WWV Radio-Controlled Clock Final Presentation

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WWV Radio-Controlled ClockFinal Presentation

• ECE 345 Senior Design ProjectJon MatzChris
  Sukhaphadhana

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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

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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

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BCD Encoded Time
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Original System Block Diagram
TMS320C541PZ1-40TI DSP
LDC-MA154RLED Clock Display
WWV Receiver
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Original Flowchart of Signal Processing
Receiver
Display
Phase-Lock Loop
Match Filter
Signal Logic
Display Driver
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Scope Changes

• Removal of LED Display - Part received was not
  as anticipated - Allow focus on signal
  processing
• - Would have required dedicated
  microcontroller

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Scope Changes

• Replace live audio input to DSP with recorded
  input - Debugging not receiver/signal/time
  dependent

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Recording System Block Diagram
Radio Shack DX396 Digital Shortwave RF Receiver
Laptop running Ace of Wav
wav file of WWV broadcast
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Decoding System Block Diagram
PC runningWindows Media Player
TMS320C541PZ1-40TI DSP Kit
PC runningTera Term Pro
wav file of WWV broadcast
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Flowchart of Signal Processing
Values stored in DSP memory
Re-sampling
Match Filter
Signal Logic
Audio Signal
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Final State Diagram
State A Decode input signal State B Utilize
internal sampling rate
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Waveform of Test Signal
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Waveform of Recorded Signal
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Waveform after Re-sampling
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General Matched Filter Design
Proakis, John G., Digital Communications, 2nd
Edition, 1989
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Final Matched Filter Design
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Waveform after Match Filter
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Waveform Comparison
Test Signal
Real Signal
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Challenges

• Unusable Systems
• Obtaining Decodable Real Signal
• Signal vs. Noise
• Appropriate Thresholds
• Revision of Logic
• Debugging the DSP

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Test Signal vs Real Signal
Test Signal
Real Signal
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Signal vs. Noise
Pulse
Noise
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Thresholds
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Threshold Levels
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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

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Recommendations

• Utilize WWVB signal - more reliable - easier to
  process - signal used by commercial products
• LED Displays - realize slightly more complex
  than anticipated

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Questions?
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Acknowledgements
Thanks to Dave CroweGary SwensonAlina
ReevesDima MoussaDan Mast