Tech m 4
Typical sources of failure in the outside plant
-75% of fiber optic troubles are caused by people( contention, maintenance activities,. -25% natural disasters (storms or earthquakes).
The FCC has regulated that DSSS. Systems use a maximum of _______ Watt of transmit power in point to multipoint configurations
1 Watt
There are two different types of building to building connectivity
1. (PtP) point to point 2. Point to multipoint (PtMP)
802.11G
1. 2.4GHz band 2.at 54mbs
An access point transmits at 75mW. It connects to a 6dBi gain omnidirectional antenna by means of a cable with a minus3dB of loss. What is the EIRP in mW?
150 mW
You are designing a direct sequence spread spectrum wireless local area network. How many co located access points can you have in an area without overlapping channels
3
What is the smallest allowable bend radio is for G652 standar single mode fiber?
30 mm
If 8 QAM channels are bonded, the maximum possible downstream throughput is
308mbps
With six nonoverlaping FHSS access points operating at 2mbps approximately how much system throughput will this 802.11 wireless network provide q¡
6mbps
The antenna receives signal at 75mW and transmits at 150mW. What is the IRS power level in the circuit
75mW
The IEEE first specifies the use of direct sequence spread spectrum in the 2.4GHz industrial, scientific and medical ISM band with which of the following standards
802.11
Transposition occurs when
A complete pair is accidentally terminated where another pair should be terminated
IPV6
A standardized IP address scheme in which a unique 128 bit address is assigned to each device connected to an IP based network
In FTTx networks, what is required to power ONTS at the cx premises
Ac power must be provided at the cx premises to power ONT
Which statements best describes a wireless LAN used in an access role?
Access points connect mobile clients to shared network resources
Spread spectrum technology
Allows us to take the same mount of inf that we previously would have sent using narrow band carrier signal and spread it out over a much larger frequency range.
Consider a cable connecting a wireless classes point to an antenna. The cable connects the transmitter to an amp. The amp connects to another sections of the cable, which then attaches to the antenna. You wish to measure the EIRP where would you take this measurement?
At the antennas element.
Using an RF power meter, you wish to measure the intentional radiator IR, where would you take this measurement?
At the antennas input
Hoes does a spread spectrum tech reduce the probability that a signal will be jammed
By transmitting over a wider frequency spectrum
What variations of the star topology are used in PON's ?
Centralized split, distributed and home run
Which of the following 802.11g channel do not overlap
Channels 2 and 7
Bus topology
Connected in series from connector to connector, daisy chain
Star Topology
Connected to a central or common location (Home RUn)
Fiber transceiver (mini node)
Converts light signal from fiber to the RF signal for coax distribution into the home.
Which two of the following spread spectrum technologies does the FCC describe for use in the license free 2.4GHz ISM band
DSSS and FHSS
REED Solomon (RS)
Docsis 3.1 used reed solomon FEC advancements , a type of forward error correction code that adds parity bit data to the data stream
What is added during modulation to Quadra tire amplitude modulation QAM channels that enable digital tv receivers to detect and repair data is lost or corrupted during transport
During modulation, FEC data is inserted into the QAM channels to enable DTV receivers to detect and repair data that is lost or corrupted during transport
Which of the following is data in an out of band data channel
Emergency alert system EAS Electronic program guide EPG STB application
Docsis ( Data over cable service interface specification )
Employs a client/server model that is comprised of 2 main elements, a cable modem termination system (CMTS) and a cable modem
1mW
Equals 0dBm
FAT Fiber access terminal
Equivalent of a tap in a coaxial system
Why can FTTX applications be more susceptible to the adverse effects of macro and micro bends than typical transmission applications?
FTTX standards use some wavelengths that are longer than the typical transmission wavelengths, and are therefore more susceptible to the adverse effects of macro and micro bends.
Which fiber to the X topology has the amps in the coaxial cable portion of the network?
Fiber to the node to maintain proper amplitude levels of the RF signal throughout the serving aera.
intentional radiator IR
In an RF device specially designed to generate and radiate RF signals. Any reference to power out of the IR refers to the power output at the Nd of the las cable or connect before the antenna.
Institute of electrical and electronic engineers (IEEE)
In the current wireless LAN market several accepted operational standards and draft in the USA are created and maintained by
Entitlement management message EMM
Indicates that the STB is receiving STB authorization data.
Docsis 3.0
Introduced downstream and upstream channel BONDING.
OFDM (Orthogonal Frequency Division Multiplexing)
Is a transmission scheme in which several independent narrowband carriers or subcarriers are modulated at a low data rate. The peak of each sub carrier aligns with the minimum power of the fb haven't or orthogonal subcarriers. With OFDM noise and interference from the network can impair only a smalll number of subcarriers, leaving the majority intact and error free. Any lost data can be recovered using errr correction.
