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Welcome to Week 9 of Digital Signal Processing.

This is our last week of class, but next week we will release a special farewell module, so let's save the goodbyes for later.

This week's module is about digital communication systems and this is where it all comes together; from complex-valued signals, to spectral analysis, to stochastic processing, sampling and interpolation: everything plays a role in the design and implementation of a digital modem. Digital communications is an extremely vast and fascinating topic and it is arguably the pinnacle achievement of DSP in the sense that it's the domain where the most extraordinary quantitative progress has been made thanks to the digital paradigm. The fact that MOOCs such as this one are available to such an incredibly vast audience is just one of the tangible results of digital communication systems. It is only fitting, therefore, to devote the last module of our class to this subject.

We will start with the basics of data modulation and demodulation and we will progress to describing how your ADSL box works by way of its direct predecessor, the voiceband modem that spearheaded the Internet revolution by allowing for the first time the delivery of substantial data rates in the home.

This module (and the accompanying homework) will really test your knowledge and understanding of everything we've done so far. Once again, because of our time limitations, we will be forced to gloss over the fine print, so to speak, and simplify things a bit. But we think we've managed to produce a self-contained primer on digital communications that will show you how things really work and that will make you curious to learn more in your next signal processing efforts.

Day 16

Video lectures:

• 9.1 - Digital communication systems
• 9.2 - Controlling the bandwidth
• 9.3 - Controlling the power

Signal of the day:

• Resolution and Space Exploration

Numerical example:

• Digital Communication Systems (Python), (access on GitHub)

Practice Homework:

• Practice Homework 16 (Solutions)

Homework (due December 28, 5:00pm CET):

• Homework 16
• Feedback 16

Day 17

Video lectures:

• 9.4 - Modulation and demodulation
• 9.5 - Receiver design
• 9.6 - ADSL

Homework (due December 28, 5:00pm CET):

• Homework 17
• Feedback 17

Notes and external resources

Some of the bibles of digital communications are Lee and Messerschmitt's and/or Proakis's eponymous textbooks.

If you're interested in the nitty-gritty implementation details of a communication systems you can take a look at ITU's recommendations for the ADSL standard or, for a more accessible although obviously dated standard, the ITU recommendation for the voiceband V.34 modem.