PC to PC Communication using Optical Digital Link

PC to PC Communication using Optical Digital Link

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PC to PC communication using Fiber Optic Digital Data Link


To Study the PC to PC communication using Optic Digital link.

Apparatus Required

  • Fiber Optics Digital Transmitter Module - 01
  • Fiber Optics Digital Receiver Module - 01
  • Plastic Fiber cable 1 meter - 01
  • PC(computer) - 02
  • CRO - 01
  • Adapter +15V/ DC - 02
  • Patch Chords - 04
  • PC to PC cable - 02


PC to PC communication

Fiber optic digital link was used to transmit and receive the data from one place another place .In this digital link will be supporting 1Mbd speed data communication. It will be act as an optical data modem. So we can use this digital link system in various sectors. And this digital link was used RS 232 serial port for communication.


The heart of the transmitter is a light source. The major function of a light source is to convert an information signal from its electrical form into light. Today's fiber-optic communications systems use, as a light source, either light-emitting diodes (LEDs) or laser diodes (LDS). Both are miniature semiconductor devices that effectively convert electrical signals into light. They need power-supply connections and modulation circuitry. All these components are usually fabricated in one integrated package.


Fig: Transmitting LED HFBR 1251

This type LEDs needs external Driver circuits. Here we used IC 75451 for drive the LED.

Optical fiber

The transmission medium in fiber-optic communications systems is an optical fiber. The optical fiber is the transparent flexible filament that guides light from a transmitter to a receiver. An optical information signal entered at the transmitter end of a fiber - optic communications system is delivered to the receiver end by the optical fiber.

Model Diagram for Plastic Fiber cable


This is multi mode plastic fiber cable, in this fiber cable core diameter 1000 micron and fiber cladding index 1.402.


The key component of an optical receiver is its photo detector. The major function of a photo detector is to convert an optical information signal back into an electrical signal (Photocurrent). The photo detector in today's fiber - optic communications systems is a semiconductor photodiode (PD). This miniature device is usually fabricated together with its electrical circuitry to from an integrated package that provides power-supply connections and signal amplification.


Fig:Receiving Photo Diode HFBR 2521

In this type Photo Diode have internal driver circuits. So no need any external driver.


  • Connect +15V adapter to both transmitter and receiver module.
  • Switch (sw1) ON the transmitter Module, CRO, PC 1, PC 2 and receiver module (sw1).
  • Connect PC to PC cable between PC 1 to transmitter module P5 connector and receiver module P8 connecter to PC 2.
  • Connect the 1 m Plastic fiber cable between transmitter modules LED to receiver module Photo Diode.
  • Connect the CRO Probe, positive to P7 and negative to Ground P8.
  • Now open the hyper terminal at transmitter side PC and transmit any character.
  • Now we get transmitted data output on CRO.
  • Connect P7 and P9 using patch chord at transmitter module.
  • Connect the CRO probe positive to receiver module P3 test point and negative to P2 test point. Now we receive the transmitted data.
  • Connect P3 and P7 using patch chord at receiver module.
  • Open hyper terminal at receiver side PC.
  • Now type any character in transmitter side PC and check the receiver side PC receives that character.
  • Refer below steps, both transmitter and receiver side PC’s.

Transmitter Side

1. Open new hyper terminal page and type connection name



2. Select communication port and press OK



3. Set the bits rate - 9600,data bits - 8, Parity – None, Stop bits – 1, Flow control – None and press OK



4. Type the transmitting characters

Receiver Side

1. Open new hyper terminal page and type connection name



2. Select communication port and press OK



3. Set the bits rate - 9600,data bits - 8, Parity – None, Stop bits – 1, Flow control – None and press OK



4. Check the receiving data’s


Refer below links for more experiments:

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