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Mantenimiento de Redes HFC Quito, Septiembre 2013

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Page 1: Mantenimiento - Dia 2.pdf

Mantenimiento de Redes HFC

Quito, Septiembre 2013

Page 2: Mantenimiento - Dia 2.pdf

Mantenimiento de la señal de Retorno

Page 3: Mantenimiento - Dia 2.pdf

Nodo Óptico SG-4000

Page 4: Mantenimiento - Dia 2.pdf

Configuración de la Base

Presenter
Presentation Notes
orward Band Forward band configurations use up to four SG4-R receivers in the following combinations: Split�Split redundant Segmented 2X Segmented 2X redundant Segmented 4X Return Band Four common RF outputs are served by a single SG4-R/* receiver.�Four common RF outputs are served by either of two SG4-R/* receivers. Two SG4-R/* receivers – each drives one pair of RF outputs.�Two pairs of SG4-R/* receivers – each pair drives one pair of RF outputs. Four SG4-R receivers each drive an individual RF output. Return band configurations use up to four analog optical transmitters in the following combinations: Combined Single Combined redundant Split�Split redundant Segmented All four RF returns are combined and are input to a single return transmitter.�All four RF returns are combined and are input to two return transmitters.�Two pair of RF returns are combined and each is input to a return transmitter. Two pair of RF returns are combined and each is input to two return transmitters. Each RF return is input to a dedicated return transmitter
Page 5: Mantenimiento - Dia 2.pdf

Configuración del Lid

Page 6: Mantenimiento - Dia 2.pdf

Nodo a 1GHz – Diseño 750Mhz

Page 7: Mantenimiento - Dia 2.pdf

SG4-R Receptor

Presenter
Presentation Notes
eature Wavelength selection jumper Optical power test point Receiver JXP attenuator RF output test point Receiver enable Fault indicator�Linear Mid-stage Equalizer Description Used with 1310 nm or 1550 nm transmitters, the wavelength selection jumper on top of the SG4-R/* optimizes the optical power test point and optical power status indicator calibration for the system wavelength. Note that the jumper has no effect on the optical-to-RF performance (gain, flatness, and slope) of the module. Enables monitoring of the optical power level at the input to the module. The nominal scale factor is 1.0 V/mW. JXP style interstage pad that enables you to make forward path gain adjustments. -20 dB test point that enables you to measure carriers throughout the forward band. A green LED (ON) that provides visual indication of the receiver’s enable status. A red LED that illuminates when the module is disabled. Passive plug-in board that helps develop the overall station slope and affects all of the RF modules attached to the receiver. You can access the LME by removing the receiver chassis cover.
Page 8: Mantenimiento - Dia 2.pdf

Test Point Óptico

Page 9: Mantenimiento - Dia 2.pdf

SG4-Transmisor

Presenter
Presentation Notes
Feature Input JXP attenuator RF input test point Optical power test point (see below) Transmitter enable Fault indicator Description JXP style attenuator pad that enables you to make return path gain adjustments to set the proper into the laser. This pad value is factory set to 6 dB in anticipation of 28 dBmV total power at the node housing input. Select the proper pad value required to measure −5 dBmV total power at the RF input test point. −28 dB test point that enables you to measure the total power in the return band in order to select the appropriate JXP. The nominal power level at this test point is –5 dBmV total power. Enables monitoring of the optical output level of the module. The nominal scale factor is 1.0 V/mW when the module is enabled under normal operating conditions. Note that the optical power test point does not track changes in optical power due to the laser tracking error. A green LED (ON) that provides visual indication of the transmitter’s enable status. A single red LED that lights when the module current is outside the normal operating range, the laser output power is below normal limits, or the laser current is above normal limits. Because the laser output requires a short period of time to stabilize, it is acceptable for the fault indicator to illuminate during the stabilization interval (approximately 10 seconds).
Page 10: Mantenimiento - Dia 2.pdf

SG4-RF Module

Page 11: Mantenimiento - Dia 2.pdf

SG4000 - Energización

Page 12: Mantenimiento - Dia 2.pdf

Señal de Retorno

Page 13: Mantenimiento - Dia 2.pdf

Downstream Punto a Multipunto

Nodo

Headend

Presenter
Presentation Notes
Headend signals are point-to-multipoint transmissions. Any noise introduced into a downstream leg after the node affects only that leg.
Page 14: Mantenimiento - Dia 2.pdf

Upstream: Multipunto a Punto

Nodo

Headend

Presenter
Presentation Notes
Return signals are multipoint-to-point transmissions. Noise introduced in one leg can degrade the return performance of all legs.
Page 15: Mantenimiento - Dia 2.pdf

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

Page 16: Mantenimiento - Dia 2.pdf

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

Page 17: Mantenimiento - Dia 2.pdf

• 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

Page 18: Mantenimiento - Dia 2.pdf

Igualacion de Energia

50Mhz 750Mhz

E1

E2

Page 19: Mantenimiento - Dia 2.pdf

Módulo Láser

FotodiodoMonitor

FotodiodoMonitor

DiodoLáser

DiodoLáser Aislador

OpticoAisladorOptico

RefrigeranteTermoeléctricoRefrigerante

Termoeléctrico PigtailPigtailLentesLentes ConectorAPC

ConectorAPC

Presenter
Presentation Notes
APC- Contacto Físico en Angulo
Page 20: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
Page 21: Mantenimiento - Dia 2.pdf

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

Page 22: Mantenimiento - Dia 2.pdf

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)

Page 23: Mantenimiento - Dia 2.pdf

Laser Clipping

InputSignal

OutputSignal

OpticalOutputPower

Laser Drive Current

InputSignal

OutputSignal

OpticalOutputPower

Laser Drive Current

Laser en operacion Linear Laser en Clipping

Presenter
Presentation Notes
Lasers modulated by high RF drive levels will distort or clip the original signal. Clipping of analog signals will be displayed as white text horizontal flashes on a TV screen while the bit-error-rate of a digital signal will increase causing loss of data.
Page 24: Mantenimiento - Dia 2.pdf

Medición del RetornoAm

plitu

de

FREQUENCY (MHz)

5 25 3515 40

1 MHz Service 6 MHz Service

Presenter
Presentation Notes
35 MHz 10 x log = 75.4
Page 25: Mantenimiento - Dia 2.pdf

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

Page 26: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
35 MHz 10 x log = 75.4
Page 27: Mantenimiento - Dia 2.pdf

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

Page 28: Mantenimiento - Dia 2.pdf

Calibración (Método 2)

FromChannel

ModulationOptical

Transmitter

Combiner

HL

Headend

Node

TV

CombGenerator

SpectrumAnalyzer

Video Modulator

Vacant Channel

OpticalReceiver

Presenter
Presentation Notes
Inject the RF level directly into the optical transmitter and adjust the optical receiver in the Headend for the same RF output level as the input (Unity Gain). This becomes the reference level, do not adjust this this level again. 2.Determine from System Design the return RF level to the node. 3.Inject this level prior to the gain block after adjusting the return generator output level to equal the input level + the combined passive loss of the test point, diplex filter couplers etc. 4.Pad the input of the gain block for the reference level established in the headend.
Page 29: Mantenimiento - Dia 2.pdf

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.

Presenter
Presentation Notes
Once the node levels are set, continue to the first amplifier in cascade. Injection levels are set based on the optimum input level to the return amplifier. Adjust the return generator output level = the optimum input level + the combined passive loss of the test point, diplex filter couplers etc. Equalization and padding are performed after the input levels to the amplifiers are set. Insert the proper equalizer for a flat display as viewed on the TV receiver. Pad the output of the amplifier for reference levels established in the headend.
Page 30: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
Once the node levels are set, continue to the first amplifier in cascade. Injection levels are set based on the optimum input level to the return amplifier. Adjust the return generator output level = the optimum input level + the combined passive loss of the test point, diplex filter couplers etc. Equalization and padding are performed after the input levels to the amplifiers are set. Insert the proper equalizer for a flat display as viewed on the TV receiver. Pad the output of the amplifier for reference levels established in the headend. Once the node levels are set, continue to the first amplifier in cascade. 2.Determine from System Design the return RF level to the Amplifier. 3.Inject this level prior to the gain block after adjusting the return generator output level to equal the input level + the combined passive loss of the test point, diplex filter couplers etc. 4.Equalize for a flat response at the optical receiver in the Headend display display at the as viewed on the TV receiver. 5.Pad the output of the gain block for the reference level established in the headend.
Page 31: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
Once the node levels are set, continue to the first amplifier in cascade. Injection levels are set based on the optimum input level to the return amplifier. Adjust the return generator output level = the optimum input level + the combined passive loss of the test point, diplex filter couplers etc. Equalization and padding are performed after the input levels to the amplifiers are set. Insert the proper equalizer for a flat display as viewed on the TV receiver. Pad the output of the amplifier for reference levels established in the headend.
Page 32: Mantenimiento - Dia 2.pdf

