Post on 22-Mar-2018
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Broadband System - A
Satellites are spaced every2nd degrees above earth
TVTRANSMITTER
Cable area
"C" BandToward satellite 6.0 GHzToward earth 4.0 GHz
"L" BandToward satellite 14.0 GHzToward earth 12.0 GHz
Headend
CATV CATV -- 101.101.
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Broadband System - A
To give you plenty of time to read the details of each presenta tion,you’ll need to press the RIGHT ARROW KEY (����) on your PC, soyou can have access to the next slide. This will be the same for allfuture presentations in this seminar.
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Before we start the Seminar on Broadband system, let have a lo okat the beginning of the CATV industry in North America.
This will help you better understand what are the requiremen ts forto-day’s Broadband System.
This presentation is only a general idea and every subject in thispresentation will be explained in more details in futurepresentations.
Broadband System - A
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Broadband System - A
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Broadband System - A
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CATV : Community Antenna TV television
CATV systems started in around 1952 and were a one waycommunication system, using coaxial cable and RF amplifier s.These CATV systems distributed television signals, from adistribution center (Head end ) to all the homes in a the cabledarea.
These systems then, were capable of only distributing betwe en2 to 4 TV channels. From been able to distribute 2 to 4 TVchannel at their start, some of the systems finally carried a smuch as 12 television channels and some FM music.
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In both country, Canada and the USA , you required a license tooperate a CATV system.
In the United States, the cities give the permit to operate a C ATVsystem and the FCC controls the technical data.
Federal
Communications
Commission
In Canada, the license is warded by the CRTC
•Canadian
•Radio
•Telecommunications
•Commission
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• TV Stations, VHF or UHF.
• FM Stations.
• Satellites, 4 and 12 GHz (around 1975).
• AML (microwave system).
• TV Program from local studio.
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4.5 MHz 3.59 MHz
6.0 MHz 0
-10
-20
-30
-40
-50
-60
-70
dBVideo section4.2 MHzAnalog
technology
Audio section0.9 MHz
FM technology
Color section
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CHCH--22 :: 5555..2525 MHzMHz CHCH--77 :: 175175..2525 MHzMHz
CHCH--33 :: 6161..2525 MHzMHz CHCH--88 :: 181181..2525 MHzMHz
CHCH--44 :: 6767..2525 MHzMHz CHCH::--99 :: 187187..2525 MHzMHz
** 7373..55 MHzMHz IntInt.. disasterdisaster freqfreq andand otherother .. CHCH--1010 :: 193193..2525 MHzMHz
CHCH--55 :: 7777..2525 MHzMHz CHCH--1111 :: 199199..2525 MHzMHz
CHCH--66 :: 8383..2525 MHzMHz CHCH--1212 :: 205205..2525 MHzMHz
FMFM :: 8888 toto 108108 MHzMHz CHCH--1313:: 211211..2525 MHzMHz
** Notice,Notice, thethe differencedifference inin frequency,frequency, betweenbetween CHCH--44 andand CHCH--55,, whichwhichisis notnot aa multiplemultiple ofof 66 MHzMHz TheThe reasonreason being,being, thatthat 7373..55 MHzMHz isisallocatedallocated asas anan internationalinternational disasterdisaster frequency,frequency, thatthat isis usedused byby thetheRedRed CrossCross andand somesome otherother internationalinternational organizationorganization..
VHF Television Signal Frequency.
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UHF Television signal.
CH-14 : 471.25 MHz to CH-69 : 805.25 MHz
All UHF signals, like the VHF signals, are located in a 6.00MHz spacing, the UHF stations are located between 471 to810 MHz
UHF channel, CH-37 , 609.25 MHz, in generally not used as itis employed for Radio Astronomy.
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Each television channel leaving the head end are controlled by;
•Channel processor, ( RF in, RF out)
•Modulator, ( Baseband in, RF out)
•Satellite Receiver, (4 or 12 GHz in, RF out)
All of the television channels are then combined together wi th achannel combiner before they are transmitted to the coaxialsystem.
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Processor
Modulator
SatelliteReceiver
Microwave
Receiver
RF Combiner
First Amplifier
of the CATV system
Inputch.
IFfreq.
Outputch.
Outputch.
IFfreq.
Basebandsignal
ModulatorOutput
ch.IF
freq.Baseband
signal
Combining Signal at a CATV Head end
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FM stationsFM stations22 66 77 1313
12 channel plan12 channel plan
This number television twelve (12) channels was the maximum possible before the delivery of Push Pull amplifier .