Visual Line-of-Sight (VLOS).
Is defined as the apparently straight line from the object in sight (transmitter) to the observers eye (receiver).
Direct sequence spread spectrum DSSS
Is method of sending data in which the transmitting and receiving systems are both on a 22MHz wide set of frequencies. Most used of the spread spectrum types. Due to its ease of implementation and high data rates.
Which of the following is a characteristic of a spread spectrum system
Low output power
What does 802.11ac use in order to have up to 8 streams ?
MIMO
Diffraction (of a Wave)
Occurs when a surface with a sharp irregularities or some sort of rough surface obstructs the radio path between a transmitter and receiver. Diffraction describes a wave bending around an obstacle, whereas refraction describes a wave bending through a medium. Taking the rock in the pond example.
Scattering of a wave
Occurs when the medium though which a wave travels consists of objects with dimensions that are small compared to the wavelength of the signal, and the number of obstacle per unit volume large scattering can occur when a wave strikes an uneven surface and is reflected in many directions simultaneously. Exambles- streeet sings, lamppost, sand, rock, etc.
OLT
Optical line terminal
SDU
Single dwelling unit
The feeder fiber in the pedestal enclosure can be ?
Spliced to the drop fiber, or can be preconnectorized cable to attach to the drop fiber
A short or cross can be caused by
Staple, screw, or nail penetrating the wiress insulation 2. Ect
Frequency hopping spread Spectrum
Technique tat uses frequency agility to spread the data over a minimum of 75 and a maximum of 79 of carrier frequencies in the 2.4GHz . Is a method of sending data where the transmission and receiving systems hop together along a repeatable pattern f frequencies
Which component of an FHSS system created more overhead than that found in DSSS system
The Inter frame spacing
IEEE 802.11
The Original wireless LAN standard that specifies the slowest data transfer rates in both spectrum RF and infrared transmission technologies
To avoid VSWR which of the following wireless LAN devices must have matching impedance ?
The antenna connector and the amp circuit
How does an antenna create a gain in the received RF signal
The antennas shape focuses the received signal into a tighter beam
Watt W
The basic unit of power, defined as one ampere of currrent at one Volt
Which statement best describes gain in an RF signal?
The increase of the RF signals amplitude caused by an external power source.
Which statement best describes return loss in an RF circuit?
The los of signal energy caused by reflection in the signals path
Voltage Standing Wave Ratio (VSWR)
The ratio of forward power to reverse power. Reverse power occurs when there is a mismatched impedance between devices in an RF system. An RF signal reflected at a point of impedance mismatch in the signal path causes high VSWR. To understand VSWR imagine water flowing through two garden hoses. As long as the 2 hoses are the same diameter water flows through them seamlessly. But if one is significantly larger than the next hose down the line, back pressure would occur.
What does the Hybrid fiber/coax (HFC) network architecture offer broadband cable operators
To enable broadband cable operators to make gradual, or staged, transition to an all fiber optic cable infrastructure
PON ultimate goal
To make it possible to deliver to the customer data rates that exceed On gigabit pero second
What the of test equipment is designed specifically to test and diagnose twisted pair cable
Twisted pair cable tester
Degree to which the fresnel zone can be blocked
Typically 20 - 40 percent blockage introduces little to no interference into the link. But we dont want more then 20 percent. RF link is more than 20 percent blocked, or if new construction or tree growth blocks an active link, raising the height of the antennas will usually alleviate the problem
NO dial tone
Typically related to network problems 1. Confirm EMTA is working properly by testing directly to it 2. Check if cxs CPE has been off hook for a period of time 3. Make sure batteries are working in cordless devices 4. Check faults in telephone station wiring such as shorts, open, or ground faults
Continuos dial tone
Unable to break or interrupt the dial tone when dialing a number 1. Confirm correct polarity of the phone wiring
Hybrid topology
Used combination of star, bus and ring topologies
Different connectors
Variety fiber connectors including FC/PC, SC and others.
Which of the following organizations promotes 802.11b and later wifi ?
WECA
Bluetooth tech which is included as part of the IEEE 802.15, is an example of which spread spectrum tech?
WPAN
To what basic principle does each axiom adhere to
Whatever is done must be done in both sides of the equation
Split pairs occur
When 2 wires from different pairs are connected to each other's pin locations
Milliwatt
When implementing wireless LANs power levels as low as 1 milliwatt can be used for a small area and power levels on a single wireless LAN segments are rarely above 100mW.
