Inotech WT-1550-EM30 series User manual

1550nm external modulated
optical transmitter
operating manual

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Table of Contents
Table of Contents.......................................................................................................- 1 -
Safety Instruction.......................................................................................................- 2 -
1. Overview............................................................................................................... - 3 -
1.1About This Manual.......................................................................................- 3 -
1.2 Product Description......................................................................................- 3 -
1.3 ProductApplications.................................................................................... - 4 -
2. Technique Parameters............................................................................................- 5 -
2.1 Optical Parameters........................................................................................- 5 -
2.2 Model Test Indicators...................................................................................- 5 -
2.3 Test Condition...............................................................................................- 6 -
2.4 Technical Data Sheet....................................................................................- 6 -
3. Panel Interface and Menu System Description..................................................... - 7 -
3.1 Front Panel....................................................................................................- 7 -
3.1.1 Indicator Description..........................................................................- 7 -
3.2 Rear Panel.....................................................................................................- 8 -
3.3 Power Module.............................................................................................. - 8 -
3.3.1 220V Power Module...........................................................................- 8 -
3.3.2 48V Power Module.............................................................................- 8 -
Safety Instruction

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1. Overview
1.1 About This Manual
This instruction manual is a complete guide to install and operate the (1RU)
WT-1550-EM30 series 1550nm external modulated optical transmitter. Please read
the entire manual before beginning installation.
This manual applies to WT-1550-EM30 series external modulated optical
transmitter.
•Chapter 1 gives general information about the WT-1550-EM30 series 1550nm
external modulated optical transmitter.
•Chapter 2 describes the complete technical specifications of WT-1550-EM30.
•Chapter 3 describes the front/rear panel interfaces and menu system.
•Chapter 4 tells you how to install WT-1550-EM30 series external modulated optical
transmitter.
•Chapter 5 tells you the communication setting of WT-1550-EM30.
•Chapter 6 describes maintenance and what to do in the event of problems.
1.2 Product Description
WT-1550-EM30 series optical transmitter is a 1550nm DFB laser external
modulated transmitter. It is specially developed for the CATV signal that satisfies
HFC network, and the long-distance transmission of cable phone and cable data.
Working principle
WT-1550-EM30 series transmitter has 7 function modules: RF control, DFB laser,
optical modulator, SBS control, CSO control, communication/display control and
power supply.
Automatic gain control circuit (AGC) or manual gain control circuit (MGC)
amplifies the RF signal. AGC or MGC control makes the optical modulator maintain a
suitable input level. Use the detected RF root-meansquare(RMS)-total power to
calculate the optical modulation index(OMI).
In general we recommend using the AGC function, and special users can use the
MGC function to adjust the CNR/CSO/CTB performance indexes.
The core of transmitter is the optical modulator. The 1550nm signal input the
optical modulator, make the laser intensity changed follow the external RF signal
voltage, and then generate the AM optical signal.

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Stimulated Brillouin Scattering (SBS) occurs, when the optical input power is
greater than a certain threshold value. SBS generate the lower frequency
backscattered light which will attenuate the transmission light and return to the laser
while destroying its performance. Causing optical power fluctuation, generates large
noise, and seriously deteriorates the system carrier to noise ratio (CNR). To improve
the SBS threshold, WT-1550-EM30 series optical transmitter adopts SBS control
technology which is independent researched and developed by ourselves. The
threshold value can be set up to 19dBm.
The optical modulator has a two-way optical signal output. Parts of that signal
are routed to an InGaAs photodiode. This detection of the optical signal has two
functions:
1) Detect whether the laser is normal working. Once the output optical power is
2dB lower than standard power, alarm will be set off.
2) Detect CSO distortion to optimize the bias point of the optical modulator. For
working normal the detector circuit needs at least two carrier signal inputs with an
interval of 24MHz. There is a CSO initialization program in the boot process. If the
CSO install failed, the RF indicator will flash red, see details in 6.2 Troubleshooting.
Block Diagram
1.3 ProductApplications
•High-performance long-distance transmission
•High-power distribution network
•Redundancyloop architecture
•FTTx network
•RFOG application
•DWDM network