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FM stationsFM stations2 6 7 131414 2222
21 channel plan21 channel plan
With Push Pull amplifier, it became possible to car ry Mid Band channels nine (9) between 121 to 170 MHz, for a tot al of 21 channels
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FM
transmitter
TV
transmitter
Head end
CATVsystem
Satellitereception
TVtransmitter
FMtransmitter
4GHz
12GHz
MicrowaveSystem
SatellitesSatellites
Up LinkUp LinkTransmissionTransmission
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Coaxial cable consist of :
•75 ohms cable.•Center conductor.•Foam (hold the center conductor in place)
•Aluminum tube.•Sometimes covert with PVC jacket.
Coaxial cable is the most common way to distribute television channel.
•It frequency range is from 5 to 1000 MHz
•It is also capable of handling 90 Volts AC requires to operate RF amplifiers.
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5 50 300 550 865 1,000 MHz
TYPEMain coaxial cable: LossP-III-500 0.16 0.52 1.31 1.82 2.33 2.52 dB/100’P-III-625 0.13 0.42 1.08 1.51 1.94 2.07 “ “P-III-750 0.11 0.30 0.78 1.25 1.60 1.74 “ “
Main drop installation cable:RG-59 0.86 1.95 4.45 5.95 7.52 8.12 “ “RG-6 0.58 1.53 3.55 4.90 6.10 6.55 “ “
Above loss are giving @ 68 degrees F. or 20 degre es C.
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850
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850
Input next amplifier after 30 dB spacing at 860 MHz
60 o
-40 o
140 o
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9.
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Signal after cable equalizer
50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850
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Output previous amplifier
Behaviour of the coaxial cable versus temperature c hange
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RF amplifier amplifies the signal when it becomes w eak
4 output amp. 2 output amp. 1 output amp.
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Connectors are required to make the connection betw een the amplifiers and the passives equipments on the coaxi al cable.
Ingress Sleeve
Connection toOutside tube
Connection to
central conductor
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RF splitter and coupler give the possibly to send s ignal into two or more directions.
Inputcable
Outcable
Outcable
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Standby powersupply are working
on 110 volts ACor
36/48 Volts DC
Power supply delivers 60 or 90 volts AC thru the coaxial cable, to permit RF amplifiers to work.
They can be Non-Standby and Stand-By
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RG-59 or RG-6
Multitap make the connection between the CATVsystem and the customer equipment.
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BTD BLE
Power Passing
Tap50-750 MHz5-40 MHz
From Headend
RG-59 or RG-6
A CATV system
26RF amplifier Coaxial cable Power Supply
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Broadband CATV systems are now a very complex, Bi-direction alcommunications network, called; HFC (Hybrid Fiber Coaxial) usingFiber Optic and Coaxial Cable technologies.
These systems are now delivering the following;
•Analog Television programs.
•Television on demand or pay per view television.
• Digital Television.
•HDTV (High Definition Television).
•High speed Internet service, by Cablemodem .
•Security system .
•IP telephony (VoIP).
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HFC Broadband systems are using fiber optic technology totransport the signals for the longest distance, between the head endto a NODE (optical receiver ). The node transfers the light signal to RFsignal. The signals then continue thru the coaxial system to feed allthe customers. The coaxial system permits to deliver the sig nals atless cost. Fiber optic delivers a better quality signal than coaxialcable, this is why fiber optic is used to transport the signal for thelong distance.
A HFC system is a bi-directional system, and the working band widthfrom the head end to the customer is: 50 to 870-1,000 MHz, and fromcustomer to the head end is: 5 to 40 or 42 MHz .
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23 40 43 50
51 77
50MHz
225MHz
225MHz
380MHz
380MHz
550MHz
F M s t a t io n sF M s t a t io n s 1 4 2 2
In a modern Broadband system, the frequencies below 550 MHz a re generallyused for the transport analogical channels (NTSC).
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DD = Digital, Data, IP Telephony, Video On Demand= Digital, Data, IP Telephony, Video On Demand
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DD DD DD DD DD D DD
550MHz
870MHz
Standard Television channels can be replaced by digital tel evision or otherdigital services (Data, Cable modem, Security system, IP Te lephonysystem, etc .) on a modern HFC system.
In a modern Broadband system, the frequencies above 550 MHz a re generallyused for the transport of the digital portion of the HFC syste m. QAM digitalchannels and standard television channels can well exits si de by side.
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Response of a 870 MHz HFC system
15 to 20dBmV
300MHz
450MHz
225MHz
121.25MHz
108MHz
50MHz
550MHz
750MHz
870MHz
80 NTSC, Analog channels. 220 MHz of 64 or 256 QAM signals.
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core
cladding
coating
9 mc
The transmitted light is guided down the fiber by reflecting off the outside of thecore. The core's index of refraction is slightly higher than that of the surroundingcladding to insure internal refraction. The core is surroun ded by optical materialcalled the cladding. The cladding causes the light to remain inside the core. Thecore and the cladding are usually made of ultra-pure glass ca lled silica. Thematerials need to be ultra-pure because impurities in the ma terial can lead to areduction of power output. Impurities can add to absorption and scattering,which would reduce the effectiveness of the fiber. The buffe r coating covers thecore and the cladding. The buffer coating is generally made o f plastic, whichprotects the fiber from moisture and other damages.
