various ct level questions Flashcards
Two causes for an aerial lift to cease functioning while aloft
Hydraulic lift malfunctionInoperable upper controls
Three aerial lift operational hazards
ElectrocutionInjuries from falling, equipment failure, and unstable maneuveringTraffic lanes
Describe how the commtech’s role may contribute to a successful preventative maint. program?
Respond quickly and efficiently to restore serviceperform work without degrading or interrupting serviceWork toward preventative maint. rather than repair
Three main causes of aerial lift accidents?
stability problemsoperator errorviolating OSHA regulations
How often are vehicle maint. checks completed?
Daily, weekly, monthly, bi-monthly, and semi-annually
Once completed the FCC form 320 is kept in?
The public file
Output C/N improves by _____ for each dB the input is raised?
1dB
What are two fiber splicing methods?
FusionMechanical
Hum modulation is measured in?
Percentages
Why is 16 QAM a faster modulation technique than QPSK?
Four amplitude levels are used.(2 above and 2 below each axis)
What is considered to be a ‘headend’ FCC POP test?
Differential Gain Differential Phase
T or F The video carrier under test must be on for the CTB measurement?
False
What do you test prior to operating from the aerial lift bucket
Always test the lift controls from the ground daily and verify that all are operating properly
7 Touchstones
DiversityRespectQualityEthicsEnthusiasmEmployee FocusFlexibility
What is an advantage that rebuilding a system has over an upgrade
Rebuilding increases the useable bandwidth
A reflection with the same polarity as the launch reflection indicates a(n)?
Open
What is Comcasts goal for network reliability?
4 nines / 99.99%
ICFR must be measured through a _______
Set-top-box
The _______ is the load-bearing component of an aerial hardline cable installation
Strand
What is meant by single mode?
One wavelength
Batteries should be within ____ VDC of each other
.3VDC
Which architecture offers the highest level of reliability?
Ring
Maximum length of data carrying CAT5
328’ or 100 meters
Three parts of fiber
Core CladdingCoating
Three criteria for positioning your aerial lift
Minimize reachAvoid overhead obstaclesProvide safe and proper lift rotation
What material is used for doping fiber amps in the 1550nm band?
Erbium
When a loss of AC is determined to be a power company problem you should?
Contact the power company and follow your systems stand-by generator procedures
Deactivate anonymous call rejection
*87
Refractive index
Ratio of the velocity of light of two mediums of optical glass
Port-to-port isolation
The difference between the two output ports with the input port terminated
What is the cut-off freq. for a sub-split diplex filter at/around
50 Mhz
A cable with a single strength member in the center surrounded by the color coded buffer tube is known as?
Loose tube
Number of cycles of an AC waveform that occur in one second?
Frequency
What type of guy is used when strand changes direction?
Side Guy
What causes beats?
Unwanted carriers entering the systemCo-channelAmp levels running several dB higher than specified
How much time should be added to the 3-4 second rule when towing a trailer?
2 seconds
What is the maximum variation within a 24hr adjacent channel interval?
3dB
When performing a proof-of-performance, what is the maximum variation within a 6mo interval?
8dB
Initiate call trace
*57
How many times must the 24hr level variation test be performed?
4
Why didn’t the skeleton cross the road?
He didn’t have the guts!
Calculation for Wavelength?
Freq / speed of light
Laser Classes
ANSI Standard Z-136Class 1: Safe as long as not disassembledClass 2/2A: Eye hazard if beam is viewedClass 3A: Eye hazard if collected or focused on the eyeClass 3B: Eye hazard if the direct or reflected beam is viewedClass 4: Eye and skin hazard
What is the OTDR “dead zone” and how do you overcome its effect?
The length of fiber nearest the OTDR that is affected by the recovery of the receiver from the laser test pulse.Overcome by using a “launch fiber” sometimes called a “pulse suppressor”
4 types of AC waveforms?
Sine SquareQuasi-squareSawtooth
A reliability of “five nines” would allow how much downtime per year?
5.24 mins.
What is required to safely operate your aerial lift vehicle at the work site?
Properly using decalsUnderstand operational hazardsUtilize proper traffic controls techniques and safety equipment
Laser commonly used for downstream laser transmitters?
(DFB) Distributive Feedback
Hazards involved in parking an aerial lift on a slope
Reduced stabilityPlaces additional stress on the rotation systemRequires extra precaution to avoid overturning the vehicle
What doe s a spectrum analyzer do?
Continually scans the spectrum and has ‘zoom’ functionality
The effect that causes the optical signal to remain within the core of the optical fiber is called?
total internal reflection
What PPE should always be worn while working in your bucket?
Hardhat, gloves, safety boots, and eye protection
What situations require aerial rescue of an aerial lift operator?
Mechanical failureOperator falling out of the bucketUpper controls becoming inoperable
What component converts AC power to DC power needed to operate an amplifier?
DC power pack
Three protection methods used when working above 4ft on a tower?
Double lanyardFixed cable systemRetractable device
When does the 2-15ft rule apply?
when setting up a road side work zone 2ft from the curb or 15ft from the edge of the road
Amount of time it takes a waveform to complete 1 cycle?
