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BPSK RF Receiver

BPSK RF Receiver. Team 10 Michael Russell Shawn Kuo Amit Patel. Objective. Successfully demodulate BPSK data sent at RF from one DSP to another Demonstrate feasibility of programmable back-end receiver Develop future tool for DSP lab. End-user Benefits.

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BPSK RF Receiver

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  1. BPSK RF Receiver Team 10 Michael Russell Shawn Kuo Amit Patel

  2. Objective • Successfully demodulate BPSK data sent at RF from one DSP to another • Demonstrate feasibility of programmable back-end receiver • Develop future tool for DSP lab

  3. End-user Benefits • A quick and simple point-to-point digital communication solution • Scalable module that is capable of handling multiple demodulation schemes without hardware redesign • Capable of receiving over a large frequency range

  4. Original Design Review

  5. Software Implementation • Differential BPSK • Pi-Radian Ambiguity • Symbol Quantization and Unmapping • Phase-Locked Loop • Carrier Recovery • Coherent Detection • Symbol Timing

  6. Differential BPSK Symbol Mapping

  7. Phase-Locked Loop

  8. Symbol Timing

  9. Simulation Results Generated BPSK Waveform Received BPSK Waveform

  10. RF Receive Stage

  11. RF Stage - Preselector

  12. Preselector Matching Network Input Impedance

  13. Measured Signals • Transmitted signal • Signal after preselector • Signal after mixing (baseband) • Unfiltered DDS signal (LO) • Filtered DDS signal

  14. Transmitted Signal

  15. Filtered Signal

  16. Filtered Signal

  17. Baseband Signal

  18. Unfiltered DDS (LO)

  19. Filtered DDS (LO)

  20. Output Interface • Write decoded characters to memory and serial port simultaneously • Interact with serial port through Tera Term

  21. Q I Symbol B Symbol A Q I Symbol B Symbol A Theoretical Probability of Error Constellation Constellation w/Noise

  22. Received Symbol: Q I Symbol B Symbol A Theoretical Probability of Error Mapping Result: Q(sqrt(2*Energy/Noise)) or Q(sqrt(2*SNR))

  23. Calculating SNR The SNR was calculated by measuring separately measuring the signal power and the noise power after the preselector filter.

  24. Calculated Byte Error (upper bound) Took 125KB of data Accurate for large amounts of noise Good order of magnitude approximation for low noise Calculated Probability of Error

  25. Error Results

  26. Variation in Frequency Drifting in DDS Temperature Result Tolerance of PLL

  27. Successes • Demodulated BPSK data sent at RF from one DSP to another • Demonstrated feasibility of programmable back-end receiver • Breadboard design produced expected behavior

  28. Challenges • Transmitting BPSK signal at RF • Used passive mixer and DDS • Used coaxial channel instead of air • Bandlimiting Signal • Use of Narrow Bandwidth Crystal Filter • Matching Network • Working around Serial Port interrupts

  29. Future Developments Rev1.1 • Solve Serial Port Issues for live data • Printed Circuit Board • Add Faster A/D • Implement more Demodulation Schemes

  30. Questions???

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