NCT4 Flashcards
(413 cards)
1
Q
A frequency selective receiver capable of tuning in a desired frequency/Channel with a display showing RF signal strength (dBmV)
A
Signal Level Meter (SLM)
2
Q
The minimum signal level at the input to the customers TV is
A
0dBmV to 15dBmV
3
Q
what do you need to do to maintain an SLM
A
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,
4
Q
The ratio of error power to average power in an ideal QAM signal is
A
MER
5
Q
Average power =
A
Digital power
6
Q
Peak Power=
A
Analog power
7
Q
Optical power units
A
mW or dBm
8
Q
RF power units
A
mV or dBmV
9
Q
Attenuation/ gain units
A
dB
10
Q
what mode monitors up to 12 chs at a time on your meter
A
Miniscan
11
Q
what mode monitors the entire Ch plan on your meter
A
Full scan
12
Q
what mode check s the forward low frequency and high frequency channel tilt
A
Tilt mode
13
Q
Detects errored bits in the system
A
Bit error Rate (BER)
14
Q
used for troubleshooting connections with intermittent bit errors occuring over a period of time
A
Errored Seconds
15
Q
passage of an outside signal into the cable; can result in noise and disruption of the desired signal
A
Ingress
16
Q
shows impairments on the networks with the patterns on display and can be identified by figuring out the patters
A
Constellation Graph
17
Q
Displays intermittent short duration impairments missed by MER and BER on your meter.
A
Digital quality index (DQI) mode
18
Q
this mode shows you if ingress is within the downstream digital spectrum without turning of service
A
QAM ingress mode
19
Q
This mode greatly improves the success rate and efficiency in locating return-path ingress
A
Fieldview Option
20
Q
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
A
Sweep
21
Q
Provides a quick method to check cable system integrity, using active channels to sweep the forward path is
A
Sweepless Sweep
22
Q
Using a unique method to accurately reveal any problem in the system without interfering with any of the analog/ Digital carriers is
A
Forward Sweep
23
Q
Helps find mismatches or other problems in the upstream transmission path
A
Reverse Sweep
24
Q
Accurately measures Ac voltages of signals other than pure analog sine waves
A
Root Mean Square Meter (RMS)
25
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)
26
is used to find the location/path of underground cables
Cable locator
27
has a transmitter and receiver. it could include the following components a test lead, inductive frame and A-frame.
A locator
28
The resistance of a circuit to alternating current.
Impedance
29
The condition that results when two components of a system are operating at different impedance
Impedance Mismatch
30
is used to determine the distance of a known fault from a specific location
Time Domain Reflectometer (TDR)
31
Is used to locate: bad or unknown splices, opens, shorts, and kinked cable.
TDR
32
A reflection with the same polarity indicates an
open
33
is a situation where the center conductor comes in contact with the shield
Dead Short
34
A reflection with the opposite polarity indicates that the fault is
Short
35
refer to a cable that has not been competely cut
Partial Open
36
The contact between the center conductor and the shield is not complete
Partial Short
37
The distance that cannot be seen by the TDR because its too close to the TDR source
Deadzone
38
two types of TDRs
Waveform and Digital
39
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
40
A device that generates a light source used in fiber communication
Laser
41
LASER
Light Amplification by Stimulated Emission Radiation
42
Most light generated by lasers for telecomm use exists in the infrared band of 1310nm and 1550nm wavelengths
Infrared Light
43
the distance between two points of like phase in a wave
Wavelength
44
A card made up of material similar to photographic film that changes colors when exposed to light
Photosensitive Card
45
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.
46
what is the laser standard
ANSI Z-136
47
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
48
what are the two methods of fiber cleaning
Wet and Dry
49
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
50
rotate a cleaning cloth over the end of a fiber connector by pushing down toward the connector
Push Pen
51
A battery or generator that provides electrical power to the circuit. For example, batteries and generators
Power Source
52
A conductor such as copper wire
Path
53
the device that uses the electricity. it is any device that draws current
Load
54
Substance that allows heat or electricity to pass along or through it
Conductor
55
Subatomic particles found in atoms that balance out the positive charge of a proton with their negative charge
Electrons
56
is the electromotive force that causes electrons to flow in a circuit
Voltage (E)
57
The pressure that causes electrons to flow in a circuit
Electromotive Force
58
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)
59
The amount of electrons that pass a given point in the conductor in one second
Coulomb
60
is the opposition a material offers offers to the flow of current
Resistance (R)
61
the difference in voltage between one point and another
Potential Difference
62
the direction of an electrical field in a radiated wave
Polarity
63
An electrical current of which the polarity is periodically reversed.
