last updated 3.2.2003


S-72.227 Digital Communication Systems

Spring 2003

Writing a lecture diary

In your Lecture Diary you address the following elements:

Discuss what were the essential elements of this lecture? (Do not copy lecturing slides but use your own words!) Use many figures! You may use Mind Mapping chart to show the logical connections of the lecture topics.

Discuss why these concepts and this information is important for science, society and you. Suggest if the studying of this topic could be made more fruitful.

Give a critical point of view of a single lecturing topic: How this could be applied, why it should be applied! Discuss what you could not comprehend! How this lecturing topic could be illustrated?

What is a consequence of this topic with respect of applications? Where and how this topic is applied?

Guide for grading of lecture diaries

Each student participating to the lecture diary - module of this course  must grade at least eight lecture diaries. One should read the lecture diary carefully through and justify how it covers the four key topics (Contents, Motivation, Understanding and Application) as explained in the previous section.

In addition, in your grading you should

Grading of Lecture Diary is always subjective. However, by following the lecture carefully by yourself you enable more justified comments. Return your grade and attached comments on next tutorial. See the following example of a Lecture Diary:

LECTURE DIARY 12.9.2002 (example)

Mathew Matts (don't include your student number)

Lecture topic: Exponential Modulation (lecture 2)

Contents: This lecture discussed about exponential modulation that is used for instance in FM-radios. In analysis of FM we noticed that it can not be analyzed as simply as linear modulation techniques. Therefore one must use a set of special cases to find out how it works. This is done gradually such that first narrow band modulation is discussed and then wideband modulation with tones and finally wideband modulation with arbitrary modulation signal. This was used also to determine the required bandwidth. Detection of FM was discussed. It was interesting to note that FM and AM detection carries some similarities as shown in the figure below:

Motivation: Considering EM is important for two reasons. First is gives a set of ideas to analyze non-linear systems. One can see that their analysis is not necessary more difficult than analyzing linear systems but one needs to have a grip how problems can be simplified or to extract the essential elements. Secondly, analyzing EM forms basics to understand phase shift keying modulation, for instance its spectral presentations.

Understanding: In this lecture understanding of FM-AM conversion was interesting. It is a handy way to convert phase changes to amplitude changes for detection. One must use limiters to cut-out channel introduced amplitude distortion. Also channel may introduce FM-AM conversion that is alleviated by equalizer. Therefore, this is an interesting topic having many applications. Also software radio was discussed that I got so interested that I went to the Web and found an interesting article ( Only a brief look revealed that the introduction of A/D conversion can change receiver structure a great deal. However, signal properties are still the same - only their processing is now based on making DSP-based calculations. I wonder if there exists any simulation tools that can be used to study software radios more closely?

Applications: EM is used because it can dramatically improve post detection SNR still this is paid by increased transmission bandwidth. EM is applied in analog radios and in TVs sound channel. Various phase modulation techniques as QPSK and M-PSK are a form of EM. GSM - system applies Gaussian Shift Keying that is a filtered phase modulation technique having narrow bandwidth and smooth envelope. In the web page I found that in modern digital systems, as in satellite or in cellular communications, M-level EM is practically always combined to efficient channel coding as Turbo-coding or concatenated coding.

Writing a project work

Project work is a documented Matlab assignment that is done in groups listed below. It consists of an analytical and simulation part. In you work you should demonstrate how Matlab simulations can be used to verify analytical theory. Report's table of contents should include at least the following section

Pay especially attention to explaining carefully results and how well simulations worked in verifying analytical theory. Project work guides will be delivered on tutorials on 26.2.2003 and the respective report submission deadline is on 26.3.2003.  Project works are graded by course personnel.


Project work groups