EE471: Advanced Communications Lab


Course Objective

To provide an introduction to design of the physical layer in a communication system.


The objective is to communicate bits using a computer speaker as the transmitter and a microphone as the receiver. We will use scilab on a linux PC for this purpose. A basic familiarity with linux and scilab will be a prerequisite. The lab work is strictly individual. This lab is inspired by Prof. John Barry's acoustic modem assignment at Georgia Tech.


The entire experiment is divided into Parts 1 through 10 as described below. We meet every Monday at 2 pm in the new DCF PC lab. On Week x, Part x will be described briefly for about 20 minutes. Your task in the lab will be to understand Part x and try programming it in scilab. Part x will have to be demonstrated to TAs for grading at the start of the lab on Week x+1. Part x+1 cannot be implemented without finishing Part x.
  1. Kick-off meeting (Aug 18, 2008)

    Some preliminaries will be discussed in this meeting.
    Tasks for the week

    Practice transmitting sound files on scilab. Understand the format. Practice recording the sound using a sound recorder in Linux. Read the recorded waveform in scilab. Understand sampling frequency of transmission and reception.

  2. Week 1 (Aug 25, 2008), Part 1: Channel sounding

    Obtain and plot the magnitude frequency response of the channel. Identify bands for ideal transmission. Identify data rate for ideal channel assumption.

  3. Week 2 (Sep 1, 2008), Part 2: QAM transmitter I (ideal channel, low BW usage)

    Using the parameters chosen during Part 1, design a 4-QAM and 16-QAM transmitter. Record the received waveform. Observe the transmit and received spectrum. Compare the transmitted waveform and received waveform on a plot. Try to synchronize the samples manually.

  4. Week 3 (Sep 8, 2008), Part 3: Sample synchronization and correlation receiver

    Automatically determine the sample at which the recorded waveform starts to correspond to the transmitted waveform. The silent periods will have to be removed from the received waveform before processing.

    Build a correlation receiver for QAM transmitter I. Plot the received constellation.

  5. Week 4 (Sep 15, 2008), Part 4: QAM transmitter II (maximize BW usage)

    Design a 4-QAM and 16-QAM transmitter with a suitable raised-cosine transmit filter for maximizing bandwidth usage. Observe the transmit and received spectrum.

    Try using the ideal correlation receiver from Part 3. Plot the received constellation. Can you adjust transmission parameters to make this work?

  6. Week 5 (Sep 22, 2008), Part 5: Matched filter

    Design a filter matched to the raised-cosine transmit filter. Use this filter in the receiver as the correlator. Plot the received constellation. Can you adjust transmission parameters to make this work?

  7. Week 6 (Sep 29, 2008), Part 6: Linear equalizer I

    Build an adaptive linear equalizer in the receiver after the matched filter in Part 5. Use known training symbols at the start of transmission.

  8. Week 7 (Oct 6, 2008), Part 7: Linear equalizer II

  9. Week 8 (Oct 13, 2008), Part 8: Linear equalizer III

  10. Week 9 (Oct 20, 2008), Part 9: BER plots

  11. Week 10 (Oct 27, 2008), Part 10: Simple coding

  12. Week 11 (Nov 3, 2008), Catch-up

  13. Week 12 (Nov 10, 2008), Catch-up