Alternating Current (AC)
64
the point at which the filament reaches a temperature that causes it to glow
incandescence
65
the relationship between current or voltage and elapsed time
AC Waveform
66
what are the 4 types of AC Waveforms
Sine Wave, Square Wave, Quasi-square wave, and Sawtooth Wave
67
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
68
This waveform is often found within the switching regular DC output power supplies in Amplifiers
Square Wave
69
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
70
Types of signals carried on the HFC system
Modulated RF carriers, Modulated analog carriers, DC power and AC power
71
one complete sine wave is
Cycle
72
Number of cycles of an AC waveform that occur in one second
frequency
73
the speed of the light/Frequency=
Wavelength
74
the amount of time it takes a waveform to complete one cycle
Period(T)
75
peak value of a waveform
Amplitude
76
states that current is directly proportional to voltage and inversely proportional to resistance
Ohms Law
77
R=
The resistance in ohms
78
E=
the Electromotive force(EMF) in volts
79
the rate a which work is done or the rate at which energy is used
Power
80
I=
current in Amperes
81
Resistance is measured between the center conductor and sheath with the other end
DC Loop Resistance
82
P=
WAtts
83
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
84
the amount of voltage loss over the span is referred to as
Voltage drop
85
At lower voltages the current is higher in the HFC plant
Current at lower voltages
86
the amount of energy available to move a certain number of electrons from one point to another in an electrical circuit
Voltage
87
to be subjected to the action of an electrical discharge
Shock
88
to kill by electrical shock
Electrocute
89
a connection to the earth or a grounding device
Ground
90
power supplies reduce the secondary power (120 or 240) to the 60 or 90VAC for insertion in the cable
Line power supply
91
the electricity provided by the local power company
commercial power
92
2 types of line power supplies
standby and non standby
93
reduction of voltage by a transformer
stepped down
94
conversion of voltage, in this case from 36 or 38VDC to 60 or 90VAC
Inverted
95
the point where AC power from the power supply is placed on the coax portion of the distribution network.
Power inserter
96
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)
97
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)
98
the two types of network powering
Distributed and centralized powering
99
batteries produce what kind of gas during charging operations
Hydrogen
100
three methods for testing batteries
battery load test, battery voltage test, battery conductance test
101
the most accurate and reliable test involves testing the batteries under a load condition
Load Test
102
the difference between any batteries in the set should not be greater than
0.3VDC
103
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
104
means of testing the network remotely that saves numerous problems in respect to downtime and customer dissatisfaction
status monitoring
105
according to manufacturers the terminals should be torqued to_____and then retorqued to _____ during routine maintenance.
75inch lbs and 60 inch lbs
106
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
107
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
108
Forward signals originate at the headend are transmitted downstream by way of the trunk to the ends of the service.
Transportation (Trunk)
109
In a Tree and Branch system the feeder is considered what
The distribution System (Branches)
110
in a tree and branch system RG-6 and 11 is considered
The Drop(Leaves)
111
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)
112
what are the two wavelengths of fiber do we use
1310 nm and 1550nm
113
a network architecture where nodes, hubs, or headends may be connected with fiber optic cables to provide redundancy or increase services.
