Motorola SG 2000 Provozní pokyny stáhnout pdf (Strana 15)

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6 Overview

AT&T SLW2500 Installation and Operation Manual

Forward Path

The multiple receiver functionality of the platform accommodates split-band applications. A

typical split-band configuration has analog signals in the 54 MHz to 450 MHz band feeding one

receiver. Digital transmissions or narrowcast signals are carried between 450 MHz and

870 MHz on another fiber and processed by the second receiver.

Figure 2-5 provides a diagram of the signal flow-path through the SLW2500:

Figure 2-5

Signal flow diagram

JXP

(-20 dB)

-0.5

-0.25

Port 1 power

Port 2 power

Port 1

Port 2

-1.0 dB

-0.5 dB

-1.0 dB

-0.5 dB

FEQ

-1.0 dB

0.0 dB

-4.0 dB

-4.0

-5.0 dB-2.0 dB-2.0 dB0.0 dBSi PP-1.0 dB-1.5 dB0.0 dB

0.0 dB

-1.0 dBSG2-LR

(Broadcast receiver)

Optical input

(-3 dBm to +3 dBm)

Optical input

(-3 dBm to +3 dBm)

Optical input

(-1 dBm nominal)

Optical output

(0 dBm nominal)

SG2-LR

(Narrowcast receiver)

SG2-DFBT

(Transmitter)

SLW25-RPLR

(Return path receiver)

-0.5 dB

Local channel

Hardware

external

to the node is

inserted into

this loop to

implement the

add/drop option.

add/drop option

-1.0 dB

0.0 dB

FBS with

CMTS option

+24 V

+5 V

-10.5

-16.0

24 dB

E-GaAs PP

23 dB

Lid E-pack

(-20 dB)

Forward path

configuration plug in

19.0 dBmV at -3 dBmV input

1550 nm, 4% peak OMI per channel

9 dBmV nominal total input power

at the transmitter RF input port.

Retain electrical and mechanical

interface compatibility with SG2 optical

transmitter modules

+57.5 dBmV virtual output at each port

at 870 MHz, -3 dBm input, 1550 nm,

4% peak OMI per channel.

15 dBmV total return input power

(all ports combined) for low band return

power diplexer loss is 0.5 dB.

Total extra forward path loss = 3.0 dB

• Input section = 1.0 dB

• Interstage section = 1.0 dB

• Output section = 1.0 dB

-4.0 dB

17.5 dB

* E-GaAs PD

17.5 dB

Veri-

losser

Te mp

sensor

Driver

TC curve

generator

Power

supply

SlopeResp

JXPJXP

JXP

HPF

JXP

(-20 dB)

-0.25 dB-4.0 dB

-9.0 dB

-16.0 dB

-6.0 dB

(-20 dB)

-0.5

-0.25

Port 3 power

Port 4 power

Port 3

Port 4

-1.0 dB

-0.5 dB

-1.0 dB

-0.5 dB

LPF

JXP

0.0 dB

-0.25 dB

(-20 dB)

-0.25 dB

-0.25

0.25 dB

16.0 dB

Port 4 power

Port 3 power

Port 2 power

Port 1 power

Power input port

Fuses and/or shunts used

as required for application

+24 V

+5V

Gas tube

or FTEC

16.0 dB

-3.25 dB

-3.25

-3.25 dB

HPF

Resp

LPF

JXP

To assess fiber link status, the optical-power monitor circuit is active at all times. An integrated

optical bulkhead connector and module link status indicators enhance fiber management and

reduce troubleshooting time.

A plug-in board is available to configure the SLW2500 lid board for single or narrowcast

receiver arrangements. A low-noise pre-amplifier hybrid amplifies the signal to a level suitable

for connection to the RF chassis.

At the input to the RF chassis, a flatness circuit compensates for hybrid and accessory response

signatures. A variable attenuator circuit enables fine adjustment of the output level. It is driven

by the standard thermal control unit (TCU) to compensate for temperature variations.

The MDR-*/* circuit board provides a fixed linear equalizer for 870 MHz. The MDR-*/* also

compensates for the low frequency roll-off inherent in plug-in diplexers.

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