1 Broadband System Broadband System - - A A CATV CATV - - 101. 101. Satellites are spaced every 2nd degrees above earth TV TRANSMITTER Cable area "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz Headend
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Broadband System Broadband System -- AA
CATV CATV -- 101.101.
Satellites are spaced every2nd degrees above earth
FM : 88 to 108 MHzFM : 88 to 108 MHz CHCH--13: 211.25 MHz13: 211.25 MHz
* Notice, the difference in frequency, between CH* Notice, the difference in frequency, between CH--4 and CH4 and CH--5, which 5, which
is not a multiple of 6 MHz. The reason being, thatis not a multiple of 6 MHz. The reason being, that 73.5 MHz73.5 MHz is is
allocated as an international disaster frequency, that is used ballocated as an international disaster frequency, that is used by the y the
Red Cross and some other international organization. Red Cross and some other international organization.
VHF TelevisionVHF Television Signal.Signal.
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UHF Television signal.UHF Television signal.
CHCH--14 : 471.25 MHz to CH14 : 471.25 MHz to CH--69 : 805.25 MHz69 : 805.25 MHz
All All UHFUHF signals, like the signals, like the VHFVHF signals, are located in a 6.00 signals, are located in a 6.00
MHz spacing, the UHF stations are located between MHz spacing, the UHF stations are located between 471 471 to to
810 MHz810 MHz. .
UHF channel, UHF channel, CHCH--3737, , 609.25 MHz609.25 MHz, in generally not used as it , in generally not used as it
is employed for Radio Astronomy.is employed for Radio Astronomy.
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Each television channel leaving the headend are controlled by;Each television channel leaving the headend are controlled by;
••Channel processor, ( RF in, RF out)Channel processor, ( RF in, RF out)
••Modulator, ( Baseband in, RF out)Modulator, ( Baseband in, RF out)
••Satellite Receiver, (4 or 12 GHz in, RF out) Satellite Receiver, (4 or 12 GHz in, RF out)
All the television channels are then combined together with a All the television channels are then combined together with a
channel combiner before they are sent to the coaxial system. channel combiner before they are sent to the coaxial system.
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Combining Signal at a CATV HeadendCombining Signal at a CATV Headend
Processor
Modulator
Satellite
Receiver
Microwave
Receiver
RF Combiner
First Amplifier
of the CATV system
Inputch.
IFfreq.
Outputch.
Outputch.
IFfreq.
Basebandsignal
Modulator
Outputch.
IFfreq.
Basebandsignal
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FM stationsFM stations22 66 77 1313
12 channel plan12 channel plan
This number television channels (12) was the maximum This number television channels (12) was the maximum
possible before the delivery of Push Pull amplifier. 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 carry Mid Band With Push Pull amplifier, it became possible to carry Mid Band
channels (9) between 121 to 170 MHz, for a total of 21 channels channels (9) between 121 to 170 MHz, for a total of 21 channels
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FM
transmitter
TV
transmitter
Headend
CATVsystem
Satellitereception
TVtransmitter
FMtransmitter
4GHz
12GHz
MicrowaveSystem
SatellitesSatellites
Up LinkUp Link
TransmissionTransmission
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Coaxial cable consist ofCoaxial cable consist of ::
••75 ohms cable.75 ohms cable.
••Center conductor.Center conductor.
••Foam Foam (hold the center conductor in place)(hold the center conductor in place)
••Aluminum tube.Aluminum tube.
••Sometimes covert with PVC jacket.Sometimes covert with PVC jacket.
Coaxial cable Coaxial cable is theis the most common way to distribute television channel.most common way to distribute television channel.
••It frequency range is from 5 to 1000 MHzIt frequency range is from 5 to 1000 MHz
••It is also capable of handling It is also capable of handling 90 Volts AC90 Volts AC requires to operate RF amplifiers.requires to operate RF amplifiers.
Behaviour of the coaxial cable response versus temperature change
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RF amplifier amplifies the signal when it becomes weakRF amplifier amplifies the signal when it becomes weak
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Connectors are required to make a connection between the Connectors are required to make a connection between the
amplifiers and the passives equipments on the coaxial cable.amplifiers and the passives equipments on the coaxial cable.