First requirement to be considered a spread spectrum
When the bandwidth is much wider than what is required to send the inf 2. It must use low power
WAP
WiFi Protected Access
WEP
Wired Equivalent Privacy
Point-to-Multipoint Topology
Wireless connections between 3 or more buildings. In Which one building is the focal point of the network design . Typically use omnidirectional antennas in the central hub building and semi directional antes on each of the outlying spoke buildings
What does the radio FR over glass provide as envisioned by broadband cable operators ?
With the time to make a seamless transition from the legacy HFC to over Gigabit PON or ethernet PON
An open
circuit is a break in the circuit path.
SNR
signal to noise ratio provides an assessment pf the OOB channel quality that is equivalent to the MER of a QAM channe.
Two keys points that are important to understand about antennas are
1. Antennas convert electrical energy into RF waves in the case of transmitting antena, or RF waves into electrical energy in the case of receiving antenna. 2. The physical dimensions pf an antenna such as its length are directly related to the frequency at which the antenna can propagate waves or receive propagated waves.
When troubleshooting a DTV issue tech should use the stb diagnostic screen to
1. Check the stb service authorization 2. Verify stb reception of authorization messag data 3.obtain QAM channel inf 4.confirm return path operation 5.check internal stb health.
Which of the following are possible effects VSWR can have on RF circuits ?
1.damaged transmitter circuits 2.unstable output power 3.changes in signal power
Six steps to troubleshooting
1.identify 2.analyze 3. Isolate 4.diagnose 5. Resolve 6.verify
Which of the following are or were wifi compliant
802.11b and g
A wireless link connects two nodes across a large warehouse. Blocking as mucha s 50 percent of the fresnel zone between two nodes antennas are metal shelves, light fixtures, and other obstructions. In this situation, which of the following statements is true
Although visual LOS maybe clear, RF LOS is obstructed.
Which of the 6 troubleshooting steps can be combined and performed at the same time or performed out of sequence
Analysis, isolation, and diagnostics
In which one of the following applications might you deploy a wireless LAN in a distribution layer role?
As a building to building bridge linking corporate network segments
Why would a DSSS system be more susceptible to narrowband interference than frequency hopping spread spectrum system
DSSS transmit over a single smaller frequency band for the duration of the communication session
Deductive
Deductive reasoning can also be referred to as top down logic. All men are mortal, Aristotle is a man, therefore Aristotle is mortal.
802.11g
Describes data transfer rates equally as fast as 802.11a and boasts the backward compatibility to 802.11b required to make inexpensive upgrades possible
Refraction
Describes the bending of a radio wave as it passes through a medium o a different density. The wave will be best such that its direction changes (such as a pool of cold air lying in a valley, wave will be reflected away from the intended signal path. Refraction can become a problem for long distance RF links. As atmospheric conditions change, the RF waves may change direction, diverting the signal away from the intended target. ¡
The Fresnel Zone
Is important to the integrity of the RF link bc it defines an area around the Line Of sight LOS that can introduce RF signal interference if blocked . Objects in the fresnel zone such as trees and hilltops and buildings can diffract or reflect the main signal away front the receiver changing the RF LOS
Which statement best describes narrowband transmission?
It is susceptible to noise which can overpower the signal
Wifi protected setup (WPS)
It's really hackable, is not a good thing to use on a wifi network
A ski obtains high speed Internet access through a WISP. In which role is the wireless network operating?
Last mile data delivery
point-to-point connectivity
Links are wireless connections between only 2 buildings. PtP connections are almost always use semi directional or high fly directional antennas at each end of link. The low gain provided by omnidirectional antennas restricts the PtP link power to a value much lower than the maximum the FFC allows
802.11n
Offers 600 MB's throughput accords 4 40MHz channels. Multiple input, multiple output (MIMO) technology (2 or more transmitters and receivers and antennae in each device) can be used to support the faster data rates. 802.11n can run over 2g and 5g frequencies
A university Campus consists of 5 buildings, a centrally located administration building and 4 adjacent buildings housing classrooms, labs and so forth. A wired network serving the buildings users in each building. The admin building network is the campus backbone. It uses wireless Links to connnect each adjacent buildings network to th campus backbone. Which type of antenna would typically be located on the admin building ?
Omnidirectional
What are the 3 primary elements of a PON?
Optical line terminal (OLT) The optical distribution network (ODN) Optical network unit (ONU)
ONU/ONT
Optical network unit/optical network terminal
Unshielded twisted par (UTP)
Pairs of insulated and unshielded copper wires inside a cable that are twisted symmetrically to minimize crosstalk with other pairs of woes in the Same cable
What are the optical splitters?
Passive branching devices that divide an optical signal across a number of output ports in the forward direction and combine multiple signals onto a common optical fiber in the return direction.