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2. TechniqueParameters
2.1 Optical Parameters
Item Unit Value
Optical Wavelength nm 1545～1560 (or specified by the user)
Side-mode Suppression ratio dB >30
Relative Intensity Noise dB/Hz <-160
WavelengthAdjustment
Range
GHz +/-50GHz
Optical Power
dBm
2*7, 2*8, 2*9, 2*10
SBS Threshold Value
dBm
+13
～
+19 (Continuously adjustable)
Laser Linewidth
MHz
0.3
2.2 Model Test Indicators
Test Model C42 D59 D84 D84
Channel Plan CENELEC42 PALD59 PALD84 PALD
Channel Number
TV/FM/QAM64
42/0/0 59/0/0 84/0/0 30/0/48
Bandwidth Noise 5 5 5 5
CNR Tx/Rx 55.5 54.0 52.5 54.5
CNR Link 1 55.0 53.5 52.0 54.0
CNR Link 2 53.0 52.5 50.5 52.5
CNR Link 3 50.5 50.5 49.0 51.0
CSO Tx/Rx and Link 1 64 65 65 70
CSO Link 2 63 65 65 70
CSO Link 3 62 64 63 65
CTB 65 65 65 68

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2.3 Test Condition
First stage
EDFA
First
paragraph
fiber length
Second
stage
EDFA
Second
paragraph
fiber length
RX SBS
(dBm)
Tx/Rx
No
No
No
no
0dBm
13.5
Link 1
No
35km
no
no
0dBm
13.5
Link 2
16dBm
65km
no
no
0dBm
16
Link 3
13dBm
50km
13dBm
50km
0dBm
13.5
Rx with 8 pA/ÖHz input noise current density; EDFA with 5dB noise figure; RF input level at 80
dBμV / TV channel;
2.4 Technical Data Sheet
Item
Unit
Technical Parameters
RF range
MHz
47
～
1003
RF flatness dB +/-0.75
RF return loss
dB
>16
RF input impedance
Ω
75
RF input connector type
F type
Rated input level
dBµV
80
Input level range
dBµV
78~96 (AGC mode, modulating signal)
AGC control range
dB
+3
～
-3
MGC adjustable range dB 0~15
Optical connector
SC/APC, FC/APC
Operating temperature
°C
-5
～
45
Storage temperature
°C
-30
～
+70
Power Source
Specification
V
90
～
265VAC
36
～
72VDC
Consumption
W
≤60
Dimension
mm
483(L)
×
455(W)
×
44(H)
Total Weight
kg
5.5

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3. Panel Interface and Menu System Description
3.1 Front Panel
1
Power indicator
2
AGC indicator
3
RF modulation degree indicator
4
Laser indicator
5
LCD
6
ESC key
7
UP key
8
DOWN key
9
Enter key
10 RF input port (or on the rear
panel, optional)
11
-20dB RF input test port
3.1.1 Indicator Description
Power indicator One power supply
LED yellow
Two power supplies
LED green
AGC indicator
AGC mode
LED green
MGC mode
LED off
RF modulation degree
indicator
Normal
LED green
Abnormal
LED flash red
Laser indicator
Bias current, cooling current and
output power are all normal
LED green
At least one of bias current,
cooling current and output power
is abnormal
LED flash red
3.2 Rear Panel
1
Ground stud
2
Power module
3
Fan
4RF input port (or on the front
panel, optional)
5
RS232 interface
6
LAN interface
7Optical output interfaceA (or
on the front panel, optional)
8Optical output interface B (or
on the front panel, optional)

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3.3 Power Module
3.3.1 220V Power Module
1
Mounting screws
2
220V power outlet
3
Fuse
4
Power switch
3.3.2 48V Power Module
1
Mounting screws
2
+ Positive terminal block
3
- Negative terminal block