Cable Theory 102/201 Flashcards
1
Q
RF
A
Radio Frequency
2
Q
Defined as the physical length of one cycle of the voltage waveform.
A
Wavelength
3
Q
In free space, a RF that is a very high frequency AC Waveform, travels at what speed
A
Speed of Light
4
Q
Mandates certain frequency levels for various types of communication
A
FCC
5
Q
a set list of frequencies at which channels transmit; can be analog, digital, or data
A
Channel Plans
6
Q
A cable transmission can be transmitted and received in either of these formats
A
analog or digital
7
Q
an analog signal is a what type of waveform?
A
continuous waveform
8
Q
a digital signal has two discrete values that are often expressed as what
A
0 and 1
9
Q
The degradation in analog transmission affects the amount of fine detail here
A
the picture quality
10
Q
The height of the radio wave is also called this
A
amplitude
11
Q
The height(amplitude) of the radio wave represents various aspects of the broadcast such as these two things
A
color and brightness
12
Q
AM
A
Amplitude Modulation
13
Q
PM
A
Phase Modulation
14
Q
FM
A
Frequency Modulation
15
Q
(AM) Amplitude Modulation is used for this
A
Video
16
Q
(PM) Phase Modulation is used for this
A
Color
17
Q
(FM) Frequency Modulation is used for this
A
Audio
18
Q
Can be compressed and/or Encoded, Unlimited copying or regeneration, Allows error checking, Easily stored and retrieved, Less loss of quality over distance, No noise or distortion accumulation, High immunity to interference. Are all advantages of what?
A
digital broadcasting
19
Q
the signal format by which digital cable channels are encoded and transmitted via cable
A
QAM or Quadrature Amplitude Modulation
20
Q
works by modulating the amplitude of two incoming carrier waves to one RF carrier wave, thus doubling the effective bandwidth
A
QAM or Quadrature Amplitude Modulation
21
Q
For a customer to receive a QAM signal, the signal must be what
A
Demodulated
22
Q
The effect of moving electrons provides this, that powers lights, radios, televisions, and appliances in most homes around the world
A
AC or Alternating Current
23
Q
The human voice produces what type of waveform at different frequencies
A
AC Waveforms
24
Q
HFC power supplies transform AC waveforms into this
A
Quasi Square AC Waveforms
25
Four common types of waveforms you'll encounter in telecommunications are
Sine, Square, Quasi-square, Saw Tooth
26
on an ac waveform. this is Usually represented on the vertical axis
Current
27
a graphic display which shows the flow of current over an elapse of time
AC Waveforms
28
shown in the waveform above the horizontal axis
Positive polarity
29
shown in the waveform below the horizontal axis
Negative polarity
30
The relationship of an AC waveform displayed as a graph
Current or Voltage, and Elapsed Time
31
This is the type of waveform that powers your power supplies, home appliances, and the television channels that carry program information to your customers' homes
Sine
32
This waveform is often found within the switching regulator DC output power supplies in amplifiers.
Square
33
A CATV power supply without a load produces this waveform that combines a non linear increase and decrease of current with an extended maximum positive and negative peak value
Quasi Square
34
this is the waveform that is typically used to drive the horizontal trace on a spectrum analyzer
Sawtooth
35
defined as one complete sine wave
Cycle
36
the number of cycles of an AC waveform that occur in one second and is measured in hertz
Frequency
37
CPS
Cycles per second
38
Hz
Hertz
39
T
Period
40
the amount of time it takes a waveform to complete 1 cycle
Period
41
The peak value of an AC waveform is also known as this
Amplitude
42
Random, Fluctuating signals on the network not part of the channels,audio/video or data carriers
Noise
43
Unwanted outside signal entering or exiting the coaxial cable through cracks, breaks, loose connectors, and poorly shielded drops
Ingress/Egress
44
Three signals combining to create a distortion
Composite Triple Beat (CTB)
45
When two or more carries encounter a non linear device, such as a loose connection where some oxidation has occurred
Common Path Distortions (CPD)
46
Two signals combining to create a distortion. occur at .75 MHz and 1.25 MHz above and below the desired carrier frequency
Composite Second Order (CSO)
47
The introduction of outside signal into the HFC Network
Ingress
48
This can hamper digital signals, cause noise, and picture ghosting.