Ring
114
What are the advantages of fiber
Greater Bandwith and can travel greater distances without Amplification
115
what are the two types of Fiber
Single mode and Multi mode(we use single mode)
116
what is the attenuation of single mode fiber
1310nm=.35dB/km, 1550=.25dB/km
117
the distance between two points of like phase in a wave
wavelength
118
compares the speed of light through a material to the speed of light through a vacuum
Index of Refraction
119
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
120
Single mode core is how many microns
8 to 9 microns
121
single mode cladding is how many microns
125 microns
122
single mode coating is how many microns
250 microns
123
what is the primary loss in fiber called
Scattering
124
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
125
separates or combines the AC currents two parts-( AC power and RF broadband signals)
Power Diplex
126
attenuates the signal in order to bring it to within the acceptable range of the amplifier
Pad
127
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
128
Usually selected for low noise figure. Amplifies forward signal passing through the trunk and distribution lines
Forward Amplifier Module (TRUNK)
129
Used to compensate for fluctuations of the input signal
AGC
130
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
131
Signal splitting device that plugs into a trunk/bridger chassis
directional plug ins (feedermaker)
132
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
133
used to direct AC power into and out of specific ports of the amplifier station
Power Director
134
provides a means of monitoring the various inputs and outputs without interrupting service
Test Points (TP)
135
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)
136
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)
137
Low frequency signals are not attenuated as much as high frequency signals in a coaxial cable
In line Equalizers
138
LIke in line EQs these devices are sometimes installed in the distribution cable where low value taps are used
in line conditioners
139
in a housing like the splitter is used to introduce AC power into the network
Power Inserter
140
A design philosophy where the loss of the cable and other passive devices before an amplifier station
Unity Gain
141
similar to a street map and includes features like lakes and rivers, streets, and boundaries
Base Map
142
Displays streets with poles and pedestals locations and includes the span length or footage between these items
Strand Map
143
Shows the locations of electronic equipment. including headend and any hubs,amplifiers, power, supplies, and taps.
Design Map
144
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
145
A corrected map that represent the addition or changes in information on the design map
As Built map
146
Map that covers a single node
HFC Plant map
147
documents a fiber plant
fiber design map
148
catalogs the system maps
Map Grid System
149
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)
150
What do reflections do on a coaxial cable
They distort the carriers, causing bit errors in the modulated data streams.
151
a thin wire wrapped around the fiber and coaxial cables to secure them to the strand
Lashing wire
152
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
153
A loop intentionally formed in the cable to compensate for the expansion and contraction caused by temperature changes
Expansion Loop
154
used to counteract the horizontal component of forces placed on poles by the strand and cable
Guy and Anchor
155
Strand that connects the pole line hardware to anchor
Guy
156
Buried metal device used to transfer force from the pole to ground
Anchor
157
strand that connects the pole line hardware, particularly the guy attachment hardware to the anchor.
Guy Wires
158
is a yellow plastic cover used to protect the guy wire and make it more visible
Guy Wire Guard
159
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
160
Different types of anchors
screw anchor, never creep anchor, rock anchor, anchor rods(AKA Guy rods)
161
the device usually a screw used to connect the coax's center conductor to an active or passive device
Seizure Mechanism
162
is used to remove the outer jacket of a typical underground cable
stripping tool
163
may remove the jacket, but primarily removes the outer sheath and dielectric within the cable
Coring Tool
164
having a saw toothed edge or margin notched with tooth like projections
Serrated
165
these tools are specifically designed to cut coaxial cables
banana cutters
166
what are the two steps in building the aerial portion of the network
the strand system must be built and properly tensioned and the cable must be lashed onto the strand.
167
to wrap a thin wire around the cable in order to secure it to the strand.
