This presentation will give you a general idea of the subjects on the 18 CATV-HFC seminars that are available from: 1
Broadband System - A Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (1)-CATV - 101. TV TRANSMITTER Headend Cable area 2
CATV : Community Antenna TV television CATV systems started in around 1952 and were a one way communication system, using coaxial cable and RF amplifiers. These CATV systems distributed television signals, from a distribution center (Head end) to all the homes in a the cabled area. These systems then, were capable of only distributing between 2 to 4 TV channels. From been able to distribute 2 to 4 TV channel at their start, some of the systems finally carried as much as 12 television channels and some FM music. 3
0 6.0 MHz -10-20 Video section 4.2 MHz Analog technology -30 db -40-50 -60 Audio section 0.9 MHz FM technology Color section -70 3.59 MHz 4.5 MHz 4
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. His frequency range is from: 5 to 1000 MHz It is also capable of handling 90 Volts AC requires to operate RF amplifiers. 5
Broadband System B Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (2)-Head end of a CATV-HFC system. TV TRANSMITTER Headend Cable area 6
Welcome to a Seminar on Broadband Network. Here are the subjects that we will be covering during future seminars; The Coaxial cable. The RF section of the Broadband system. The fiber optic section of the CATV-HFC system. The Distortions on a Broadband system. The Passives equipments. The Maintenance of the CATV, HFC system. The Test equipments needed for a Broadband system. Understanding Bi-directionality of a Broadband system. Understanding Cable modem, QPSK, 64 and 256 QAM signal. More on DOCSIS. 7
Head end Equipment for a Broadband System. 44 channels Combining network. Front end test point. Head end equipment connection. 8
Combining a Head end for a Broadband System. Combining Network from 50 to 870-1,000 MHz Sometime an RF amplifier Can be required. 9
Broadband System C Satellites are spaced every 2n degr es abov earth "C" Band Toward satellite 6.0 GHz "L" Band Toward earth 4.0 GHz Toward satellite 14.0 GHz Toward earth 12.0 GHz TV TRANSMITTER Headend Cable area Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (3)-Headend Instruments CATV-HFC TV TRANSMITTER Headend Cable area 10
Head end Antennas. An antenna installation, may demand many different equipments. 11
Head end of a Broadband System. 12
Broadband System - D Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (4)-Coaxial Cable and Fibre Optic. TV TRANSMITTER Headend Cable area 13
Coaxial Cable. Return Loss. When the cable impedance is not exactly 75 ohms, there will be an impedance mismatch and a reflection of energy if it is connected to an ideal 75 ohms signal source. This reflection can be quantified in terms of the return loss: RL = 20 LOG Z DEVICE - Z0 Z DEVICE + Z0 Where Z DEVICE is the complex characteristic impedance of the device (ohms) and Z0 is 75 ohms for CATV system. Since the cable impedance is within a few ohms of 75, the return loss, as opposed to the cable s structural return loss, is very good and usually better then 37 db. The structural return loss, which deals with return loss at particular frequencies, will be discussed next. 14
Coaxial Cable Behaviour with Temperature. One more problem with coaxial cable and temperature changes, is the moving of the cable while been supported by the strand. Coaxial cable will required expansion loops at each pole to minimized this movement, weather there is equipment or not at each pole location. Where equipment should be placed 15
How Fibre Optic is Made. Below is a fibre which consist of the CORE where light is been propagated, CLADDING which keep the light inside the CORE and BUFFER which is colour coated and permit the identification of the fibre. 16
Fibre Optic Cable. Loose tube fibre Ribbon fibre Fibre optic cable comes in many flavours, most common flavours, are losses tube fibre and ribbon fibre. These fibre cables can also be armoured for duck placing or buried installation or just plain jacketed for aerial placing. Arial Fibre Optic Cable Figure 8 Fibre Optic Cable Armoured Fibre Optic Cable 17
Broadband System - E Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (5)-Passive Equipments. TV TRANSMITTER Headend Cable area 18
Passive Equipment in a Broadband System The Power Inserter is the junction between the coaxial system and the power supply, it introduce 60 or 90 Volts AC from the Power Supply. The Power Inserter are usually capable of handling 20 amperes. Fuses can be installed on each leg for better protection. 19
Passive Equipment in a Broadband System Example of the input signal required and the thru loss at a multi tap supplying: + 16.0 dbmv level at the customer s drop. Thru loss of the multi tap: 1.7 db @ 870 MHz Input Level: 34.0 dbmv Output Level: 32.3 dbmv 16 dbmv output At 870 MHz. 20
Broadband System F Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (6)-CATV-HFC Outside Plan. TV TRANSMITTER Headend Cable area 21
Outside Plan. 22
Outside Plan Equipments. Cable been lashed 23
Broadband System - G Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (7)-CATV-HFC RF Amplifiers. TV TRANSMITTER Headend Cable area 24
RF Amplifiers Selecting the right amplifier, usually require a amplifier with forward and a return path section. The forward amplifier required for today s needs are either: 50 to 750, 50 to 870 and 50 to 1,000 MHz bandwidth. The return path can be from: 5 to 40 / 42 or 5 to 65 MHz 5 40 50 750 870 1,000 MHz 5 65 85 750 870 1,000 MHz 25
RF Amplifiers Type of amplification circuit used in modern RF amplifiers; Single ended transistor Single ended transistor Push Pull transistor 180 Push Pull transistor 180 180 180 Power Doubling transistor To day s Circuitry can be: Push pull Power Doubler GaAs 26
fuse fuse RF Amplifiers A One Output, High Gain Amplifier. 870 MHz 50 MHz 870 MHz 50 MHz 50 MHz 870 MHz to status monitoring -20 db 40 MHz 5 MHz JXP RF AC RF/ AC 870 MHz RF/ AC AC RF -20 db EQ JXP BODE BRD JXP 50 MHz 5 40 MHz MHz 5 40 MHz MHz Manual Gain Control ADU JXP -20 db -20 db EQ JXP 5 MHz 40 MHz from status monitoring JXP -16 db ICS Drive ICS JXP to status monitoring 24 Vdc vcc Power Supply 90 / 60 Vac fuse 38 db gain, minimum full @ 1,000 MHz. 27
RF Amplifiers with an AGC control. Input next amplifier after 30 db cable spacing at 870 MHz 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 31 30 850 31 30 29 29 28 28 27 27 26 26 25 24 23-40 o 25 24 23 Temperature Swing @ 870 MHz From - 40 C to + 40 C 22 22 21 20 o 21 Temperature Swing @ 300 MHz From -40 C to + 40 C 20 19 18 40 o 20 19 18 17 Signal after cable equalizer 17 16 16 4 15 9 9 15 14. 2 14 5 13 13 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 AGC Ch. 28
Broadband System - H Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (8)-Fibre Optic. TV TRANSMITTER Headend Cable area 29
Fibre Optic Milestones. 1854 John Tyndall demonstrated the optical waveguide principle. 1960 Theodore Maiman developed the first laser. 1972 4 db/km loss fibre fabricated. 1982 Single mode fibre optic first reported. 1991 SONET telecommunications standards created. 1995 DWDM deployment began. 1998 > 1 Tbps demonstrated on one fibre. 2000 L-Band System and 40 Gbps transport system demonstrated. 30
Optical Transmitter. Electrical to Optical (E-O) Converter Light Out Electrical In - + Variable Intensity = Analog Blink On & Off = Digital 31
Classifying Light. Power (Watts or Decibels) dbm is typical measurement unit of optical power It is measured with a: Optical Power Meter Color (Wavelength) 300nm (blue) to 700nm (red) is visible to humans eyes. Fiber Optic systems use ONLY Infrared (850, 1310, & 1550nm) Visible Light Spectrum UV IR 300nm 700nm 32
Broadband System - I Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (9)-Fibre Optic Management System. TV TRANSMITTER Headend Cable area 33
Interconnection Outside to Inside Fibre mounted in a frame rack. From the Interconnection centre, the fibre optic cable usually goes to a connection rack, which can be 19 or 23 wide. The CATV industry uses 19 frame. The TELCO industry uses a 23 frame. These racks contains Fibre Interconnection System, Passive equipments and Transmission and receiving Equipments. 34
Fibre optic COUPLER / SPLITTER One NODE feed from single optical transmitter Optical Transmitter NODE Two NODES feed with outside optical coupler Optical Transmitter NODE Optical Coupler NODE Optical Transmitter Two NODES feed with inside optical coupler NODE NODE Optical Coupler 35
Fibre Interconnection Centre STUB Cable Connecting section Often a connecting housing will be order with a STUB cable. This stub cable will then be connected at one end with proper connectors and the other end will be spliced to the junction box. This STUB cable needs to be FT-4 or FT-6, which are flamed retarded cable. FT-4 is used when the cable stay on the same floor, and FT-6 is used when the cable goes from floor to floor. This STUB cable can be of any length, sometime as much as 150 mt. 36
Broadband System - J Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (10)-CATV-HFC System Distortions TV TRANSMITTER Headend Cable area 37
Distortions in a Broadband System. In this section we will learn how to calculate the distortions in a Broadband System. This presentation will help understand, why the system performs better closer to the head end and get worst, toward the end of the system. 38
Distortions in a Broadband System. Here are the distortions we will covering in this section; Distortion of second order. Distortion of third order Cross modulation. Composite third order, CTB. Composite second order, CSO. Noise. Hum. 39
Distortion in a Broadband System. CTB & X-Modulation calculation of a cascade of RF amplifiers. Xmod. CTB. 20log10 2 20log10 3 20 * 10 log10 ( -XM 1 + -XM 2 ) 20 10 20 10 Cross modulation & CTB: Are always given as negative number. 20 * 10 log10 ( -XM 1 + -XM 2 ) 20 10 20 10 20 * 10 log10 ( -XM 1 + -XM 2 ) 20 10 20 10 For each db change in output level, the change of CTB and Xmod. is 2.0 db. Each time we double the cascade, CTB and Xmod. get worse by 6.02 db. 40
Distortion in a Broadband System. All distortions. You need to calculate the distortions of the CASCADE of the RF amplifiers and then married (add) these distortions to the Optical NODE, to get the actual system s distortions. NODE CASCADE of RF amplifiers Then add the NODE distortions. 41
Broadband System - K Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (11)-Bi-Directionality on a Broadband System. TV TRANSMITTER Headend Cable area 42
Bi-Directionality on a Broadband System. All RF amplifier must be equipped with a bi-directional filter at each input and outputs to permit an HFC system to operate in a bi-directional way. Section RF 50-1,000 MHz Section RF 50-1,000 MHz 5-40 / 50-1,000 MHz Coaxial Cable Filter Bi-Directional Filter Bi-Directional 5-40 / 50-1,000 MHz Coaxial Cable Section RF 5-40 MHz Section RF 5-40 MHz 43
Bi-Directionality on a Broadband System. A Broadband HFC Communication system utilized two types of communications technology: Fiber optic technology is used to transport signal for the long distance. Usually one fiber transmits forward signal (50-870 MHz from the Head end to a Optical Node and one more fiber transmits return signal (5-40 MHz) from a Node to the Head end. Coaxial cable is used from the NODE and it is transmitting in both directions (50-870 / 5-40 MHz), from the Optical Node to the each subscribers. The OPTICAL NODE, transfers Light Signal, coming from the Head end, to Electrical Signal (RF and Digital), sending these signals to each subscribers by coaxial cable. The OPTICAL NODE, also Transfers Electrical Signal (RF and Digital) from all the customers to light signal, sending them to the Head end. 44
Adjusting the Return Signal on a Broadband System. Adjusting the forward section, is something, technician have been doing for year. Adjusting the reverse system is quite different, it either requires: Two technicians communicating, to properly adjust the return amplifier. 2 or 4 Modulators to be transported at each amplifier, a Spectrum Analyzer at the Head end, connected to a Modulator, and a TV set at each amplifier. Or the use specialized equipment, We need to adjust the Gain and Slope of the return amplifier at 1 to have the proper input signal level at: 2 45
Bi-Directionality on a Broadband System. All optical NODE must be equipped with a Photo diode on the forward path, a bidirectional filter at each output of the coaxial system to permit an HFC system to operate in a bi-directional way and a return Laser to transmit return signal toward the head end. Photo diode RF Amp. Fibre 50-1,000 MHz Fibre 5-40 MHz Filter Bi-Directional 5-40 / 50-1,000 MHz Coaxial Cable LASER 46
Broadband System - L Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (12)-Alignment and System Maintenance. TV TRANSMITTER Headend Cable area 47
Broadband Head end Combining. Combining Network 48
Final Adjustment of the Head end. Some test equipments are able to give you a general view of the system by the selection of some of the channels in the operating spectrum. 49
Final Adjustment of the Head end. Response of a well aligned head, using a sweep system. Using a sweep generator, located at the head end. The actual signal of the HFC system. 50
Broadband System - M Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (13)-Home Installation. TV TRANSMITTER Headend Cable area 51
Customer s Installation 52
Customer s Installation 53
Customer s Installation Response of a High Pass Filter for no Internet service. 5 50 1000 MHz This High Pass Filter is often installed at all the customer premise, where no Cable modem service is required. This help keep the return system free of Ingress, coming from customer. 54
Broadband System - N Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (14)-Test Equipments Required for a HFC System. TV TRANSMITTER Headend Cable area 55
RF test equipment can be divided in two sections. Equipments capable of reading the strength of a Television Channels. TV channel signal strength Digital signal (Power meter) Multi channel reading (Slope or Tilt) Spectral view of all the channels carried by an HFC system C/N measurement. Distortion measuring (C-N, CTB and CSO) Frequency Response (Peak & Valley response) QAM reading (BER, MER and FEC) Return alignment tool. (Response and Ingress) Ingress reading (Leakage) 56
Test equipments for fibre optic communication Test equipments required for the fibre optic section are the following; Power meter. Light Source. OTDR (Optical Time Domain Reflect meter). OSA (Optical Spectrum Analyser). Talk Set. Visual Fault Locator Optical Fibre Identifier. Optical Scope. PMD Analyzer. 57
ield trength eter 0 Video 300 to 400 KHz 6.0 MHz Audio 300 to 400 KHz Most FSM read between 300 to 400 KHz of band width. -10-20 How it is display on the Field Strength Meter -30 db -40-50 -60-70 3.59 MHz 4.5 MHz 58
Power meter. Power meter are required to measure the power output of the optic transmitting equipment, the input of the receiving equipment and the actual loss of a fibre optic link. GN-6025 Freq.: 800 to 1700 nm. +5 to 70 dbm GN-6025C * Freq.: 800 to 1700 nm. +20 to 60 dbm * Best for HFC system. 59
OTDR (Optical Time Domain Reflect meter) Printed view of two fibre optic links measurements. 60
Broadband System O Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (15)-CLI Cumulative Leakage Index TV TRANSMITTER Headend Cable area 61
Leakage Terminology Radiation. Egress Ingress Leakage uv M (Micro volts per Meter) CLI (Cumulative Leakage Index) 62
Ingress / Egress Ingress: RF signal leaking into the coaxial plant. Egress: RF signal leaking out of the coaxial plant. 63
Broadband System P Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (16)-DOCSIS, QPSK, QAM signal and Cable Modem System. TV TRANSMITTER Headend Cable area 64
Understanding DOCSIS Operating System. A Cable system operating with Cable Modems required, A bi-directional HFC or CATV system. A Cable Modem Termination System at the Head end or Hub site. A 100 BaseT or better connection to Internet or Servers. A 6 MHz of 64 or 256 QAM data channel operating from: 88 to 870 MHz. A 3.2 MHz of QPSK or 16 QAM operating between 16 to 40 MHz on the return section of the system for DOCSIS 1.0. At least one Cable Modem installed at a customer on the system. 65
Understanding DOCSIS Operating System. One other standard that will be repeated very often in the following lecture; CMTS. Cable Modem Termination System The above unit is what controls all the data to and from all Cable modem on the HFC system. 66
Understanding DOCSIS Operating System. Nominal DOCSIS Downstream Data Rate in 6-MHz Channel Modulation type 64 QAM 256 QAM Symbol rate 5.057 MSs 5.360 MSs Total data rate 30.34 Mbps 42.9 Mbps Effective data rate 27 Mbps 38 Mbps Nominal DOCSIS Upstream Data Rate for QPSK Bandwidth 200 khz 400 khz 800 khz 1600 khz 3200 khz Symbol rate 0.16 MSs 0.32 MSs 0.64 MSs 1.28 MSs 2.56 MSs Total data rate 0.32 Mbps 0.64 Mbps 1.28 Mbps 2.56 Mbps 5.12 Mbps Effective data rate 0.3 Mbps 0.6mbps 1.2 Mbps 2.3 Mbps 4.6 Mbps Nominal DOCSIS Upstream Data Rate for 16 QAM Bandwidth 200 khz 400 khz 800 khz 1600 khz 3200 khz Symbol rate 0.16 MSs 0.32 MSs 0.64 MSs 1.28 MSs 2.56 MSs Total data rate 0.64 Mbps 1.28 Mbps 2.56 Mbps 5.12 Mbps 10.24 Mbps Effective data rate 0.6 Mbps 1.2 Mbps 2.3 Mbps 4.5 Mbps 9.0 Mbps 67
Broadband System - Q Satellites are spaced every 2nd degrees above earth "C" Band Toward satellite 6.0 GHz Toward earth 4.0 GHz "L" Band Toward satellite 14.0 GHz Toward earth 12.0 GHz (17)-DOCSIS Simplify. TV TRANSMITTER Headend Cable area 68
DOCSIS Simplified Data Over Cable Service Interface Specification (DOCSIS) is an international standard DOCSIS which defines the communications and operation support interface requirements for data over cable system. It permits the addition of high-speed data transfer to an existing cable TV (CATV) system. It is employed by many cable television operator to provide Internet access over their existing hybrid fibre coaxial (HFC) structure. The first DOCSIS specification was version 1.0 issue in March 1997, with revision 1.1 following in April of 1999. Because of increased demand for symmetric, real-time service such as IP telephony, DOCSIS was again revised to enhance upstream transmission speed and (QoS)Quality of Service; this revision - DOCSIS 2.0 was released in January 2002. 69
DOCSIS Simplified DOCSIS 3.0 The new DOCSIS 3.0 standard that features IPv6 and channel bonding which enables multiple downstream and upstream channels to be used together at the same time by a single subscriber. DOCSIS 3.0 Downstream speed is 160 Mbps and 120 Mbps Upstream. Channel bonding in computer is an arrangement in which two or more NETWORK INTERFACE on a host computer are combined for redundancy or increased throughput. Internet Protocol Version 6 (IPv6) is a network layer IP standard used by electronic devices to exchange data across a packetswitched internet work. It follows IPv4 as the second version of the Internet Protocol to be formally adopted for general use.. 70
DOCSIS Simplified Speed Test Summary At my home in Montreal, Quebec, Canada Date: 13-01-2007 Time: 13.13 Date: 4-12-2010 Time: 12.45 71
DOCSIS Simplified Throughput Calculations Downstream DS symbol rate = 5.057 Symbols/s or Mbaud. A filter roll-off (Alfa) of about 18 % gives 5.057 X (1+.18)= ~6 MHz wide haystack as shown in figure 3-30 db 6 MHz 64=2 to the 6 th power. Using the exponent of 6 means six bits per symbol for 64 QAM and would give 5.057 X 6 30.3 Mbps. After the entire FEC and MPEG overhead is calculated, this leaves about 28 mbps for payload. This payload is further reduced 5.057 MHz because it s also shared with DOCSIS signalling. figure 3 72
These presentations should give you a good idea of the way these seminars are presented. If you require more information, please get in touch with us at: Email: lamarrea@videotron.ca Tel: 514-767-3687 < Click on the upper arrow on your browser to go back to previous page. 73