steel or aluminum conductor core provide?
They reduce the magnitude of the eddy currents and skin effect on the conductor.
What happens when a conductor is moved through, or cuts, the flux lines that run longitudinally from the north pole to the south pole of a magnet?
When a conductor is moved through, or cuts, the flux lines that run longitudinally from the north pole to the south pole of a magnet, it creates current flow in the conductor.
What happens when there is mutual inductance between two inductors?
When mutual inductance occurs between two inductors, electrical energy is transferred from the primary inductor to the secondary inductor.
What is meant by phase difference?
When the two waveforms reach their maximum and minimum magnitudes at different times, the waveforms are out-of‑phase with each other, meaning that there is a phase difference between waveforms.
In the three-and-branch architecture, how is the downstream signal from the trunk fed to the distribution branches
Within each trunck amplifier, a portion of the downstream is fed to a bridger amplifier to boost the signal before being split and routed to the distribution branch
What type of waveform is produced by the ferroresonant transformer in hybrid fiber/coax (HFC) network power supplies?
Without a load, the ferroresonant transformer in HFC network power supplies produce a quasi-square wave that has a slightly rounded shape at its maximum and minimum peak values.