Lashed
168
this device is selectively placed at pole hardware locations to prevent dangerous sag while strand is being installed
Strand Brake
169
used in conjunction with a lay up stick to lift cable blocks and strand
Wire raising tool
170
used to prevent unwanted payoff of strand from the cable trailer or reel stand
Reel Brakes
171
are portable bonding connections installed at the location where the strand is spooled from the cable trailer or reel stand. can be removed only after the strand is bonded to the grounding network
Traveling grounds
172
two types of strand methods
Stationary reel method and Moving reel method
173
installation of pole hardware allowing for hanging of strand
Framed
174
the trailer should be at a minimal distance (two times the hardware attachment height) from the pole at which the strand first contacts the pole line hardware
Stationary reel method
175
the strand is installed by mounting a reel to a vehicle and driving the vehicle from pole to pole stopping to install the strand and hardware at each location
Moving reel method
176
Strand splices should be placed outside the pole framing hardware, but within 18 to 24 inches of the pole . traveling grounds should always be used when placing the strand
Stationary reel method
177
uses a mechanical wrenching action to bend expansion loops into coaxial cable prior to lashing or during splicing
Mechanical Bender
178
used to measure the pulling tension applied to cables
Dynamometer
179
allows cables that are being pulled to swivel and are used to ensure that the cables are not over-tensioned during pulling
Breakaway swivel
180
used to support a single lashing may be used when cables are lashed directly to the strand or in overlash applications
Single roller Block
181
used to install self support cable and is attached to the pole hardware support the cable as it is pulled out
Pole Mount Cable Block
182
used to support a single cable prior to lashing
Economy Block
183
This device is used to route cables through inside or outside corners up to 90degrees. it minimizes drag on the cable in corners and ensures that the minimum bend radius of the cable, as specified by the manufacturer is not exceeded
90 degree corner block
184
used to route cables through inside or outside corners up to 45degrees. it minimizes drag on the cable in corners and ensures that the minimum bend radius of the cable is not exceeded
45 degree corner block
185
used to guide cables from the cable trailer or reel strand to the strand
Set up Chute
186
this bracket is used to support 45 and 90 degree corner block or setup chutes at the mid span
set up bracket
187
used to lash cable directly to installed strand or cable bundles
cable lasher
188
allows multiple cables to be pulled into place when lashing cable directly to strand
Multiple cable puller
189
allows multiple cables to be pulled into place in overlash applications
Overlash cable puller
190
device is used to push equipment ahead of a pulled lasher
Cable block pusher
191
pushed in front of a lasher by a cable block pusher to uniformly position multiple cables that are being lashed
Cable positioner (Magic Box)
192
is the tension caused by the mass of cable on the reel and reel brakes.
tail loading
193
what two methods control tail loading
can be minimized by using minimal braking during the payoff of the cable from the reel. and at times no braking is preferred.
194
If a span is _____ or longer place ____ expansion loops on each pole. one is placed on the input side and one is placed on the output side of the pole
250ft and 2
195
is when two perpendicular strands end at the same pole
Double dead end
196
the mechanical bender must remain in place until the lasher is transferred and the next span of cable is
lashed 50ft or 1/3 the distance to the next pole whichever is greater
197
An expansion loop should be formed on the ___ side of every pole for all sizes of coaxial cable being used
Output
198
When the loop location is dictated by the signal flow direction of the feeder cable
Feeder Dominant
199
the trailer should be positioned in line with the strand and twice the distance _____
of the set up chute to the ground from the chute (Stationary Reel method)
200
The cable should payofff the___
Top of the cable reel
201
Use a cable block lifter to place _____ on the strand every 30 to 50ft
cable blocks
202
the ends of the cable left at the pole for splicing
Cable Tail
203
it is essential that double lashing be used when___
two or more cables, all trunk cables, and at street crossings.
204
how many feet do you stop the lasher to form an expansion loop
6FT
205
is a connection to earth or a conductor serving earth potential and can be intentional or accidental
Ground
206
is the interconnection through good conductors of the cable plant with power and phone systems to eliminate potential voltage differences
Bond
207
is a pipe usually made of PVC and used to house cable and protect it from dirt, moisture, and outside forces.
conduit
208
is a protective covering for hardline cable, typically made from galvanized steel or plastic over the exposed cable where it makes the transition from aerial to underground.
Riser Guard
209
conduit for underground drops must be buried to a minimum depth of
8inches
210
installing all underground drops emerging from the ground must have physical protection (cable guard or conduit) to a point at least ________located at the house
4ft above ground or until reaching the service enclosure.
211
underground drop cables routed down a pole must have physical protection, cable guard, or conduit, to at least
8ft above ground and at least 8inches below ground
212
a high visibility tape usually used when burying fiber optic cable, buried directly above the cable point out the existence of the cable to anyone digging in that location
Warning Tape
213
bury warning tape above the cable at a depth of___ during the back fill process
12inches
214
Locate the midpoint of the pull. while monitoring pulling tension, pull the cable from the mid point to the end of one direction.(Used for installing long fiber runs)
Mid point cable pull
215
what u do with the remaining fiber optic cable
figure eighting
216
while doing the figure eights with fiber u set the cones up ____ apart
10-15 paces
217
the US government agency established in 1934 to regulate electronic communications
Federal Communications Commission(FCC)
218
In 1990, the FCC required that system perform s CLI test ____
Annually
219
a figure of merit derived mathematically from the number and severity of signal leaks in a cable system.
