Synchronization in Digital Communication

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Synchronization in Digital Communication

• By Bader Al-Kandari and Josh Mason
• Advisors Dr. Thomas L. Stewart, Dr. In Soo Ahn

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Project Design Review Contents

• Project Summary
• Functional Description
• Transmitter/Receiver Block Diagrams
• Hardware/Software
• Preliminary Results
• Original Work Schedule
• Work Completed
• Revised Work Schedule
• Questions?

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• The purpose of this project is the development
  of a Quadrature Amplitude Modulation (QAM) signal
  communication system in order to test
  synchronization methods of digital communication
  systems.

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Functional Description
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Functional Description

• Inputs
• Transmitter
• Signals from a function generator
• Stored Data
• Receiver
• QAM signal
• Stored Data

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Functional Description

• Outputs
• Transmitter
• QAM signal
• Receiver
• Recovered Data
• Matlab/Simulink Data Acquisition

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Functional Description

• Modes of Operation
• Transmitter Real Time Modulation
• Receiver Real Time Demodulation

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Transmitter Block Diagram
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Transmitter Block Diagram
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Transmitter Block Diagram
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Transmitter Block Diagram

• Adaptable for stored data inputs
• Differential Coding
• Possibility of M-Level QAM

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Receiver Block Diagram
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Hardware/Software

• TI c6713 DSP
• 8 KHz, 32 KHz, 44.1 KHz, 48 KHz, and 96 KHz
• Matlab/Simulink
• Code Composer Studio

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Preliminary Results

• QAM Simulink Development
• 4-QAM Transmit/Receive
• DSP interfacing/testing
• Digital filtering
• Analog source
• Data Source

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Original Schedule

• Practical Theoretical
• 12/1/2005 Proposal Presentation Proposal
  Presentation
• Winter Break Work on Website Work on Phase
  distortion
• 1/24/2006 Fully Develop DSP I/O correction
• 1/31/2006 w/ Matlab/Simulink 
• 2/7/2006 Begin Documentation 
• 2/14/2006 Test/gather data of Finalize 4-QAM
• 2/21/2006 implemented 4-QAM 
• 2/28/2006 Documentation/Tutorial Finish up any
  remaining
• 3/7/2006 Work phase distortion problems
• 3/21/2006 8-QAM testing/data  
• 3/28/2006 gathering Begin work on 8-QAM
• 4/4/2006 Documentation/Tutorial and 16-QAM
• 4/11/2006 16-QAM testing 
• 4/18/2006 Documentation Documentation
• 4/25/2006 Presentation Presentation
• 5/2/2006  

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Tasks Completed

• RTDX Testing
• Phase Tracking using Phase Lock Loop

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RTDX Testing

• Success Using m-files
• Unable to succeed using block diagram modeling

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RTDX Testing (m-file)

• M-file has RTDX input channel and output channel
• Increments the values of an array passed into the
  input channel
• Program then reads the output channel
• Literally runs on DSP

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RTDX Testing (m-file)

• 1 2 3 4 5

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RTDX Testing (m-file)
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RTDX Testing (Block Diagram)
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RTDX Testing (Block Diagram)
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PLL Subsystems

• Phase Detector (PD)
• Loop Filter (LF)
• Oscillator
• 1Voltage Controlled (VCO)
• 2Direct Digital Synthesizer (DDS)

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PD Implementation
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PD models
Cross product terms (CPT) model
Inverse tangent model
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Comparison
CPT PD
Atan2 PD
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Loop Filter
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Design equations for LF
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LF

• Loop filter is PI integrator
• Why?
• y(n) y(n-1) k1x(n) k2x(n-1)

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DDS
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DDS Simulation
Frequency 40 Hz
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Complete model
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Model on 6713
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Simulation parameters and specs

• Input frequency 42 Hz
• LF natural frequency 5 Hz
• DDS running frequency 40 Hz
• Fs 8000 Hz

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Simulation results
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Laboratory results
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Phase error
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Filter output at 41 Hz
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Whats Left

• Differential Coding
• 2-D Slicer
• Automatic Gain Control
• Symbol Timing
• RTDX or Comparative Method

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Revised Project Schedule
  Bader Al-Kandari Josh Mason
3/7/2006 Fully Debug PLL Document RTDX Document
Break Research Symbol Timing Research Diff Coding
3/21/2006 Symbol Timing Differential Coding
3/28/2006 Symbol Timing Differential Coding
4/4/2006 2-D Slicer DiffCoding/Prepare for Student EXPO
4/11/2006 2-D Slicer Data Preparations
4/18/2006 Automatic Gain Control Automatic Gain Control
4/25/2006 Documentation Documentation
5/2/2006 Presentation Presentation
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Questions?

• ! 45

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Inverse tan PD
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Atan2 simulation results
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Lab results
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Lab results