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T k’T
Mono-mode fiber optic operating frequencies in a HF C system are 1310 or 1550 nanometers .
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Performance Characteristics of single mode fibre op tic.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0800 1000 1200 1400 1600
nm
a
b c d e
Spectral Attenuation ( typical fiber ):
SINGLE-MODE STANDARD FIBER OPTIC
dB
ALLWAVE SINGLE-MODE FIBER OPTIC
Spectral Attenuation ( All Wave fiber ):
dB
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0800 1000 1200 1400 1600
nm
Loss at :850 nm = 1.31 dB/km
1310 nm = 0.33 dB/km1550 nm= 0.19 dB/km
Loss at :850 nm = 1.31 dB/km
1310 nm = 0.33 dB/km1550 nm= 0.19 dB/km
The standard fiber optic is mostly used for every d ay signal transport.The new AllWave fiber is used for the DWDM and long distance transport.
Notice that the humidity peak at 1400 nm, have been removed on AllWave fiber
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Dual armored fiber optic cable.
Non-metallic covert fiber optic cable.
Fig-8 Self supporting fiber optic cable.
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Optical Transmitter (5-1,000 MHz)
Return Optical Receiver
5-40 MHzOptical Node
5050--870 MHz870 MHz
55--40 MHz40 MHzCoaxial CableCoaxial Cable
55--40 / 5040 / 50--870 MHz870 MHz
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RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp. RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.RF Amp.
30 km of P-III-625 coaxial cable
The amplifiers are spaced at 22 dB @ 450 MHz, for th is distance80 RF amplifiers will be required
Above, shows advantage of fiber optic, over coaxial cable, which are:
•Better Carrier to Noise, CTB, CSO specifications at t he end of the system.
•The 30 km fibre link will give more stable signal e ven with temperature change.
•The fibre optic link will require less actives equi pments than a coaxial link.
•A 30 km coaxial section will require 80 amplifiers ( with P-III-625 cable).
•A 30 km fibre optic link will require a 10 dBm optical transmitter (operating @ 1310 nm) at the head end and one optical receiver at the other end.
C/N will be: 40.97 dBC/N will be: 40.97 dB
30 Kilometres of fibre optic, operating at 1310 nm will means a 9.9 dB loss.
C/N will be: 52.00 dB
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An OTDR uses microwave technology to verify the qua lity and the length of fiber optic.
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Headend EquipmentCablemodem
IP-Telephone
RSVP
Monitoring System
NODE
Fiber optic Return 5 / 40 MHz
Fiber Optic Forward 50 / 870 MHz
Coaxial SectionCoaxial Section
Optical EquipmentOptical Equipment
Optical InterconnectionOptical Interconnection
RF InterconnectionRF Interconnection5 to 42 MHz5 to 42 MHz
RF Sweep
Coaxial Return 5 / 40 MHz
Coaxial Forward 50 / 870 MHz
50 to 52 or 73.5 MHz
Return Alignment andReturn Alignment and
Ingress Control SystemIngress Control System
RF InterconnectionRF Interconnection50 to 870 MHz50 to 870 MHz
T1 / OC 192to Tel Co
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300MHz
450MHz
225MHz
121.25MHz
108MHz
50MHz
550MHz
750MHz
870MHz
47.0 dBmV
37.0 dBmV
4 dB6 dB
10 dB 11.5 dB
48.5 dBmV
Response of a Optical Receiver or a RF amplifierfor a 870 MHz HFC system.
80 NTSC, Analog channels.80 NTSC, Analog channels. 220 MHz of 64 or 256 QAM signals.
44Optical receiver Coaxial cable Fiber optic cable Bi-directional RF amplifier
Each pocket (Each pocket (sectionsection) of a HFC system can have 50 to 1,500 subs.) of a HFC system can have 50 to 1,500 subs.
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•Head end of a HFC system.
•Description of a HFC Head end.
•Coaxial cable - Fibre optic.
•Passive equipments for a HFC system.
•Description of the outside plan.
•RF Amplifiers.
•Fibre optic.
•Fibre optic management.
•System distortion calculation.
•Understanding bi-directionality.
•Adjusting a HFC system.
•Home installation.
•Test equipments required for a HFC system.
•CLI. (Ingress & Egress)
•CMTS, DOCSIS, QAM signal. Cable modem.
•Mode on DOCSIS.
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We will come back in more details in all the subjects seen so far in future seminar.
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