Optical SmartLink EE513 Communication Electronics Zheng Wang Xin Li Jialock Wong

Introduction To provide an all-in-one solution in a box through fiber  To implement fiber optic audio, intercom and data multiplexer Source:

Goals To study more about communication electronics such as fiber communication, DSP technology and multiplexing methods To create a group oriented project To create a fiber audio communication system with programmable DSP

Benefits Flawless audio No electromagnetic interference No crosstalk between channels No radiation of signals Savings Fiber cable is only 5% as expensive as multipair Installation savings: light weight, small diameter Personal safety: fiber do not spark or shock, Repair and replacement savings: less prone to damage and corrosion

Implementations Integrate audio and data streaming over fiber optics cable in analog format Support multiple channels Implement FM multiplexing Implement DSP programmable analysis such as spectrum analysis and signal conditioning at the receiver module

Procedures and timeline Design and Simulate in Multisim (Workbench):2/1 Build and analyze circuit:2/15 Code DSP program using TI C6211:3/15 Test Overall circuit :3/24 Lab Demo:4/7

Block Diagram Multiplexer Transmitter Optical Fiber Receiver Demultiplexer DSP TI C6211

Schematics (Redesigned Circuit) Transmitter Receiver

Multisim Simulation Results Frequency Response

Multisim Results: Waveforms TransmitterReceiver

Pictures of Built Circuits

Laboratory Analysis  To analyze frequency response  To analyze supported inputs  To measure output performances  Instruments used: Agilent digital function generator, HP oscilloscope and Labview

Laboratory Results Frequency responses

Laboratory Results Waveforms  Sinusoidal wave input Noise presents

Laboratory Results  Square wave input

Laboratory Results  Real-time Music playback (DEMO) Original Music (Input) Recorded Music at Receiver (Output)

Result Analysis and Summary Limited Bandwidth – 3kHz Small SNR – loss is very significant Incompatible with pulse signal input Summary Video and data cannot be supported Bandwidth limits number of channels

New Implementations Due to the hardware limitations, we will  implement DSP for signal conditioning and signal analysis  scale down usable channels to 2 channels  use digital filters or crystal filters to demultiplex FM signal

DSP Implementation: Matlab Embedded Target for TIC6211

Example - MATLAB link for CCS Studio Development Tools Top: Original Signal Center: Filtered signal with slight delay Bottom: Spectrum calculated by Matlab This method will be used to cancel environmental noise and analyzing signal quality

Functionality of DSP Due to bandwidth limitation, we need a high quality filter to demultiplex frequency modulated signals at both 1kHz and 3kHz.  2 choices: Crystal filter or DSP digital filter Noise canceling  cancel environmental noise Signal Analysis  Spectrum analyzer and SNR indicator

Summary Designed circuit has narrow bandwidth We decided not to redesign the circuit, but to challenge ourselves by squeezing more information over limited bandwidth information