Period
Goals of using proper traffic control techniques
Reduce accidents, minimize the chance of injury to employees and the public, reduce the chance of damage to private and public property, minimize the possibility of claims and litigation arising from work zone accidents, reducing confusion to motorists, expedite traffic flow, improve public image
What causes a stationary (or slightly moving)vertical bar in the video portion of a channel?
Cross Modulation
T or F a CLI flyover can be done at 450 meters?
True
How many phase angles are there in QAM?
4(0/360, 90, 180, and 270 degrees)
LASER
Light AmplificationStimulated byEmission ofRadiation
What is the function of the video bandwidth filter on a spectrum analyzer?
Takes the RF energy that has already passed through the RBW filter and the detector and smoothes it out
Nyquist’s Rule?
C/N gets worse by 3dB each time the number of amps doubles.
Gated testing is ________
The ability to perform an intrusive test, non-intrusively.
How do you prevent accidental contact with electrical power?
Position your bucket lower than any power lines or components ie. transformers
Ratio of the velocity of light of two mediums of optical glass?
Refractive Index
What are the advantages of an HFC network?
Enhanced picture qualityIncreased reliabilityDecreased cost of system maint.
Components included in an aerial lift inspection
Bolts, welds, hydraulic oil level, hydraulic oil lines, loose objects on the boom and in the bucket, lower and upper controls, leveling system, decals, and bucket.
Minimum Clearance Requirements
300V or less: Avoid Contactover 300V under 750V: 12 inchesover 750V under 2 KV: 18 inchesover 2 KV under 15 KV: 24 inchesover 15 KV under 37 KV: 36 inchesover 37 KV under 87.5 KV: 42 inches
Types of decals
Danger WarningCautionOperating Instructions / Notice
Which fiber is considered to be the first fiber in the bundle?
Blue fiber, blue tube
What is the purpose of an EQ in a CATV amplifier?
It compensates for cable loss
When are aerial lift inspections conducted
Daily WeeklyMonthly
Ohms law for voltage?
E=IxR
1 complete sine wave?
Cycle
What are the different fiber connectors?
FC: ferruled connectorSC: snap connectorAPC: angle polished connectorUPC: ultra polished connectorLCSC: Special optical fiber connector used in gigabit Ethernet devices
Loop resistance is equal to the sum of the resistance of its_______and_______?
Center conductorSheath
How do you stand in your bucket to avoid falling out?
Feet flat on the floor of the bucket
How do you raise and lower tools and equipment from the bucket?
Hand line
What do you evaluate before ascending in an aerial lift?
Evaluate the desired work position of your bucket
Ohms law for current?
I=E/R
T or F Hum Modulation must be checked on at least 2 channels?
False
What is the first priority in an emergency rescue operation where the operator is injured or incapacitated?
The safety of the personnel involved
Fiber work area
Flat smooth surfaceDark colorResistant to the chemicals you’ll be using
In fiber what is the largest cause of attenuation?
Scattering
Three Federal aerial lift safety rules?
OSHAANSIDOT
To prevent stress on the fiber, cable manufacturers put about 1% more fiber in the cable then the length of the cable itself to allow for some “stretch”. This is called?
Lay loss factor
If you detect a leak coming from a customers house you must?
Notify the customer and arrange for access so that repairs can be made
What must you do prior to working aloft in your bucket?
always put on an approved fall arrest system (five point harness and deceleration lanyard)
Three aerial lift limits
Boom lift capacityBucket load capacityChassis weight
T or F CLI measurements are included in the FCC POP tests
False
What is the first thing you should do after an accident?
Protect / Secure the scene
The 24hr level variation tests must be performed at what intervals?
5-7 hours apart
Activate speed dial 8?
*74
Low cost narrow bandwidth laser used in the return path of two-way networks?
Fabry-Perot
What are the two common wavelengths used for optical fiber?
1310nm1550nm
Two main risks associated with operating an aerial lift?
electrocution injuries caused by falling
How often are FCC proof of performance tests performed?
Twice a year
How many test channels are needed for a 700Mhz system proof-of-performance?
10
DOCSIS
DataOverCableServiceInterfaceSpecification
Ingress?
Undesired signals entering the cable plant
For every dB the levels of an amplifier are raised, the carrier to Xmod ratio gets________?
2dB worse
How do you secure / optimize the stability of your aerial lift vehicle?
Maintain proper tire pressurePosition the vehicle near the work siteFace the vehicle up or down slopeHead the boom uphill and maintain the boom beyond the center of the vehicleUse outrigger padsDo not exceed a 5deg slope
Star code for last number dialed?
*69
What “absolute measurement” do you make with a power meter?
optical power
Three areas of lift inspections
truckboombucket
The FCC form used to monitor CLI performance is?
FCC form 320
A leak between 54-216 Mhz must not exceed
20umv at 3 meters
When using a TDR to find a fault you should?
Test the cable from both ends and cut the overlapping portion in half
Formula for C/N
C/N=L1-(NF-59.2)
The FCCs concern with CATV signal leakage is due to?
Interference with navigational and communications equipment
Methods used to perform CLI tests are?
Fly overSystem ride out
Commtech work shirts should be made of what material?
100% cotton
Which pad value is typically used in return amplifiers?
Zero
Ohms law for resistance?
R=E/I
T or F it does not matter which fiber is spliced first when restoring a cut fiber during an outage?
False
What is “7” equal to in binary?
0111
What gas is produced when batteries are charging?
Hydrogen