INGRESO y EGRESO

Page 33: Mantenimiento - Dia 2.pdf

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

Page 34: Mantenimiento - Dia 2.pdf

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

Page 35: Mantenimiento - Dia 2.pdf

Que es Egreso

26KFFTGeneral

InstrumentGeneral

Instrument

11 22

33 44

Egreso debido a conector en mal estado

Egreso debido a acometida en mal estado

Page 36: Mantenimiento - Dia 2.pdf

Que es Egreso

Damage to cable (shield)

Pedestal

Page 37: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
Basically Ingress/Egress is a 2-way street. If signals can leak out of the system, external signals can also get into the system.
Page 38: Mantenimiento - Dia 2.pdf

Ingress Level Distribution

Page 39: Mantenimiento - Dia 2.pdf

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

Page 40: Mantenimiento - Dia 2.pdf

*

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

Page 41: Mantenimiento - Dia 2.pdf

• 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

Page 42: Mantenimiento - Dia 2.pdf

• 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

Presenter
Presentation Notes
A copy of Part 76 is included at the end of this section.
Page 43: Mantenimiento - Dia 2.pdf

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

Page 44: Mantenimiento - Dia 2.pdf

Las señales deben ser medidas con1) Calibrador de campo CLI2) Antena Dipolos HorizontalHorizontal(Resonant Half Wave)

Procedimientos FCC

Page 45: Mantenimiento - Dia 2.pdf

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

Page 46: Mantenimiento - Dia 2.pdf

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

Page 47: Mantenimiento - Dia 2.pdf

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

Page 48: Mantenimiento - Dia 2.pdf

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

Page 49: Mantenimiento - Dia 2.pdf

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

Page 50: Mantenimiento - Dia 2.pdf

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

Page 51: Mantenimiento - Dia 2.pdf

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

Page 52: Mantenimiento - Dia 2.pdf

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

Page 53: Mantenimiento - Dia 2.pdf

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

Presenter
Presentation Notes
Also see RD-17, pg. 52
Page 54: Mantenimiento - Dia 2.pdf

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( )

Presenter
Presentation Notes
Example; Convert -41 dBmV measured at 100 MHz to µV/m µV = 1000 x 10 = 1000 x 10 = 1000 x 0.00891 = 8.91 µV µV/m = 8.91 x 0.021 x 100 = 18.72 µV/m
Page 55: Mantenimiento - Dia 2.pdf

Practical Considerations Convert µV/m to dBmV

V(dBmV) = 20 log10

E(µV/m)0.021 x f(MHz)

( )1000

Presenter
Presentation Notes
Example; convert 18.72 µV/m measured at 100 MHz to dBmV V(dBmV) = 20 log10 = 20 log10 (8.914 / 1000) = 20 log10 (0.008914) = 20 x (-2.0499) = -40.99 dBmV
Page 56: Mantenimiento - Dia 2.pdf

Typical terrestrial signal leakage monitoring.

Typical terrestrial signal leakage monitoring.

Page 57: Mantenimiento - Dia 2.pdf

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

Page 58: Mantenimiento - Dia 2.pdf

•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

Page 59: Mantenimiento - Dia 2.pdf

• 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

Page 60: Mantenimiento - Dia 2.pdf

Common Path Distortions (CPD)

Page 61: Mantenimiento - Dia 2.pdf

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)

Presenter
Presentation Notes
Common Path Distortions (CPD) - When metal-to-metal contact of a cable to housing, tap or splice, mechanism is not optimum, or it is corroded, an oxide layer is formed. This oxide layer exhibits a non-linear transfer characteristic. When this corroded contact is near a high level signal, such as after an amplifier, mixing of the downstream signals generate upstream signals in the return path at 6 MHz spacing intervals.
Page 62: Mantenimiento - Dia 2.pdf

Common Path Distortion