Ingress SleeveIngress Sleeve
Connection toConnection to
Outside tubeOutside tube
Connection toConnection to
central conductorcentral conductor
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RF splitter and coupler give the possibly to send RF splitter and coupler give the possibly to send signal signal
intointo two or more directions. two or more directions.
Inputcable
Outcable
Outcable
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Standby powerStandby power
supply are workingsupply are working
on 110 volts ACon 110 volts AC
oror
36/48 Volts DC36/48 Volts DC
Power supply delivers 60 or 90 volts AC thru the Power supply delivers 60 or 90 volts AC thru the
coaxial cable, to permit RF amplifiers to workcoaxial cable, to permit RF amplifiers to work..
They can be NonThey can be Non--Standby and StandStandby and Stand--ByBy
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RGRG--59 or RG59 or RG--66
Multitap make the connection between the CATVMultitap make the connection between the CATV
system and the system and the customer equipment.customer equipment.
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BTD BLE
Power
Passing
Tap
50-750 MHz5-40 MHz
From HeadendFrom Headend
RGRG--59 or RG59 or RG--66
A CATV systemA CATV system
26RF amplifier Coaxial cable Power Supply
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Broadband CATV systems are now a very complex, BiBroadband CATV systems are now a very complex, Bi--directional directional communications network, called; communications network, called; HFCHFC ((HHybrid ybrid FFiber iber CCoaxial) using oaxial) using Fiber Optic and Coaxial Cable technologies. Fiber Optic and Coaxial Cable technologies.
These systems are now delivering the following;These systems are now delivering the following;
••Analog Television programs.Analog Television programs.
••Television on demand or pay per view television.Television on demand or pay per view television.
••High speed Internet service, by CablemodemHigh speed Internet service, by Cablemodem..
••Security systemSecurity system..
••IP telephony (VoIP).IP telephony (VoIP).
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HFC Broadband systems are using fiber optic technology to HFC Broadband systems are using fiber optic technology to transport the signals for the longest distance, between the headtransport the signals for the longest distance, between the headend end to a NODE (optical receiver). The node transfers the light signato a NODE (optical receiver). The node transfers the light signal to RF l to RF signal. The signals then continue thru the coaxial system to feesignal. The signals then continue thru the coaxial system to feed all d all the customers. The coaxial system permits to deliver the signalsthe customers. The coaxial system permits to deliver the signals at at less cost. Fiber optic delivers a better quality signal than coaless cost. Fiber optic delivers a better quality signal than coaxial xial cable, this is why fiber optic is used to transport the signal fcable, this is why fiber optic is used to transport the signal for the or the long distance. long distance.
A HFC system is a biA HFC system is a bi--directional system, and the working bandwidth directional system, and the working bandwidth from the headend to the customer is: from the headend to the customer is: 50 to 87050 to 870--1,000 MHz1,000 MHz, and from , and from customer to the headend is: customer to the headend is: 5 to 40 or 42 MHz5 to 40 or 42 MHz. .
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23 40 43 50
51 77
50
MHz
225
MHz
225
MHz
380
MHz
380
MHz
550
MHz
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 In a modern Broadband system, the frequencies below below 550 MHz are generally 550 MHz are generally
used for the transport used for the transport analogical channels (NTSC).analogical channels (NTSC).
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DD = Digital, Data, IP Telephony, Video On Demand= Digital, Data, IP Telephony, Video On Demand
78 103
DD DD DD DD DD D DD
550
MHz
870
MHz
Standard Television channels can be replaced by digital televisiStandard Television channels can be replaced by digital television or other on or other
digital services (digital services (Data, Cablemodem, Security system, IP Telephony Data, Cablemodem, Security system, IP Telephony
system, etcsystem, etc.) on a modern HFC system..) on a modern HFC system.
In a modern Broadband system, the frequencies above 550 MHz are In a modern Broadband system, the frequencies above 550 MHz are generally generally
used for the transport of the digital portion of the HFC system.used for the transport of the digital portion of the HFC system. QAM digital QAM digital
channels channels andand standard television channels can well exits side by side.standard television channels can well exits side by side.
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Response of a 870 MHz HFC systemResponse of a 870 MHz HFC system
15 to 20dBmV
300MHz
450MHz
225MHz
121.25MHz
108MHz
50MHz
550MHz
750MHz
870MHz
80 NTSC, Analog channels.80 NTSC, Analog channels. 220 MHz of 64 or 256 QAM signals.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 offThe transmitted light is guided down the fiber by reflecting off the outside of the the outside of the
core. The core's index of refraction is slightly higher than thacore. The core's index of refraction is slightly higher than that of the surrounding t of the surrounding
cladding to insure internal refraction. The core is surrounded bcladding to insure internal refraction. The core is surrounded by optical material y optical material
called the cladding. The cladding causes the light to remain inscalled the cladding. The cladding causes the light to remain inside the core. The ide the core. The
core and the cladding are usually made of ultracore and the cladding are usually made of ultra--pure glass called silica. The pure glass called silica. The
materials need to be ultramaterials need to be ultra--pure because impurities in the material can lead to a pure because impurities in the material can lead to a
reduction of power output. Impurities can add to absorption and reduction of power output. Impurities can add to absorption and scattering, scattering,
which would reduce the effectiveness of the fiber. The buffer cowhich would reduce the effectiveness of the fiber. The buffer coating covers the ating covers the
core and the cladding. The buffer coating is generally made of pcore and the cladding. The buffer coating is generally made of plastic, which lastic, which
protects the fiber from moisture and other damages.protects the fiber from moisture and other damages.
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T k’T
MonoMono--mode fiber optic operating frequencies in a HFC mode fiber optic operating frequencies in a HFC
system aresystem are 11310310 oror 15501550 nanometers.nanometers.
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Performance Characteristics of single mode fiber optic.Performance Characteristics of single mode fiber optic.
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/km
1550 nm= 0.19 dB/km
Loss at :850 nm = 1.31 dB/km
1310 nm = 0.33 dB/km
1550 nm= 0.19 dB/km
The standard fiber optic is mostly used for every day signal traThe standard fiber optic is mostly used for every day signal transport.nsport.
The new AllWave fiber is used for the DWDM and long distance traThe new AllWave fiber is used for the DWDM and long distance transport.nsport.
Notice that the humidity peak at 1400 nm, have been removed on ANotice that the humidity peak at 1400 nm, have been removed on AllWave fiberllWave fiber
30 km of30 km of PP--IIIIII--625 coaxial 625 coaxial cable cable
The amplifiers are spaced at 22 dB @ 450 MHz, for this distanceThe amplifiers are spaced at 22 dB @ 450 MHz, for this distance
80 RF amplifiers will be required80 RF amplifiers will be required
Above, shows advantage of fiber optic, over coaxial cable, whichAbove, shows advantage of fiber optic, over coaxial cable, which are:are:
••Better Carrier to NoiseBetter Carrier to Noise, CTB, CSO, CTB, CSO specificationspecificationss at the end of the system.at the end of the system.
••The 30 km fibre link will give more stable signal The 30 km fibre link will give more stable signal even witheven with temperature change.temperature change.
••The fibre optic link will require less actives equipments than tThe fibre optic link will require less actives equipments than the he coaxialcoaxial link.link.
••AA 30 30 kkm coaxial section will require 80 amplifiers.m coaxial section will require 80 amplifiers.
••AA 30 km fiber optic link will require 30 km fiber optic link will require aa 1100 dBmdBm optical transmitter and one optical receiver.optical transmitter and one optical receiver.
C/N will be: 40.97 dBC/N will be: 40.97 dB
30 Kilometres of fibre optic, operating at 1310 nm will 30 Kilometres of fibre optic, operating at 1310 nm will
means a 9.9 dB loss.means a 9.9 dB loss.
C/N will be: 52.00 dBC/N will be: 52.00 dB
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An OTDR uses microwave technology to verify the quality and the An OTDR uses microwave technology to verify the quality and the length of fiber optic.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 amplifierResponse of a Optical Receiver or a RF amplifier
for a 870 MHz HFC system.for a 870 MHz HFC system.
80 NTSC, Analog channels.80 NTSC, Analog channels. 220 MHz of 64 or 256 QAM signals.220 MHz of 64 or 256 QAM signals.