Project Overview

The project that Team MCP Nano will be working on was created by the three team members as well Dr. Ken Noren and Dr. Suat Ay.  The project goal is to use free space optical communcations to transfer data between various sources.  The problem to be solved includes integration of transmitter/receiver circuitry, encoding/decoding circuit  and ability to connect with a user interface all onto one IC chip.   The chip is designed to allow two way communication between devices over a long distance, approximately 5 m.  

Specifications


  • 100kHz signal transmission
  • Range of 2+meters
  • Reliable transmission protocol
    • IRdA (Infrared Data Association)
    • UART (Universal Asynchronous Receiver-Transmitter)
    • RC5 (Rivest Cipher)
  • Total power dissipation of TX < 500mW
  • Total power dissipation of RX < 150mW
  • 5V single-ended power supply
  • Field-Programmable-Gate-Array (FPGA) interface

Historical Background

On June 3, 1880, Bell conducted the world's first wireless telephone transmission between two buildings, some 213 meters apart. Its first practical use came in military communication systems. The German army for example employed the Lichtsprechgerät 80 (light speaking device) in their World War II anti-aircraft defense units. The invention of lasers in the 1960s revolutionized free space optics. Military organizations were particularly interested in it because of its very secure nature (directed beams). 


FSO Today


Many simple and inexpensive consumer remote controls use low-speed communication using infrared (IR) light (Consumer IR technologies). Advanced Free Space Optical (FSO) systems are most commonly employed for last mile communications in urban environments (instead of expensive fiber optics). These systems can function over distances of several kilometers as long as there is a clear line of sight between the source and the destination. It features several advantages over traditional RF communication systems:

  • Ease of deployment (air as a transmission medium)
  • License free (typical operating frequency of an 800nm IR laser is 1.25 MHz)
  • Very secure (narrow directed beam)
  • Immune to electromagnetic interference
  • High bit rates and low error rates
  • Protocol transparency

One of the major tradeoffs is optical interference (Fog/Snow/Smog) resulting in 10-100 DB/km attenuation. Another challenge comes from pointing instability (eg. due to wind / swinging skyscrapers / etc.), which can cause the beam to shift focus and requires very complex correction systems.