ct3 week 2 Flashcards
a feature in Scout that shows the presence (or absence of) faults called linear distortions in the RF portion of the return path
Scout Flux
a technology that encodes, compresses, and decodes video and audio so we can pack multiple programs in the same space as we used to carry one TV station
MPEG2
The Wifi password on all XM meters
defaultkey
VOM
Volt Ohm Meter
A test instrument used to measure AC and DC voltage, current, and resistance in ohms
Volt Ohm Meter (VOM)
Passage of signal intended to remain within the cable into the outside world
Egress
Name 3 of the 6 test you can do on the Polarity Tester
Open Ground, Open Neutral, Open Hot, Hot & Ground Reversed, Hot & Neutral Reversed, Correct polarity
The CATV frequency spectrum is between
5 and 1002 MHz
With this app you can pay your bill, manage appointments, view or edit your WiFi Network name or password, and troubleshoot your devices. No Lines. No Waiting
Xfinity My Account
Constant power adjustment messages between the CMTS and the device
Compression
This happens when any downstream or upstream channel is impaired and the device stops using them
Partial Bonding
Maximum upstream before PHT fail
54 dBmV
Minimum DSSNR level before PHT fail
33 dB
Maximum downstream before PHT fail
13 dBmV
Minimum downstream before PHT fail
-13 dBmV
Minimum upstream before PHT fail
25 dBmV
a measurement of how consistent the signal response is from the beginning to the end of the channel space
In-Channel Frequency Response (ICFR)
a software application designed in response to a need for a simple and consistent way to proactively communicate information about the network’s health
Watchtower
Formula for cable loss
Cable loss = Footage x Cable loss per foot
Formula for total loss
Total loss = Cable loss + Passive loss
Formula for Expected Level
Expected Level = Starting level – Total loss
For a series-6 cable at 54 MHz, the attenuation is
2 dB per 100 feet
For a series-6 cable at 750 MHz, the attenuation is
6 dB per 100 feet
For a 2-way splitter, the signal loss is
4 dB
For a 4-way splitter, the signal loss is
8 dB
For an 8-way splitter, the signal loss is
12 dB
The difference between transmitted and received power resulting from the loss through equipment, lines, or other transmission devices; usually expressed in decibels
Attenuation
A cable television system’s master control operation where signals are received and delivered on various cable system channels
Headend
The process of converting data into a coded form (ciphertext) to prevent it from being read and understood by an unauthorized party
Encryption
DRM
Digital Rights Management
HDCP
High-bandwidth Digital Content Protection
Signal security can be applied at these 3 locations
Headend, Tap, and Set-top box
The process of converting data into a coded form (ciphertext) to prevent it from being read and understood by an unauthorized party.
Encryption
What are the two types of traps/filters
Positive and Negative
Type of trap that block a channel or channels from being received by a cable TV customer
Negative
Type of trap that removes an interfering carrier from a channel that a customer wants to receive
Positive
DRM
Digital Rights Management
HDCP
High-bandwidth Digital Content Protection
What are the two common content protection measures
DRM and HDCP
Any technology used to protect the interests of owners of content and services (such as copyright owners).
Digital Rights Management (DRM)
A specification developed for protecting digital entertainment content that travels over HDMI cables
High-bandwidth Digital Content Protection (HDCP)
Front-line employee that answers customer telephone calls, or works at a Service Center. Formerly referred to as a “call rep.”
Customer Account Executive (CAE)
A mandate by the Federal Communications Commission which requires cable operators only deploy digital set-top boxes that have a PC card slot for a multichannel CableCARD to decrypt channels
Separable Security
A removable security card available from cable TV providers, translates encrypted signals on the Comcast network
CableCARD
What date did the FCC begin requiring service providers to make CableCARDs available
July 1st, 2004
OES requires a jumper to be installed if the trap exceeds this length
The length of a locking terminator
What is the frequency range of RF signals
5-1002 MHz
electromagnetic wave used to transport information from one point to another
Radio Frequency (RF)
the basic example of a signal that can be generated, transmitted, and received with RF equipment.
Sine wave
RF is characterized by what three elements
Wavelength, Frequency, and Amplitude
an electromagnetic signal above the audio and below the infrared frequencies.
Radio Frequency (RF)
the distance between two consecutive peaks or troughs of a waveform
Wavelength
defined as the space occupied by one complete cycle of a wave.
Wavelength
If the frequency of a signal increases, what happens to the wavelength
It becomes shorter
difference between a signal’s maximum or minimum value during one cycle and usually indicates signal strength or intensity.
Amplitude
What is Amplitude measured in
Volts
the number of times a signal goes through a complete cycle
Frequency
What is frequency measured in
Hertz
What is an unwanted alteration of the original shape of a signal called?
Signal Distortion
A range of wavelengths of electromagnetic emission.