PON
Passive optical network
What are the three categories to fiber optic cable in a PON?
Placed in three categories trunk, branch and drop to identify the cables location in the nework
The ratio of the chipping code to data bits for a direct DSSS signal is called which of the following
Process Gain
Multi port service terminal (MST)
Provides access to connect fiber optic drops from the Cxs premises into the network.
Last mile
Refers to the communication infrastructure wired or wireless that exists between the central offficer of the telecom company and the end user. Helps companies to send signal to rural areas where usually wouldn't
Which RF behaviors occurs when RF signals traverse changing atmospheric conditions over long distances.
Refraction
Which of the following statements is true concerning gain and loss measurements on. Wireless network.
The signal strength in mW increases tenfold for each 10dB of gain
Which statement best describes dwell time in a frequency hopping spread spectrum system
The time a radio transmits on a specific frequency.
Which of the following are methods we could use to prevent VSWR in a circuit?
Use impedance matched cables and connectors 2. Use. High quality calibrated equipment 3. Use good quality tight fitting connectors
802.11ac
Utilized the 2 and 5G band. Using advanced encoding technologies, wider bandwidth channels, multiple radios, clients can achieve wireless rates as high as 1.3 GBPS.
Absorption
When a signal strikes an object and is absorbed into the material of the object in such a manner that it does not pass through, reflect off, or bend around the object. Examples- concert, cement, pavement, wood and tress.
An antenna
Without it's typically associated amps and filters is a passive device. The antenna can created te effect of amplification by virtue of its physical shape. Amplification can results from focusing the RF radiation in a tighter beam.
Institute of electrical an electronics engineers (IEEE)
Worlds largest technical professional association composed of engineers, scientists and professionals dedicated to advancing innovations and technological excellence for the benefit of humanity via publications, conferences, technology standards, and profesional and educational activities.
What is the maximum practical number of synchronized co located radios that can be used with a frequency hoppping spread spectrum system
12
A wireless network adapter transmits at 100 mW. An external dBi gain Yagi antenna with -3dB loss cable is attached. What is the IR power output.
17 dBm
ONU and ONT
At the customers premises there are 2 devices. ONU connects the cx premises to the ODN, and the ONT provides the electrical interfaces to the cx premises equipment
Noise problems in phone
Most common the of telephone noise 1. Static- can be caused by loose o corroded connections, poorly installed jacks, broken wires, or defective CPE 2. Hum can be caused by grounding or shielding problems in the station wiring, poor terminations, or poor grounding and bonding connections. 3. Crosstalk is the amount of signal picked up through electromagnetic induction 4. Radio interference is most likely caused corroded or poor connections which can act as radio detectors as welll as poor bonding and GDing.
Docsis 3.1
Orthogonal frequency division multiplexing (OFDM) and low density parity check (LDPC) were introduced.
802.11ac is the current wireless Ethernet standard
1. Runs in the 5GHz band 2. Up to 1 GBPS 3. Up to 8 streams with MIMO 4. Muti'user MIMO, can talk to 4 different users at the same time.
Causes of slow data throughput
1. Slow content delivery network (CDN= speeds 2. Noise or ingress in the broadband network 3. Excessive network traffic 4. High or low Tx, causes modem to retransmit data 5. The cxs LAN or computer speed.
Which IEEE draft or standard was the first to introduce tech capable of providing 54mbs data rates while remaining backward compatible with 11mbps direct sequence spread spectrum systems
802.11g
True statements about fusion splicing
1. Electronic splicer shows the loss in the signal caused by the splicing process 2. After splicing, hold the fiber by the heat shrink tubing 3. After heating the shrink tubing, let the tubing cool 15-20 scs before touching it
Why is it standard industry practice to use pigtail splicing as the preferred method of terminating single mode fiber ?
Bc it is faster and more reliable than installing connectors in the field.
802.11b
Data transfers rates faster than 802.11 and a more restrictive cope of transmission techs, using only directive sequence spread spectrum (DSSS) tech. First standard promoted as wifi by the WECA
Electronic program guide EPG
Enables the cx to navigate and choose from 100s of DTv channels
Equivalent Isotropically Radiated Power (EIRP)
Is the power actually radiated by the antenna element. It is important bc it is regulated by the FCC and bc it is used in calculating wether or not a wireless link is viable.
Which statement best describes frequency hopping spread spectrums use of frequency agility
It changes frequencies often access 2.4GHz band
Transposing
Moving a quantity or term from one side of the equal sign to the other side and changing it's sign
802.11a
Much faster data transfer rate than 802.11b but lacks backwards compatibility and uses the 5GHz frequency bands
One milliwatt is equal to which of the following
OdBm And 1/1000 watt
