NCT4 Flashcards
A frequency selective receiver capable of tuning in a desired frequency/Channel with a display showing RF signal strength (dBmV)
Signal Level Meter (SLM)
The minimum signal level at the input to the customers TV is
0dBmV to 15dBmV
what do you need to do to maintain an SLM
Keep the battery charged, clean the battery terminals regularly,keep the SLM clean by wiping it gently:dry the display screen to prevent spots, do not use any type of polish or cleaner on the display ,and a regular calibration should be made and logged,
The ratio of error power to average power in an ideal QAM signal is
MER
Average power =
Digital power
Peak Power=
Analog power
Optical power units
mW or dBm
RF power units
mV or dBmV
Attenuation/ gain units
dB
what mode monitors up to 12 chs at a time on your meter
Miniscan
what mode monitors the entire Ch plan on your meter
Full scan
what mode check s the forward low frequency and high frequency channel tilt
Tilt mode
Detects errored bits in the system
Bit error Rate (BER)
used for troubleshooting connections with intermittent bit errors occuring over a period of time
Errored Seconds
passage of an outside signal into the cable; can result in noise and disruption of the desired signal
Ingress
shows impairments on the networks with the patterns on display and can be identified by figuring out the patters
Constellation Graph
Displays intermittent short duration impairments missed by MER and BER on your meter.
Digital quality index (DQI) mode
this mode shows you if ingress is within the downstream digital spectrum without turning of service
QAM ingress mode
This mode greatly improves the success rate and efficiency in locating return-path ingress
Fieldview Option
Service quality depends on transmitting signals with the highest carrier to composite noise and the lowest intermodulation distortion. The majority of all transmission errors can be detected by measuring the frequency response of the network is
Sweep
Provides a quick method to check cable system integrity, using active channels to sweep the forward path is
Sweepless Sweep
Using a unique method to accurately reveal any problem in the system without interfering with any of the analog/ Digital carriers is
Forward Sweep
Helps find mismatches or other problems in the upstream transmission path
Reverse Sweep
Accurately measures Ac voltages of signals other than pure analog sine waves
Root Mean Square Meter (RMS)
This meter is used to measure AC and DC voltages and currents as well as resistance and has a digital display
Digital Multi meter (DMM)
is used to find the location/path of underground cables
Cable locator
has a transmitter and receiver. it could include the following components a test lead, inductive frame and A-frame.
A locator
The resistance of a circuit to alternating current.
Impedance
The condition that results when two components of a system are operating at different impedance
Impedance Mismatch
is used to determine the distance of a known fault from a specific location
Time Domain Reflectometer (TDR)
Is used to locate: bad or unknown splices, opens, shorts, and kinked cable.
TDR
A reflection with the same polarity indicates an
open
is a situation where the center conductor comes in contact with the shield
Dead Short
A reflection with the opposite polarity indicates that the fault is
Short
refer to a cable that has not been competely cut
Partial Open
The contact between the center conductor and the shield is not complete
Partial Short
The distance that cannot be seen by the TDR because its too close to the TDR source
Deadzone
two types of TDRs
Waveform and Digital
extremely thin flexible thread of pure cladded glass able to carry millions of times the information of a traditional copper wire and do it over greater distances
Optical Fiber
A device that generates a light source used in fiber communication
Laser
LASER
Light Amplification by Stimulated Emission Radiation
Most light generated by lasers for telecomm use exists in the infrared band of 1310nm and 1550nm wavelengths
Infrared Light
the distance between two points of like phase in a wave
Wavelength
A card made up of material similar to photographic film that changes colors when exposed to light
Photosensitive Card
Laser Classification
Class1-safe as long as they are not disassembled.; Class-2/2A Eye hazard if beam is viewed.;Class-3A Eye hazard if collected or focused on the eye.; Class3B Eye hazard if the direct or reflected beam is viewed.; Class4 eye and skin hazard.
what is the laser standard
ANSI Z-136
A method to lock and mark one end of a line in order to allow someone to safely work on the other end
Lockout Tag-out
what are the two methods of fiber cleaning
Wet and Dry
Materials needed for wet method
Lint free wipes, Isopropyl(better than 90%) as recommended by the manufacturer, and lint free swabs or urethane foam heads
rotate a cleaning cloth over the end of a fiber connector by pushing down toward the connector
Push Pen
A battery or generator that provides electrical power to the circuit. For example, batteries and generators
Power Source
A conductor such as copper wire
Path
the device that uses the electricity. it is any device that draws current
Load
Substance that allows heat or electricity to pass along or through it
Conductor
Subatomic particles found in atoms that balance out the positive charge of a proton with their negative charge
Electrons
is the electromotive force that causes electrons to flow in a circuit
Voltage (E)
The pressure that causes electrons to flow in a circuit
Electromotive Force
is the flow of electrons through a conductor. is measured in amperes and is designated mathematically in ohms law as the letter I
Current (I)
The amount of electrons that pass a given point in the conductor in one second
Coulomb
is the opposition a material offers offers to the flow of current
Resistance (R)
the difference in voltage between one point and another
Potential Difference
the direction of an electrical field in a radiated wave
Polarity
An electrical current of which the polarity is periodically reversed.
Alternating Current (AC)
the point at which the filament reaches a temperature that causes it to glow
incandescence
the relationship between current or voltage and elapsed time
AC Waveform
what are the 4 types of AC Waveforms
Sine Wave, Square Wave, Quasi-square wave, and Sawtooth Wave
this waveform represents the characteristics of the voltage/current that feeds homes, powers power supplies, and the television channels that carry the program information to your customers homes
Sine Wave
This waveform is often found within the switching regular DC output power supplies in Amplifiers
Square Wave
A CATV power supply without a load produces a near square wave that combines a non linear increase and decrease of voltage or current with extended maximum positive and negative peak value.
Quasi Square Wave
Types of signals carried on the HFC system
Modulated RF carriers, Modulated analog carriers, DC power and AC power
one complete sine wave is
Cycle
Number of cycles of an AC waveform that occur in one second
frequency
the speed of the light/Frequency=
Wavelength
the amount of time it takes a waveform to complete one cycle
Period(T)
peak value of a waveform
Amplitude
states that current is directly proportional to voltage and inversely proportional to resistance
Ohms Law
R=
The resistance in ohms
E=
the Electromotive force(EMF) in volts
the rate a which work is done or the rate at which energy is used
Power
I=
current in Amperes
Resistance is measured between the center conductor and sheath with the other end
DC Loop Resistance
P=
WAtts
Current at any point in the line in the HFC plant is equal to the sum of the individual Ampere current draws of the active devices being fed from that point.
AC Current in the Broadband Network
the amount of voltage loss over the span is referred to as
Voltage drop
At lower voltages the current is higher in the HFC plant
Current at lower voltages
the amount of energy available to move a certain number of electrons from one point to another in an electrical circuit
Voltage
to be subjected to the action of an electrical discharge
Shock
to kill by electrical shock
Electrocute
a connection to the earth or a grounding device
Ground
power supplies reduce the secondary power (120 or 240) to the 60 or 90VAC for insertion in the cable
Line power supply
the electricity provided by the local power company
commercial power
2 types of line power supplies
standby and non standby
reduction of voltage by a transformer
stepped down
conversion of voltage, in this case from 36 or 38VDC to 60 or 90VAC
Inverted
the point where AC power from the power supply is placed on the coax portion of the distribution network.
Power inserter
a filter that will only allow the higher RF frequency signals to pass directly from RF port to port
high pass filter (relating to power inserter)
a filter present on each leg to direct the flow of the lower frequency AC power, which prevents the RF Signal from traveling into the power supply and causing signal leakage
Low Pass filter(Relating to power Inserter)
the two types of network powering
Distributed and centralized powering
batteries produce what kind of gas during charging operations
Hydrogen
three methods for testing batteries
battery load test, battery voltage test, battery conductance test
the most accurate and reliable test involves testing the batteries under a load condition
Load Test
the difference between any batteries in the set should not be greater than
0.3VDC
measuring the impedance of the battery with a conductance meter and documenting that value when its new. Batteries less than 50% of their as new conductance values are known to be bad
Battery conductance test
means of testing the network remotely that saves numerous problems in respect to downtime and customer dissatisfaction
status monitoring
according to manufacturers the terminals should be torqued to_____and then retorqued to _____ during routine maintenance.
75inch lbs and 60 inch lbs
what points should be kept in mind while checking battery terminals
is there an in line fuse in the battery cable, check the fuse holder and fuse. make sure the terminals are properly greased with an approved corrosion inhibitor such as NCP-2 or NO-OX
the topology where signals originate in the headend and are transmitted long distances via trunk cables which have branches for directing the signal to customers
Tree and Branch
Forward signals originate at the headend are transmitted downstream by way of the trunk to the ends of the service.
Transportation (Trunk)
In a Tree and Branch system the feeder is considered what
The distribution System (Branches)
in a tree and branch system RG-6 and 11 is considered
The Drop(Leaves)
A network architecture developed by the cable industry which typically uses fiber optic cables to bring signals to selected areas of the system called Node Service Area, which are usually based on the number of subscribers to be served
Hybrid Fiber Coax(HFC)
what are the two wavelengths of fiber do we use
1310 nm and 1550nm
a network architecture where nodes, hubs, or headends may be connected with fiber optic cables to provide redundancy or increase services.