Spectrum
Regulatory responsibility for the radio spectrum is divided between these two administrations
Federal Communications Commission (FCC) and National Telecommunications and Information Administration (NTIA)
NTIA
National Telecommunications and Information Administration
Forward path frequency range for legacy systems
54-1002 MHz
Return path frequency range for legacy systems
5-42 MHz
Forward path frequency range for mid-split systems
85 MHz - 1.2 GHz
Return path frequency range for mid-split systems
5-85 MHz
passive and active equipment in a Mid-Split system must be designed to operate in this frequency range
5-1,675 MHz
Comcast uses MoCA at this frequency range
1125-1625 MHz
used to express a ratio between two signal power levels, i.e., the loss of signal through a splitter.
dB
Absolute signal power that describes the signal at a specific location
dBmV
1 millivolt across 75 Ohms is equal to this
0 dBmV
A telephones signal strength used to be measured in this
Bels
How many decibels are in a Bel?
10
A cable signal can be transmitted and received in these two formats?
Analog and Digital
What are the 3 different carrier parts that make up the analog waveform?
video, audio, and color
The number of frequency and amplitude variations in an analog waveform
infinite
Changing the characteristics of a wave is known as this:
Modulation
process of encoding a simple radio wave, also known as the carrier wave, with data.
Modulation
The modulation technique that Comcast uses to encode digital cable channels is called
Quadrature Amplitude Modulation (QAM)
modulates the amplitude of two incoming carrier waves (I signal and Q signal) to one RF carrier wave.
Quadrature Amplitude Modulation (QAM)
Two examples of devices that demodulate a QAM signal
Set-top boxes and cable modems
refers to reducing the number of bits required to carry information (such as digital video images) by removing the redundant bits in the data.
Digital Compression
MPEG
Moving Picture Experts Group
the name of a family of standards used for coding audio-visual information in a digital compressed format.
Moving Picture Experts Group MPEG
MPEG method splits the signal into these three types of encoded pictures:
Key Frames (I), Predictive frames (P), and Bi-Directional Frames (B)
Pictures which contain all the information to be transmitted and serve as a reference point
Key Frames (I)
Pictures which carry information about which pixels change in relation to the i-frame
Predictive Frames (P)
Pictures which carry information about which pixels change in relation to the i-frame for transmitted and to-be-transmitted frames
Bi-directional frames (B)
The collection of frames to be transmitted in one unit of time is called what?
Picture Group
A list of channel numbers and their associated stations for a particular headend
Channel Map
Is the difference between transmitted and received power resulting from the loss through equipment, lines, passive devices, or other transmission devices.
Attenuation
What are the 5 factors that affect attenuation?
Frequency, Temperature, Dielectric, Center conductor diameter, Cable length
Passage of an outside signal into the cable; can result in noise and disruption of the desired signal.
Ingress
Passage of signal intended to remain within the cable into the outside world
Egress
a figure of merit derived mathematically from the number and severity of signal leaks in a cable system.
Cumulative Leakage Index
According to FCC, leakage should not exceed 20 microvolts per meter at 3 meters between these frequencies
54-216 MHz
fcc leakage limits over 216mhz
no more than 15 microvolts per meter at 30 meters
fcc leakage limits at less than 54mhz
no more than 15 microvolts per meter at 30 meters
fcc leakage limits between 54-216 mhz
no more than 20 microvolts per meter at 3 meters
According to FCC, leakage should not exceed 15 microvolts per meter at 30 meter at these frequencies
0-54 MHz and above 216 MHz
a condition where external frequencies or interfering signals leak into the cable network, and is more prominent in lower frequencies.
Ingress
defined as random, fluctuating signals on the network, which are not part of the channel’s audio/video or data carriers.
Noise
A form of low frequency electromagnetic interference, which can affect a customer’s service
Hum
It is the amplitude distortion of a signal caused by the modulation of the signal by components of the power line frequency.
Hum
Displayed as black horizontal bars progressing up the TV
Hum
The frequency cycle in which hum creates one black horizontal bar
60Hz
a measure of how well symbols can be differentiated from the random noise, distortion, or interference accumulated within a 6 MHz channel
Modulation Error Ratio (MER)
a direct indication of the fidelity of the transportation medium and determines how much margin the system has before failure.
Modulation Error Ratio (MER)
the rate of errored bits compared to the total number of bits received in one second of time.
Bit Error Rate (BER)
What is the ideal BER of a 256 QAM channel
1xE-9
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 (FEC)
MER
Modulation Error Ratio
BER
Bit Error Rate
defined as the ratio of signal power to the noise power and is expressed in dB.
Signal-to-Noise Ratio (SNR)
SNR
Signal-to-Noise Ratio
This digital processing technique makes channel mapping possible
Modulation
Frequency range: Broadcasting TV Channels 2-4
54-72 MHz
Frequency range: Broadcasting TV channels 5-6
76-88 MHz
Frequency range: Radio Astronomy
73-74.6 MHz
Frequency range: Aeronautical radionavigation
74.8-75.2 MHz
What 2 frequencies do we use when using cable math with the rule of thumb
54 MHz and 750 MHz
The difference between transmitted and received power resulting from the loss through equipment, lines, or other transmission devices; usually expressed in decibels.
Attenuation
