NCT4 v2 Flashcards
Random electron activity in the atoms that make up the conductor
Thermal Noise
Noise floor in a 4MHz bandwidth @ 68*F is called:
Termination Noise
Difference in a peak carrier level to the noise floor:
Carrier to Noise
Amount of noise in a 4MHz bandwidth on a 75 Ohm cable @ 68*F
-59.16dB
FCC Spec for C/N
43dB
Undesired change in the waveform of a signal
distorion
Crossing of Modulation from one channel to another
XMOD or Cross Modulation
XMOD appears as
Vertical bars in the picture
2nd harmonics of any 2 channels are typically _____ below the sum/difference products
6dB
CTB products fall within _____ of the video carrier
30 KHz
Tilting the output of an amplifier improves:
Distortion performance
CSO beats fall @ __________ above the video carrier
1.25MHz +/- 15 KHz
unwanted sum/difference frequencies resulting from heterodyning of 2 or more signals
Beats
A horizontal bar in the picture is _______ Modulation
Hum
Primary cause of Hum (60Hz)
Power Passing Choke (60Hz)
A source of hum in older systems (120Hz)
Series regulated DC Power supplies (120Hz)
3 parts of fiber
Coating, Cladding, Core
When light stays in the core, this is called
Total Internal Reflection
2 wavelengths used in HFC Networks
1550nm & 1310nm
Most common type of fiber used in the cable industry
Single Mode Fiber
Wavelength is ________ proportional to frequency
Inversely
A shorter wavelength means a _______ Frequency
Higher
Compares the speed of refracted light in a material to the speed of light in a vacuum
Index of Refraction
One Billionth of a meter
nanometer
Device that takes the RF and modulates it onto an optical wavelength
Optical Transmitter
Optical transmitters use this type of diode
Laser Diode
What device detects light and demodulates it to RF
Optical Receiver
An optical receiver uses this type of Diode
Photo Diode
C/N Formula
L1-(NF-59.2)
Formula for C/N @ end of cascade
C/N1-10logN (C/N1 is equal to the C/N of a single amplifier in the cascade, N=Number of amplifiers)
XMOD Formula
XMOD1 - 20logN
CTB Formula
CTB1 - 20logN
Devices that are used to compensate for the forward and return loss
Amplifiers
What device compensates for the uneven cable loss in coax?
Equalizer
Amplifier input EQs are selected to do what?
Provide flat inputs to the first stage of amplification
amplifier interstage EQs are selected to do what?
Provide output tilt
Forwards trunk amplifiers are selected for their what?
Low Noise Figure (NF)
What compensates for fluctuations in the input signal?
AGC
The name of the frequency that is monitored by the AGC
Pilot
It provides a means to monitor levels with out interrupting service
Test Point
This device has substantial isolation between it’s output & tap port:
Directional Coupler (DC)
What device has both a DC & Splitter built into it?
Tap
What device is considered to be the customer interface point?
Tap
This device compensates for reverse tilt on the feeder
In-Line EQ
This device has a diplex filter & a pad that will only affect the return
In-Line Conditioner
This device uses a low pass filter to prevent RF from entering the Power Supply
Line Power Inserter (LPI
This map only shows the poles & Strand
Strand Map
This map is the point where actives are added to the network
Design Map
This map shows the network changes from the original design as the design needed to be modified when it was being built
As-Built
This map shows only one Node
HFC Plant Map
The numbering system used to catalog plant maps is called:
Map Grid System
CLI
Cumulative Leakage Index
Leaks _____ and greater are included in the CLI calculation
50uV/m
CLI is performed how often?
annually
What form is used to submit CLI to the FCC?
320
Leakage monitoring must be performed how often?
Every 90 days
During Leakage monitoring, leaks _____ and greater must be logged and repaired
20uV/m
Leakage logs must be kept on file for how many years?
2
Signal levels that are ________ or higher must be offset
38.75dBmV
A method used to pin point a leak
Triangulation
FCC requires that measurements are made with a ______ antenna
Dipole (1/2 Wave Pole)
CTB falls within ______ of the video carrier
30KHz (all channels EXCEPT 5 & 6)
AM
Amplitude Modulation
PM
Phase Modulation
FM
Frequency Modulation
Modulation used for Video
Amplitude Modulation
Modulation used for Color
Phase Modulation
Modulation used for Audio
Frequency Modulation
The video carrier is ______ higher than the lower edge of the channel
1.25 MHz
The color carrier is ________ from the video carrier
3.58 MHz (4.83MHz from lower edge of channel)
The audio carrier is _________ from the video carrier
4.5 MHz
CSO fall ________ above the video carrier
1.25MHz +/- 15KHz
CTB are within _______ of the video carrier
30KHz
The speed at which a wavefront passes through a medium, relative to the speed of light.
Velocity of Prorogation
The difference in voltage between one point and another is called
Potential Difference
Substance that allows heat or electricity to pass along or through it is called
A Conductor
The difference of an electrical field in radiated wave is
Polarity
Subatomic particles found in atoms that balance out the positive charge of a proton (within the nucleus) with their negative charge
Electrons
An electrical current, of which the polarity is periodically reversed
Alternating Current
Frequency Divided by the speed of light =
Wavelength
_____ is the amount of time it takes an AC waveform to complete one cycle
Period
The peak value of an AC waveform is also known as its
amplitude
1 complete sine wave =
Cycle
number of an AC waveform that occur in 1 second
Frequency
Ohms Law
E=IxR
R=
the resistance in Ohms
E=
The electromotive force (EMF) in volts
I=
The current in Amperes
A design philosophy where the loss of the cable and other passive devices before an amplifier station equal the gain of the amplifier
Unity Gain
A representation of the networks response to a sweep signal and the effects of all the network components such as cable, connectors, passive devices, and the signatures added by the amplifiers
Sweep Response
The difference in cable attenuation or amplifier gain between lower and higher Frequencies on the network
Tilt
The difference in gain between the ends of a band of frequencies
Slope
A gradual or sharp attenuation of gain (versus Frequency) at either or both ends of the spectrum
Roll-off
a sharp reduction in the amplitude of a narrow band of frequencies within the networks overall response
Suck out
an active device used to increase the level of an input signal. Used in a cable system to compensate for the effect of attenuation caused by coaxial cable and passive devices
Amplifier
Small plug-in device used to attenuate signals to the correct operating levels
Pad
A device used to reduce signal strength
Attenuator
In a cable amplifier it is typically a small, plug in device used to compensate for the fact that coaxial cable attenuation varies as the square root of frequency
Equalizer
The effect a particular type of amplifier has on the overall frequency response
Signatures
the difference between in amplitude between the most positive (Peak) and the most negative (Valley) levels of a electrical signal
Peak to Valley
Outline or multiple images of the primary TV picture offset to either side
Ghost
Caused by direct pickup (off air signal getting into the cable system)
Leading Ghost
An oscillator controlled so that it maintains a constant phase angle relative to a reference signal source
Phase Locked
Usually caused by signal reflection
Following Ghost
The unwanted sum and/or difference frequencies resulting from heterodyning (mixing) of two or more signals
Beat
A method of reception using an RF current of the proper magnitude and phase relation so the received voltage is if the same nature as the original wave
Zero Beat
caused in one channel by the same carrier from another transmitter operating on the same channel
Co Channel interference
chemical change caused by a reaction to Oxygen such as rust
Oxidation
A theoretical temperature equivalent to the absolute absence of heat equal to - 273.15 degrees C or -459.67 degrees F
Absolute Zero
Noise added to the response due to a lack of or improper termination
Termination Noise
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