Writing Lecture Diary
In your Lecture Diary you address the following elements:
Contents
Discuss what were the essential elements of
this lecture? (Do not copy lecturing slides but use your own words!) Use figures!
You may use Mind Mapping chart to show the logical connections of the lecture
topics.
Motivation
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.
Understanding
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?
Applications
What is a consequence of this topic with
respect of applications? Where and how this topic is applied?
NOTE: Lecture Diaries can increase your
grade max by 0.5 (pass/failed).
LECTURE DIARY 1.4.2005 (example)
Student: Mathew Matts 22341G (matts@hut.fi)
Lecture topic: Exponential Modulation
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 (http://www.nml.org/n_1999-3.htm). 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.
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Practical notes
In order to realize flexible diary management, please follow the listed simple rules: