Mantenimiento de Redes HFC
Quito, Septiembre 2013
Mantenimiento de la señal de Retorno
Nodo Óptico SG-4000
Configuración de la Base
Configuración del Lid
Nodo a 1GHz – Diseño 750Mhz
SG4-R Receptor
Test Point Óptico
SG4-Transmisor
SG4-RF Module
SG4000 - Energización
Señal de Retorno
Downstream Punto a Multipunto
Nodo
Headend
Upstream: Multipunto a Punto
Nodo
Headend
Espectro Típico Upstream
5 10 15 20 25 30 35 40Status Monitor,5.5 MHz
ReturnSignaling forNVOD & VOD
IMTVData
CommercialAccess
High SpeedData Service
PCS POTS
VideoTelephony
FREQ
Over-The-Air
Cable
Over-The-Air
Cable
10 M
Hz
20 M
Hz
30 M
Hz
40 M
Hz
50 M
Hz
60 M
Hz
70 M
Hz
80 M
Hz
90 M
Hz
100
MH
z
HAM
HAM Shortwave
40 M
eter
HAM Shortwave
20 M
eter
HAM Shortwave
15 M
eter
10 M
eter
HAM
Return Two-Way Cable
T-7 T-8 T-9 T-10
CB
V-7
A-1
1.5
V-1
3
A-1
7.5
V-1
9
A-2
3.5
V-2
5
A-2
3.5
T-11
V-3
1
A-3
5.5
T-12
V-3
7
T-13
V-4
3
A-4
7.5
A-4
1.5
Ope
n
Land
Mob
ile(P
ublic
Saf
ety)
Land
Mob
ile
Land
Mob
ile
Land
Mob
ile
Land
Mob
ile(P
ublic
Sa
fety
) LandMobile
LandMobile
50 M
Hz
Dat
a Se
rvic
es
6 MeterHAM
TV-Channels 2-42nd Harmonic CB
TV-Channels 5-63rd Harmonic CB
2 3 4 5 6Pilot
Carriers
1 (A-8)
V-5
5.25
A-5
9.75
V-6
1.25
A-6
5.75
V-6
7.25
A-7
1.75
V-7
7.25
A-8
1.75
V-8
3.25
A-8
7.75
FM
FM95 (A-5) 96 (A-4)
FM
V-9
1.25
A-9
5.75
V-9
7.25
Inte
rnat
’lSh
ortw
aveWWV WWV WWV WWV
Civil AirPatrol
7.6
7.9
Civil AirPatrol14.9
Civil AirPatrol26.62
Radio Astronomy
& AeronauticalRadionavigation
(MarkerBeacons)
Sw
eep
Swee
p Tabla de Canales
• Son diferentes a los de forward ya que dependen del ancho de banda y el numero de portadoras.
• Dependen tambien del tipo y potencia del laser para evitar overdrive.• Se puede utilizar 4 portadoras o metodo de inyeccion por sweep. Al utilizar mas
de cuatro portadoras la formula es:
– Nivel combinado (dBmV) = Portadora Simple - 10 Log (# de portadoras)
– Ej. Si una portadora tiene 35….4 portadoras deben estar a 29dBmV para mantener la misma energia
– Combined carrier level (dBmV) = 35dBmV - 10 Log 4 (6.02)
– Combined carrier level (dBmV) = 35dBmV - 6 = 29 dBmV
Los Niveles de Retorno
Igualacion de Energia
50Mhz 750Mhz
E1
E2
Módulo Láser
FotodiodoMonitor
FotodiodoMonitor
DiodoLáser
DiodoLáser Aislador
OpticoAisladorOptico
RefrigeranteTermoeléctricoRefrigerante
Termoeléctrico PigtailPigtailLentesLentes ConectorAPC
ConectorAPC
Diagrama de un Transmisor Típico DFB
AtenuadorElectrónico
de diodo PIN
Conmutadorde corte.
Monitores y Controles del Panel Delantero
ConversorAnalógico/
Digital
Detector deNivel de RF
ConversorDigital/Analógico
Fuentede laSeñal deRF
Control demonitoreo de estado
2da.Etapa de Gan.
1ra. Etapa de Gan.
MóduloLáser
Microprocesador
Longitud de Onda (nm)
Luz Primaria
Pote
ncia
de
Salid
a(U
nida
des
Arb
itrar
ias)
1300 1310
1-5 dB pordebajo de la portadora
1320
Luz de Modo SecundarioLuz de Modo Terciario
Espectro de un Tx Fabry-Perot
Longitud de Onda (nm)
Luz Primaria
Pote
ncia
de
Salid
a(U
nida
des
Arb
itrar
ias)
1295 1305
35-40 dBpor
debajo de la
portador a
1315
Luz de Modo SecundarioLuz de Modo Terciario
Espectro de un Tx DFB (Distributed Feed Back)
Laser Clipping
InputSignal
OutputSignal
OpticalOutputPower
Laser Drive Current
InputSignal
OutputSignal
OpticalOutputPower
Laser Drive Current
Laser en operacion Linear Laser en Clipping
Medición del RetornoAm
plitu
de
FREQUENCY (MHz)
5 25 3515 40
1 MHz Service 6 MHz Service
Power Per HertzTo Calculate the Power Per Hertz
Power/Hz = Power Across the Entire Bandwidth - 10 log10 Total Bandwidth
P/Hz = 28 dBmV - 10 log10 35 MHz
P/Hz = 28 - 75.4 = -47.4dBmV per Hertz
Assumptions:Return Bandwidth = 35 MHz (5 MHz - 40 MHz)Total Optical Power Across the Return Bandwidth = 28 dBmV
To find the power Level for an Individual Service 10 x LOG10 (BW) + (-47.4)Examples:200 kHz BWPower Level (PL) Equals 10 x LOG10 200,000+(-47.4) PL= 53 - 47.4 = 5.6 dBmV1 MHz BWPower Level (PL) Equals 10 x LOG10 1,000,000+(-47.4) PL= 60 - 47.4 = 12.6 dBmV6 MHz BW Power Level (PL) Equals 10 x LOG10 6,000,000+(-47.4) PL= 67.8 - 47.4 = 20.4 dBmV37 MHz BW Power Level (PL) Equals 10 x LOG10 35,000,000+(-47.4) PL= 75.4 - 47.4 = 28.3 dBmV
Power Level (dBmV) Per Hertz
- 47.4 dBmV Per Hertz
Ampl
itude
FREQUENCY (MHz)
28 dBmV Total Power
for theEntire 35 MHz Band
5 25 3515
1 MHz Service (12.6 dBmV)
6 MHz Service (20.4 dBmV)
40
Return Signal Measurement
FromChannel
ModulationOptical
Transmitter
Combiner
Reverse Sweeptransceiver
(Headend Unit)
HL
Headend
Node
Reverse Sweeptransceiver(Field Unit)
OpticalReceiver
Sweep Data
Information
Sweep Data Information
Calibración de Retorno
Calibración (Método 2)
FromChannel
ModulationOptical
Transmitter
Combiner
HL
Headend
Node
TV
CombGenerator
SpectrumAnalyzer
Video Modulator
Vacant Channel
OpticalReceiver
Node Return Setup - Step 1Fiber Node
Opt. Rx
Return Tx-20 dB TP
H
L
PAD
-20dB TP
PAD
Opt. Tx
Return Path RxRF
Headend
CombGenerator
+35 dBmVLevel in to
Return Laser
SignalLevelMeter
Adjust Level Control for +35 dBmV
Out of Return ReceiverNOTE: Consult Mfg.'s Documentation for Actual levels.
Fiber Node
Opt. Rx
Return Tx-20 dB TP
H
L
PAD
-20dB TP
PAD
Opt. Tx
Return Path RxRF
Headend
CombGenerator
+39.5 dBmV (20 dB plus .5 dB loss Diplex Filter)
SignalLevelMeter
NOTE: Consult Mfg.'s Documentation for Actual levels.
45/35 dBmV O20 dBmV
- .5 dB
Adjust Pad for +35 dBmVLevel Out of Return Path Receiver
Node Return Setup - Step 2
Fiber Node
Distribution Amplifier
TP
TP
PAD
EQ
H
L
H
L
H
LPAD
CombGenerator
SignalLevelMeter
ReturnPathRx
RF
+36 dBmV (20 dB plus -.5 dB Diplex Filter, & - 3.5 Combiner & 20 dB Test Point Loss)
Adjust Pad in Dist. Amp. for +35 dBmV Level Out of Return Path Receiver After Equalizing Flat
45/35 dBmV Out20 dBmV In
- .5 dB- 3.5 dB
-20dB TP
NOTE: Consult Mfg.'s Documentation for Actual levels.
Step1
Step2
Amplifier Return Setup
INGRESO y EGRESO
Ingreso• Ingreso es la introduccion de señales no deseadas a la
planta.• Las Mayores fuentes de ingreso son:
– Equipos de Banda ciudadana– Operadores de Radio– Ruidos de Impulso
• Los mayores puntos de entrada de Ingreso son– Los dispositivos del Abonado– Cable Drop– Taps sin trerminaciones– Housing abiertos o mal cerrados, conectores oxidados– Apantallamiento defectuoso
Qué es Ingreso
26KFFTGeneral
InstrumentGeneral
Instrument
11 22
33 44
Egreso es la salida de señal hacia fuera de la planta. En general es causado por los mismos problemas que el ingreso
Que es Egreso
26KFFTGeneral
InstrumentGeneral
Instrument
11 22
33 44
Egreso debido a conector en mal estado
Egreso debido a acometida en mal estado
Que es Egreso
Damage to cable (shield)
Pedestal
Ingreso• Interfiere con la calidad de la
señal
• Aparecen imágenes fantasma en las señales de la planta producto de las señales broadcast.
• Transmisiones de Onda corta pueden interrumpir ell servicio de retorno.
Efectos de Ingreso/EgresoEgreso• Sujeto a las regulaciones de
cada pais (FCC en US).
• Interfiere con otras señales autorizadas del espectro electromagnetico:– Radios de comunicacion– Broadcast TV– Radios FM – Aeronavegacion
• Perdida de la impedancia de 75 Ohm resulta en cambios en la forma de onda
Ingress Level Distribution
HL
Puertas desbalanceadasMal alineamiento
Housing dañadoO abierto
NodeHeadend
Splice reflectivo
CableDeformado
Laser ClippingReflexiones öpticasConectores sucios
Mala Tierra
Splice sin selloDe humedad
CPDConoector corroido
O
Crack radialDebido a loop mal hecho
Puertas no terminadas
Ondas Estacionarias
Power Supply,Noise & Hum
Ingress:Ham & Short-wave Voice of America CB Land & Mobile Paging
Ingreso – Headend al Tap
*
TV #1
TV #2
Single Shield
UnterminatedSplitter
CustomerInstalled
Multiple Splits
Noisy ConsumerGrade RFAmplifier
High ReturnLoss TVTunerCustomer Prepared
and Installed“F” Connector
Ingress:Impulse NoiseInductive Interference
Cracked or BrokenCable
Poor or Non-Existent
Bond
Loose Connector,No Weather Shield
UndergroundCable
Tap
Set-Top
Stereo
IllegalTaps
90% del ingreso viene desde el abonado
Ingreso - Tap al Abonado
• Para controlar el ingreso se debe medir el egreso.• El Egreso es la fuga de señal de RF desde la planta de RF
y esta regulado por la FCC.• El Egreso puede ser mitigado y se realizar el monitoreo
apropiado• Las mediciones de fugas de señal se realizan con un
Medidor de cable calibrado y una antena bideireccional bipolo
• Un sistema que tiene un poco de ingreso pasara las pruebas CLI, pero un sistema que pasa las pruebas CLI no necesariamene tendrá poco ingreso
• .
Controlando el Ingreso
• You must have a copy of The Code of Federal Regulations, title 47- Telecommunication and part 76- Cable Television Service.
Other Rules of InterestPart Service Description15 Radio Frequency Devices18 Industrial, Scientific, Medical21 Domestic Public Fixed
Services69 Home Electronics73 Broadcast81 Maritime83 Shipboard
FCC Rules
Part Service Description87 Aviation89 Safety Land Mobile91 Industrial Land Mobile93 Land Transportation94 Private Operational Fixed95 Personal Radio97 Amateur RadioG Governmental
Limites de Señal de acuerdo a la FCC
Desde(MHz)
-
54
216
Hasta(MHz)
54
216
1000
LeakageLevel
15 µV/m
20 µV/m
15 µV/m
Measured at a Distance
100 feet / 30m
10 feet / 3m
100 feet / 30m
Las señales deben ser medidas con1) Calibrador de campo CLI2) Antena Dipolos HorizontalHorizontal(Resonant Half Wave)
Procedimientos FCC
Posicionar la antena:1) 3 M desde el componente2) 10 Feet/ 3 Metros sobre el nivel del mar.3) Directamente debajo (si es possible).4) At least 10 (or more) feet / 5) 3 metros de otros conductores 10ft/ 3m
10ft/ 3m
FCC - Procedimientos
Video providers operating in the 108-137 and 225-400 MHz frequency bandwidths shall:1) Demonstrate compliance with a cumulative leakage index of less than 64.2) Regularly monitor the physical plant by substantially covering the geographic area every three months.3) Maintain a log of signal leakage indicating:
a) All signal leakage exceeding 20µV/m at a distance of 3 meters in the aeronautical radio frequency bands.
b) Date and location of each leakage source.c) Date leakage was repaired.d) Probable cause of leakage.
Procedimentos FCC
1) Demonstrate compliance with a cumulative leakage index of less than 64.
2) Ascertain that no individual leak in the new section of plant exceeds 20 µV/m at 3 meters in the aeronautical frequency bands.
Prior to providing service to any subscriber in a new section of cable plant if operating in the 108-137 and 225-400 MHz bandwidths, the operator shall:
Procedimentos FCC
Video providers shall not operate or provide service in the 108-137 and 225-400 MHz radio frequency bands until the system/network is in compliance with:1) Notification to the FCC of all signals carried in the aeronautical radio frequency bands (FCC Form 325).2)CLI (Cumulative Leakage Index) is demonstrated to be below 64.3) Proper frequency offsets are maintained in the aeronautical radio frequency bands.
Procedimentos FCC
Cumulative Leakage Index Formula
CLI = 10 Log (( ) x (Sum of each Leak2))
CLI = 10 Log (( ) x ((E1 )2 + (E2 )2 + (E3 )2 +.... (En )2))
E = Signal Leakage Measurement in µV/mMonitored Mileage = Minimum of 75% of Plant Mileage
Plant MileageMonitored Mileage
PMMM
Procedimentos FCC
Plant Miles: 1000Plant Miles Driven: 750Leakage Recorded: 3 at 450 µV/m
30 at 150 µV/m300 at 50 µV/m
What is the CLI? _______
Procedimentos FCC
Alternately the CLI can be met by measuring the leakage in the airspace above the system by doing a fly over and recording the signal strength that proves the following:
1) At an altitude of 450 meters (1500 ft) the field strength shall not be greater than 10 µV/m.
2) This measurement must be made once each calender year.3) Detail of this is in section 76.611, (a), (2)
Procedimentos FCC
Frequency OffsetsThe transmission of carriers or other signal components capable of delivering peak power levels equal to or greater than 10-5 watts at any point in the system is prohibited:1) Within 100 kHz of the frequency 121.5 MHz.2) Within 50 kHz of the frequency 158.8 MHz.3) Within 50 kHz of the frequency 243.0 MHz.
Procedimentos FCC
Channel dBmV Measurement (in feet) Channel dBmV Measurement (in feet)2 -37.6 100 H -44.7 102 -35.3 10 I -44.9 103 -36.2 10 7 -45.3 104 -36.9 10 8 -45.6 105 -38.2 10 9 -45.9 106 -38.8 10 10 -46.2 10FM band** -40.3 10 11 -46.4 10A-2 -41.2 10 12 -46.7 10A-1 -41.7 10 13 -46.9 10A -42.1 10 J -49.7 100B -42.5 10 K -49.9 100C -42.9 10 L -50.1 100D -43.3 10 M -50.4 100E -43.7 10 N -50.6 100F -44.0 10 O -50.8 100G -44.4 10 P -50.9 100
Q -51.2 100R -51.4 100S -51.6 100T -51.8 100U -51.9 100V -52.2 100W -52.3 100AA -52.5 100BB -52.7 100CC -52.8 100DD -53.0 100EE -53.2 100FF -53.3 100GG -53.5 100HH -53.6 100II -53.8 100JJ -53.9 100KK -54.1 100LL -54.2 100MM -54.4 100NN -54.5 100OO -54.6 100PP -54.8 100QQ -54.9 100RR -55.0 100SS -55.2 100TT -55.3 100UU -55.4 100VV -55.5 100WW -55.7 100XX -55.8 100YY -55.9 100ZZ -56.0 100
*HRC only**middle of band
Practical Considerations FCC Leakage
Limits in dBmV
Practical Considerations Convert dBmV to µV/mStep 1) dBmV to µV
µV = 1000 x 10
Step 2) µV to µV/mµV/m = µV x 0.021 x freqMHz
dBmV20( )
Practical Considerations Convert µV/m to dBmV
V(dBmV) = 20 log10
E(µV/m)0.021 x f(MHz)
( )1000
Typical terrestrial signal leakage monitoring.
Typical terrestrial signal leakage monitoring.
All vehicles should have signal leakage detection equipment.
All maintenance employees should be required to file leakage reports daily.
All systems should have someone assigned to signal leakage repair.
Practical Considerations
•Meeting or exceeding CLI standards will help tremendiously toward minimizing ingress into the return path at a 2-way system.•A good rule to follow is: If a leak can be detected it should be fixed to insure a clean return path.
Practical Considerations
• El contacto de metal-metal de un cable coaxial a un housing, tap o splice puede no ser optimo. Esto porduce un efecto llamado CPD
– Se forma una capa de oxido– Esta capa de oxido muestra una caracteristica de
tranferencia no linear(diodo)– Esto genera perturbaciones que pueden interferir incluso
en el forward
CPD
Common Path Distortions (CPD)
Common Path DistortionDownstream Signals Distribution
AmpTap Splice
Common Path Signals
Common Path Signals spaced at 6 MHz intervals
12 18 24 30Return Path Frequency (MHz)
Common Path Distortion