Ingress
49
Minimum acceptable ingress at 5-18MHz
-20 dBc
50
Minimum acceptable ingress at 18-42MHz
-30 dBc
51
Sources of RF interference fall into these two categories
intentional and unintentional
52
List 4 of the 12 Intentional sources of RF interference are
AM, Shortwave, FM and Tv broadcast transmitters; Remote controls; Cell phones; Taxi, police and aircraft radios; Microwave ovens; Motion Sensors; Radar systems
53
Unintentional RF sources are most commonly devices that produce a what
Electrical spark
54
3 Common sparking sources include what
Electric welders, Brush-type motors, Relays and switches
55
This is inevitable and occurs in every system
Noise
56
The conversion of an analog signal into a digital signal to improve signal quality by reducing interference.
Digital Conversion
57
The process of compressing digital video to reduce the bandwidth required
Digital Compression
58
The modulation scheme by which digital cable channels are encoded so they can be transmitted via cable
QAM Modulation
59
measuring the quality of a digital signal so it can be maintained within a desirable range
Digital Signal Quality
60
Can interfere with an analog signal and reduce its clarity
Thermal Noise
61
This type of bit are regenerated rather than amplified.
Digital bits
62
As long as the signal is received and read before its level cannot be properly recognized, transmission distance is this
virtually unlimited
63
The process of converting an analog signal into a digital signal is called this
analog to digital conversion
64
ADC
analog to digital conversion
65
Basic steps of the ADC process
Sampling, Quantization, Encoding
66
Process used to reduce the bandwidth required for video
Digital Compression
67
In digital compression the video frames are split into these two types
Key and Predictive
68
Key video frame type is comprised of this information
static information
69
Predictive video frame type is comprised of this information
information that changes from frame to frame
70
a device or software that enables compression or decompression to take place
video codec
71
QAM
Quadrature Amplitude Modulation
72
the signal format by which digital cable channels are encoded so they can be transmitted via cable
Quadrature Amplitude Modulation or QAM
73
Works by modulating the amplitude of two incoming carrier waves to one rf carrier wave
Quadrature Amplitude Modulation or QAM
74
Five primary indicators available to assist in measuring signal quality
Constellation diagram, Modulation Error Ratio (MER), Bit Error Rate (BER), Forward Error Correction (FEC), QAM ingress
75
Measures incoming signal quality by providing a graphical representation of the signal within a box
Constellation diagram
76
In perfect data transmission conditions, each bit of an incoming signal appears as what in the constellation diagram
a dot in the center of each box
77
In less than perfect data transmission conditions, each bit of an incoming signal appears as what in the constellation diagram
toward an outer edge of each box
78
in constellation diagrams, this indicates that a signal disturbance is causing an error in the bit rate
signal appears toward an outer edge of each box
79
These two things can cause a bit error
Noise and Ingress
80
MER
Modulation Error Rate
81
a measure of signal quality (in dB)
Modulation Error Rate or MER
82
A determination of how much margin the system has before failure
Modulation Error Rate or MER
83
the ratio of average symbol power to average error power
Modulation Error Rate or MER
84
An acceptable MER for a 256 QAM channel measured at the STB or Modem is what
35dB
85
BER
Bit Error Rate
86
A ratio of errored bits compared to the total number of bits received in one second of time
Bit Error Rate or BER
87
Occurs when, due to a distorted signal, an incorrect decision is made
Bit error
88
Ideal BER of a 256 QAM channel of 40Mbps
1.0E-09 (1 error per one billion bits)
89
Theoretical perfect BER
0.0E- 00
90
FEC
Forward Error Correction
91
A system of error control for data transmission where the transmitting device adds additional data to a signal in order to detect errors
Forward Error Correction or FEC
92
Many FEC codecs can also generate this
Bit Error Rate signal
93
Located in the area of 32dB
the MER Cliff
94
To ensure the highest quality digital services, technicians should confirm MER values are reading at this
35dB
95
Any impairment in the customers drop system will be reflected in this signal quality measurement