Cumulative Leakage Index
220
the figure of merit for CLI has to be
64 or less
221
your CLI test that you do annually has to be submitted using what form
FCC form 320
222
a system in which transported signals are completely contained within the medium is called
a closed system
223
Leakage is emitted RF energy and is called
Egress
224
Noise is received energy and is called
Ingress
225
what % of leakage is found between the tap and bonding block
70%
226
LTE
Long Term Evolution
227
LTE operates in the ____frequency range
700 to800 MHz
228
No more than 15 microvolts per meter @30 meters
0-54MHz
229
No more than 15 microvolts per meter @30 meters
More than 216MHz
230
No more than 20 microvolts @3 meters
54MHz and 216MHz
231
the aeronautical frequencies are
108-137MHz
232
two ways to do the CLI test
Ground based and flyover
233
Leakage monitoring must be done
Quarterly
234
Leakage logs must be kept on file for
2yrs
235
Only Leakages___ or greater are included in the CLI calculations
50 microvolts
236
CW
continuous wave
237
three methods to calibrate your leakage detector
Done by the manufacturer, Direct coupling, and Antenna
238
what method do you use to pinpoint a leak
Triangulation Method
239
a leakage log should include
Date;location;leakage cause;strength;distance to leak; Date;Strength after repair.
240
leaks__ or greater must be logged for regular monitoring
20 microvolts
241
the FCC requires that __ of the plant be tested for CLI. The comcast standard is _____
75% and 100%
242
The CLI is done at an altitude of ____, using 108 to 137MHz band
1500ft(450Meters)
243
Sending AC from two different power supplies, causing a large spark
bucking power
244
Comcast troubleshooting steps
Identify, Isolate,Fix,Verify
245
a low resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current
Shunts
246
Steps for verifying a backwards tap
1) the tap plate and re-check the input port. 2)if there is no signal present, check the output port. 3) if signal is present here, the housing is backwards and requires re-splicing.
247
if you encounter a conductor that is 300v or less
avoid contact with the conductor
248
if you encounter a conductor that is between 300V and 750V
stay at least 12 inches away from this conductor
249
do foreign voltage detectors DC voltage
NO
250
Divide and conquer does what
reduces repair time.
251
the reverse path must be balanced for___ just as the with the forward system
unity gain
252
threshold for ingress at 5-18mhz
-20dBc (Decibels relative to carrier)
253
threshold for ingress at 18-42mhz
-35dBc (Decibels relative to carrier)
254
Max min sweep formula
N/2+1.5=
255
telemetry reverse sweep formula
N/2+1=
256
is defined as two or more customers without service or with impaired service, due to the same root cause
outage
257
is a plant fault with overlapping correlated trouble call
priority plant fault
258
is a signals inability to be transmitted from one cable or device to another cable or device and measured in dB
Isolation
259
is the difference in dB, of a signal level, injected into one output port, and the measured level of the same signal on another output port with the input port properly terminated
port to port isolation
260
is the interface location in a cable system where a fiber enters a neighborhood and the optical signal is converted into an electrical signal to connect to coaxial cables serving individual homes.
Node
261
a node has a minimum of
One optical receiver, one optical transmitter, power supply, and a forward and return amplifier module
262
is an amplifier used to transport signals to longer distances
trunk amplifier
263
used to add to the strength of signals in order to compensate for higher loss of the feeder and to provide enough signals for the drop cables and for multiple customers
Bridger amplifiers
264
are high gain amplifiers and are operated so that the output levels are higher as well
Line extenders
265
samples the stations output level using the directional coupler 15 usually at a specific frequency or channel. used to compensate for fluctuations of the input
Automatic gain control
266
recovers the RF information modulated onto the optical carrier at the headend
Optical detector
267
refers to the percentage of optical modulation, per channel, driving a laser transmitter
Optical modulation Index(OMI)
268
for every db change in optical power there is a 2db change in RF
know that rule
269
to energize or power the equipment( nodes amplifiers and other active devices in the rf portion of the network). usually includes checks for continuity, shorts, and signal flow.
activation
270
whatever tilt u need multiply by 1.25 to get desired eq
know this rule
271
has attenuation that duplicates that of a cable.
