What is a Direct Modulated Optical Transmitter

  Today, let’s learn about a optical transmitter, especially called Direct Modulated Optical Transmitter equipment via three topics: working principle, products preview and Performance Features.

Working Principle

  Modern fiber-optic communication systems generally include an optical transmitter to convert an electrical signal into an optical signal to send into the optical fiber, a cable containing bundles of multiple optical fibers that is routed through underground conduits and buildings, multiple kinds of amplifiers, and an optical receiver to recover the signal as an electrical signal. The information transmitted is typically digital information generated by computers, telephone systems, and cable television companies.

A optical transmitter working principle diagram

A optical transmitter working principle diagram

  Laser is the most expensive machine components, machines equipped with microprocessors. The microprocessor software to monitor the working state lasers, operating parameters from the panel LCD display. Once the laser operating parameters deviate from the permissible range set by the software, the microprocessor will automatically turn-off laser power. Flashing yellow light prompts alarm panel LCD prompts cause of the malfunction (non-human factors that can not be damaged laser). RF pre-distortion technology, ensuring the case of CSO-performance system for maximum CNR.

Products preview

19 “1U standard rack, with built-in high performance switching power supply, the transmitter can be 85 ∽ 265Vac City Network voltage work.

  FOT series Optical Transmitter products adopt the high linearity, optical isolation, the DFB, thermoelectric cooling DFB laser produced by ORTEL 、AOI、Fujitsu、Mitsubishi and other world-renowned semiconductor companies. It can provide high-quality images, digital or compressed digital signal long-distance transmission for cable television and telephone communications. Built-in RF driver amplifier and control circuitry to ensure the machine’s CNR, CTB, CSO target. Comprehensive and reliable optical circuits and laser output power stability Temperature stability of thermoelectric cooler control circuit to ensure optimal machine performance and long-life laser stability.

Front and Back panel view of A Optical transmitter

Front and Back panel view of A Optical transmitter

  • Quality: original system optimization control technology and RF pre-distortion technology ensure that the system can acquire the maximum CTB, CSO, and SBS targets in the case of excellent performance CNR.
  • Reliability: The 19 “1U standard rack, built-in high-performance dual switching power supply,it can work in the backup at 85 ∽ 265Vac City Network Voltage, MS-level automatic switching; chassis cooling automatic temperature control.
  • Intuitive: The laser is the most expensive machine components, machine equipped with microprocessor monitors the working state of the laser, the panel LCD window displays the operating parameters. Once the laser operating parameters deviate from the permissible range set by the software, micro-processing will automatically turn off laser power, yellow light goes on to warn, the panel LCD prompts the cause of troubles.
  • Power plug: Aluminum structure using plug switching power supply, allows for heat dissipation and replacement. And dual power supply hot and cold backup.

Performance Features

  The main technical indicators is as following:

Optical parameter  
Laser typeSee products overview
Optical wavelength1310, 1550±10nmspecified by user
Side mode Suppress Ratio≥45dBSMSR
Equivalent noise intensity≤-145dB/HzRIN (20~2700MHz)
Optic modulation modeInternal Modulation
Optical output power1 ~ 10mW (1550nm)
1~26mW (1310nm)
Optic return loss≥50dB
Optical connector typeSC/APC, FC/APCspecified by user
Optical fiber typeSingle Mode
CATV Parameter
Frequency range47~862MHz
RF input level77~83dBuVAGC control
Input impedance75Ω
RF input return loss> 16dB
SAT-IF parameter
Frequency range950~2600MHz
Input level-40~-20dBmTotal input power
IMD-40dBcTotal input power ≤-20 dBm
Optic return loss≥12dB
Flatness in band± 0.75dB
RF input impedance75Ω (50Ω option)
IF connectorF-Female 75Ω
Transmit channels36CH
Power supplyAC 90~265V-48VDC option
Power consumption≤50WSingle power supply
Network interfaceRJ45 (Ethernet 10/100Mb/s)Support WEB and SNMP
Operating temperature-0~50 ℃
Storage temperature-40~85 ℃
Relative humility20%~85%
Size19’’× 14.5’’ × 1.75’’W*D*H

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