PBJ Morse Co'

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PBJ Morse Co.

• We put the FUN back in FUNction

Carolyn Salisbury CEO Brent Diley Anthony
Riccelli Ryan Roby Tyler Thompson
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AM Radio Transceiver

• Large antennas are required to efficiently
  radiate electromagnetic energy.
• Impractical
• The lower the frequency,
• the bigger the antenna

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Problems

• Find a way to send a low frequency signal as a
  high frequency signal to reduce antenna size
• Receiving antenna must recover the original
  signal by shifting its spectrum back to the
  baseband

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Objectives

• Shift the frequency spectrum of the audio signal
  to a higher frequency band my multiplying it by a
  high frequency signal.
• Use envelope detector that consists of a diode
  rectifier and a bandpass filter to recover the
  original signal.

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Approach

• Demonstrate the working principle of the AM
  broadcasting with a Morse coded signal of SOS
  in SIMULINK.
• Frequency of audio tone shall be 800 Hz within an
  audio bandwidth of 4 kHz.
• Carrier frequency shall be 50 kHz

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Spectral Analysis

• Compute the spectrum
• Results

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Spectral Analysis

• Compute the spectrum
• Results

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Spectral Analysis

• Compute the spectrum
• Results

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Spectral Analysis

• Compute the spectrum
• Results

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Spectral Analysis

• Results Continued

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Spectral Analysis

• Results Continued

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Spectral Analysis

• Results Continued

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Spectral Analysis

• Compute the spectrum
• Results

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System Design

• Minimizes static
• Cleanest signal

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System Design

• Chebyshev Filter
• Faster decay
• More passband ripple
• Minimizes the error
• between the idealized
• filter characteristic of
• the actual over the range of the filter

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Implementation

• Bode plot of Chebychev
• filter

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Implementation

• SOS Tone Signal Generator

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Implementation

• AM Radio Transceiver

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System Testing

• Demonstration
• Testing results
• System worked as designed and implemented

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Test Result Analysis

• The signal must be less than 2 seconds long or
  aliasing will occur.
• Mu had to be 0.7 instead of 0.8

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Summary

• Project was a success
• We were able to send a low frequency signal by
  multiplying it by a carrier signal and recovering
  the original signal

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Conclusions

• Theres always something new to learn in MATLAB
• Helped to understand real world applications of
  Signals and Systems
• Suggestions for future work
• More time for research, developing solutions and
  analyzing results

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Any Questions?