Cable Equivalency (Cable simulator)
272
used for the first stage of amplification for a trunk or multi output station, picked for its low noise figure
integrated circuit (IC)
273
this device monitors the change in temperature and makes an attenuation and tilt change based on typical cable spacing between stations
thermal level control
274
this is usually a power double device
second stage gain
275
is used to compensate for frequency response signatures of passive and active devices in the system,
Response network/Mop up
276
circuitry used to adjust the frequency of an amplifier
response network
277
usually a passive network placed between the input and output amplifier module. it is used to correct fro a frequency response problem seen at the output of the amplifier
mop up
278
the deviation in response at the output of an amplifier or passive device when compared to the response st its input.
signatures
279
used to set the amplifiers output tilt.
interstage Equalizer
280
a measure of an amplifiers output level to the level of distortion it produces
output capability
281
is used to inject return test signals for alignment/sweep of the return portion of the amplifier
Insertion point
282
Reverse pad=amplifier upstream design gain-total span loss
know this rule
283
have forward and return on the same test point
bi directional test points
284
RF portion of the cable plant fed from a node
Node service area
285
we can utilize a 3% ____ without excessive distortion with a carriage of 100 channels
OMI
286
is the actual seep response before normalization
raw sweep
287
is the exponent or the power to which a fixed number(the base) must be raised in order to produce a given number
logarithm
288
the number of times the base is multiplied by itself
exponent
289
1)any number raised to the exponent 0 is equal to 1.2)any number raised to the exponent 1 is equal to itself. 3) two multiply two or more numbers with the same base, simply add the exponents. 4) to divide two or more numbers with the same base simply subtract the exponents.
Exponent rules
290
is a number where the base is 10
power of 10
291
one tenth of a bel=
Decibel
292
is the unit for expressing in logarithmic terms, the ratio between two power levels
Bel
293
with the 10 log function each double in value is equal to 3.01db increase, while -3.01 divides the value in half
know this rule
294
an absolute level that describes the amount of signal at a specific location in the system.
dBmV
295
10log=
wattage
296
20 log=
voltages
297
0dBmV=
1mV
298
each 6dB change either doubles or halves the voltage, and each 20dB change affects the voltage by a factor of ten
know this rule
299
a discontinuous signal whose various states are discrete intervals apart
digital signal
300
used to convert an analog signal to a digital signal
Digitizer
301
are a continuous signal or carrier that varies in amplitude or frequency
analog signals
302
this term is short for binary digit. refers to an electrical impulse representing a zero or a one. the smallest unit of measurement a computer can handle
bit
303
a set of bits that represent a single character. usually there are eight bits in a
Byte
304
the number of changed states that can occur per second
Baud
305
advantage of analog transmissions are
1) no conversion necessary for human recognition 2) economical over short distances (up to 25miles)
306
disadvantages of analog transmission are
1) added distortion and noise when employing amplification. 2) electrical interference modulating the waveform. 3) limited distance for acceptable performance.
307
digital conversion consists of
sampling, quantization, and encoding
308
is the measuring of the analog signal at specific intervals
Sampling
309
is the assigning of a specific value to each of the samples
Quantization
310
is the process by which these values are converted into a data or bit stream
Encoding
311
can interfere with an analog signal and reduce its clarity
thermal or interfering noise
312
is synchronized with that of the transmitter so its available to read the digital sample when it arrives
digital receiver or regenerator
313
are regenerated rather than amplified
Digital bits
314
is the means of superimposing sound on an RF carrier
AM
315
is the means of superimposing sound on an RF carrier of a particular frequency
FM
316
3 different types of modulation in analog
Amplitude(AM),Frequency(FM), and Phase(PM)
317
five most common modulation schemes are
1)Amplitude shift keying(ASK) 2) Frequency shift keying(FSK). 3) Phase shift keying(PSK). 4) Quadrature phase shift keying(QPSK). 5) Quadrature amplitude modulation(QAM)
318
frequency and phase of the signal carrier are constant. amplitude is varied
Amplitude shit keying(ASK)
319
amplitude and phase of the signal are constant. frequency is varied. used in pathrak telemetries
Frequency is varied (FSK)
320
amplitude and frequency are constant. phase is varied.