Ring
What are the advantages of fiber
Greater Bandwith and can travel greater distances without Amplification
what are the two types of Fiber
Single mode and Multi mode(we use single mode)
what is the attenuation of single mode fiber
1310nm=.35dB/km, 1550=.25dB/km
the distance between two points of like phase in a wave
wavelength
compares the speed of light through a material to the speed of light through a vacuum
Index of Refraction
the reflection that occurs when light strikes an interface at an angle of incidence greater than the critical angle allowing it to be continually reflected from the interface between two materials with different refractive indices
Total Internal Reflection
Single mode core is how many microns
8 to 9 microns
single mode cladding is how many microns
125 microns
single mode coating is how many microns
250 microns
what is the primary loss in fiber called
Scattering
separates(and recombines) the forward and reverse signals from the coax cable so they can be routed to and from the appropriate components within the amplifier station
Diplex filter
separates or combines the AC currents two parts-( AC power and RF broadband signals)
Power Diplex
attenuates the signal in order to bring it to within the acceptable range of the amplifier
Pad
compensates for the unequal attenuation properties of the coaxial cable. usually selected to produce flat broadband signals to the input of the first stage of Amplification
Equalizer
Usually selected for low noise figure. Amplifies forward signal passing through the trunk and distribution lines
Forward Amplifier Module (TRUNK)
Used to compensate for fluctuations of the input signal
AGC
Similiar to an AGC maintains the proper tilt(caused by temperature change in a specified amount of coaxial cable) and output level despite changes in the input signals
ALS
Signal splitting device that plugs into a trunk/bridger chassis
directional plug ins (feedermaker)
Converts AC power(60V-90V Quasi Square wave) to DC power(typically 24VDC)needed to operate the stations modules and regulates the DC output voltages to provide a stable and constant output
DC Power Pack
used to direct AC power into and out of specific ports of the amplifier station
Power Director
provides a means of monitoring the various inputs and outputs without interrupting service
Test Points (TP)
will have substantial isolation between the output and tap ports if all ports see a good 75 ohm match. Isolation for signal paths between the tap and output port is usually 25dB or greater
Directional Coupler (DC)
A tap is used to extract a specific amount of signal from the feeder system and distribute it for connection of customer drops and contains a directional coupler that feeds a single splitter.
Taps (Customer interface point)
Low frequency signals are not attenuated as much as high frequency signals in a coaxial cable
In line Equalizers
LIke in line EQs these devices are sometimes installed in the distribution cable where low value taps are used
in line conditioners
in a housing like the splitter is used to introduce AC power into the network
Power Inserter
A design philosophy where the loss of the cable and other passive devices before an amplifier station
Unity Gain
similar to a street map and includes features like lakes and rivers, streets, and boundaries
Base Map
Displays streets with poles and pedestals locations and includes the span length or footage between these items
Strand Map
Shows the locations of electronic equipment. including headend and any hubs,amplifiers, power, supplies, and taps.
Design Map
Offer the layout of the system in a condensed form. shows how active devices are cascaded and how they are connected to the headend, hub, or node. power supplies are also noted
Amplifier schematics or Tree Map
A corrected map that represent the addition or changes in information on the design map
As Built map
Map that covers a single node
HFC Plant map
documents a fiber plant
fiber design map
catalogs the system maps
Map Grid System
is the measure of the cables ability to maintain impedance at all frequencies due to the many micro reflections introduced during manufacturing. The industry Specs call for a minimum of 15dB, but the higher the better
Structural Return Loss (SRL)
What do reflections do on a coaxial cable
They distort the carriers, causing bit errors in the modulated data streams.
a thin wire wrapped around the fiber and coaxial cables to secure them to the strand
Lashing wire
load bearing component of an aerial coaxial cable installation. Its usually a 1/4 or3/8 inch zinc coated steel wire to which the cable is lashed
Strand
A loop intentionally formed in the cable to compensate for the expansion and contraction caused by temperature changes
Expansion Loop
used to counteract the horizontal component of forces placed on poles by the strand and cable
Guy and Anchor
Strand that connects the pole line hardware to anchor
Guy
Buried metal device used to transfer force from the pole to ground
Anchor
strand that connects the pole line hardware, particularly the guy attachment hardware to the anchor.
Guy Wires
is a yellow plastic cover used to protect the guy wire and make it more visible
Guy Wire Guard
Different types of Guys
Down Guy, Head Guy, Terminal Guy, Side Guy, Pole to stub guy, pole to pole guy, sidewalk guy, and storm guy
Different types of anchors
screw anchor, never creep anchor, rock anchor, anchor rods(AKA Guy rods)
the device usually a screw used to connect the coax’s center conductor to an active or passive device
Seizure Mechanism
is used to remove the outer jacket of a typical underground cable
stripping tool
may remove the jacket, but primarily removes the outer sheath and dielectric within the cable
Coring Tool
having a saw toothed edge or margin notched with tooth like projections
Serrated
these tools are specifically designed to cut coaxial cables
banana cutters
