Explains how passband and baseband representations of signals are related in digital communications. Shows how QAM passband signals are generated from lowpass (baseband) constellation points (effectively "up converting" them to the passband), and then shows how the demodulation process at the receiver "cancels out" the up conversion and recovers the baseband signals. This shows that the baseband representation is enough to capture (mathematically) the input-output relationship that results from the modulation/demodulation process.
Related videos: (see http://www.iaincollings.com)
• What is a Constellation Diagram? https://youtu.be/kfJeL4LQ43s
• Fourier Transform of cos function: https://youtu.be/McITNfo3LKc
• Convolution with a Delta function: https://youtu.be/TIcfY19dk0c
• What is a Matched Filter? https://youtu.be/Ci-EjiMJo3I
• What is the Fourier Transform? https://youtu.be/G74t5az6PLo
• How do complex numbers relate to real signals?: https://youtu.be/TLWE388JWGs
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