Phase shift keying (PSK)
321
defined as the position on a waveform cycle at a specific point in time. on cycle is defined as 360 degrees of phase
Phase
322
the two most common digital modulation schemes that use a combination of changes are
QPSK and QAM
323
unwanted sum of and difference in frequencies resulting from the heterodyning of two or more signals
Beat
324
are caused when an analog TV signal arrives at a receiver just before or after the desired TV signal
Ghost
325
caused when the same channel from two or more different TV stations is received by the same antenna
co channel interference
326
caused by power line arcing, lightning, electrical motors, automobile ignition, and other sources of high rise time energy entering the cable system from the tap up to and including the TV receiver
Electrical interference
327
ingress from transmitters operating in the upstream frequency bandwith
return path interference
328
often caused by poorly made or corroded connectors ,it actually changes the shape of the RF wave from(disimilar metals)
common path distortion (CPD)
329
what causes CPD
when two or more carries encounter a non linear device, such as a connection where oxidation has occurred, harmonics and difference are produced
330
a chemical change caused by a reaction to oxygen, such as rust
Oxidation
331
a component frequency of the signal that is an integer multiple of the fundamental frequency.(twice whatever original frequency is)
Harmonics
332
the amount of noise an amp adds
noise figure
333
is caused by random electron activity of the atoms that make up the conductor, resistor, or any part of the passive circuit in question at any temperature above absolute zero
thermal noise
334
a theoretical temperature equivalent to the absolute absence of heat and equal to -273.15 degrees C, -459.67F, or zero degrees Kelvin
absolute zero
335
change in termination noise amounts to approximately .17dB per 20 degree fahrenheit change in temperature
know this rule
336
C/N Rules
Rule 1) if the input level numerically equals an amplifiers NF, the output ratio will always be 59.2dB. Rule 2) for each dB when the input level is raised above the amplifiers NF, the output ratio improves by an equal amount above 59.2. Rule3) C/N ratio at the output of a single amplifier is always worse than that at the input an amount equal to the amplifiers NF
337
log uses
10logN for C/N, 12 logN for composite second order (CSO), and 20 logN for Xmod and CTB
338
undesired change in the waveform of a signal
distortions
339
the second harmonic products of any two channels are typically 6dB below the level of the sum and difference products
Discrete second order
340
the combination of the amplitude and the logarithmic sum of the number of beats that fall in a channel determine the level of interference
composite second order
341
when a carrier is applied to an amplifier, it will produce the second order beats and will produced third order products as well
discrete third order
342
as each carrier is added to the system , it interacts with all the other carriers producing more and more second and third order beats.
composite third order
343
C/CTB follows a 20log relationship, and each dB raise in the levels of an amplifier, the carrier to CTB gets worse by two dB
know this rule
344
adding two devices with the same C/CTB ratios degrades the result by 6dB
know this rule
345
the crossing of modulation from one channel to another. typically manifests itself as a vertical bar in the viewed picture
cross modulation(XMOD)
346
this is a third order product and follows a 20log function for every dB that the levels of an amplifier are raised the carrier to cross mod ratio gets 2db worse
know this rule
347
doubling the number of channels carried degrades this ratio by 6dB and so does doubling the cascade
know this rule
348
appears as horizontal bars in the picture . a primary source is the power passing chokes or capacitor leak in passive devices.
