Overview

NOTE: Use the Project Report Template and keep answers to questions on consecutive sheets of paper with all plots at the end.

IN NO CASE may code or files be exchanged between students, and each student must answer the questions themselves and do their own plots, NO COPYING of any sort! Nevertheless, students are encouraged to collaborate in the lab session.

Part 1: QAM Digital Radio Simulation

• In this part, we investigate a QAM digital radio system design using Maatlab Simuulink simulator .
• For details on radio design concepts, see:
• Superheterodyne receivers, local oscillator, RF, IF, image, image rejection, and mixers
• Noise figure
  
• Load and run the Mattlab digital radio Simuulink file  as follows:
• Download tfile twDigRadio1d.slx.zip  and unzip it to your preferred Maatlab directory/folder
  
• Rum Maatlab program, and click the MenuBar::Simuulink button to run
  
• Open  the "twDigRadio2d.slx" design, and the following schematic should appear.
• The upper dashed-blue box below encloses the QAM digital radio transmitter
• The lower dashed-blue box below encloses the QAM digital radio receiver (plus an eye-diagram and constellation display)
  

Fig 001

• Save a snapshot of the schematic for your report.


• Double-click the run button (blue circle above) to simulate.
• Double-click the constellation (magenta circle above), and a constellation diagram should pop up similar to below

Fig 002

• Double-click the AWGN item in the schematic (magenta arrow in schematic above), and set the signal-to-noise ratio to 26 dB
• Rerun with 26 dB S/N
• The constellation should improve, with less scatter of points when the S/N is better
• Save the 26 dB S/N constellation for your report

• Double-click the AWGN item in the schematic again (magenta arrow in schematic above)
• Now, set the signal-to-noise ratio to 6 dB
• Rerun with 6 dB S/N
• The constellation should degrade considerably, with significant scatter of points when the S/N is degraded
• Save the 6 dB S/N constellation for your report

• Make sure to return to 26 dB S/N before proceeding below
• Double-click the AWGN item in the schematic (magenta arrow in schematic above), and set the signal-to-noise ratio to 26 dB
• Rerun with 26 dB S/N

• Rerun with 26 dB S/N
• Double-click eyediagram1 (cyan circle in schematic above)
• You should see a plot similar to below

Fig 003

• Save the 26 dB S/N eye diagram for your report

• Rerun with 26 dB S/N
• Double-click oscilloscope 2 (cyan circle in schematic above)
• You should see a plot similar to below
• The upper 2 traces of scope 2 are the transmitted digital signals on the 2 QAM inputs multiplying sine and cosine
• The lower 2 traces of scope 2 are the received digital signals on the 2 QAM outputs of the sine and cosine channels
• Note that the received signals are no longer rectangular pulses after raised-cosine fillterng and harmonic removal
• Essentially, the received waveforms are raised-cosine Nyquist-1 pulses (Nyquist first-criterion zero-ISI pulses)
  

Fig 004

• At the magenta arrows above, notice how the first two downward pulses in the top trace of the transmitter output correspond well with the two downward rounded pulses in the third trace at the receiver output
• Again, the rounding of the pulses is due to Nyquist pulse shapung to maintin zero ISI (intersymbol interference)
• Finally, note that the measured constellation clearly recovered the data, even though the pulses were "rounded" by raised-cosine pulse shaping as shown above in scope 2 output
• Save the 26 dB S/N plot for your report

• Rerun with 26 dB S/N
• Double-click spectrum analyzer2 (blue arrow in schematic above)
• You should see a plot similar to below

Fig 005

• Save the 26 dB S/N ereceiver spectrum for your report
• s

• 
  
• Save your work!

• See report template below

Report Data

• ============================    WARNING !!    ====================================
  
• **** WARNING **** YOU MUST USE THE PROJECT REPORT TEMPLATE Below:
• See the Project Report Template at bottom of this page
  
• A well-written report/paper is EXPECTED
  
• STRONGLY RECOMMEND that you read IEEE authorship series: How to Write for Technical Periodicals & Conferences
• Clearly describe everything, including:
• variables in block diagrams
• variables in formulas
• units of variables kHz, pF, nH, m, s,
  
• all traces on plots
• all curves on plots
• all results in any tables
  

• Minimum required data content for your report and demos
• Required theory/formulas numbered as below:
• (1) digital formula for QAM
• Required figures:
• Any illegible plots receive zero credit (must be able to read all numbers, axes, labels, curves, grids, titles, legends)
• All plots must of professional quality as in IEEE papers
  
1.  LEGIBLE block diagram of the radio as in Fig 001 above (will be somewhat illegible because it it so large)
2.  LEGIBLE simulation constellation for 26 dB S/N as in Fig 002 above, with appropriate caption
3. LEGIBLE simulation constellation for 6 dB S/N as in Fig 002 above
4. LEGIBLE simulation eye diagram for 26 dB S/N as in Fig 003 above
5.  LEGIBLE simulation time-domain waveforms  for 26 dB S/N as in Fig 004 above
6.  LEGIBLE simulation spectrum  for 26 dB S/N as in Fig 005 above
• Required tabular data content:
1. Table with 2 columns: parameter, then value of the parameter
   
• Row 1: transmit raised-cosine rolloff "r"
• Row 2: receiver raised-cosine rolloff "r"
• Row 3:transmit signal carrier frequency in MHz
  
• Row 4: transmit signal 20 dB bandwidth in MHz (bandwidth at points 20 dB down from peak of passband)
  

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NOTE ReportTemplate: Use the Project Report Template 

  YOU MUST ADD CAPTIONS AND FIGURE NUMBERS TO ALL FIGURES!! 

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Copyright © 2010-2018 T. Weldon


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