WWV Radio-Controlled Clock Design Review

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					WWV Radio-
Controlled Clock
Final Presentation


   ECE 345 Senior Design Project
              Jon Matz
       Chris Sukhaphadhana
Objectives
  Build upon our knowledge of DSP and
   DSP programming to decode and
   display the time encoded within the RF
   signal from the radio station WWV
  Learn about a real application of RF
   communication
RF Signal
   • 5 or 10 MHz HF Carrier
   • Voice Announcements
   • 800 ms 1500 Hz pulse to signal a new hour
   • 800 ms 1000 Hz pulse to signal a new minute
   • 5 ms 1000 Hz pulse to signal a new second
   • Var. length 100 Hz pulses for BCD encoded time
BCD Encoded Time
Original System Block Diagram


                      TMS320C541PZ1   LDC-MA154R
       WWV Receiver        -40         LED Clock
                         TI DSP         Display
Original Flowchart
of Signal Processing


Receiver                  Phase-Lock                                   Display
           Match Filter                Signal Logic   Display Driver
                             Loop
Scope Changes
    Removal of LED Display
     - Part received was not as anticipated
     - Allow focus on signal processing
     - Would have required dedicated
       microcontroller
Scope Changes
    Replace “live” audio input to DSP with
     recorded input
      - Debugging not receiver/signal/time
        dependent
Recording System
Block Diagram


       Radio Shack
          DX396          Laptop running    wav file of
     Digital Shortwave    Ace of Wav      WWV broadcast
       RF Receiver
Decoding System
Block Diagram


                  PC running     TMS320C541PZ1
  wav file of    Windows Media         -40        PC running
 WWV broadcast       Player        TI DSP Kit    Tera Term Pro
Flowchart of Signal Processing


Audio Signal   Re-sampling   Match Filter   Signal Logic   Values stored in
                                                            DSP memory
Final State Diagram




     State A: Decode input signal
     State B: Utilize internal sampling rate
Waveform of Test Signal
Waveform of Recorded Signal
Waveform after Re-sampling
General Matched Filter Design




              Proakis, John G., Digital Communications, 2nd Edition, 1989
Final Matched Filter Design
Waveform after Match Filter
Waveform Comparison




     Test Signal      Real Signal
Challenges
  Unusable Systems
  Obtaining Decodable “Real” Signal
  Signal vs. Noise
  Appropriate Thresholds
  Revision of Logic
  Debugging the DSP
Test Signal vs Real Signal




      Test Signal       Real Signal
Signal vs. Noise




       Pulse       Noise
Thresholds
Threshold Levels

            How to
         differentiate   … from this?
            this…
Project Successes
  Creation of Test Signal
  Capture of “Live” Signal
  Design & Implementation of Match
   Filter
  Logic Simulation with Recorded Signal
  Logic Implementation with Test Signal
  Display of Decoded Time
Recommendations
    Utilize WWVB signal
     - more reliable
     - easier to process
     - signal used by commercial products

    LED Displays
      - realize slightly more complex
        than anticipated
Questions?
Acknowledgements
  Thanks to:
  Dave Crowe
  Gary Swenson
  Alina Reeves
  Dima Moussa
  Dan Mast

				
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posted:8/31/2012
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