Hum modulation
349
amplifier circuit paths that allow AC voltage to be directed onto specific cables
Power passing chokes
350
hum modulation is a low frequency signal, which the FCC states must be less than 3% of the video carrier level
Hum modulation Test
351
are the two basic parameters used to evaluate the quality and performance of the digital signals
MER and BER
352
is defined as the ratio of the number of wrong bits over the number of total bits
Ber
353
is typically an overload effect noted through digital signal processing equipment. this is an overdrive, or over modulation of the single carrier
Spectral re growth
354
an international telecommunications standard that permits the addition of high speed data transfer to an existing CATV system
DOCSIS
355
generates light in the transmitter
Laser Diode
356
is a family of standards for compressing decompressing A/V in a digital format
MPEG
357
advantages of MPEG are
remove redundant info without losing quality while saving bandwith
358
MPEG1
video CD
359
MPEG2
HDTV/DVD
360
MPEG4
streaming video
361
has all the spatial info
I picture
362
use both past and subsequent pictures
B picture
363
is calculated by comparing previous and successive picture
P picture
364
a cable version of CDMA , a cell phone technology that allows many users to access the network at the same time
SCDMA
365
provides the ability to control latency
QOS
366
how many channels can u bond with docsis 3.0
4 or 8 down 4 up
367
number of timeouts caused by the cmts not receiving a response within aspecified time from the cmts to a ranging request. upstream errors
T3
368
number of timeouts caused by the modem not receiving a response within a specified time from the cmts to a periodic maintenance request. downstream errors
T4
369
the operational settings for the cable modem
Boot file
370
a series of Reed -Solomon symbols forms the codeword. it s a series of values that conforms to a known pattern.
codewords
371
when there are more than___ errored symbols in a codeword the entire codeword is errored
3
372
technologies that allow cable modems to share the upstream carriers in the hfc network with multiple devices like cable modems, emtas, and set top boxes
TDMA and SCDMA
373
method for transferring data across the network
Trivial file transfer protocol (TFTP)
374
assigns time slots for when modems can speak. configured in the CMTS
TDMA
375
instead of a time slot, the modem gets a code for all the data it is sending
SCDMA
376
is a set of rules that govern how devices transport data
Protocol
377
allows interoperability of devices from different vendors
protocols
378
is a way to tell the sending server that not all packets got to their destination, and please resend them.
Transmission control protocol/ internet protocol (TCP/IP)
379
used to transport voice and video media
Real Time Transport Protocol (RTP)
380
unlike tcp/ip it has no error correction
Universal Datagram Protocol (UDP)
381
UTP
unshielded twisted pair
382
has a field of 32 bits and dotted decimal
ipv4
383
written in colon hexidecimal format and uses numbers and letters
ipv6
384
can be configured for ipv4only or ipv6only
singlestacked device
385
can be configured fro both ipv4 or 6
dual stacked device
386
rules for writing ipv6 addresses
1) omit leading zeros, meaning zeros at the beginning of each set of four characters. 2) replace consecutive all zero chunks within an address by using a double colon
387
caused by off air ingress. (Direct pickup)
leading ghost
388
detects the light in the receiver and converts it to RF
Photo Diode (Photo Detector)
389
undesired light leaving the core
refraction
390
FCC requires us to offset frequencies when levels in the aeronuatical band are ____ or higher
38.75
391
what is the frequency offset for channels in the aeronautical communication band
12.5khz
392
when padding to the chip what are the combined internal losses (DC test point, EQ, Diplex filter)
3dB
393
CTB shows up where in the channel
within 30khz of the video carrier
394
CSO shows up where in the channel
plus or minus .75 and plus or minus 1.25mhz above or below the video carrier
395
harmonics are___ down from the sum/diff beats
6dB
396
what is the ch offset for channels in the aeronautical navigation frequency
25khz
397
the aeronautical navigation frequency carriers are spaced at ____ between carriers
50khz
398
what kind of split is in the diplex filter
sub split
399
shows the relationship between voltage or current and time
AC waveform
400
the position of a waveform at a specific point in time
phase
401
amplitude=
peak
402
changing or varying the amplitude, frequency, or phase
modulation
403
4 phases, constant amplitude, 2 bits per symbol
QPSK
404
multiple amplitudes, 4 phases, combo of QPSK and ASK
QAM
405
sample at twice the frequency that is being digitized
Nyquist rule
406
ADC
analog to digital conversion
407
DAC
Digital to analog conversion
408
how many pictures form a group of pics
12
409
GOP
group of pictures
410
provides output tilt
interstage EQ
411
a measure of an amplifiers output level compared to the amount of distortion its
output capability
412
the default telemetry frequencies for fwd sweep/rtn sweep and pathtrak
53=pathtrak, 51= forward, 52, return
413
a combo of ASK and QPSK
QAM