MER
96
Allows the user to see signal interference, under a 64 or 256 QAM modulated signal, without turning the carrier off
QAM ingress
97
Was designed for Best Effort Service and uses request/grant mechanisms to access upstream bandwidth
Docsis 1.0
98
Uses Signal Quality of Service association per modem
Docsis 1.0
99
Provides in-line 56-bit DES encryption/decryption to secure the privacy of the connection
Baseline Privacy
100
Has capacity for symmetric and is interoperable and backwards compatible DOCSIS 1.x
Docsis 2.0
101
Has more upstream capacity and reflects improved robustness against interference
Docsis 2.0
102
DOCSIS
Data Over Cable Service Interface Specification
103
Set of standards that defines how information is packaged and transported by coaxial cables
DOCSIS
104
Four most notable enhancements in DOCSIS 3.0 over previous versions
Internet Protocol Version 6 (IPV6), Channel Bonding, Enhanced QOS, Increased data security
105
The addresses in IPv6 are this long
128 bits
106
IPv4 address is written in this
decimal,separated by periods
107
IPv6 address is written in this
hexadecimal, separated by colons
108
Can be used once in an IPv6 address to replace multiple fields of zeros
double colon (::)
109
The typical throughput per 256 QAM DOCSIS channel
42.88Mbps
110
When it is necessary to do this, be sure to take into account the size and modulation of your channel and multiply that number by the number of channels allocated to the data services
identify the size of your pipe
111
Instructs to look for additional channels. combines multiple bandwidths, and enables the addition of channels
Channel Bonding
112
MPEG
Moving Picture Experts Group
113
Family of standards used for coding audiovisual information in a digitally compressed format
Moving Picture Experts Group (MPEG)
114
The compression is done by storing information that is redundant, between successive images, in memory
Moving Picture Experts Group (MPEG)
115
Enables all of the information of a TV signal to fit into as little bandwidth as possible, without changing the quality
Moving Picture Experts Group (MPEG)
116
MPEG standard for video CDs
MPEG 1
117
MPEG standard for DVD and HDTV
MPEG 2
118
MPEG standard for Interactive TV, Video on cell phones, Internet Streaming
MPEG 4
119
A MPEG video is a sequence of these three kinds of encoded pictures:
I, P, B pictures
120
In a normal sequence of final video, there are 12 pictures, also known as
frames
121
I- Picture
intra-coded picture
122
single compressed picture that contains all the spatial information of a video picture
intra-coded picture (I-picture)
123
GoP
Group of Pictures
124
The starting and ending point in a GoP
I- Pictures
125
All pictures before the next I-picture are called this
Group of Pictures (GoP)
126
P-Pictures
Predicted Pictures
127
Contain picture data that is compressed based on the nearest I or P-picture.
Predictive Pictures or P-pictures
128
More highly compressed than I-pictures.
Predictive Pictures or P-pictures
129
Macroblocks coded with forward prediction from previous I or P Pictures
Predictive Pictures or P-pictures
130
B-Pictures
Bi-directional pictures
131
Use both past and subsequent pictures as references for calculating compression data
Bi-directional pictures or B-Pictures
132
Coded with forward/backward prediction from previous/next I or P references
Bi-directional pictures or B-Pictures
133
May be coded with no prediction
Bi-directional pictures or B-Pictures
134
There are three server network architectures for the implementation of Video on Demand services
Centralized Architecture, Distributed Architecture, Hybrid
135
VOD
Video On Demand
136
Network Server architecture that is implemented by first locating the servers channel modulation in a regional headend or hub
Centralized on Demand
137
This Network Server architecture usually results in a reduction in the number and complexity of maintenance activities, centralizes hardware asset management, and lessens the number of locations requiring secure program content storage
Centralized on Demand
138
Servers and content, or assets, are placed in most, if not all, headends and hubs of an HFC system in this Network Server architecture
Distributed on Demand
139
Network Server architecture that is Used as a primary centralized server that links to locally distributed services.
Hybrid on Demand
140
This Network Server architecture reduces demand on the backbone networks as well as on all servers
Hybrid on Demand
